JP2001210998A - Method for mounting flexible substrate and reinforcing board used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing a flexible substrate from being curled and a reinforcing board which can surely fix the substrate and easily separate from an adhesive and is applicable to the other substrate, when the substrate reinforced by placing the reinforcing board with the adhesive is mounted on an electronic part and then the substrate is separated from the reinforcing board. SOLUTION: An adhesive 2 is placed on the whole surface of the reinforcing board 3. Although the adhesive 2 may be densely placed on the whole surface of the reinforcing board 3, it may be placed in stripes with gaps or in many uniformly distributed islands. In the adhesive 2 in stripes with gaps, the magnitude of adhesive force can be adjusted by the gaps. When the substrate 1 is separated from the reinforcing board 3, a small metal wire is inserted like a wedge between the substrate 1 and the adhesive 2 on the reinforcing board 3 and is moved along the surface of the reinforcing board 3, whereby the substrate 1 can be separated without being excessively bent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit board (flexible board), which is attached to a rigid reinforcing plate provided with an adhesive material on the surface thereof, and reinforced. The present invention relates to a method for mounting a flexible substrate on which electronic components are mounted, and in particular, a method for peeling and removing a flexible substrate after a mounting process from an adhesive material of a reinforcing plate, and a reinforcing plate suitable for use in such a mounting method. About.

[0002]

2. Description of the Related Art Since a flexible substrate is deformable, it can be inserted and mounted even in a space having a narrow and complicated shape, such as a small electronic device such as a digital camera. Has come to be used a lot. However, since the flexible substrate is flexible and has low rigidity, it is difficult to handle it in the process of mounting electronic components such as capacitors, resistors, and ICs, or in the process of transporting the flexible substrate before and after the process. Generally, a substrate is detachably attached to a rigid backup plate (reinforcement plate) made of an aluminum plate or the like by mechanical engagement means, and the flexible substrate is kept in a plate shape for a necessary period.

However, when the flexible board is attached to the reinforcing plate by mechanical engagement means, it takes a considerable amount of time and effort to attach and detach the flexible board to and from the flexible board. In order to form a pin hole that fits in the flexible board, a mechanical link with the reinforcing plate, which is not related to its original function, is placed on the flexible board, which does not want to take up a little useless space for miniaturization. There is a problem that it is necessary to provide a space for joining. To cope with this problem, Japanese Unexamined Patent Publication No. 3-262194 discloses a method in which a band-shaped adhesive material corresponding to both edges of a flexible substrate is provided on a reinforcing plate.
An improved technique of reinforcing the flexible substrate by sticking both edge portions of the flexible substrate on a reinforcing plate with the belt-shaped adhesive material is disclosed.

According to the improved prior art, as shown in FIG.
There is an advantage that it can be easily attached by sticking to the surface of the reinforcing plate 3 provided in a belt shape.

However, on the other hand, when the flexible board 1 is separated from the adhesive 2 of the reinforcing plate 3 as shown in FIG. 4 after the completion of the mounting process, the end of the flexible board 1 is grasped as shown by an arrow. When a tension is applied in the perpendicular direction to separate the flexible substrate 1 from the adhesive 2, a strong bending stress is intensively generated at the bent portion 1 ′ of the flexible substrate 1 at the moment of separation from the adhesive 2 and exceeds the elastic limit. Severe bending deformation remains. As a result, the flexible substrate 1 after being removed from the reinforcing plate 3 is curled as shown in FIG. 5, so that there is a problem that the flexible substrate 1 becomes extremely difficult to handle in a subsequent assembling step or the like.

Further, in recent flexible substrates, there is a demand for increasing the area of the flexible substrate to be larger than that of a conventional flexible substrate or for increasing the density of printed wiring to reduce the width of element wires and the distance between them. Although it is becoming stronger, such a relatively large-sized flexible substrate 1 is used in FIG.
If only the both ends are adhered to the reinforcing plate 3 with the adhesive 2 as shown in FIG. 13 or FIG. 13, the central portion of the flexible substrate 1 cannot be fixed securely.
A part of the flexible substrate 1 that is not fixed may move in the thickness direction at the time of mounting or may be displaced in the surface direction.

As a result, for example, a paste containing fine solder particles (called a solder paste or cream solder) is placed on the flexible substrate 1 at the beginning of the mounting process to form an opening pattern having a predetermined shape. When applying (printing) through a mask having solder, since the thickness of the solder paste applied layer is not constant or is not applied at a predetermined position, a bridge is formed between the wires in a reflow step of heating and melting the solder. (Short circuit) or the mounting state of the electronic components becomes unstable, so that the possibility of defective products increases.

The entire surface of the flexible substrate is permanently adhered to the reinforcing plate with an adhesive or the like before the mounting process, and after the electronic component mounting process has been completed, the product is produced with the reinforcing plate attached. However, as a matter of course, since such a substrate has no flexibility, when such a substrate is mounted on an electronic device or the like, the degree of freedom of deformation, which is a characteristic of the flexible substrate, is known. Can not be inserted into narrow gaps of irregular shape, and since it is not planned to remove the reinforcing plate from the board after mounting electronic components on such a board, this is a comparative object of the present invention. Can not be.

A conventional reinforcing plate 3 as shown in FIG.
Since a pair of narrow adhesive materials 2 are provided at positions corresponding to both end edges of a specific flexible substrate 1,
The reinforcing plate 3 cannot be diverted to a flexible substrate having a different size or shape. Therefore, the conventional reinforcing plate with an adhesive material has no flexibility with respect to the application object, and it is necessary to prepare and selectively use different types of reinforcing plates for each of a large number of types of flexible substrates. However, there is a problem that the mounting process becomes complicated by that much, which also contributes to an increase in cost.

[0010]

SUMMARY OF THE INVENTION The present invention addresses the above-mentioned problems in the prior art and provides an electronic component after reinforcing a flexible substrate by attaching it to a reinforcing plate provided with an adhesive material. In the method of mounting a flexible substrate, when the flexible substrate is removed from the reinforcing plate after the mounting is completed, the flexible substrate does not undergo permanent deformation such as curl, and can be easily separated from the reinforcing plate. Suitable for use in such a method of removing a flexible substrate and a method of mounting an electronic component on such a flexible substrate,
While the flexible board can be fixed securely,
It is an object of the present invention to provide a reinforcing plate that is easy to peel at the time of removal and has a high degree of freedom with respect to an application object.

[0011]

According to the present invention, there is provided a method for solving the above-mentioned problems.
A method for removing a flexible substrate from a reinforcing plate in a method for mounting a flexible substrate using a reinforcing plate provided with an adhesive material as described in (1). In this method, when the flexible substrate on which the electronic components are mounted is peeled off from the adhesive of the reinforcing plate and removed, a thin metal wire is cut in a wedge shape between the flexible substrate and the adhesive, and both ends of the thin metal wire are removed. The thin metal wire is moved along the surface of the reinforcing plate while pulling, so that the flexible substrate is smoothly separated from the adhesive material of the reinforcing plate by the wedge action of the thin metal wire. At this time, the end of the flexible substrate need only be held with a small force, and there is no large bending deformation applied to the flexible substrate by applying a large tension, so that no excessive bending stress is generated. There is no danger of permanent deformation remaining on the substrate and curling.

In the method of removing a flexible substrate according to the present invention, the thin metal wire is simultaneously moved and the end of the flexible substrate is gripped and pulled in a direction at an acute angle with respect to the surface of the reinforcing plate. By applying the tension, peeling of the flexible substrate due to interruption of the thin metal wire can be promoted. Since the traction direction is at an acute angle of 90 ° or less with respect to the surface of the reinforcing plate, there is no possibility that excessive bending deformation occurs in the flexible substrate. If the cross section of the thin metal wire has an edge, the edge cuts between the adhesive of the reinforcing plate and the flexible substrate, so that the wedge action of the thin metal wire is further promoted.

The present invention further provides a reinforcing plate suitable for use in a method of mounting a flexible substrate including the above-described method of removing a flexible substrate.
The present invention provides a reinforcing plate provided with an adhesive as described in (1). In this reinforcing plate, since the adhesive is provided so as to be substantially evenly distributed over the entire surface of the reinforcing plate to which the flexible substrate is attached, even the entire area of a large-sized flexible substrate is reliably reinforced. Since the flexible board is fixed to the board and reinforced, the displacement of the flexible board in the thickness direction and the plane direction is reliably prevented, and high-precision mounting becomes possible, and the occurrence rate of defective products is reduced.

Further, unlike the conventional reinforcing plate, there is no position where the adhesive strength of the adhesive is locally increased, and the adhesive strength is substantially uniform over the entire area of the flexible substrate. When detaching, the peeling is performed smoothly. In addition, since the adhesive is provided substantially evenly over the entire area of the reinforcing plate, the degree of freedom regarding the shape and size of the applicable flexible substrate is increased, and it can be diverted to many different types of flexible substrates. Therefore, the mounting process is simplified, and the equipment cost and operation cost are reduced.

On the surface of the reinforcing plate, the adhesive may be densely provided without gaps, or the adhesive may be divided into a plurality of portions to form a gap of an appropriate size between each portion. You may. In the latter case, the average adhesive strength of the adhesive can be adjusted by changing the size of the gap. As an arrangement pattern when the adhesive is divided into a plurality of portions in this manner, for example, the divided adhesive may be arranged so as to be striped as a whole, or each of the divided adhesives may be The islands may be formed and they may be substantially evenly distributed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method of mounting a flexible substrate according to the present invention, a reinforcing plate 3 made of a rigid material such as an aluminum plate is used similarly to the prior art shown in FIGS. In a state where the flexible substrate 1 is attached to the adhesive 2 provided on the reinforcing plate 3 and reinforced, a paste containing a solder particle, an adhesive or the like is applied to a predetermined position of the flexible substrate 1 through a mask, for example. (Printing), and a plurality of electronic components (not shown) are mounted thereon and heated to perform a mounting process of fixing the electronic components on the flexible substrate 1. It is necessary to separate the reinforcing plate 3 from the adhesive 2 and remove it.

At this time, as shown in FIG. 4, if the end of the flexible substrate 1 is gripped and pulled up in a right angle direction,
As described above, the flexible substrate 1 undergoes permanent bending deformation and curls as shown in FIG. 5, and it becomes difficult to handle the flexible substrate 1 in subsequent steps. Therefore, the present invention provides a new detaching method as illustrated in FIGS.

That is, in this detaching method, a tough metal wire 4 such as a thin piano wire or a stainless steel wire is cut from the end between the flexible substrate 1 and the adhesive material 2 and then the metal wire is cut. As shown by an arrow a in FIG. 1, the flexible substrate 1 is peeled off from the adhesive material 2 by the wedge action of the thin metal wire 4 by moving both ends of the metal wire 4 along the surface of the reinforcing plate 3 as indicated by an arrow a in FIG. It is. The peeling of the flexible substrate 1 by the thin metal wires 4 pulls the end of the flexible substrate 1 in a direction at an angle sufficiently smaller than a right angle with respect to the surface of the reinforcing plate 3 as shown by an arrow b in FIG. By applying an appropriate amount of tension to the flexible substrate 1, the flexible substrate 1 can be smoothly generated. At this time, even though the force applied to the end of the flexible substrate 1 is relatively small, the peeling action by the thin metal wire 4 is sufficiently performed. In some cases, it is only necessary to grasp and hold the part.

The wedge action of the thin metal wire 4 and the peeling action due to the wedge action are performed as shown in the illustrated embodiment.
Can be fully exhibited by using
Is further strengthened when is a triangular cross section having an edge.
However, since the wedge action of the thin metal wire 4 having an edge has directionality, the two ends of the thin metal wire 4 are gripped so that the thin metal wire 4 is not twisted when the both ends of the thin metal wire 4 are pulled in the direction of arrow a. It is necessary to pay attention to the structure of the part.

As shown in FIG. 2, the flexible substrate 1 is peeled off by the wedge action of a thin metal wire 4 interposed between the flexible substrate 1 and the adhesive 2 of the reinforcing plate 3 so that the flexible substrate 1 is moved by arrows c and d. In the opposite direction. Therefore, a part of the flexible substrate 1 is moved by an arrow c
Even if it is subjected to bending deformation in the direction of, the part immediately after that comes into contact with the thin metal wire 4 and receives tension,
Since the bending deformation of the same magnitude in the direction of the arrow d opposite to the arrow c is received, the bending deformation of the flexible substrate 1 in the directions of the arrows c and d, or the inside thereof, Successive reverse bending stresses are offset. Moreover, since the thin metal wire 4 has a small diameter, the traction force b is small, and the direction in which it acts is also a small angle (a sharp angle) with respect to the reinforcing plate 3, so that the flexible substrate 1 is curled by bending deformation thereof. There is no possibility that such permanent deformation remains.

As described above, in the mounting method using the reinforcing plate 3 provided with the adhesive 2, the flexible substrate 1 is peeled off from the reinforcing plate 3 by the wedge action using the thin metal wire 4 and removed. In addition, since no excessive bending stress or bending deformation occurs in the flexible substrate 1 at the time of removal, there is no possibility that the soldering portion or the bonding portion of the electronic components (not shown) mounted on the flexible substrate 1 may be damaged, and the soldering may be performed. Since the reliability of the part and the adhesive part is improved,
The rate at which defective products are generated on the mounted flexible substrate 1 is reduced.

Further, according to the present invention, the step of mounting the electronic components on the flexible substrate 1 is reinforced by using the reinforcing plate 3 provided with the adhesive 2 and attaching the flexible substrate 1 to the reinforcing plate 3. Since it is executed after the above, similar to the case of a substrate made of a rigid body, it is possible not only to mount each electronic component at a predetermined position on the flexible substrate 1 accurately, but also to remove the flexible substrate 1 from the reinforcing plate 3. This is also easy, so the efficiency of the mounting process is improved.

As long as the removal method of the present invention is used in combination, the mounting method using the reinforcing plate 3 provided with the adhesive material 2 has many advantages, but the prior art shown in FIGS. When the adhesive 2 is provided only at both ends of the flexible substrate 1 as described above, as described above, the occurrence of defective products due to the flexible substrate 1 not being completely fixed on the reinforcing plate 3 Concerns, narrow adhesive 2
The use of the adhesive material 2 having a strong adhesive force in order to compensate for the effect of (1) causes strong bending deformation when the mounted flexible substrate 1 is removed from the reinforcing plate 3, so that the bending deformation remains as permanent deformation. There's a problem.

Therefore, some embodiments of the reinforcing plate 3 or the adhesive 2 in consideration of the arrangement of the adhesive 2 so as to sufficiently cope with such a problem will be described. 6 and 7 show a first embodiment of the reinforcing plate 3 provided by the present invention. In the reinforcing plate of the first embodiment, the adhesive 2 is provided so as to cover almost the entire surface of the reinforcing plate 3. The area or shape of the adhesive 2 is determined according to the average area or shape of various flexible substrates 1 having different sizes and shapes to be applied. In this case, there is no need for the flexible substrate 1 and the reinforcing plate 3 to completely overlap with each other.

In the case of the first embodiment, since the area of the adhesive 2 is sufficiently large, the flexible substrate 1 can be fixed sufficiently stably even if the partial adhesive force is small. Therefore, by using the adhesive material 2 having relatively low adhesive strength, when the flexible substrate 1 is detached from the reinforcing plate 3, the operation of peeling the flexible substrate 1 from the adhesive material 2 becomes easy. Also in this case, it is needless to say that it is desirable to use the detaching method according to the present invention shown in FIGS. 1 and 2 described above.

The adhesive 2 provided on the reinforcing plate 3 of the present invention
For example, silicone-based adhesive material (silicone rubber)
As described above, it is preferable that the adhesive strength is not easily reduced even when the flexible substrate 1 is repeatedly attached and detached, and that the heat resistance is high so as to withstand the heating in the mounting process. Adhesive 2
Can be easily adjusted by increasing or decreasing the amount of an additive compounded therein. This point is the same for the second embodiment and the following embodiments of the reinforcing plate 3 or the adhesive 2.

FIG. 8 shows a second embodiment of the reinforcing plate 3 of the present invention. In the reinforcing plate 3 of the second embodiment, the adhesive 2 is provided so as to form stripes composed of a large number of fine streaks. Such an arrangement of the adhesive material 2 may be obtained by cutting a thin sheet of the film-like adhesive material into an elongated ribbon shape, and affixing the thin sheet to the surface of the reinforcing plate 3 in parallel with each other,
A mask having an opening conforming to the arrangement shape of the adhesive 2 may be placed on the reinforcing plate 3, a viscous adhesive containing a volatile solvent may be applied, and the solvent may be evaporated by heating. Of course, when the adhesive 2 is provided in other embodiments, the same method can be used.

In the case of the second embodiment, a large number of streaky adhesives 2
Are arranged so as to form stripes as a whole, so that the adhesive 2 is macroscopically substantially uniformly distributed on the surface of the reinforcing plate 3. In this case, the adhesive strength of the adhesive 2 can also be adjusted by changing the size of the gap between the streaky adhesives 2. In addition, since the adhesive force is generated evenly on the surface of the reinforcing plate 3, the flexible substrate 1 is located at the center of the flexible substrate 1 as in the prior art.
There is no fear that the holding state becomes unstable, and there is an advantage that substantially the same effect can be obtained as in the case where the adhesive material 2 is provided evenly over substantially the entire surface of the reinforcing plate 3 as in the first embodiment. .

From the same idea as in the second embodiment, in the reinforcing plate 3 of the third embodiment shown in FIG. 9, a large number of circular island-shaped adhesive members 2 are evenly arranged on the surface of the reinforcing plate 3. ing. Also in this case, as in the second embodiment, the distribution of the adhesive 2 is substantially uniform on the surface of the reinforcing plate 3, so that the adhesive force is substantially uniform anywhere on the surface of the flexible substrate 1 attached thereto. Is obtained. Although the adhesive material 2 of the third embodiment has a circular island shape, an arbitrary shape such as a square, a rectangle, another polygon, a star, or the like can be adopted as the deformation. Further, a mixture of these shapes or a mixture of islands having different sizes may be used. In short, even when the adhesive 2 is separated into a plurality of portions, the adhesive 2 may be arranged substantially uniformly over the entire effective portion of the reinforcing plate 3 holding the flexible substrate 1.

As described above, when the adhesive 2 provided on the surface of the reinforcing plate 3 is separated into a plurality of portions, the portion where the adhesive 2 is provided on the surface of the reinforcing plate 3 is provided. Slight irregularities corresponding to the thickness of the adhesive material 2 are formed between the non-existing portions. If the unevenness is unacceptable in view of the accuracy of the flexible substrate 1 held thereby and the possibility of defective products, an adhesive material is applied to the reinforcing plate 3 as in the fourth embodiment shown in FIG. Shallow recess 5 to accommodate 2
Is formed, and the adhesive material 2 is provided in the recess 5, so that the height of the surface of the reinforcing plate 3 and the surface of the adhesive material 2 may be made uniform. Thereby, unevenness on the surface of the reinforcing plate 3 due to the adhesive 2 is eliminated.

The pressure-sensitive adhesive 2 can be composed of a single layer, but as shown in FIG.
The adhesive 2 can be provided as a laminate of a plurality of adhesives having different adhesive strengths. This is suitable when the adhesive material 2 made of a sheet-like film is adhered on the surface of the reinforcing plate 3, and the adhesive force of each adhesive material layer is weakest when it comes into contact with the flexible substrate 1. When the flexible substrate 1 is removed from the reinforcing plate 3, an adhesive 2
This is preferable because there is no fear of the adhesion.

Adjusting the adhesive strength of the adhesive 2 to an appropriate level can be achieved by increasing or decreasing the amount of the additive of the adhesive 2 as described above, or by adjusting the adhesive as shown in the embodiments of FIGS. 2 can be easily achieved by separating the plurality of parts into a plurality of parts and adjusting the size of the gap formed between the respective parts. However, as in the sixth embodiment shown in FIG. This can also be achieved by forming a concave portion 6 on the surface of the substrate 2 to reduce the area of adhesion to the flexible substrate 1 as necessary. By adjusting the adhesive strength of the adhesive material 2 to an appropriate size in this way, the flexible substrate 1 is smoothly separated from the adhesive material 2 when the flexible substrate 1 is removed using the thin metal wires 4 as described above. To

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a flexible substrate is separated from a reinforcing plate provided with an adhesive in a mounting method of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG. 1;

FIG. 3 is a perspective view showing a state in the middle of attaching a flexible substrate to a conventional reinforcing plate provided with an adhesive material, or peeling the flexible substrate therefrom by a normal method.

FIG. 4 is an enlarged cross-sectional view showing a state in which a flexible substrate attached to a reinforcing plate is peeled off by a normal method in order to explain a problem of the related art.

FIG. 5 is a perspective view showing a state in which a flexible substrate peeled by a normal method is curled.

FIG. 6 is a cross-sectional view showing a flexible substrate attached to a reinforcing plate having an adhesive.

FIG. 7 is a cross-sectional view showing a first embodiment of an adhesive provided on a reinforcing plate.

FIG. 8 is a sectional view showing a second embodiment of the adhesive.

FIG. 9 is a sectional view showing a third embodiment of the adhesive.

FIG. 10 is a sectional view showing a fourth embodiment of the adhesive.

FIG. 11 is a sectional view showing a fifth embodiment of the adhesive.

FIG. 12 is a sectional view showing a sixth embodiment of the adhesive.

FIG. 13 is a perspective view showing a problem when a flexible substrate is attached to a reinforcing plate provided with an adhesive in a conventional manner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Flexible board 1 '... Linear bent part which arises in a flexible board 2 ... Adhesive material 3 ... Reinforcement plate 4 ... Fine metal wire 5 ... Recessed part of a reinforcing plate 6 ... Recessed part of an adhesive material

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Gentaro Masuda 1-1-1 Showa-cho, Kariya-shi, Aichi F-term in DENSO Corporation (Reference) 5E313 AA02 AA12 AA35 AB02 AB03 CC05 DD13 EE22 FF12 FG05 FG06 FG08 FG10

Claims (8)

[Claims] 1. A method for mounting an electronic component on a flexible substrate after providing an adhesive on a surface of a rigid reinforcing plate, reinforcing the flexible substrate by attaching the flexible substrate to the adhesive of the reinforcing plate, and mounting the electronic component on the flexible substrate. When the flexible board on which the electronic components have been mounted is removed from the adhesive of the reinforcing plate, a thin metal wire is cut in a wedge shape between the flexible board and the adhesive, and both ends of the thin metal wire are pulled, so that the reinforcing plate is pulled. Removing the flexible substrate from the reinforcing plate by moving the thin metal wire along the surface of the substrate to peel the flexible substrate from the adhesive of the reinforcing plate. 2. At the same time as the movement of the thin metal wire, the end portion of the flexible board is pulled in a direction at an acute angle to the surface of the reinforcing plate, and a tension is applied to the flexible board. The method for removing a flexible substrate from a reinforcing plate according to claim 1, wherein the method promotes peeling. 3. The method for removing a flexible substrate from a reinforcing plate according to claim 1, wherein the thin metal wire has an edged cross section. 4. A method for mounting an electronic component on a flexible substrate after providing an adhesive on a surface of a rigid reinforcing plate, reinforcing the flexible substrate by attaching the flexible substrate to the adhesive of the reinforcing plate, and then mounting the electronic component on the flexible substrate. A reinforcing plate, wherein the adhesive is provided substantially uniformly over the entire surface of the reinforcing plate to which the flexible substrate is attached. 5. The reinforcing plate according to claim 4, wherein the adhesive is provided without a gap. 6. The reinforcing plate according to claim 4, wherein the adhesive is divided into a plurality of portions, and a gap is formed between each portion. 7. The reinforcing plate according to claim 6, wherein the adhesive material divided into a plurality of portions has a stripe shape as a whole. 8. The reinforcing plate according to claim 6, wherein each of the adhesive materials divided into a plurality of portions has an island shape.