JP2006203148A - Multilayer printed circuit board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of multilayer printed circuit boards by an IVH for manufacturing the multilayer printed circuit boards with higher productivity by a simpler process, and for providing high interlayer bonding strength without causing problems of warp or the like, and also to provide the multilayer printed circuit board manufactured by the manufacturing method. <P>SOLUTION: A manufacturing method of multilayer printed circuit boards stacks: an insulating substrate; a conductive layer circuit provided on one surface of it; a single-sided wiring board substrate having bumps of a conductive material obtained by filling via-holes formed in the insulating substrate with the conductive material; an adhesive sheet layer comprising an adhesive sheet, and having a through hole of a diameter larger than that of the via-hole at a position corresponding to the via-hole; and other wiring board substrates, and collectively lamination presses them so that the bumps are inserted into the through hole. A multilayer printed circuit board is manufactured by the manufacturing method. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a multilayer printed wiring board in which a plurality of printed wiring boards are laminated, and a multilayer printed wiring board manufactured by the manufacturing method.

  The multilayer printed wiring board is known as a technique that enables high-density mounting of components and can connect the components at the shortest distance (meaning that they are electrically connected; hereinafter simply referred to as connection). IVH (Interstitial Via Hole) is a technology applied to the manufacture of multilayer printed wiring boards that require higher density mounting. Filling holes formed between adjacent layers with a conductive material, It is characterized by connecting. According to IVH, an interlayer connection can be formed only in a necessary portion, and a component can be mounted on a via hole, thereby enabling high-density wiring with a high degree of freedom.

  For example, Fujikura Technical Report No. 103, pages 49-51 (announced in October 2002) describes a multilayer printed wiring board produced by laminating a heat-resistant film represented by polyimide by IVH. FIG. 8 is a process diagram showing the manufacturing process of this multilayer printed wiring board.

  First, the copper bonding layer 21 of a single-sided copper-clad laminate 22 (Cupper Clad Laminate: CCL, FIG. 8a) in which one side of a resin film 20 (insulating substrate) made of polyimide resin is coated with a copper bonding layer 21 is etched. A circuit is formed (FIG. 8b). Next, after bonding a polyimide-based adhesive sheet layer 23 to the other surface (FIG. 8c), drilling is performed with a laser to form a via hole 24 (FIG. 8d). A wiring board substrate 26 (FIG. 8e) obtained by filling the via hole with the conductive paste 25 by screen printing and a copper-clad laminate 27 on which a circuit is formed are laminated while being aligned (FIG. 8f). The multilayer printed wiring board 28 is obtained by pressurizing with a cure press and performing interlayer adhesion (FIG. 8g).

  In this method, formation of the via hole 24 and screen printing are performed after the adhesive sheet layer 23 is bonded to the resin film 20. Therefore, when the resin film 20 and the adhesive sheet layer 23 are bonded together, it is necessary to bond both of them, and therefore, it is necessary to heat the glass to the glass transition point (Tg) of the adhesive sheet layer 23 or higher. That is, in this method, heating was required twice, that is, the step of bonding the resin film 20 and the adhesive sheet layer 23 and the step of interlayer adhesion.

  Further, in this method, when a thermoplastic resin having a low Tg is used for the adhesive sheet layer 23, it may be plasticized again by heating such as reflow after completion as a wiring board, and peeling may occur. On the other hand, when a thermoplastic resin having a high Tg is used, it is necessary to perform heating at the time of bonding the resin film 20 and the adhesive sheet layer 23 at a high temperature, which causes deterioration of the conductive paste 25. In addition, when a thermosetting resin adhesive is used, it is difficult to obtain sufficient interlayer adhesion strength at the interlayer bonding stage because a part of the adhesive is already cured at the bonding stage. There is.

  Furthermore, since the elastic modulus and the coefficient of thermal expansion of the copper adhesive layer 21 and the copper adhesive laminate 22 and the adhesive sheet layer 23 are largely different from each other, warping or the like is caused when the resin film 20 and the adhesive sheet layer 23 are bonded. Stress distortion occurs. As a result, there is a problem that misalignment is likely to occur in the via hole formation stage and the defect rate is increased.

  As a method for solving this problem, a thermoplastic polyimide sheet imparted with a thermosetting function is used for the adhesive sheet layer, and when the sheet and the copper-clad laminate are bonded together, the thermoplastic polyimide has a Tg or higher. In addition, a method of heating at a temperature lower than the curing start temperature (Ts) of the thermosetting component and heating at a temperature higher than Ts at the time of interlayer adhesion is disclosed in JP-A-2004-95963. Item 12). By this method, peeling due to reflow or the like can be prevented, and sufficient interlayer adhesion strength can be obtained. Japanese Patent Application Laid-Open No. 2004-95963 proposes to use a film made of a resin having a Tg of 110 ° C. or lower and a room temperature elastic modulus of 1300 MPa or lower in order to prevent warping during bonding (paragraph 0035). ).

  However, even by the method described in Japanese Patent Application Laid-Open No. 2004-95963, it is necessary to perform heating twice in the bonding stage and the interlayer adhesion stage, and each temperature must be changed. This causes an increase in cost. Furthermore, since the resin used is of a specific type and the Tg and room temperature elastic modulus are limited to a specific range, the selection range is narrow.

Therefore, it has been desired to develop a method for producing a multilayer printed wiring board by IVH, which solves the problems of the prior art.
JP 2004-95963 A (Claim 12, paragraph 0035) Fujikura Technical Review No. 103, pp. 49-51 (announced in October 2002)

  The present invention is a method for producing a multilayer printed wiring board by IVH, which can produce a multilayer printed wiring board by a simpler process and does not cause a problem of warping during bonding, and has a large interlayer adhesion. It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board capable of obtaining strength and a multilayer printed wiring board manufactured by the manufacturing method.

  As a result of investigation, the inventor has formed a via hole reaching a conductor circuit in an insulating substrate, and further has a wiring board substrate having a conductive bump formed in the via hole, and a via hole at a position corresponding to the via hole. A multilayer printed wiring board can be manufactured in a simpler process by laminating and pressing the adhesive sheet layer having a larger through-hole and another wiring board base material in a lump, and bonding them together The present inventors have found that a large interlayer adhesive strength can be obtained without causing the problem of warp during the process.

According to a first aspect of the present invention, there is provided:
Obtained by filling a conductive material into an insulating substrate, a conductive layer circuit provided on one surface thereof, and a via hole formed in the insulating substrate so as to reach the conductive layer circuit and open on the other surface. Single-sided wiring board substrate having a conductive bump formed thereon,
An adhesive sheet layer having a through-hole having a diameter larger than the via hole at a position corresponding to the via hole, and another wiring board substrate having a conductive layer circuit at a position corresponding to the via hole;
At least three layers,
A multilayer printed wiring board characterized in that the adhesive sheet layer is sandwiched between the wiring board substrates and the bumps are inserted so as to be inserted into the through holes, and these are laminated and pressed together. It is a manufacturing method.

  The single-sided wiring board substrate can be manufactured by forming via holes, bumps, and conductive layer circuits on an insulating substrate having a conductive layer attached to one surface. Here, as an insulating board | substrate with which the conductive layer was affixed on the one surface, the polyimide resin base material (CCL) with a copper foil in which copper foil was affixed on the single side | surface is illustrated.

  The via hole (bottomed hole) can be formed by drilling using a laser or the like at a position where interlayer connection of the insulating substrate is desired. The via hole penetrates the insulating substrate, one end opens on the surface opposite to the surface to which the conductive layer is attached, and the other end reaches the conductive layer. In addition, you may form a small diameter hole also in electroconductive layers, such as copper foil. If this hole is formed, it functions as an air bleed hole for venting air in the via hole when the conductive material is filled into the via hole by screen printing, and the filling becomes easy.

  After the via hole is formed, the via hole is filled with a conductive material to form a bump. The method for filling the conductive material is not particularly limited, and examples thereof include a method for filling the conductive material by screen printing. Examples of the conductive material include silver paste, copper filler and carbon mixture paste, solder cream, and low melting point metal.

  A conductive bump is a protrusion of a conductive material formed on a via hole, and is formed to connect to a conductive layer circuit of another wiring board substrate. The method for forming the bumps of the conductive material is not particularly limited. For example, a release layer is formed on the insulating substrate, a via hole penetrating the insulating substrate and the release layer is formed, and the conductive material is formed in the via hole. Examples of the method for forming the protruding portion by peeling the release layer after filling the film are exemplified. Examples of the release layer include a polyethylene terephthalate (PET) masking film, and these are pasted on an insulating substrate to form a release layer. As another method of forming the bumps of the conductive material, there is a method of filling the via hole with the conductive material and further applying a conductive paste or the like thereon by screen printing.

  The conductive layer circuit can be formed, for example, by etching the conductive layer. For example, after forming a resist layer circuit pattern on the conductive layer, the conductive layer is immersed in an etchant that corrodes, and the portion other than the circuit pattern is removed, and then the resist layer is removed (wet etching). Is done. Examples of the etchant in this case include a ferric chloride-based etchant mainly composed of ferric chloride, a cupric chloride-based etchant, and an alkali etchant. Normally, the circuit is formed before the via hole is formed, but may be formed after the via hole is formed or after the bump is formed.

  The adhesive sheet layer is obtained by forming a through hole having a diameter larger than the diameter of the via hole at a position corresponding to the via hole in the adhesive sheet. Forming a through hole at a position corresponding to a via hole means that when the single-sided wiring board substrate and the adhesive sheet layer are overlapped, the exit of each via hole is included in the opening of the through hole, that is, the bump penetrates. It means that a through hole is formed so as to be inserted into the hole. The through hole formation method is not particularly limited, and a laser drilling method, a method of mechanically drilling using a drill, or the like can be employed. As the adhesive sheet for forming the adhesive sheet layer, those having a thickness of about 10 μm to 100 μm are usually used, preferably 15 μm to 70 μm. When the thickness is less than 10 μm, the adhesive sheet layer does not sufficiently expand during the laminating press for interlayer adhesion, and the gap between the bump and the adhesive sheet is difficult to be eliminated. On the other hand, if it exceeds 100 μm, it becomes difficult to form a bump having a projection length corresponding to this thickness.

  The adhesive sheet layer is overlaid on the bump side of the single-sided wiring board substrate having the above bumps, and another wiring board base material having a conductive layer circuit at a position corresponding to the via hole is further stacked thereon. These are collectively laminated and pressed to produce a multilayer printed wiring board. That is, a single-sided wiring board substrate on which bumps are formed and another wiring board substrate having a conductive layer circuit are bonded by an adhesive sheet layer sandwiched between them to produce a multilayer printed wiring board. . Another wiring board substrate having a conductive layer circuit has an insulating substrate and a conductive layer circuit provided on one or both surfaces thereof, and a part of the conductive layer circuit corresponds to the bump. It is the wiring board base material provided in the position to do.

  Other wiring board base materials can be manufactured by, for example, forming a circuit by performing etching or the like on a copper foil of a polyimide resin film having a copper foil attached to one or both sides. As will be described later, the other wiring board substrate has an insulating substrate and conductive layer circuits provided on both surfaces thereof, and the space between the conductive layer circuits on both surfaces is filled in the through holes. An example of the double-sided wiring board substrate connected by the conductive material is also illustrated.

  The multilayer printed wiring board of the present invention has at least three layers of the single-sided wiring board substrate, the adhesive sheet layer, and another wiring board substrate, and the adhesive sheet layer is sandwiched between the wiring board substrates, In addition, the bumps are stacked so as to be inserted into the through-holes, and these are collectively stacked and pressed. That is, since the multilayer printed wiring board of the present invention can be produced by a single laminating press, high productivity can be obtained.

  The lamination press can be performed by heating and pressurizing with a cure press or the like. Since the diameter of the through-hole formed in the adhesive sheet layer is larger than the diameter of the via hole, there is a gap between the adhesive sheet layer and the bump before the start of the lamination press. Is expanded until it contacts the conductive material of the bump, and this gap is eliminated. In addition, when the bump is plastically deformed, the bump may be deformed by the laminating press, and the gap may be eliminated. In this way, the wiring board substrate on which the bumps are formed and the other insulating substrate having the conductive layer circuit are firmly bonded by the adhesive sheet layer.

  When stacking a single-sided wiring board substrate, an adhesive sheet layer and another wiring board substrate, it is preferable to perform temporary bonding that is simple bonding to prevent misalignment during lamination or lamination press. Is performed under conditions that are much milder than those of conventional bonding. For example, in the case of an epoxy adhesive, a heating time of about 10 to 60 seconds is sufficient at a temperature of about 120 to 140 ° C., and in the case of a polyimide adhesive, a temperature of about 170 to 200 ° C. A heating time of about 60 seconds is sufficient. As a result, the number of times of heating is reduced compared to the conventional method, and a multilayer printed wiring board can be manufactured by a simpler process. Further, there is no warping due to heating during the pasting, which was a problem of the prior art. Furthermore, even when a thermosetting resin is used as the adhesive, it is heated at the bonding stage and is not partially cured, so that a large adhesive strength can be obtained during interlayer adhesion.

  The manufacturing method of the multilayer printed wiring board of this invention is applicable also when there exist two or more said single-sided wiring board base materials, an adhesive sheet layer, etc. In this case, the adhesive sheet layers and the wiring board base material are alternately stacked, and these are collectively laminated and pressed. Here, the wiring board substrate is meant to include both the single-sided wiring board substrate and the other wiring board substrate. That is, the adhesive sheet layer is sandwiched between the single-sided wiring board base materials or between the single-sided wiring board base material and the other wiring board base material so that the bumps are inserted into the through holes. The lamination press is performed collectively. Claim 2 corresponds to this aspect.

  According to the manufacturing method of the present invention, the adhesion by heating is only required once in the laminating press, and it is not necessary to perform the bonding by heating each time each wiring board substrate is formed as in the conventional method. Therefore, the manufacturing process can be greatly simplified, and no warp or the like occurs, so that problems such as misalignment do not occur.

  The other wiring board base material includes an insulating substrate and conductive layer circuits on both surfaces thereof, and a conductive layer on both surfaces by a conductive material filled in through holes penetrating the insulating substrate. A double-sided wiring board substrate in which circuits are connected can be used. Claim 3 corresponds to this aspect.

  Such a double-sided wiring board substrate includes, for example, a process of forming a circuit by etching or the like on a copper foil of a polyimide resin film having a copper foil attached to both surfaces, and copper foils on both surfaces ( It can be manufactured by a method having a step of forming a through hole penetrating the conductive layer) and the polyimide resin film (insulating substrate), filling the through hole with a conductive material, and connecting the copper foils on both surfaces. it can. Either the step of forming the circuit and the step of connecting the copper foil may be performed first. Further, formation of a circuit, formation of a through hole, and filling of a conductive material can be performed in the same manner as described above.

  When the other wiring board substrate is a single-sided wiring board substrate or a double-sided wiring board substrate in which the conductive layer circuits on both surfaces are not connected, the other wiring board substrate is the uppermost part. Are stacked and pressed together on the adhesive sheet layer. The uppermost adhesive sheet layer means a layer closest to the outermost side among the adhesive sheet layers used for bonding between the multilayers in which circuits are connected to each other.

  When the other wiring board substrate is a double-sided wiring board substrate in which conductive layer circuits on both surfaces are connected, the other wiring board substrate is placed on the uppermost adhesive sheet layer. It may be overlaid or may be overlaid on an adhesive sheet layer other than the top. Another adhesive sheet layer is superimposed on the double-sided wiring board base material that is overlaid on the adhesive sheet layer other than the uppermost part, and further, the single-sided wiring board base material has its bump as the other adhesive sheet. The layers are stacked so as to be inserted into the through-holes of the layers. In some cases, the adhesive sheet layer and the single-sided wiring board base material are further overlapped, and then these are laminated and pressed together.

  The diameter of the through hole of the adhesive sheet layer is preferably 1.5 to 5 times, more preferably 3 to 5 times the diameter of the via hole of the wiring board substrate, that is, the diameter of the bump. If it is less than 1.5 times, the alignment when the adhesive sheet layer and the wiring board substrate are stacked is not easy, and the bumps are not likely to be inserted into the through holes of the adhesive sheet layer. On the other hand, when it is 5 times or more, it becomes difficult to spread until the adhesive sheet layer comes into contact with the bumps at the time of the lamination press, and there is a possibility that the gap between the two is not eliminated. Claim 4 corresponds to this preferred embodiment.

  As a material for forming the conductive layer circuit of the single-sided wiring board substrate and the other wiring board substrate, a material mainly composed of copper is usually used. A fifth aspect of the present invention provides a method for manufacturing a multilayer printed wiring board corresponding to this aspect. Examples of the material mainly composed of copper include copper or an alloy mainly composed of copper. As a material for the conductive layer circuit, a silver paste, a copper paste obtained by copper plating, or the like can be used besides copper.

  Examples of the insulating substrate constituting the single-sided wiring board substrate include resin films mainly composed of PET and polyimide. A resin film mainly composed of polyimide is a heat-resistant film, and can meet the demand for high heat resistance corresponding to the use of lead-free solder. In addition, the loss in high frequency transmission is smaller than that of a resin containing ceramic or glass cloth, and the insulating substrate can be made thinner and stronger. Claim 6 corresponds to this preferable mode. In addition, also about the insulating substrate which comprises the said other wiring board base material, the resin film which has a polyimide as a main component is illustrated preferably.

  The material (adhesive) of the adhesive sheet that forms the adhesive sheet layer is thermoplastic polyimide resin, thermosetting resin such as epoxy polyimide, imide resin, etc. Examples thereof include resins. Claim 7 corresponds to this aspect. Among the above examples, in the case of a resin having a thermosetting function mainly including thermoplastic polyimide, a thermosetting epoxy resin, and a thermosetting imide-based resin, a sufficient adhesive force is ensured after heat curing. preferable.

  When using adhesive sheets formed mainly of thermosetting epoxy resins, they have low water absorption, so even after being exposed to a high-temperature and high-humidity atmosphere, the resistance (the conductive material filled in the via hole and the conductive layer) The contact resistance of the film hardly increases. Therefore, since it is exposed to a high-temperature and high-humidity atmosphere after it is completed as a multilayer printed wiring board, the resistance of the entire circuit rises and does not significantly affect the function of the multilayer printed wiring board. It is preferable to use an adhesive sheet mainly composed of a conductive epoxy resin. Claim 8 corresponds to this more preferable aspect.

  The adhesive sheet forming the adhesive sheet layer may be a laminate of two or more kinds of resin layers. For example, from a thermosetting epoxy resin, a laminated layer of a high Tg (200 ° C. or higher) cured polyimide resin used for a copper-clad laminate and the like, and further a thermosetting epoxy resin laminated thereon. An adhesive sheet is exemplified.

  In addition, if the longitudinal elastic modulus of the adhesive sheet is 3 GPa or less, the stress during the reflow test is reduced, which is advantageous. On the other hand, if the longitudinal elastic modulus is less than 0.001 GPa, the elongation becomes too large and it may be difficult to handle. Therefore, from this viewpoint, it is preferable to use an adhesive sheet having a longitudinal elastic modulus (Young's modulus) of 0.001 GPa or more and 3 GPa or less. Claim 9 corresponds to this preferred embodiment.

  In order to facilitate component mounting, the multilayer printed wiring board is desired to be flat. However, if an adhesive sheet with a low elastic modulus is used, deformation such as warpage is large during pressing, and the multilayer printed wiring board There was a problem that a convex part arises in a board. Therefore, an adhesive sheet that does not cause this problem is desired, and this requirement is particularly strong for the outermost adhesive sheet close to the mounting portion of the component. From this point of view, an adhesive sheet made of a material having high rigidity and hardly deformed is preferably used.

  However, on the other hand, the adhesive sheet formed of a single material having high rigidity has a problem that it is small in elongation and weak against thermal stress. This problem can be solved by a composite material combining a material having high rigidity and a flexible adhesive. Claims 10 and 11 correspond to a form using an adhesive sheet formed of this composite material, and it is easy to form a flat multilayer printed wiring board, and the problem is that the elongation is small and weak against thermal stress. Provides a preferred embodiment which has also been solved.

  That is, claim 10 is the method for manufacturing the multilayer printed wiring board, wherein the adhesive sheet is a sheet obtained by impregnating a highly rigid porous material with an adhesive. A manufacturing method of a board is provided, and the manufacturing method of the multilayer printed wiring board according to claim 11, wherein the adhesive sheet sandwiches a highly rigid insulating film layer between two adhesive layers. The present invention provides a method for producing a multilayer printed wiring board, which is characterized by being a sheet formed by the above method.

  Even in this case, the same adhesive as described above can be used as the adhesive. As the porous material having high rigidity, a material having an elastic modulus of 50 GPa to 200 GPa is preferable. Specifically, for example, a non-woven fabric such as aramid or other fibers having rigidity or glass fibers can be used. The impregnation method is not particularly limited, and examples thereof include a method of dissolving and dissolving the adhesive in a solvent and then evaporating and removing the solvent.

  A highly rigid insulating film layer is preferably a film made of a material having an insulating property and an elastic modulus of 5 GPa to 10 GPa. Specifically, for example, a polyimide film marketed under a trade name such as Upilex-25S (manufactured by Ube Industries) can be used.

  The present invention further provides a multilayer printed wiring board manufactured by the method for manufacturing a multilayer printed wiring board described above (claim 12). The multilayer printed wiring board of the present invention is used for manufacturing various electrical products as a wiring board capable of mounting components at high density.

  According to the method for producing a multilayer printed wiring board by IVH of the present invention, a multilayer printed wiring board comprising a plurality of wiring board substrates can be produced by a single laminating press. Thus, a multilayer printed wiring board can be manufactured with high productivity by a simple process. Furthermore, the problem of the curvature at the time of bonding the insulating substrate provided with the conductive layer and the adhesive sheet layer does not occur, and a large interlayer adhesive strength can be obtained. In particular, even in the case of producing a multilayer printed wiring board composed of a large number of wiring board substrates, such as in the case of laminating two or more single-sided wiring board substrates, the heating and laminating process may be performed only once. The effect of improving productivity compared with the conventional technology is great.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. In addition, this invention is not limited to this form, The change to another form is also possible unless the meaning of this invention is impaired.

  FIG. 1 is a process diagram showing a manufacturing process of an example of a single-sided wiring board substrate used for forming a multilayer printed wiring board. Using a single-sided copper-clad laminate 3 (CCL, FIG. 1a) in which a 12.5-μm thick copper bonding layer 2 (copper foil, conductive layer) is provided on one side of a polyimide resin sheet 1 (insulating substrate) having a thickness of 25 μm, The copper paste layer 2 is masked and wet etched to form a circuit pattern on the copper paste layer 2 (FIG. 1b).

  Next, a release layer 4 made of PET having a thickness of 50 μm is pasted on the surface of the polyimide resin sheet 1 opposite to the surface on which the copper pasting layer 2 is provided (FIG. 1c). 1 to 8 via holes 5 (bottom holes, blind vias) of 100 μm are formed at predetermined positions (FIG. 1d). Although UV-YAG laser was used for laser processing in this example, it is not limited to this, and other lasers can be used, and via holes can be formed by methods other than laser processing. It is.

  Next, after conducting desmearing treatment to remove smears such as resin or copper foil oxide remaining due to drilling remaining in the via hole 5, the via hole 5 is cleaned, and a conductive material made of silver paste is used for screen printing. Using the squeegee plate, the via hole 5 is filled and filled from the surface side of the release layer 4 by squeezing to form the conductive material filling portion 6 (FIG. 1e). Thereafter, the release layer 4 is removed to form a conductive bump 7 having a 40 μm protrusion (FIG. 1 f) to obtain a single-sided wiring board substrate A. Even if the release layer 4 is not attached as described above, the bumps 7 can be formed by filling the via holes 5 with filling, drying, bump printing, and drying.

  FIG. 2 is a process diagram showing a production process of an example of an adhesive sheet layer used in the method for producing a multilayer printed wiring board of the present invention. A through-hole 12 having a diameter of 250 to 400 μm is opened using a drill at a position corresponding to the bump 7 of the wiring board substrate A of the adhesive sheet 11 (FIG. 2A) having a thickness of 25 μm to obtain an adhesive sheet layer B ( FIG. 2b). In addition, when the thickness of the adhesive sheet is about 100 μm or less, it is possible to use a laser instead of a drill for forming such a through hole.

  FIG. 3 is a process diagram showing a manufacturing process of another wiring board substrate laminated with the single-sided wiring board substrate A and the adhesive sheet layer B. In this example, a double-sided copper-clad laminate (CCL) is used in which a 12.5 μm-thick copper bonding layer 13 (copper foil, conductive layer) is provided on both sides of a 25 μm-thick polyimide resin sheet 14 (insulating substrate) ( FIG. 3a). The double-sided wiring board base material C which provided the circuit which consists of the copper adhesion layer 13 on both surfaces of the polyimide resin sheet 14 is obtained by masking and wet-etching the copper adhesion layer 13 of both surfaces, respectively (FIG. 3b). For example, instead of the double-sided copper-clad laminate, a single-sided copper-clad laminate can be used to obtain a single-sided wiring board substrate provided with a circuit only on one side, and this can be used.

  FIG. 4 is a process diagram showing a process for producing the multilayer printed wiring board of the present invention by laminating the single-sided wiring board base A, the adhesive sheet layer B and the double-sided wiring board base C obtained as described above. It is. First, the bump 7 (via hole) of the single-sided wiring board substrate A, the through hole 12 of the adhesive sheet layer B, and the copper bonding layer 13 (copper land) forming the circuit of the double-sided wiring board substrate C are arranged in series at each position. Then, the positioning pins are overlapped through the positioning holes so that the adhesive is temporarily cured within a temperature range where the adhesive is not completely cured (FIG. 4a). Holes for positioning (not shown) are opened in the single-sided wiring board base A, the adhesive sheet layer B, and the double-sided wiring board base C by laser processing or the like before lamination.

Then, it heats and pressurizes at 180-220 degreeC and 10-40 kg / cm < ² > with the machine according to a vacuum press machine or a vacuum press machine. Since the through hole 12 of the adhesive sheet layer B is larger than the diameter of the bump 7 (via hole diameter), the adhesive sheet 11 and the bump 7 are not in contact with each other in the initial stage of the press. As a result, the adhesive sheet 11 and the bump 7 come into contact with each other, and the multilayer printed wiring board 15 of the present invention is formed (FIG. 4b). Since the pressurization is continued while cooling after completion of heating, almost no warping or the like occurs.

  The example of FIG. 4 is an example of manufacturing a multilayer printed wiring board of the present invention by bonding one layer of a single-sided wiring board substrate and another wiring board substrate using an adhesive sheet layer. The manufacturing method of a multilayer printed wiring board is applicable also when using the single-sided wiring board base material of two or more layers. FIG. 5 is a process diagram showing a process for producing a multilayer printed wiring board of the present invention using a two-layer single-sided wiring board substrate.

  Single-sided wiring board bases A1 and A2 manufactured in the same manner as the single-sided wiring board base A, adhesive sheet layers B1 and B2 manufactured in the same manner as the adhesive sheet layer B, and double-sided wiring board bases C The double-sided wiring board base material C ′ produced in the same manner is laminated as shown in FIG. 5a, and the same is applied to the vacuum press machine or the machine equivalent to the vacuum press machine in the same manner as in the example of FIG. The multilayer printed wiring board 16 of the present invention is formed by pressurizing and heating (FIG. 5b).

  FIG. 6 is a process diagram showing a process for producing a multilayer printed wiring board of the present invention using a two-layer single-sided wiring board base material, similar to the example of FIG. 5, but double-sided wiring in the case of the example of FIG. Instead of the board substrate C ′, a double-sided wiring board substrate in which the conductive layer circuit (copper layer) on both surfaces is connected by a conductive material filled in a via hole penetrating the insulating substrate. An example using C ″ is shown. The multilayer printed wiring board 17 of the present invention is formed in the same manner as the example of FIG. 5 except that C ″ is used instead of C ′ (FIG. 6B).

  FIG. 7 is a process diagram showing a process for producing a multilayer printed wiring board of the present invention using a three-layer single-sided wiring board base and a double-sided wiring board base in which conductive layer circuits on both surfaces are connected. However, unlike the example of FIG. 6, this is an example in which a double-sided wiring board substrate C ″ is used inside the cross section. Single-sided wiring board substrate A1, adhesive sheet layer B1, single-sided wiring board substrate A2, adhesive The process is the same as the example of FIG. 6 until the sheet layer B2 and the double-sided wiring board substrate C ″ are stacked in this order. Thereafter, on the double-sided wiring board substrate C ″, the adhesive sheet layer B3 and the single-sided wiring board substrate A3 are overlaid so that the bumps of A3 are inserted into the through holes of B3. 4 to 6, the multilayer printed wiring board 18 of the present invention is formed by applying pressure and heating with a vacuum press or a machine similar to the vacuum press (FIG. 7b).

Test Example A 10 cm square sample (without bonding of the adhesive sheet layer) prepared in the steps shown in FIGS. 1a and b and a 10 cm square sample (in the adhesive sheet layer) prepared in the steps shown in FIGS. 8a, b and c. After pressing under conditions of 180 ° C., 30 kg / cm ² and 30 minutes, the dimensional change rate (10-point average) was measured, and the state of warpage was visually determined.

  The dimensional change rate of the sample without bonding of the adhesive sheet layer was 0.01%, and no warpage was observed. On the other hand, the dimensional change rate of the sample with the adhesive sheet layer bonded was 0.12%, and warping was observed. This result shows that when there is no bonding of the adhesive sheet layer, the dimensional change is small and the warp is excellent.

  As a conductive material composed of a silver paste, an epoxy paste resin (a mixture of 70 parts by weight of bisphenol A and 30 parts by weight of bisphenol F was mixed with flaky silver having an average particle size of 2.6 μm to 55% of the total volume. 1 to 4 except that the volume% and the latent curing agent added and mixed) and the adhesive sheet shown in Table 1 were used (however, the release layer 4) A multilayer printed wiring board was prepared in such a manner that the number of via holes 5 was 8 and the diameter of the through hole 12 was 300 μm). Table 1 shows the results of measuring the reflow non-defective rate and the reliability after reflow (resistance change after leaving at high temperature and high humidity) for the obtained multilayer printed wiring board. In addition, Table 1 also shows the results of measuring the longitudinal elastic modulus (Young's modulus) of the adhesive sheet.

Each evaluation value was measured and evaluated as follows.
Reflow non-defective rate: The multilayer printed wiring board was heated at a temperature of 260 ° C. for 5 seconds and a total heating time of 300 seconds, and the ratio of the multilayer printed wiring board having a resistance change within 10% was obtained.
Reliability after reflow (resistance change after leaving at high temperature and high humidity): The range of resistance change rate (%) after being kept in an atmosphere of 85 ° C. and humidity of 85% for 1000 hours was determined. Here, the resistance value is a value obtained by measuring the resistance value of the circuit coupled with the silver paste filled in the eight via holes by the four-terminal method. The resistance of the silver paste and the resistance of the conductive layer (circuit) , And the total contact resistance of the silver paste and the conductive layer. A multilayer printed wiring board having a resistance change of 20% or less was regarded as a non-defective product, and the range of the resistance change rate and the ratio of non-defective products are shown in Table 1.
Longitudinal elastic modulus (Young's modulus): IPC-TM-650 2.4.19, based on Tensilon method, tensile speed 50 mm / min. Measured with

＊１： 新日鐵化学株式会社製熱可塑性ポリイミド系ボンディングシート
＊２： 巴川製紙製熱硬化性エポキシ系ボンディングシート（低弾性高接着フィルム）
＊３： 巴川製紙製熱硬化性イミド系ボンディングシート（高耐熱性接着フィルム）
＊４： 味の素ファインテクノ製ボンディングシート

* 1: Thermoplastic polyimide bonding sheet manufactured by Nippon Steel Chemical Co., Ltd. * 2: Thermosetting epoxy bonding sheet (low elasticity, high adhesive film) made by Yodogawa Paper
* 3: Ayukawa Paper's thermosetting imide bonding sheet (high heat-resistant adhesive film)
* 4: Ajinomoto Fine Techno bonding sheet

In addition, although the following evaluation was also performed about the reliability after the reflow of the said multilayer printed wiring board, in any case, the yield rate of 100% was obtained.
Heat cycle: A multilayer printed wiring board having a resistance change of 10% or less after repeating a cycle of holding at −40 ° C. for 30 minutes, raising the temperature and holding at 125 ° C. for 30 minutes 1000 times was determined as a good product.
High-temperature standing: A multilayer printed wiring board having a resistance change of 10% or less after leaving at 85 ° C. for 1000 hours was regarded as a good product.
Low temperature standing: A multilayer printed wiring board having a resistance change of 10% or less after leaving at -40 ° C. for 1000 hours was regarded as a good product.
Migration after standing at high temperature and high humidity: A multilayer printed wiring board having a resistance of 10 ⁸ Ω or more after leaving at 85 ° C. and a humidity of 85% for 1000 hours was regarded as a good product.

  From the results of the above test examples, it is clear that the multilayer printed wiring board according to the present invention does not cause the problem of warping when the manufacturing process is bonded. Further, the multilayer printed wiring board of the present invention has a large interlayer adhesion strength, but, as is clear from the results shown in Table 1, etc., has an excellent reflow yield rate and reliability after reflow. In particular, even when thermosetting epoxy resin is used as the adhesive sheet, excellent reflow yield rate equivalent to or better than when using thermoplastic polyimide resin or thermosetting polyimide resin, reliability after reflow It is clear from the results in Table 1 and the like.

  In addition, when an adhesive sheet made of Espanex SPB-035A, TLF-Y, TLF-B having a longitudinal elastic modulus in the range of 0.001 GPa or more and 3 GPa or less is used, a particularly excellent reflow yield rate is obtained. Has been obtained. Further, when an adhesive sheet made of TLF-Y, a thermosetting epoxy resin, is used, particularly excellent reliability after reflow is obtained.

It is process drawing which shows 1 process of an example of the manufacturing method of this invention. It is process drawing which shows 1 process of an example of the manufacturing method of this invention. It is process drawing which shows 1 process of an example of the manufacturing method of this invention. It is process drawing which shows 1 process of an example of the manufacturing method of this invention. It is process drawing which shows 1 process of another example of the manufacturing method of this invention. It is process drawing which shows 1 process of another example of the manufacturing method of this invention. It is process drawing which shows 1 process of another example of the manufacturing method of this invention. It is process drawing which shows the process of the manufacturing method of the conventional multilayer printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 14 Polyimide resin sheet 2, 13, 21 Copper adhesion layer 3, 22 Copper adhesion laminated board 4 Release layer 5, 24 Via hole 6 Conductive substance filling part 7 Bump 11 Adhesive sheet 12 Through-hole 20 Resin film 25 Conductive paste 27 Copper-clad laminate 26, A, A1, A2, A3 Single-sided wiring board substrate 23, B, B1, B2, B3 Adhesive sheet layer C, C ′, C ″ Double-sided wiring board substrate 15, 16, 17, 18 , 28 Multilayer printed wiring board

Claims (12)

Obtained by filling a conductive material into an insulating substrate, a conductive layer circuit provided on one surface thereof, and a via hole formed in the insulating substrate so as to reach the conductive layer circuit and open on the other surface. Single-sided wiring board substrate having a conductive bump formed thereon,
An adhesive sheet layer having a through-hole having a diameter larger than the via hole at a position corresponding to the via hole, and another wiring board substrate having a conductive layer circuit at a position corresponding to the via hole;
At least three layers,
A multilayer printed wiring board characterized in that the adhesive sheet layer is sandwiched between the wiring board substrates and the bumps are inserted so as to be inserted into the through holes, and these are laminated and pressed together. Production method.   2 or more of the single-sided wiring board substrate, 2 or more of the adhesive sheet layer, and the other wiring board substrate, the adhesive sheet layer is sandwiched between the wiring board substrates, and the bumps penetrate the 2. The method of manufacturing a multilayer printed wiring board according to claim 1, wherein the layers are alternately stacked so as to be inserted into the holes, and these are collectively laminated and pressed.   The other wiring board base material has an insulating substrate and conductive layer circuits on both surfaces thereof, and a conductive layer circuit on both surfaces by a conductive material filled in a through hole penetrating the insulating substrate. The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the substrate is a double-sided wiring board base member connected between the two.   4. The multilayer print according to claim 1, wherein the diameter of the through hole of the adhesive sheet layer is 1.5 to 5 times the diameter of the via hole of the single-sided wiring board substrate. A method for manufacturing a wiring board.   The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 4, wherein the conductive layer circuit is made of a material mainly composed of copper.   The method for producing a multilayer printed wiring board according to any one of claims 1 to 5, wherein the insulating substrate is a resin film mainly composed of polyimide.   The multilayer printed wiring board according to any one of claims 1 to 6, wherein the adhesive sheet mainly comprises a thermoplastic polyimide resin, a thermosetting epoxy resin, or a thermosetting imide resin. Method.   The method for producing a multilayer printed wiring board according to claim 7, wherein the adhesive sheet is mainly composed of a thermosetting epoxy resin.   The method for producing a multilayer printed wiring board according to claim 7 or 8, wherein a longitudinal elastic modulus of the adhesive sheet is 0.001 GPa or more and 3 GPa or less.   The method for producing a multilayer printed wiring board according to any one of claims 1 to 9, wherein the adhesive sheet is a sheet obtained by impregnating a highly rigid porous material with an adhesive.   The multilayer printed wiring board according to any one of claims 1 to 9, wherein the adhesive sheet is a sheet obtained by sandwiching a highly rigid insulating film layer between two adhesive layers. Production method. A multilayer printed wiring board manufactured by the method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 11.

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