JP2018167458A - Release film and method for manufacturing flexible printed board - Google Patents

Abstract

To provide a release film capable of satisfactorily preventing breakage of the release film by expansion of an end side of a cushion layer.SOLUTION: A release film 30 is used when a cover film 20 is laminated for a base laminate 10 having an insulating resin layer 11 and a pattern layer 12 includes: a base layer 31 containing a polyester-based resin as a main component; a cushion layer 33 which contains an olefin-based resin as a main component, covers the cover film 20 by heating and pressurizing and follows unevenness of the cover film 20 and the base laminate 10; and an adhesive layer 32 which sticks the cushion layer 33 to the base layer 31 and has a trap part 34 that protrudes and is exposed from an end side of the cushion layer 33 existed thereon.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a release film and a method for producing a flexible printed board.

  There is a laminating process in the manufacturing process of the flexible printed circuit board. In the laminating step, a cover film is laminated on a base film (an intermediate product of a flexible printed board) having a pattern layer obtained by etching a copper foil. At this time, not only the cover film is laminated, but also a release film to be peeled later is attached. And the adhesiveness of the cover film with respect to the uneven | corrugated | grooved part of a pattern layer is made favorable by heating, pressing a cover film to a pattern layer through a mold release film. An example of such a technique is disclosed in Patent Document 1.

Japanese Patent No. 5765018

  By the way, when a cover film is laminated on a base film through a release film as disclosed in Patent Document 1, there is a problem that an adhesive for the cover film flows out. That is, when the cushion layer of the release film is insufficiently inserted into the opening or edge of the cover film, the adhesive material flows out in response to pressure or heating, and the effective area of the copper foil is reduced. There is.

  In order to solve such a problem, it has been studied to use a material having good followability for the cushion layer. However, since the cushion layer with good followability itself melts by heat, there is a problem that the cushion layer spreads from the end side of the release film. And since the thin part is formed in the spread cushion layer, there exists a problem that a release film will be partially torn at the time of peeling of a release film.

  Moreover, the current release film is discarded when the cover film is laminated. Therefore, there is a problem that resources are wasted and the cost is increased by the need for a new release film.

  The present invention has been made on the basis of the above circumstances. (1) To provide a release film capable of satisfactorily preventing tearing of the release film due to the spread of the end side of the cushion layer; (2) Waste of resources. It is an object of the present invention to provide at least one of a releasable release film and a method for producing a flexible printed circuit board.

  In order to solve the above problems, according to a first aspect of the present invention, a release film used when a cover film is laminated on a base laminate having an insulating resin layer and a pattern layer, the polyester A base layer mainly composed of a base resin, a cushion layer that is mainly composed of an olefin resin, covers the cover film by heating and pressurizing, and follows the unevenness of the cover film and the base laminate, and a cushion layer. There is provided a release film comprising: an adhesive layer that is attached to a base layer and has an exposed trap portion that protrudes from an end side of the cushion layer.

  In another aspect of the present invention, in the above-described invention, the adhesive layer preferably contains an acrylic resin as a main component.

  Furthermore, in another aspect of the present invention, in the above-described invention, it is preferable that the trap portion protrudes at least 3 mm or more from the end portion of the cushion layer.

  According to another aspect of the present invention, in the above-described invention, the cushion layer preferably includes polypropylene as a main component.

  Furthermore, in another aspect of the present invention, in the above-described invention, it is preferable that the cushion layer is mainly composed of unstretched polypropylene or inflation polypropylene among polypropylene.

  Moreover, according to the 2nd viewpoint of this invention, it is a manufacturing method of a flexible printed circuit board, Comprising: A cover film is temporarily adhered with respect to the base laminated body which has an insulating resin layer and a pattern layer, and a temporary adhesion body is formed. After the first step and the first step, a base layer mainly composed of a polyester-based resin, a cushion layer mainly composed of an olefin-based resin, a cushion layer attached to the base layer, and an end of the cushion layer A second step of aligning the release film having an adhesive layer that protrudes from the portion side and has an exposed trap portion with respect to the temporary adhesive body from the cover film side; A third step of laminating the cover film on the base laminate to form a laminate by heating and pressurizing the temporary adhesive through the film, and after the third step, In the fourth step of peeling the release film whose temperature is lower than that of the laminate from the laminate, and in the release film after peeling, the cushion layer is peeled off from the adhesive layer and a new cushion layer is attached to the adhesive layer. And a step of returning to the first step again after the fifth step and repeating each step.

  According to the present invention, (1) to provide a release film that can satisfactorily prevent tearing of the release film due to the spread of the end side of the cushion layer, (2) a release film and flexible that can reduce waste of resources Providing a method of manufacturing a printed circuit board can be provided.

It is sectional drawing which shows the structure of the base laminated body and cover film which concern on one embodiment of this invention. It is sectional drawing which shows the structure of the release film which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the temporary adhesion body which concerns on one embodiment of this invention. It is sectional drawing which shows the structure of the laminated body which concerns on one embodiment of this invention. It is a top view which shows the state which looked at the laminated body shown in FIG. 4 from the upper side. It is a top view which shows the structure which concerns on another structural example of a laminated body, and a cover film exists only in the one side of the land of a pattern layer, and does not exist in the other side. It is a figure which shows the mode of position alignment of the temporary adhesive body and release film which concern on one embodiment of this invention. It is a figure which concerns on one embodiment of this invention and shows the state after pressing a release film with respect to a temporary adhesion body through a hot platen. FIG. 4 is an enlarged plan view showing a state near a boundary where a pattern layer and a cover film are bonded to each other according to an embodiment of the present invention. It is sectional drawing which shows a mode when a laminated body is cut | disconnected along the II-II line shown in FIG. It is sectional drawing which shows a mode when a laminated body is cut | disconnected along the III-III line shown in FIG. 6, and is a figure which shows the outflow of the adhesive material layer in the site | part close | similar to a cover film. FIG. 7 is a cross-sectional view taken along the line IV-IV in FIG. 6, and is a view showing the flow of the adhesive layer in a portion close to the pattern layer, although it is not a cross section of the pattern layer. It is sectional drawing which shows a mode when a laminated body is cut | disconnected along the II-II line | wire shown in FIG. 6 in the case where the release film of the comparative example 1 is used. FIG. 7 is a cross-sectional view showing a state when the laminate is cut along the line III-III shown in FIG. 6 in the case where the release film of Comparative Example 1 is used, and the adhesive layer in a part close to the cover film It is a figure which shows outflow. FIG. 7 is a cross-sectional view taken along the line IV-IV in FIG. 6 when the release film of Comparative Example 1 is used, and is a diagram showing the flow of the adhesive layer in a portion close to the pattern layer, but not the cross section of the pattern layer It is. It is a figure which concerns on one embodiment of this invention and shows the image which peels a release film from a laminated body. It is a figure which concerns on one embodiment of this invention and shows the image which peels a cushion layer from the adhesion layer. It is a figure which shows the image which affixes a new cushion layer to the adhesion layer according to one embodiment of this invention, and is a figure which shows the state just before affixing. FIG. 6 is a plan view showing a state of measurement of the length of the adhesive flowing out in the laminate 50 according to the embodiment of the present invention. It is a figure which concerns on the comparative examples 31-35 and shows about the maximum length of the outflow when PMP is made into the material of a cushion layer. It is a figure which concerns on one embodiment of this invention and shows about the maximum length of the outflow when CPP with a thickness of 20 μm is used as the material of the cushion layer. It is a figure which concerns on one embodiment of this invention and shows about the maximum length of outflow when CPP of thickness of 40 micrometers is made into the material of a cushion layer. It is a figure which concerns on one embodiment of this invention and shows about the maximum length of the outflow when CPP of thickness of 60 micrometers is made into the material of a cushion layer. It is a figure which shows the structure of the integrated object of the state which concerns on one embodiment of this invention and the formation of the flow-out part was suppressed using the release film. It is a figure which shows the structure of the integrated object in the state in which the outflow part was formed in one embodiment of this invention. It is a top view which shows the release film and insulating resin layer before lamination concerning one embodiment of this invention, and is a figure which transparently shows the positional relationship of a cushion layer and a trap part. It is a sectional side view which shows arrangement | positioning of the release film and insulating resin layer before lamination concerning one embodiment of this invention. FIG. 27 is a diagram illustrating a state in which lamination is performed from the state illustrated in FIG. 26 according to an embodiment of the present invention, in which a part of the cushion layer flows out to the outside and a flow-out portion is formed. FIG. 28 is a side cross-sectional view illustrating a state where lamination is performed from the state illustrated in FIG. 27 according to an embodiment of the present invention, in which a part of the cushion layer flows out to the outside and a flow-out portion is formed.

  Hereinafter, the manufacturing method of the release film 30 and the flexible printed circuit board which concerns on one embodiment of this invention is demonstrated below. In the following description, first, the base laminate 10 and the cover film 20 to be laminated will be described, and then the release film 30 will be described. In the following description, the Z direction is the thickness direction of each film, Z1 is the back side (upper side; front side) in FIG. 1, and Z2 is the front side (lower side; back side) in FIG.

<Configuration of base body and cover film>
FIG. 1 is a cross-sectional view showing configurations of the base laminate 10 and the cover film 20. As shown in FIG. 1, the base laminate 10 is obtained by etching a metal foil having a predetermined thickness, such as a copper clad laminate, and forming the metal foil into a desired pattern shape. The base laminate 10 includes an insulating resin layer 11 and a pattern layer 12. The insulating resin layer 11 is made of polyimide having a predetermined thickness and electrical insulation. Examples of the thickness of the insulating resin layer 11 include 25 μm (1 mil) and 12.5 μm (1/2 mil), but other thicknesses may be used.

  Further, as described above, the pattern layer 12 is a portion obtained by patterning a metal foil having a predetermined thickness such as a copper foil into a desired pattern shape by using a normal photofabrication technique such as etching. Examples of the thickness of the pattern layer 12 include 35 μm (1 oz), 17.5 μm (1/2 oz), and 12 μm (1/3 oz), but other thicknesses may be used. The base laminate 10 may have other layers.

  Note that an adhesive for bonding these layers is provided between the insulating resin layer 11 and the pattern layer 12 (not shown). The thickness of the adhesive may be 10 μm or 12 μm, for example, but the thickness can be set as appropriate.

  The cover film 20 laminated on the base laminate 10 includes a cover layer 21 and an adhesive layer 22. The cover layer 21 is made of polyimide. Examples of the thickness of the cover layer 21 include 25 μm (1 mil) and 12.5 μm (1/2 mil), but other thicknesses may be used.

  The adhesive layer 22 is mainly made of, for example, an epoxy-based adhesive, but a polyurethane-based adhesive or an acrylic-based adhesive may also be used. The adhesive layer 22 has a thickness of 28 μm, for example, but may have a thickness other than this.

  As shown in FIG. 1, the cover film 20 is provided with an opening 23. The opening 23 is a portion that has been drilled with, for example, a laser.

<About the structure of the release film>
Next, the configuration of the release film 30 will be described. FIG. 2 is a cross-sectional view showing the configuration of the release film 30. As shown in FIG. 2, the release film 30 has a base layer 31, an adhesive layer 32, and a cushion layer 33.

  The base layer 31 is composed mainly of a polyester resin. Such polyester resins include those having PET (Polyethylene Terephthalate) as the main component, those having PBT (Polybutylene Terephtalate) as the main component, those having PTT (Polytrimethylene Terephtalate) as the main component, and PEN (Polyethylene Naphthalate). , A main component of PBN (Polybutylene Naphthalate), and a mixture of those selected from these. Of these, those containing PET as a main component are particularly preferred from the viewpoint of availability. However, as long as it is a polyester resin, those listed or other than listed may be used as the main component.

  Further, the adhesive layer 32 includes, for example, an acrylic adhesive having an acrylic resin as a main component. However, the pressure-sensitive adhesive layer 32 is not limited to an acrylic pressure-sensitive adhesive, and is mainly composed of a rubber-based pressure-sensitive adhesive in which a tackifier is added to natural rubber, a silicone-based pressure-sensitive adhesive in which a tackifier is added to silicone rubber, and polyurethane. Examples include urethane-based pressure-sensitive adhesives. Among these, an acrylic pressure-sensitive adhesive is preferable because it is easily available and can be repeatedly used.

  The cushion layer 33 covers the cover film 20 from the cover film 20 side (upper side; Z1 side) when laminating the cover film 20 and the base laminate 10 by heating and pressurization, This is a portion that follows the unevenness of the base laminate 10. That is, when laminating the cover film 20 on the base laminate 10, it is a part that prevents the adhesive material from flowing out of the adhesive material layer 22 by following the unevenness existing therebetween.

  The cushion layer 33 is mainly composed of an olefin resin. Examples of such olefin resins include polypropylene resins, polyethylene resins, and polypentene resins. Among these, a polypropylene resin and a polyethylene resin are preferable in that the flow of the adhesive layer 22 can be satisfactorily suppressed. Among polypropylene resins, CPP (Cast Polypropylene) and IPP (Inflation Polypropylene) have good surface slipperiness, and even if the release film 30 is peeled off after lamination, a laminate is also obtained. Since generation | occurrence | production of 50 wrinkles can be prevented, it is especially preferable. Further, among polyethylene resins, LDPE (Low Density Polyethylene) has good surface slipperiness, and even if the release film 30 is peeled off after lamination, generation of wrinkles in the laminate 50 can be prevented. Is particularly preferred.

  Here, as is apparent from FIG. 2, the adhesive layer 32 includes a portion that is not adhered to the cushion layer 33. That is, as shown in FIG. 2, the adhesive layer 32 has a trap portion 34 that protrudes from the end side of the cushion layer 33 and is exposed to the outside. The trap portion 34 is a portion that traps (holds) the cushion layer 33 that spreads during lamination on the end side of the cushion layer 33. This prevents the cushion layer 33 from unnecessarily spreading and prevents a thin portion from being formed in the cushion layer 33. The trap portion 34 may have any size as long as it can trap the spread cushion layer 33 well, but in a direction along the surface of the release film 30 (a direction orthogonal to the Z direction). It is preferable that it exists 3 mm or more.

<About temporary adhesive and laminate>
In the following description, the base laminate 10 and the cover film 20 that are temporarily bonded will be referred to as a temporary bonded body 40. FIG. 3 is a cross-sectional view showing the configuration of the temporary adhesive body 40. As shown in FIG. 3, in the temporary adhesive body 40, the adhesive layer 22 is not sufficiently deformed, and is thus only partially bonded to the base laminate 10. FIG. 3 shows a state in which the adhesive layer 22 has not reached the surface of the insulating resin layer 11 as such an image.

  In addition, a laminate obtained by executing lamination on the temporary adhesive body 40 and completing the lamination between the base laminate 10 and the cover film 20 is referred to as a laminate 50. FIG. 4 is a cross-sectional view showing the configuration of the laminate 50. FIG. 5 is a plan view showing a state in which the laminate 50 is viewed from the upper side (Z1 side). 4 shows a state cut along line II in FIG.

  Here, the laminate 50 corresponds to the flexible printed circuit board, but it may be understood that what is formed through various processes on the laminated body 50 corresponds to the flexible printed circuit board.

  In addition, as shown in FIG. 3, the opening part 23 of the cover film 20 is aligned with the pattern part 12a (the remaining part of the metal foil) of the pattern layer 12. Thereby, after the laminate 50 as shown in FIG. 4 is formed, the pattern layer 12 is electrically connected by performing a subsequent plating process on the conductive portion provided outside the opening 23. It becomes possible. In the configuration shown in FIG. 4, the opening 23 includes a portion having a depth to the pattern layer 12 (one-step opening 231) and a portion having a depth deeper than the pattern layer 12 and to the insulating resin layer 11 (two steps). An opening 232). However, a configuration in which the two-stage opening 232 does not exist and only the one-stage opening 231 exists may be employed. The opening 23 may have any shape. For example, it may have a slit shape as shown in FIG. 5, a circular hole shape, a rectangular shape, an elliptical shape, or other shapes. Moreover, as shown in FIG. 6, it is good also as a structure which the cover film 20 exists only in the one side of the pattern part 12a of the pattern layer 12, and does not exist in the other side.

<About manufacturing method of flexible printed circuit board>

  A method for manufacturing a flexible printed board using the base laminate 10, the cover film 20, and the release film 30 having the above-described configuration will be described below. In the following description, the first to sixth steps are sequentially described, but it is needless to say that various steps other than these may exist. In the following description, the flow of the adhesive material of the adhesive material layer 22 will also be described.

(1) First Step: Formation of Temporary Adhesive Body 40 When the laminate 50 is formed, first, the temporary adhesive body 40 is formed as shown in FIG. At this time, the cover film 20 is aligned with the base laminate 10, and the cover film 20 is pressed against the base laminate 10 with a relatively light pressure. Thereby, the temporary adhesion body 40 is formed.

(2) Second step: Positioning of temporary adhesive body and release film Next, the temporary adhesive body 40 and the release film 30 are aligned. FIG. 7 is a view showing a state of alignment between the temporary adhesive body 40 and the release film 30. As shown in FIG. 7, in positioning the temporary adhesive body 40 and the release film 30, the temporary adhesive body 40 is placed on the placement plate 100. The mounting plate 100 is made of a resin that is more flexible than a metal such as PET (Polyethylene Terephthalate) or PBT (Polybutylene Terephthalate). And the temporary adhesive body 40 is preheated so that it may become predetermined | prescribed temperature, and the adhesive material layer 22 is made into a flexible state. In addition, it is preferable to preheat not only the temporary adhesive body 40 but the release film 30. FIG. Further, preheating may not be performed.

  Then, as shown in FIG. 7, the temporary adhesive body 40 and the release film 30 are aligned. At this time, after the release film 30 is pressed, the release film 30 covers the temporary adhesive body 40. The release film 30 is disposed at the position. In this alignment, the release film 30 may be in light contact with the upper surface of the temporary adhesive body 40.

(3) Third Step: Formation of Laminate 50 Next, the laminate 50 is formed by pressing the temporary adhesive 40 using the release film 30. In the laminating process for forming the laminate 50, a hot plate (not shown) is disposed on the release film 30. The hot plate is heated to a predetermined temperature such as 180 degrees. The temperature of the hot plate may be around 180 degrees as long as the adhesive layer 22 and the cushion layer 33 are melted.

  Then, the temporary adhesive body 40 is pressed with a predetermined pressing force through the hot plate and the release film 30. At this time, in the base laminate 10, the heat from the hot plate is transmitted through the release film 30, and the temperature rises rapidly. Therefore, the pressing time is, for example, about 10 seconds to 30 seconds.

  FIG. 8 is a view showing a state after the release film 30 is pressed against the temporary adhesive body 40 via a hot plate. As shown in FIG. 8, the cushion layer 33 melts, and the cushion layer 33 follows the uneven shape on the surface side of the cover film 20. Therefore, the melted cushion layer 33 enters the opening 23 or turns around to cover the side surface at the end of the base laminate 10.

  On the other hand, the adhesive layer 22 of the cover film 20 is also softened, and the adhesive constituting the adhesive layer 22 melts and flows out. Thereby, the adhesive layer 22 follows the unevenness of the surface of the base laminate 10. Therefore, the adhesive layer 22 is bonded to the base laminate 10.

  Here, when the cushion layer 33 and the adhesive layer 22 are compared, the cushion layer 33 is melted before the adhesive layer 22. Therefore, in the opening 23, the melted cushion layer 33 enters before the melted adhesive layer 22 and occupies the opening 23. Therefore, the flow of the adhesive layer 22 is suppressed at the opening 23. Similarly, at the end of the base laminate 10, the adhesive layer 22 is prevented from flowing out by covering the side surface before the melted adhesive layer 22 is covered.

  FIG. 9 is an enlarged plan view showing a state near the boundary where the pattern layer 12 and the cover film 20 are bonded together. FIG. 10 is a cross-sectional view showing a state when the laminate 50 is cut along the line II-II shown in FIG. FIG. 11 is a cross-sectional view showing a state when the laminate 50 is cut along the line III-III shown in FIG. 6, and is a view showing the flow of the adhesive layer 22 in a portion close to the cover film 20. . FIG. 12 is a cross-sectional view taken along the line IV-IV in FIG. 6, and is a view illustrating the flow of the adhesive layer 22 at a portion close to the pattern layer 12, but not the cross section of the pattern layer 12.

  On the other hand, FIG. 13 to FIG. 15 show how the adhesive material flows out of the adhesive layer 22 when Comparative Example 1 is used as a release film currently used. In Comparative Example 1, the release film uses PMP (polymethylpentene) made of polymethylpentene resin at a portion corresponding to the cushion layer 33. FIG. 13 is a cross-sectional view showing a state in which the laminate 50 is cut along the line II-II shown in FIG. 6 when the release film of Comparative Example 1 is used. 14 is a cross-sectional view showing a state when the laminate 50 is cut along the line III-III shown in FIG. 6 when the release film of Comparative Example 1 is used, and is close to the cover film 20. It is a figure which shows the outflow of the adhesive material layer 22 in a site | part. 15 is a cross-sectional view taken along the line IV-IV in FIG. 6 when the release film of Comparative Example 1 is used, and is not a cross-section of the pattern layer 12 but an adhesive in a portion close to the pattern layer 12. It is a figure which shows the outflow of the layer 22. FIG.

  Compared with the case of Comparative Example 1 as shown in FIGS. 13 to 15, when the release film 30 of the present embodiment is used, as shown in FIGS. The (flow-out part 22a) is greatly suppressed. The details of the suppression of the outflow will be described later.

(4) Fourth step: peeling the release film from the laminate After forming the laminate 50 as described above, the release film 30 is peeled from the laminate 50. FIG. 16 is a diagram illustrating an image in which the release film 30 is peeled from the laminate 50. By peeling the release film 30 from the laminate 50, the laminate 50 becomes an intermediate in the middle of manufacturing the flexible printed circuit board. Of course, this intermediate may be interpreted as a flexible printed circuit board. And the finished product of a flexible printed circuit board is obtained through various processes with respect to an intermediate.

(5) Fifth Step: Peeling off the cushion layer from the adhesive layer and attaching a new cushion layer Next, in the used release film 30, the cushion layer 33 is peeled off from the adhesive layer 32. FIG. 17 is a diagram illustrating an image in which the cushion layer 33 is peeled off from the adhesive layer 32. When the cushion layer 33 is peeled from the adhesive layer 32, the adhesive layer 32 that has been holding the cushion layer 33 with adhesive force until then is exposed again.

  After the peeling, a new cushion layer 33 is attached to the adhesive layer 32. FIG. 18 is a diagram illustrating an image in which a new cushion layer 33 is pasted to the adhesive layer 32, and is a diagram illustrating a state immediately before being pasted. And the adhesion layer 32 is adhere | attached with respect to the cushion layer 33 by pressing the base layer 31 and the adhesion layer 32 with respect to the cushion layer 33, and the new release film 30 is formed. That is, a release film 30 as a recycled product is formed by using the base layer 31 and the adhesive layer 32 again.

  In addition, after the release film 30 as a recycled product is formed, the process returns again to the first step, and a new laminate 50 is formed. At this time, the release film 30 as a recycled product is used again in the second and subsequent steps.

<About Examples>
Next, examples of the present invention will be described.
(1) Regarding Type of Cushion Layer of Release Film First, regarding a material that can be used as the cushion layer 33 of the release film 30, evaluation was performed for each type of material. Table 1 shows the evaluation results for the cushion layer 33 of each material. Here, as the cushion layer 33 of the material, CPP (unstretched polypropylene), IPP (inflation polypropylene), LDPE (low density polyethylene), OPP (biaxially stretched polyethylene) and PMP (polymethylpentene) are evaluated. It was. In each of Examples and Comparative Examples in Tables 1 to 3 below, evaluation was performed using TPX (registered trademark) manufactured by Mitsui Chemicals, Inc. as for PMP (polymethylpentene). The evaluation items are the length of the adhesive flow-out (flow-out portion 22a), the tear of the cushion layer 33 (releasability), and the wrinkles of the laminated body 50 after lamination.

  In Table 1, CPP is Example 1, IPP is Example 2, LDPE is Example 3, TPX is Comparative Example 1, and OPP is Comparative Example 2.

  In this evaluation, the base layer 31 of the release film 30 is made of PET and has a thickness of 50 μm. The adhesive layer 32 has a thickness of 7 μm. However, when the adhesive of the adhesive layer 22 flows out, the same evaluation can be obtained even if the adhesive layer 22 of another material or thickness is used as long as the adhesive strength against the flowed out adhesive is similar. It is considered. Further, the release film 30 has a trap portion 34, and the trap portion 34 protrudes 3 mm from the end portion of the cushion layer 33.

  An epoxy adhesive was used as the adhesive for the adhesive layer 22 of the cover film 20. Further, as an adhesive (not shown) between the insulating resin layer 11 and the pattern layer 12, an epoxy adhesive was used.

  Further, a vacuum press was used as the laminating apparatus. The experimental results are shown in Table 1. In the experimental results of Table 1, as the base laminate 10, the thickness of the copper pattern layer 12 is 35 μm, the thickness of the insulating resin layer 11 made of polyimide is 25 μm, the copper pattern layer 12 and the insulating resin layer 11 H1 / H2, which is the ratio of the width H1 of the pattern portion 12a and the width H2 between the adjacent pattern portions 12a, is 260 μm / 140 μm. Moreover, as the cover film 20, the thickness of the cover layer 21 made of polyimide is 25 μm, and the thickness of the adhesive layer 22 is 28 μm.

  The laminating conditions when using the laminating apparatus are as follows: the heating temperature is 185 degrees, the press pressure is 2 MPa, the preheating time is 10 seconds (the preheating temperature is equal to the heating temperature), and the pressing time is 80 seconds. In Table 1, the maximum dimension of the adhesive on the pattern portion 12a shown in FIG. 6 was measured.

  In Table 1 described above, the maximum dimension of the adhesive flowing out in the space 14 (the height position corresponding to the two-stage opening 232) between the adjacent pattern portions 12a in FIG. 6 was measured. In this measurement, “A” is the case where the maximum dimension of the flow-out of the adhesive is 50 μm or less, “B” when it is larger than 50 μm but 100 μm or less, “C” when it is larger than 100 μm but 150 μm or less, and 150 μm. The larger case was designated as “D”. “A” and “B” are acceptable levels for products, but “C” may not be acceptable as a product, and “D” is completely unacceptable as a product.

  In Table 1, the cushion layer 33 was also evaluated for tearing (releasability). In this evaluation, “B” indicates that the cushion layer 33 is not torn, and “D” indicates that the cushion layer 33 is torn. In Table 1, the wrinkles of the laminated body 50 after lamination were also evaluated. In this evaluation, “B” indicates that the laminate 50 does not have wrinkles, and “D” indicates that the laminate 50 has wrinkles.

  In the evaluation of Table 1 described above, the CPP of Example 1, the IPP of Example 2, and the LDPE of Example 3 are not suitable as materials for the cushion layer 33 in any of the three evaluation items. Therefore, the CPP of Example 1, the IPP of Example 2, and the LDPE of Example 3 are suitable as materials for the cushion layer 33. On the other hand, the OPP of Comparative Example 2 was wrinkled on the laminate 50 after lamination. Therefore, OPP is not suitable as a material for the cushion layer 33. In the PMP of Comparative Example 1, the flow of the adhesive material was larger than 100 μm on the pattern portion 12a, and the flow of the adhesive material was larger than 150 μm in the space 14. Therefore, PMP is not suitable as a material for the cushion layer 33.

  In addition, only the thing using OPP as a material of the cushion layer 33 has the wrinkle of the laminated body 50, Therefore OPP is unsuitable as a material of the cushion layer 33. This is due to the characteristics of OPP. That is, in the TMA (Thermo Mechanical Analysis) test, when the dimensional change rate when the temperature was raised was examined, it was found that the OPP significantly contracted when it exceeded 150 degrees and then fractured. On the other hand, it was found that CPP, IPP, and LDPE extend without contraction even when the temperature is increased. For this reason, when the hot plate is heated to a predetermined temperature such as 180 degrees (see the third step described above), if OPP is used as the material of the cushion layer 33, the cushion layer 33 contracts, which is the laminate. It is thought to cause 50 wrinkles.

(2) Regarding the thickness of the cushion layer of the release film Next, the thickness of the cushion layer 33 of the release film 30 was evaluated. Table 2 shows the evaluation results when the thickness of the cushion layer 33 is 20 μm (Comparative Example 3), 40 μm (Example 4), and 60 μm (Example 5). Here, the material of the cushion layer 33 is CPP, and the length of the flow of the adhesive, the tearing of the cushion layer 33 (releasability), and the wrinkles of the laminated body 50 after the lamination are evaluated as in Table 1. evaluated. The evaluation criteria are the same as in Table 1. In addition, the laminating apparatus used, the configuration of the materials and thicknesses of other members (cover film 20 and release film 30), the laminating conditions, and the like are the same as those in Table 1 described above. Accordingly, the release film 30 also has a trap portion 34.

  In the evaluation of Table 2 described above, regarding the flow-out of the adhesive, in Example 4 and Example 5, none of the three evaluation items is unsuitable as the material of the cushion layer 33. Therefore, in the case of 40 μm in Example 4 and 60 μm in Example 5, the thickness of the cushion layer 33 is suitable. On the other hand, in Comparative Example 3, the cushion layer 33 was torn. Therefore, in the case of 20 μm in Comparative Example 3, the thickness of the cushion layer 33 is not suitable.

(3) Regarding the thickness of the copper pattern layer 12, the thickness of the cushion layer 33, and the flow length of the adhesive material Next, the thickness of the copper pattern layer 12, the thickness of the cushion layer 33, and the flow length of the adhesive material An evaluation was made on this. In this evaluation, the thickness of the copper pattern layer 12 is 12 μm, 18 μm, and 35 μm, and the thickness of the cushion layer 33 is 20 μm, 40 μm, and 60 μm.

  In addition, the flow of the adhesive when PMP was applied to each thick copper pattern layer 12 was also evaluated. Table 3 shows the evaluation results when the thickness of the CPP (hereinafter simply referred to as CPP) which is the cushion layer 33 in Example 11 is 20 μm and the thickness of the pattern portion 12a (copper foil) is 12 μm. Similarly, in Example 12, the evaluation results are obtained when the thickness of the CPP is 20 μm and the thickness of the pattern portion 12a (copper foil) is 18 μm. Moreover, Example 13 is an evaluation result when the thickness of the CPP is 20 μm and the thickness of the pattern portion 12a (copper foil) is 35 μm. Moreover, Example 14 is an evaluation result when the thickness of the CPP is 40 μm and the thickness of the pattern portion 12a (copper foil) is 12 μm. Moreover, Example 15 is an evaluation result when the thickness of the CPP is 40 μm and the thickness of the pattern portion 12a (copper foil) is 18 μm. Moreover, Example 16 is an evaluation result in the case where the thickness of the CPP is 40 μm and the thickness of the pattern portion 12a (copper foil) is 35 μm. Moreover, Example 17 is an evaluation result when the thickness of the CPP is 60 μm and the thickness of the pattern portion 12a (copper foil) is 12 μm. Moreover, Example 18 is an evaluation result in the case where the thickness of the CPP is 60 μm and the thickness of the pattern portion 12a (copper foil) is 18 μm. Moreover, Example 18 is an evaluation result when the thickness of the CPP is 60 μm and the thickness of the pattern portion 12a (copper foil) is 35 μm.

  Comparative Example 11 is an evaluation result when PMP is used as the cushion layer 33 and the thickness of the pattern portion 12a (copper foil) is 12 μm. Comparative Example 12 is an evaluation result when PMP is used as the cushion layer 33 and the thickness of the pattern portion 12a (copper foil) is 18 μm. Comparative Example 13 is an evaluation result when PMP is used and the thickness of the pattern portion 12a (copper foil) is 35 μm. The evaluation criteria are the same as in Table 1. Further, the laminating apparatus used, laminating conditions, and the like are the same as those in Table 1 described above.

  In Examples 11 to 19, when the thickness of the pattern portion 12a (copper foil) is 35 μm (Examples 13, 16, and 19), the adhesive between the insulating resin layer 11 and the pattern layer 12 is used. The thickness of the adhesive is 12 μm, otherwise the thickness of the adhesive is 10 μm. Further, when the thickness of the pattern layer 12 is 12 μm (Examples 11, 14, and 19), the thickness of the insulating resin layer 11 is 13 μm, and otherwise, the thickness of the insulating resin layer 11 is 25 μm. It is.

  In the evaluation of Table 3 described above, regarding the flow-out of the adhesive, in Examples 11 to 19, the flow-out of the adhesive is 100 μm or less on both the pattern portion 12 a and the space 14. Therefore, CPP having a thickness of 20 μm to 60 μm is suitable as the cushion layer 33 for the pattern layer 12 having any thickness of 12 to 35 μm.

  Therefore, even if the dimension in the height direction of the pattern layer 12 (pattern part 12a) changes, it can be said that there is no problem in suppressing the outflow. In particular, even when the thickness of the CPP is 20 μm, the flow of the adhesive is suppressed to 100 μm or less. Therefore, when the CPP is used as the material of the cushion layer 33, the followability to the unevenness of the pattern layer 12 is good. It can be said that there is.

  On the other hand, regarding the PMP, with respect to the pattern layer 12 having a thickness of 12 μm and 18 μm, the flow of the adhesive material could be suppressed to 100 μm at any position on the pattern portion 12 a and the space 14. However, for the pattern layer 12 having a thickness of 35 μm, the flow-out of the adhesive exceeded 100 μm on the pattern portion 12a. Moreover, in the space 14, the flow-out of the adhesive exceeded 150 μm. Therefore, PMP is not suitable for use in the 35 μm pattern layer 12.

(4) Regarding the length of flow when the width of the pattern portion and the width of the space are changed Next, the release film 30 made of PMP as the cushion layer 33 and the release made of CPP as the cushion layer 33 About each of the films 30, it measured about the length of the outflow when the width L of the pattern part 12a of the base laminated body 10 and the width S of the space 14 were changed. In this measurement, the material of the cushion layer 33 was CPP, and the length of the adhesive flowing out was measured as in Table 1. Moreover, the thickness of the used laminating apparatus and other materials (base laminate 10 and cover film 20), lamination conditions, and the like are the same as those in Table 1 described above.

  The measurement of the flow-out length of the adhesive in the laminate 50 is performed as shown in FIG. That is, as shown in FIG. 19, the maximum lengths M1 and M2 of the adhesive material flowing out on the pattern portion 12a and in the space 14 are measured. On both the pattern portion 12a and the space 14, the maximum flow lengths M1 and M2 correspond to the maximum flow length from the end of the cover film 20 (cover layer 21) in the direction away from the cover film 20. doing.

  The maximum flow lengths M1 and M2 were measured by changing the width L of the pattern portion 12a and the width S of the space 14. FIG. 20 to FIG. 23 are graphs showing the measured maximum lengths M1 and M2. FIG. 20 is a diagram showing the maximum flow lengths M1 and M2 when PMP is used as the material of the cushion layer 33. FIG.

  As is apparent from FIG. 20, when the PMP is used as the cushion layer 33, the maximum length M2 of the adhesive material flowing out in the space 14 is particularly long. In FIG. 20, the width S of the space 14 is 140 μm (in the case of the comparative example 31 in which the width L of the pattern portion 12a is 60 μm, the comparative example 32 in the case of 160 μm, and the comparative example 33 of 260 μm), and 240 μm (the width L of the pattern portion 12a is In any case of Comparative Example 4 (260 μm) and 340 μm (Comparative Example 35 where the width L of the pattern portion 12a is 460 μm), the maximum flow-out length M2 is larger than 150 μm. For this reason, in the space 14, it is considered that the maximum flow length M2 becomes longer regardless of the width L of the pattern portion 12a, and is not suitable as a material for the cushion layer 33.

  Further, the maximum length M1 of the adhesive material flowing out in the pattern portion 12a is also longer than in the case of FIGS. In particular, the width L of the pattern portion 12a is 160 μm (in the case of Comparative Examples 31 and 31 in which the width S of the space 14 is 140 μm), 260 μm (in the case of Comparative Example 33 in which the width S of the space 14 is 140 μm) and ) In any case of 460 μm (in the case of Comparative Example 35 in which the width S of the space 14 is 340 μm), the maximum flow-out length M1 is larger than 100 μm. Therefore, when the width L of the pattern portion 12a is 160 μm, 260 μm, and 460 μm, the maximum flow length M1 is long, which is inappropriate.

  FIG. 21 is a diagram showing the maximum flow lengths M1 and M2 when CPP having a thickness of 20 μm is used as the material of the cushion layer 33 (Examples 21 to 25). FIG. 22 is a diagram showing the maximum flow lengths M1 and M2 when CPP having a thickness of 40 μm is used as the material of the cushion layer 33 (Examples 26 to 30). FIG. 23 is a diagram showing the maximum flow lengths M1 and M2 when CPP having a thickness of 60 μm is used as the material of the cushion layer 33 (Examples 31 to 35).

  As apparent from FIGS. 21 to 23, the maximum length M1 of the adhesive material flowing out in the pattern portion 12a and the maximum length M2 of the adhesive material flowing out in the space 14 are both 100 μm or less. Therefore, L / S, which is a combination of the width L and the width S, is 60 μm / 140 μm (Examples 21, 26, 31), 160 μm / 140 μm (Examples 22, 27, 32), 260 μm / 140 μm (Examples 23, 28). 33), 260 μm / 240 μm (Examples 24, 29, and 34), and 460 μm / 340 μm (Examples 25, 30, and 35), the maximum length M1 and M2 of the adhesive material can be kept short. ing. In particular, as apparent from comparison with FIG. 19, the maximum flow-out length M <b> 2 in the space 14 is significantly lower than when PMP is used as the material of the cushion layer 33. Therefore, any thickness CPP of 20 μm to 60 μm is suitable as a material for the cushion layer 33.

(5) Ease of peeling of the cushion layer 33 due to the presence of the trap portion 34 (prevention of tearing of the cushion layer 33) Next, in the release film 30 made of CPP as the cushion layer 33, the trap portion 34 exists. Evaluation was made regarding the ease of peeling of the cushion layer 33 (prevention of tearing of the cushion layer 33) in the case where it does and the case where it does not exist.

  The ease of peeling of the cushion layer 33 (prevention of tearing of the cushion layer 33) will be described in detail. When the release film 30 is used when the cover film 20 is laminated on the base laminate 10, the release film is used. The end portion side of the 30 cushion layers 33 spreads outward due to heating and pressurization during lamination.

  FIG. 26 is a plan view showing the release film 30 and the insulating resin layer 11 before lamination, and is a view transparently showing the positional relationship between the cushion layer 33 and the trap portion 34. FIG. 27 is a side sectional view showing the arrangement of the release film 30 and the insulating resin layer 11 before lamination. FIG. 28 shows a state in which lamination is performed from the state shown in FIG. 26, and shows a state in which a part of the cushion layer 33 flows out to the outside and a flow-out portion 33a is formed. FIG. 29 is a side sectional view showing a state in which lamination is performed from the state shown in FIG. 27, and a state in which a part of the cushion layer 33 flows out to the outside and a flow-out portion 33 a is formed.

  When the flow-out portion 33 a as shown in FIGS. 28 and 29 is formed, a portion having a smaller thickness than other portions of the cushion layer 33 is formed on the end side of the cushion layer 33. Therefore, a portion that causes the cushion layer 33 to be broken is formed, which makes it difficult to peel the cushion layer 33 from the laminate 50. Therefore, the adhesive layer 32 is provided with a trap part 34 that protrudes (protrudes) beyond the end side of the cushion layer 33, and the cushion layer 33 is easily peeled off depending on the presence or absence of the trap part 34. Evaluation was made regarding the length (prevention of tearing of the cushion layer 33).

  Table 4 shows the evaluation results. In this evaluation, the example in which the thickness of the cushion layer 33 made of CPP is 40 μm and the trap portion 34 is present is referred to as Example 40. Further, the thickness of the cushion layer 33 made of CPP is 40 μm, but the one having no trap portion 34 is used as a comparative example 40. In Example 40, the trap portion 34 protrudes 3 mm from the end portion of the cushion layer 33.

  In this evaluation, the base layer 31 of the release film 30 is made of PET and has a thickness of 50 μm. The adhesive layer 32 has a thickness of 7 μm. The thickness of the copper pattern layer 12 is 35 μm, the thickness of the insulating resin layer 11 made of polyimide is 25 μm, and the thickness of the adhesive between the copper pattern layer 12 and the insulating resin layer 11 is 12 μm. Moreover, as the cover film 20, the thickness of the cover layer 21 made of polyimide is 25 μm, and the thickness of the adhesive layer 22 is 28 μm.

  The laminating conditions when using the laminating apparatus are as follows: the heating temperature is 185 degrees, the press pressure is 2 MPa, the preheating time is 10 seconds (the preheating temperature is equal to the heating temperature), and the pressing time is 80 seconds. In Table 4, the case where the cushion layer 33 is torn is described as “Yes”, and the case where the cushion layer 33 is not torn is described as “None”.

  As apparent from Table 4, in Example 40 where the trap portion 34 exists, the cushion layer 33 was not broken. On the other hand, in the comparative example 40 in which the trap part 34 does not exist, the cushion layer 33 was torn. Therefore, when the trap part 34 exists, it is thought that the ease of peeling of the cushion layer 33 is improved and the cushion layer 33 can be prevented from being torn.

(6) About the dimension of the trap part 34 Next, it will be described how much the trap part 34 needs to project to the end part of the cushion layer 33. The trap part 34 prevents the formation of a part that causes the cushion layer 33 to be broken by sticking and holding the flow-out part 33 a having a thickness smaller than that of the cushion layer 33. Therefore, it is considered that the trap portion 34 is required to have a size that covers at least the flow-out portion 33a. That is, it is considered that the trap portion 34 may be at least as long as it corresponds to the dimension in which the flow-out portion 33 a flows out from the end portion of the cushion layer 33.

  The measurement of the flow-out dimension was performed for the configuration of Example 40 described above. And the dimension of the outflow in the outflow part 33a went to the direction away from the edge part of the cushion layer 33 before laminating, and measured how much it flowed out. At this time, a total of 10 dimensions (L1, L2, L3, L4, L5, L6, L7, L8, L9, L10) were measured at predetermined intervals along the end of the cushion layer 33 before lamination. .

  The actual measurement results are as follows. That is, L1 = 1.1 mm, L2 = 1.0 mm, L3 = 1.4 mm, L4 = 1.4 mm, L5 = 1.1 mm, L6 = 1.5 mm, L7 = 1.6 mm, L8 = 1.0 mm, L9 = 1.5 mm and L10 = 0.7 mm.

  And average value Av of these L1-L10 was computed, and also standard deviation (sigma) was computed based on the case of an average value and each dimension. Here, the probability ε out of the range obtained by adding or subtracting four times the standard deviation σ to the average value Av is known as 0.006%. Accordingly, 99.997% of the flow-out portion 33a is included in the value (cover rate C) obtained by adding the standard deviation σ to 4 times the average value Av. Therefore, the cover rate C was calculated.

  Then, the average value Av of the above-described L1 to L10 is calculated as 1.2 mm (calculated to the first decimal place), and the standard deviation σ is calculated as 0.3 mm, so the cover ratio C is calculated as 2.4 mm. It was done. If this 2.4 mm is given a slight margin and a numerical value without the first decimal place in the dimensional unit mm is calculated, it becomes 3 mm. As described above, the dimensions of the trap portion 34 are calculated.

<About effect>
According to the method for manufacturing the release film 30 and the flexible printed board having the above-described configuration, the following effects are produced.

  That is, in the release film 30 used when laminating the cover film 20 to the base laminate 10 having the insulating resin layer 11 and the pattern layer 12, a base layer 31 mainly composed of a polyester-based resin, The cushion layer 33 that follows the unevenness of the cover film 20 and the base laminate 10 while covering the cover film 20 by heating and pressurization, and the cushion layer 33 is formed with respect to the base layer 31. And an adhesive layer 32 having a trap portion 34 that protrudes from the end side of the cushion layer 33 and is exposed.

  For this reason, on the end side of the cushion layer 33, the cushion layer 33 that spreads during lamination can be trapped (held) by the trap portion 34. Thereby, the cushion layer 33 is unnecessarily spread, and it is possible to prevent the cushion layer 33 from being formed with a thin portion more than necessary. Further, the cushion layer 33 can be prevented from jumping out from the end portion of the release film 30. Therefore, it becomes easy to peel the release film 30 from the laminate 50. Further, when the release film 30 is peeled off from the laminate 50, the cushion layer 33 is hardly broken.

  Moreover, the cushion layer 33 follows the unevenness | corrugation of the said cover film 20 and the base laminated body 10, covering the cover film 20 by heating and pressurization, The cushion layer 33 has olefin resin as a main component. Therefore, it is possible to satisfactorily prevent the adhesive material from flowing out of the adhesive material layer 22. Thereby, it is possible to prevent the adhesive material that has flowed out from spreading in the pattern portion 12a and the space 14, and it is possible to prevent the spread adhesive material from becoming inoperable after the plating process.

  By providing such a cushion layer 33, it is possible to eliminate the problem as shown in FIG. FIG. 25 is a diagram illustrating a configuration of the integrated object 80 in a state where the flow-out portion 22a is formed. 25 shows an anisotropic conductive property in the laminate 50 in the vicinity of the III-III cross section shown in FIG. 6 in the laminate 50 formed using the release film 30 using PMP as the cushion layer 33. The image of the integrated object 80 in which the film 60 was affixed and the sticking target object 70 was affixed through the anisotropic conductive film 60 is shown. The anisotropic conductive film 60 has a large number of metal particles 62 dispersed in the thermosetting resin layer 61.

  As shown in FIG. 25, when the flow-out portion 22a is formed by melting the adhesive layer 22, the flow-out portion 22a is in a state of covering the pattern portion 12a by a predetermined amount. The outflow part 22a has electrical insulation. Therefore, even if the anisotropic conductive film 60 in which the metal particles 62 are dispersed is used, there is a possibility that electrical conduction cannot be established between the conductor portion 72 and the pattern portion 12a of the pasting target 70.

  In addition, when the flow-out part 22a as shown in FIG. 25 is formed as the flow of the adhesive increases, the metal particles 62 existing in the space 14 between the adjacent pattern parts 12a are in the thickness direction of the integrated object 80. In this case, it moves to the conductor portion 72 side. Therefore, when the flow-out increases, the metal particles 62 are connected in a direction crossing the plurality of pattern portions 12a, and conductivity is exhibited even in a direction crossing the plurality of pattern portions 12a. Therefore, anisotropic conductivity that shows conductivity only in the thickness direction of the integrated object 80 is hindered.

  On the other hand, the structure at the time of using the release film 30 of this Embodiment is shown in FIG. FIG. 24 is a diagram illustrating a configuration of the integrated object 80 in a state where formation of the flow-out portion 22a is suppressed using the release film 30. In FIG. 24, the anisotropic conductive film 60 is attached to the laminate 50 in the vicinity of the cross section III-III shown in FIG. 6 in the laminate 50, and further attached via the anisotropic conductive film 60. It is a figure which shows the image of the integrated object 80 on which the target object 70 was affixed.

  In the integrated product 80 shown in FIG. 24, the metal particles 62 are applied to the application object by applying a pressing force between the laminate 50 and the application object 70 with the anisotropic conductive film 60 sandwiched between the laminate 50 and the application object 70. 70, and the metal particles 62 are also in electrical contact with the pattern portion 12a. As a result, the conductor portion 72 and the pattern portion 12a are electrically connected. Thus, when the release film 30 of this Embodiment is used, an electrical continuity state can be ensured between the conductor part 72 and the pattern part 12a as shown in FIG.

  In addition, by suppressing the formation of the flow-out portion 22 a using the release film 30, the metal particles 62 existing in the space 14 between the adjacent pattern portions 12 a are in the conductor portion 72 side in the thickness direction of the integrated product 80. It is possible to prevent the movement. Thereby, it becomes possible to prevent the metal particles 62 from being connected in a direction crossing the plurality of pattern portions 12a. Therefore, anisotropic conductivity that exhibits conductivity only in the thickness direction of the integrated object 80 can be ensured.

  Here, when the miniaturization of the pattern layer 12 progresses, if the formation of the flow-out portion 22a is not suppressed, the effective area that can be electrically connected is reduced, and the miniaturization of the pattern layer 12 is hindered. However, by suppressing the formation of the flow-out portion 22a using the release film 30 of the present embodiment, a wide effective area that can be electrically connected can be secured, and the pattern layer 12 can be made finer. be able to.

  Moreover, in this Embodiment, it is preferable that the adhesion layer 32 has acrylic resin as a main component. When the adhesive layer 32 has an acrylic resin as a main component, sufficient adhesive force can be secured. Thereby, on the end side of the cushion layer 33, the cushion layer 33 spreading during lamination can be sufficiently trapped (held) by the trap portion 34. Therefore, it is possible to satisfactorily prevent the cushion layer 33 from jumping out from the end portion of the release film 30. Thereby, it becomes easy to peel the release film 30 from the laminate 50. Further, when the release film 30 is peeled off from the laminate 50, the cushion layer 33 is hardly broken.

  Furthermore, in the present embodiment, it is preferable that the trap portion 34 protrudes at least 3 mm or more from the end portion of the cushion layer 33. When the trap portion 34 protrudes at least 3 mm from the end portion of the cushion layer 33, the cushion layer 33 spread during lamination can be sufficiently trapped (held). Thereby, it is possible to satisfactorily prevent the cushion layer 33 from jumping out from the end portion of the release film 30. Thereby, it becomes easy to peel the release film 30 from the laminate 50. Further, when the release film 30 is peeled off from the laminate 50, the cushion layer 33 is hardly broken.

  Moreover, in this Embodiment, it is preferable that the cushion layer 33 has a polypropylene as a main component. When the cushion layer 33 has polypropylene as a main component, the formation of the flow-out portion 22a can be satisfactorily suppressed. Moreover, when peeling the cushion layer 33 from the laminated body 50 after lamination, it becomes possible to prevent that the cushion layer 33 is torn, and the release property of the release film 30 can be made favorable.

  Further, in the present embodiment, it is preferable that the cushion layer 33 is mainly composed of either unstretched polypropylene or inflation polypropylene among polypropylene. When these are the main components, when the cushion layer 33 is mainly composed of polypropylene, it is possible to satisfactorily prevent the flow-out portion 22a from being formed. Moreover, when peeling the cushion layer 33 from the laminated body 50 after lamination, it becomes possible to prevent that the cushion layer 33 is torn, and the release property of the release film 30 can be made favorable. Furthermore, it is possible to satisfactorily prevent wrinkles from occurring in the laminate 50 after lamination.

  Moreover, in the manufacturing method of the flexible printed circuit board of this Embodiment, in the 1st process, the cover film 20 is temporarily bonded with respect to the base laminated body 10 which has the insulating resin layer 11 and the pattern layer 12, and temporary bonding body is carried out. 40 is formed. In the second step, after the first step, the base layer 31 mainly composed of polyester resin, the cushion layer 33 mainly composed of olefin resin, and the cushion layer 33 are bonded to the base layer 31. At the same time, the release film 30 having the adhesive layer 32 having the exposed trap portion 34 protruding from the end side of the cushion layer 33 is aligned with the temporary adhesive body 40 from the cover film 20 side.

  In the third step, after the second step, the temporary adhesive body 40 is heated and pressed through the release film 30 to laminate the cover film 20 to the base laminate 10 to form the laminate 50. . In the fourth step, after the third step, the release film 30 having a temperature lower than that during lamination is peeled off from the laminate 50. In the fifth step, in the release film 30 after being peeled off, the cushion layer 33 is peeled off from the adhesive layer 32 and a new cushion layer 33 is attached to the adhesive layer 32. And after the 5th process, it returns to the 1st process again and repeats each process.

  By doing so, it is not necessary to waste the entire used release film 30 after forming the laminate 50. That is, after lamination, the cushion layer 33 is peeled off from the adhesive layer 32, and only the cushion layer 33 is discarded or reprocessed. On the other hand, since a new cushion layer 33 is affixed to the adhesive layer 32, the base layer 31 and the adhesive layer 32 are reused. Therefore, as described above, it is not necessary to waste the entire used release film 30 and the base layer 31 and the adhesive layer 32 can be reused. Therefore, waste of resources can be reduced, and cost can be reduced by the amount that does not require the entire new release film 30.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be variously modified in addition to this. This will be described below.

  In the above-described embodiment, the trap portion 34 may protrude with respect to the end portion of the cushion layer 33 over the entire outer periphery of the release film 30, and at least a part thereof is at the end portion of the cushion layer 33. On the other hand, it may protrude.

  The release film 30 may have any shape. For example, it may be a rectangular sheet or may be wound in a roll. When the release film 30 is wound in a roll shape, the cushion layer 33 divided into a predetermined dimension is formed with respect to an integrated product of the long base layer 31 and the adhesive layer 32 that can be wound in a roll shape. The trap part 34 can be formed by affixing intermittently.

  In addition, it is assumed that the release film 30 having a predetermined shape does not have the trap portion 34 at the beginning, and the trap layer 33 is removed from the outer peripheral edge portion of the release film 30 by a hot press or other technique, thereby trapping. The part 34 may be formed.

  DESCRIPTION OF SYMBOLS 10 ... Base laminated body, 11 ... Insulating resin layer, 12 ... Pattern layer, 12a ... Pattern part, 14 ... Space, 20 ... Cover film, 21 ... Cover layer, 22 ... Adhesive material layer, 22a ... Outflow part, 23 ... Opening 30 ... Release film, 31 ... Base layer, 32 ... Adhesive layer, 33 ... Cushion layer, 34 ... Trap part, 40 ... Temporary adhesive, 50 ... Laminate, 60 ... Anisotropic conductive film, 61 ... Heat Curable resin layer, 62 ... metal particles, 70 ... object to be pasted, 72 ... conductor part, 80 ... integrated object, 100 ... mounting plate, 231 ... one-stage opening, 232 ... two-stage opening

Claims (6)

A release film used when laminating a cover film on a base laminate having an insulating resin layer and a pattern layer,
A base layer mainly composed of a polyester resin;
A cushion layer that has an olefin-based resin as a main component and follows the unevenness of the cover film and the base laminate while covering the cover film by heating and pressurization,
Adhering the cushion layer to the base layer, and an adhesive layer in which there is an exposed trapped part protruding from the end side of the cushion layer;
A release film comprising: The release film according to claim 1,
The adhesive layer is mainly composed of an acrylic resin.
A release film characterized by that. The release film according to claim 1 or 2,
The trap part protrudes at least 3 mm or more from the end of the cushion layer;
A release film characterized by that. It is a release film of any one of Claim 1 to 3,
The cushion layer is mainly composed of polypropylene,
A release film characterized by that. The release film according to claim 4,
The cushion layer is mainly composed of either unstretched polypropylene or inflation polypropylene among the polypropylene.
A release film characterized by that. A method for manufacturing a flexible printed circuit board, comprising:
A first step of temporarily bonding a cover film to a base laminate having an insulating resin layer and a pattern layer to form a temporary bonded body;
After the first step, a base layer mainly composed of a polyester-based resin, a cushion layer mainly composed of an olefin-based resin, and an end portion of the cushion layer while the cushion layer is attached to the base layer A second step of aligning the release film having an adhesive layer with an exposed trap portion protruding from the side with respect to the temporary adhesive body from the cover film side;
After the second step, a third step of laminating the cover film to the base laminate to form a laminate by heating and pressurizing the temporary adhesive through the release film;
After the third step, a fourth step of peeling the release film having a temperature lower than that at the time of laminating from the laminate,
In the release film after peeling, the fifth step of peeling the cushion layer from the adhesive layer and attaching a new cushion layer to the adhesive layer;
And after each of the fifth steps, return to the first step again and repeat each step.
A method for producing a flexible printed circuit board.

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