JP2006210766A - Multilayer printed-wiring board and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer printed-wiring board, capable of obtaining high productivity when three or more layers of a wiring board, a copper foil or the like are to be laminated, that causes no problems, such as warpages when laminating, and obtaining large interlayer adhesion strength, and to provide the multilayer printed-wiring board manufactured by the method. <P>SOLUTION: The multilayer printed-wiring board employs a conductive base material (L), having a conductor bump formed, an insulation substrate having a circuit on its surface, a hole formed in the insulation substrate and filled with a conductive substance, a wiring board base material (M) having a conductor bump formed, as needed, and an adhesive sheet layer (O) having a through-hole with a diameter larger than that of the bump. The total number of the conductive base material (L) and the wiring board base material (M) is three or more. The adhesive sheet layer (O) is sandwiched between the conductive base material (L) and the wiring board base material (M). They are laminate-pressed together. Thus, the manufacturing method of the multilayer printed-wiring board is realized, and the multilayer printed-wiring board manufactured by the method is also disclosed. <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 method.

  As a method for manufacturing a multilayer printed wiring board, IVH (Interstitial Via Hole) is known in which holes formed between adjacent conductor layers (circuits) are filled with a conductive material to connect the circuits of adjacent layers (interlayer connection). It has been. With IVH, an interlayer connection can be formed only in a necessary portion, so that a high-density wiring with a high degree of freedom is possible.

  A multilayer printed wiring board manufactured by IVH is described in, for example, Fujikura Technical Report No. 103, pages 49-51 (announced in October 2002). In manufacturing this multilayer printed wiring board, first, a circuit is formed by etching a copper foil of a single-sided copper-clad laminate (CCL) in which a copper foil is attached to one side of a heat-resistant film represented by polyimide. Then, after bonding an adhesive layer on the surface opposite to the copper foil, drilling is performed, and the formed via hole (bottomed hole) is filled with a conductive paste to obtain a wiring board substrate. Thereafter, the wiring board substrate and another copper-clad laminated board on which a circuit is formed are stacked and pressed with a cure press to be bonded to each other.

  In this method, heating is required twice, that is, the stage of bonding the single-sided copper-clad laminate and the adhesive layer and the stage of interlayer adhesion, and productivity is low. In addition, the single-sided copper-clad laminate and the adhesive layer usually differ greatly in elastic modulus and coefficient of thermal expansion, so warping and stress distortion occur at the time of bonding, and misalignment is likely to occur at the via hole formation stage, etc. There is also a problem that the defect rate increases. Moreover, when producing a multilayer printed wiring board in which three or more copper-clad laminates are laminated, it is necessary to repeat the bonding of the adhesive layers and the interlayer adhesion a plurality of times, so that the productivity is further lowered.

  In Japanese Patent Laid-Open No. 8-288649, a conductive paste (bump) that flows by pressurization and heating at the time of laminating press is provided at an interlayer connection portion of a wiring board (single-sided copper-clad laminated board). And a step of laminating and integrating the adhesive layer (interlayer adhesive insulating film) having a through-hole larger than the bump and the copper foil at a position corresponding to the above and pressurizing and heating (stacking press) A method for manufacturing a multilayer printed wiring board is described. In this method, the step of bonding the wiring board (single-sided copper-clad laminate) and the adhesive layer is not necessary, and problems such as warpage during bonding can be prevented.

However, by this method, even when three or more layers of wiring boards and copper foils are laminated to produce a multilayer printed wiring board, bump formation, bonding with an adhesive layer and other copper foils or wiring boards, and laminating press steps It was difficult to obtain satisfactory productivity.
JP-A-8-288649 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, and even when three or more layers of wiring boards, copper foils, etc. are laminated, high productivity is obtained, and the problem of warpage during bonding is caused. It is another object of the present invention to provide a method for producing a multilayer printed wiring board capable of obtaining a large interlayer adhesion strength. The present invention also provides a multilayer printed wiring board manufactured by the manufacturing method.

The above issues are
Conductive base material (L) in which a bump of a conductive material, that is, a conductor bump is formed at a predetermined position on the main surface,
An insulating substrate, a circuit provided on one surface of the insulating substrate, and a via hole formed in the insulating substrate so as to reach the circuit and open on the other surface is filled with a conductive material, and a conductor is provided on the via hole. A single-sided wiring board substrate (M1) obtained by forming bumps, an insulating substrate, and a circuit on both surfaces of the insulating substrate, and a conductive material filled in holes penetrating the insulating substrate. Double-sided wiring board substrate (M2) in which the upper circuits are connected and, if necessary, conductor bumps are formed on the circuits
A wiring board substrate (M) selected from the group consisting of: an adhesive sheet layer (O) having a through-hole having a diameter larger than the diameter of the bump at a position corresponding to the bump;
The total number of the conductive substrate (L) and the wiring board substrate (M) is 3 or more,
The conductive base material (L) is arranged on one or both outsides, and the adhesive sheet layer (O) is placed between the conductive base material (L) and the wiring board base material (M) or two or more wirings. A method of manufacturing a multilayer printed wiring board, wherein the bumps are sandwiched and overlapped so as to be inserted into the through-holes between board bases (M), and these are collectively stacked and pressed (claim) Item 1) is achieved.

  As a result of the study, the inventor has a conductive base material (L) in which a conductor bump is formed at a predetermined position on the main surface, and a circuit only on one surface of the insulating substrate. Circuit on both surfaces of the single-sided wiring board substrate (M1) and / or insulating substrate having bumps to be connected to each other, and the circuits on both surfaces are electrically connected Adhesive sheet layer (O) having a through-hole having a diameter larger than the diameter of the bump at a position corresponding to the bump between each of the three or more layers in total, with the double-sided wiring board substrate (M2) having the bump A multilayer printed wiring board in which three or more layers of conductive substrates and wiring board substrates are laminated by a method of sandwiching and stacking them so as to be inserted into the through holes, and laminating and pressing them together. Can be manufactured with high productivity by a simple process, and when bonding Not occur warpage problems such as also found that it is possible to obtain large interlayer adhesion strength, and have completed the invention of claim 1.

  The present invention further provides a method for producing a multilayer printed wiring board as described below, as a preferred embodiment of the invention of claim 1.

  In the method for producing a multilayer printed wiring board, the diameter of the through hole of the adhesive sheet layer (O) is 1.5 to 5 times the diameter of the corresponding bump. A method for producing a multilayer printed wiring board (claim 2).

  The diameter of the through hole of the adhesive sheet layer (O) is preferably 1.5 to 5 times the diameter of the corresponding conductor bump. If it is less than 1.5 times, it becomes difficult to align the adhesive sheet layer (O), the conductive base material (L) and the wiring board base material (M), and the bumps are inserted into the through holes. It is easy to happen. On the other hand, when it is 5 times or more, it becomes difficult to flow until the adhesive sheet layer (O) and the bump come into contact with each other at the time of the lamination press, and there is a possibility that the gap between the two is not eliminated. More preferably, it is 3 to 5 times.

  The method for producing a multilayer printed wiring board, wherein the adhesive sheet layer (O) has a three-layer structure of an adhesive layer / insulating film layer / adhesive layer. (Claim 3).

  The adhesive sheet layer (O) bonds between the conductive substrate (L) and the wiring board substrate (M) or between two or more wiring board substrates (M). At the same time, the role of insulating the circuit between the conductive substrate (L) and the wiring board substrate (M) is also required. Accordingly, there may be a case where excellent insulating properties as well as excellent adhesive strength are required, but it is difficult to select a material having both adhesive strength and insulating properties. However, the adhesive sheet layer (O) has a three-layer structure of adhesive layer / insulating film layer / adhesive layer, and the adhesive layer has a material with excellent adhesive strength and the insulating film layer has a superior insulating property. By using, it becomes easy to select a material, and it is possible to achieve excellent insulation as well as excellent adhesive strength.

  The adhesive sheet layer (O) is also required to have a function of flowing during the laminating press to eliminate the gap between the through hole and the conductor bump. Therefore, in order to easily eliminate the gap, a material formed from a material that easily undergoes plastic deformation is preferably used.

  4. The method for producing a multilayer printed wiring board according to claim 3, wherein the insulating film layer constituting the adhesive sheet layer (O) is a resin film mainly composed of polyimide. A method for manufacturing a plate (Claim 4).

  As the insulating film layer constituting the adhesive sheet layer (O) having a three-layer structure, a resin film mainly composed of polyimide having excellent insulating properties and excellent mechanical strength is preferable.

  The method for producing a multilayer printed wiring board, further comprising: forming an insulating resin layer on the surface of the circuit board (M) having a circuit that does not come into contact with the conductor bumps and faces each other after the lamination press. A method for producing a multilayer printed wiring board, comprising: providing a multilayer printed wiring board.

  Having an opposing circuit means that an adjacent substrate has a circuit at a position facing the circuit. The circuits are not connected by bumps even after the lamination press, and therefore insulation between the circuits is required. However, by providing an insulating resin layer, the insulation can be improved.

  6. The method for producing a multilayer printed wiring board according to claim 5, wherein the insulating resin layer is made of a resin mainly composed of polyimide (Claim 6). .

  As the insulating resin layer, a resin film mainly composed of polyimide, which has excellent insulating properties and excellent mechanical strength, is preferable.

  The present invention further provides a multilayer printed wiring board manufactured by the above-described method for manufacturing a multilayer printed wiring board (Claim 7). This multilayer printed wiring board has a large interlayer adhesion strength and a high reliability of interlayer connection. Conductive bumps are directly connected to the outermost conductive substrate (L), and conductive lands can be formed directly above the bumps, improving circuit design flexibility and high-density mounting of many components. In addition, connection at the shortest distance between components is easy.

  According to the method for producing a multilayer printed wiring board of the present invention, high productivity can be obtained even when a multilayer printed wiring board having a large number of circuit layers is produced by laminating three or more layers of a wiring board substrate and the like. A large interlayer adhesive strength can be obtained without causing a problem of warpage during the alignment. In addition, the multilayer printed wiring board of the present invention manufactured by this manufacturing method has various interlayer adhesive strengths, high interlayer connection reliability, and various wiring boards capable of high-density mounting of many parts. It is suitably used for the manufacture of electrical products.

  Next, the best mode for carrying out the present invention will be described. 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.

  The conductive substrate (L) can be obtained by forming a conductor bump at a predetermined position on the main surface of the substrate made of a conductor layer. The main surface is one surface of the substrate made of the conductive layer, and refers to a surface on which conductive bumps, that is, protrusions of conductive materials are formed. The predetermined position where the conductor bump is formed is a position intended for connection between adjacent circuits.

  The conductor bump is preferably one that undergoes plastic deformation under the conditions of heating and pressurization during the lamination press. During the laminating press, the conductor bumps are plastically deformed to fill the gaps between the conductor bumps and the through holes. Examples of the material that plastically deforms under the conditions of heating and pressurization during the lamination press include silver paste, conductive paste such as copper filler and carbon mixture paste, solder cream, low melting point metal, and the like. A bump is preferably exemplified.

  The method for forming the conductor bump is not particularly limited, and examples thereof include a method in which a conductive paste or the like is applied on a conductive substrate by screen printing, a method in which the conductive bump is applied by an inkjet method, and the like.

  The height of the conductor bump is preferably larger than the thickness of the adhesive sheet layer (O) when a plastically deformable material is used. Increasing the height is preferable because the tips of the conductor bumps flow and expand during the laminating press, so that reliable electrical connection is achieved and the gap between the conductor bumps and the through holes is filled. When the conductor bump is difficult to be plastically deformed, the height of the conductor bump is preferably substantially the same as the thickness of the adhesive sheet layer (O) after the lamination press. If the height is smaller than the thickness of the adhesive sheet layer (O) after the laminating press, connection failure is likely to occur. On the other hand, if the height is larger, insufficiently bonded parts, deformation of the conductive substrate, etc. Reliability may be reduced.

  Examples of the shape of the conductor bump include a columnar shape, a conical shape, a truncated cone shape, a hemispherical shape, and a shape obtained by combining a cylindrical shape with a conical or hemispherical tip. If the height (thickness) of the conductor bump is thicker than the adhesive sheet layer (O) and its tip is deformed during laminating press, the tip is conical, frustoconical, or hemispherical, so it is easy to deform. preferable.

  A typical example of the material for forming the substrate made of the conductive layer of the conductive base material (L) is copper foil. The conductor layer is superposed on the wiring board substrate (M) and the adhesive sheet layer (O), and is usually subjected to a laminating press followed by etching or the like to form a circuit (patterning). As an etching method, for example, a circuit pattern of a resist layer is formed on a conductive substrate (L), and then immersed in an etchant that corrodes the conductive substrate (L), so that portions other than the circuit pattern are formed. And chemical etching (wet etching) for removing the resist layer. 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.

  The single-sided wiring board substrate (M1) can be manufactured by forming via holes, conductor bumps, and circuits on an insulating substrate having a conductor layer attached to one surface. Here, as an insulating board | substrate with which the conductor 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 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 on which the conductor layer is attached, and the other end reaches the conductor layer.

  After the via hole is formed, the via hole is filled with a conductive material, and a conductor bump is formed. 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.

  The method for forming the conductor bumps on the single-sided wiring board substrate (M1) is not particularly limited. For example, a release layer is formed on an insulating substrate, and a via hole penetrating the insulating substrate and the release layer is formed. Then, after filling the via hole with a conductive material, the release layer is peeled off to form the protrusion. 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 for forming the conductor bumps, there is a method in which after a via hole is filled with a conductive material, a conductive paste or the like is further applied thereon by screen printing.

  The circuit can be formed by, for example, etching the conductor layer (patterning). The etching process can be performed by the same method as that for the conductive base material (L). 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 double-sided wiring board substrate (M2) includes, for example, a process of forming a circuit by performing etching or the like on a copper foil of a polyimide film having a copper foil attached to both surfaces, and a copper foil (conductor layer) on both surfaces ) And a polyimide film (insulating substrate) are formed, and the hole is filled with a conductive material, and the method includes a step of connecting the copper foils on both surfaces. Either the step of forming the circuit and the step of connecting the copper foil may be performed first. The formation of the circuit and the filling of the conductive material into the hole can be performed in the same manner as in the case of the single-sided wiring board substrate (M1), and the both surfaces are connected by plating the wall surface of the hole. You can also.

  Formation of the holes penetrating the conductor layers on both surfaces and the insulating substrate can be performed by an NC drill, a laser, or the like.

  Conductive bumps may be formed on the circuit in the double-sided wiring board substrate (M2) as necessary. By this bump, it is possible to electrically connect to the circuit of the conductive substrate (L), the single-sided wiring board base (M1), or another double-sided wiring board base (M2).

  As described above, copper foil is exemplified as the conductor layer of the wiring board substrate (M), that is, the conductor layer that becomes a circuit after patterning.

  The total number of conductive base materials (L) and wiring board base materials (M) is 3 or more. According to the production method of the present invention, even when a multilayer printed wiring board is produced by laminating such a large number of base materials, a high productivity can be obtained because they are laminated and pressed together.

  An electroconductive base material (L) is arrange | positioned on the outer side of one or both of the laminated body which is piled up and laminated | stacked and pressed collectively. Since it is necessary to perform circuit formation by etching after laminating press on the conductive layer of the conductive base material (L), the conductive base material (L) is placed between the two wiring board base materials (M). Not.

  As a wiring board base material (M), when it consists only of a single-sided wiring board base material (M1), when it consists only of a double-sided wiring board base material (M2), a single-sided wiring board base material (M1) and a double-sided wiring board base material The case consisting of (M2) is mentioned. When the double-sided wiring board substrate (M2) does not have bumps, the substrate on both sides must be a conductive substrate (L) or a wiring board substrate (M) having bumps. The direction is reversed on both sides.

  In the manufacturing method of the multilayer printed wiring board of this invention, the wiring board base material chosen from the group which consists of said electroconductive base material (L), single-sided wiring board base material (M1), and double-sided wiring board base material (M2). (M) is overlapped while sandwiching the adhesive sheet layer (O) between the conductive substrate (L) and the wiring board substrate (M) or between two or more wiring board substrates (M). These are collectively laminated and pressed to produce a multilayer printed wiring board.

  The adhesive sheet layer (O) has a through-hole having a diameter larger than the diameter of the bump at a position corresponding to the bump. Having a through hole at a position corresponding to a bump means that the through hole is formed so that the bump is inserted into the through hole when the conductive substrate and the adhesive sheet layer (O) are stacked. means.

  The method of forming this through-hole is not particularly limited, and a laser drilling process (when the thickness is less than 100 μm), a mechanical drilling method using a drill, or the like can be employed. As described above, the diameter of the through hole of the adhesive sheet layer (O) is preferably 1.5 to 5 times the diameter of the corresponding bump (that is, inserted into the through hole), more preferably 3 ~ 5 times. When the thickness of the bump is different between the tip side and the bottom surface side, the reference bump diameter is an average of the diameters. For example, if the bump shape is a truncated cone, the diameter obtained by adding the tip diameter and the bottom diameter and dividing by 2 is the reference.

  The adhesive sheet layer (O) is sandwiched by bringing the surface having the bumps of the conductive base material (L) or the wiring board base material (M) on one side and the other side on the other side. The surface having the circuit of (M) is brought into contact with each other, and the bump is inserted into the through hole of the adhesive sheet layer (O). The bump is provided at a position corresponding to the circuit of the other wiring board substrate (M), and is connected to this circuit after the lamination press.

  The adhesive sheet layer (O) flows during the laminating press. That is, plastic deformation is performed under the heating and pressurizing conditions of the laminate. This property eliminates the gap between the bump and the through hole during the lamination press.

  As the adhesive sheet layer (O), 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 layer is not sufficiently expanded during the lamination press, and the gap between the bump and the through hole 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 present invention is characterized in that the laminating press is performed in a lump after superposing all necessary conductive base materials (L), adhesive sheet layers (O) and wiring board base materials (M). Lamination press should be performed while positioning using positioning pins, etc., in order to ensure that the bumps are inserted into the through-holes, and to ensure that the bumps are in contact with a predetermined position of the circuit portion after patterning. Is preferred.

  Lamination press is performed by heating and pressurizing with a vacuum press, a cure press, or the like. The gap between the through-hole of the adhesive sheet layer (O) and the bumps is expanded by the laminating press until the adhesive sheet layer (O) comes into contact with the conductive material of the bumps and is eliminated. When the material of the bump is fluid, the bump may also flow. Further, when the conductor layer is patterned before lamination and a step is generated, the step is also eliminated by the flow of the adhesive sheet layer (O) or the like during the lamination press.

  When the adhesive sheet layer (O) has a three-layer structure of adhesive layer / insulating film layer / adhesive layer, the material of the adhesive layer is an adhesive force between the insulating layer and the conductive substrate after lamination. Those which are high and have sufficient fluidity under the heating and pressurizing conditions during the lamination press are preferably used. However, since the insulating film layer has an insulating layer, high adhesiveness is not necessarily required for the adhesive layer.

  Therefore, the selection of the material is facilitated, and more excellent adhesiveness and insulation properties are achieved as a whole of the adhesive sheet layer (O), and the fluidity is also improved. Specifically, examples of the material of the adhesive layer include a resin mainly composed of a thermoplastic polyimide resin, a thermosetting epoxy resin, or a thermosetting imide resin. The thickness of the adhesive layer is selected from the range of 5 to 40 μm, which is required in order to obtain a sufficient adhesive force and a thickness necessary for eliminating the gap between the conductor bump and the through hole. The preferred range varies depending on the ratio of the diameter of the conductor bumps.

  As the insulating film layer of the adhesive sheet layer (O), a material having excellent insulating properties is used, and the resin film (polyimide film) mainly composed of polyimide as described above is preferably used. The thickness of the polyimide film is usually preferably in the range of 12 to 50 μm.

  The three-layer structure of adhesive layer / insulating film layer / adhesive layer is, for example, a coating device, a roll coater, and other coatings on the both sides of the insulating film layer. It can be formed by coating using a machine. Moreover, it can form also by bonding together the adhesive agent formed in the sheet form, and the insulating film.

  When the insulating resin layer is provided on the surface of the circuit board (M) that is not in contact with the conductor bump after the lamination press, that is, in the case of the aspect of claim 5, the insulating resin layer has excellent insulation. Preferred examples include those made of a material having a property and made of a resin mainly composed of polyimide as described above (polyimide film).

  The insulating resin layer is a portion where insulation between adjacent base materials is required, that is, a circuit of the base material, and is opposed to the circuit of the adjacent base material and electrically connected to the circuit of the adjacent base material. It is formed on the surface of a circuit that is not connected (a circuit that does not contact the bump). Insulation is not required for a circuit that comes into contact with the bump, that is, a circuit that is electrically connected to a circuit of an adjacent base material, and thus it is not necessary to provide an insulating resin layer.

  However, an insulating resin layer may be provided for reasons of manufacturing the insulating resin layer, etc., but if the insulating resin layer is formed at a position in contact with the conductive bump after lamination pressing, the conductive bump and Therefore, it is not formed at this position, nor is it formed around the position corresponding to the conductor bump in consideration of misalignment during the laminating press. In order to ensure the electrical connection, the diameter of the periphery where the insulating coating layer is not formed is preferably 1.5 times or more the tip diameter of the conductor bump.

  By forming the insulating resin layer, sufficient insulation can be secured even if the adhesive sheet layer (O) in this portion after the lamination press becomes thin, and the reliability of the multilayer printed wiring board is improved. As a result, the adhesive sheet layer (O) can be made thin, which is effective for improving the flexibility of the wiring board.

  Such an insulating coating layer is formed by screen-printing a liquid insulating resin or pasting an insulating film in which holes have been cut out in advance.

  Next, the example of the manufacturing method of the multilayer printed wiring board of this invention is demonstrated more concretely using figures.

(1) Production of conductive substrate (L) As a conductor layer of the conductive substrate (L), a copper foil having a thickness of 5 to 30 μm is used. FIG. 1a is a cross-sectional view of this copper foil. The copper foil is processed to form positioning marks and positioning holes (positioning pin insertion holes) at predetermined positions on the copper foil, and a copper paste is applied by screen printing. The predetermined height is 50 to 100 μm and the bump diameter is 100 μm. A conductor bump having a bump bottom diameter of 150 to 200 μm and a bump tip diameter of 30 to 70 μm is formed. If the height of one screen printing is insufficient, screen printing is performed twice or more. FIG. 1b is a cross-sectional view of a copper foil, ie, a conductive substrate (L), with conductor bumps formed thereon. Instead of the copper paste used in this example, other conductive paste such as silver paste or carbon mixture paste, solder cream, low melting point metal or the like can be used.

(2) Production of Adhesive Sheet Layer (O) FIG. 2 shows a production process of the adhesive sheet layer (O). The adhesive sheet layer (O) of this example has a three-layer structure of adhesive layer / insulating film layer / adhesive layer. FIG. 2 a is a cross-sectional view thereof, and both adhesive layers are made of a thermosetting epoxy resin, and the thicknesses thereof are 10 to 25 μm, respectively. An insulating film layer is a polyimide film layer, Comprising: The thickness is 12-25 micrometers. A through-hole having a diameter of 300 μm (three times the bump diameter) is drilled at a predetermined position (position corresponding to the bump) of the laminate having the three-layer structure. Also, positioning marks and positioning holes are made. It is also possible to open using a laser instead of a drill. FIG. 2 b is a cross-sectional view of the laminate (adhesive sheet layer (O)) after the through holes are formed. The adhesive sheet layer (O) thus produced is referred to as an adhesive sheet layer O1.

  In addition, a through-hole having a diameter of 300 μm (three times the bump diameter) is drilled at a predetermined position (position corresponding to the bump) of the sheet made of adhesive and having a thickness of 50 μm, and the adhesive sheet layer (O) (shown) Not obtained.) The adhesive sheet layer (O) thus produced is referred to as an adhesive sheet layer O2.

(3) Production of single-sided wiring board substrate (M1) FIG. 3 is a process diagram showing a production process of an example of a single-sided wiring board substrate used for forming a multilayer printed wiring board. A single-sided copper-clad laminate (CCL, FIG. 3a) in which a 12.5 μm-thick copper foil is pasted on one side of a polyimide film 1 having a thickness of 25 μm is used, and the copper foil 2 is masked and wet-etched. A circuit pattern is formed on the substrate (FIG. 3b).

  Next, a release layer 4 made of PET having a thickness of 50 μm is pasted on the surface of the polyimide film 1 opposite to the surface on which the copper foil 2 is provided (FIG. 3 c). A via hole 5 (bottomed hole, blind via) is formed (FIG. 3d). 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. 3e). Thereafter, the release layer 4 is removed to form a conductor bump 7 having a protrusion with a height of 40 μm (FIG. 3 f), thereby obtaining a single-sided wiring board substrate M <b> 1. 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.

(4) Preparation of double-sided wiring board substrate (M2) FIG. 4a is a double-sided copper-clad laminate in which copper foil 12 is pasted on both sides of polyimide film 11 (CCL, Espanex SB18-25-18 manufactured by Nippon Steel Chemical Co., Ltd.). FIG. The copper foil 12 on both sides of this double-sided copper-clad laminate is masked and wet etched to form a circuit pattern on the copper foil 12. Then, the through-hole 13 is formed in this double-sided copper-clad laminate (FIG. 4b). The through hole 13 is formed by an NC drill or a laser. After the through hole 13 is formed, a conductive material made of silver paste is filled in the through hole 13 by squeezing using a squeegee plate used for screen printing, and a conductive material filling portion 14 is formed. The foils 12 (circuits) are connected (FIG. 4c). The double-sided wiring board substrate (M2) thus produced is referred to as a double-sided wiring board substrate M2A.

  The double-sided wiring board substrate (M2) on which the bumps are formed is formed by bump-printing a conductive material made of silver paste on one side of the through-hole 13 filled with the conductive material, and drying to form the bump 15 (Fig. 4d). The double-sided wiring board substrate (M2) having the bumps thus produced is referred to as a double-sided wiring board substrate M2B. Bump formation can also be performed using a release layer, as in the case of the single-sided wiring board substrate (M1), instead of bump printing and drying.

(5) Production of Wiring Board Base Material M3 FIG. 5a is a cross-sectional view of a single-sided copper-clad laminate (CCL, Espanex SC18-25-00 manufactured by Nippon Steel Chemical Co., Ltd.) in which a copper foil is pasted on one side of a polyimide film. . The copper foil on one side of this single-sided copper-clad laminate was patterned by etching to form a circuit, and a wiring board substrate M3 was obtained (FIG. 5b). A positioning mark and a positioning hole are also formed in the wiring board substrate M3.

  Next, the conductive base material (L), single-sided wiring board base material (M1), double-sided wiring board base material M2A, double-sided wiring board base material M2B, adhesive sheet layer O1, and adhesive obtained as described above. The process of manufacturing the multilayer printed wiring board of the present invention by superposing and laminating using the agent sheet layer O2, the wiring board substrate M3, etc. will be described with reference to the drawings.

  FIG. 6 shows a multilayer printed wiring board produced by laminating and pressing a conductive substrate (L), a single-sided wiring board base (M1), and a double-sided wiring board base M2A while sandwiching the adhesive sheet layer O1. It is process drawing which shows a process.

(1) Superposition First, positioning pins are used in the order of conductive base material (L), adhesive sheet layer O1, single-sided wiring board base material (M1), adhesive sheet layer O2, and double-sided wiring board base material M2A. Then, superimpose so that bumps and through holes overlap. FIG. 6 a is a cross-sectional view showing this overlapping state.

(2) Pressing Thereafter, temporary bonding is performed within a temperature range where the adhesive layer is not completely cured. Furthermore, these are pressed (pressurized) and heated together by a vacuum press. FIG. 6 b is a cross-sectional view of the laminate after the lamination press. The conductor bumps and the adhesive layer flow during the laminating press to fill the gaps between the bumps and the through holes and the steps of the circuits formed on the single-sided wiring board substrate (M1) and the double-sided wiring board substrate M2A. . Since the pressurization is continued while cooling after completion of heating, almost no warping or the like occurs.

(3) Patterning After the lamination press is completed, the multilayer printed wiring board of the present invention is obtained by masking the copper foil of the conductive base material (L) and performing appropriate wet etching to perform patterning. FIG. 6 c is a cross-sectional view of the multilayer printed wiring board thus obtained.

  FIG. 7 is a process diagram showing a process of manufacturing a multilayer printed wiring board in which a single-sided wiring board substrate (M1) is further laminated on the multilayer printed wiring board in the example of FIG.

(1) Forming an insulating resin layer A method of pasting an insulating liquid polyimide on a surface of a part of a circuit of a single-sided wiring board substrate (M1) or bonding an insulating polyimide film in which holes have been cut out in advance. An insulating resin layer is formed by the above. FIG. 7a shows a single-sided wiring board substrate (M1) on which this insulating resin layer is formed. This is designated as a single-sided wiring board substrate M1A. Here, a part of the circuit in which the insulating resin layer is formed is a part that does not come into contact with the conductor bump after the lamination press and has a circuit that faces the circuit.

(2) Superposition First, conductive base material (L), adhesive sheet layer O2, single-sided wiring board base material M1A, adhesive sheet layer O2, double-sided wiring board base material M2A, and other single-sided wiring board base materials (M1) ) In this order, the positioning pins are used so that the bumps and the through holes overlap. FIG. 7b is a cross-sectional view showing this superposed state. As is clear from FIG. 7b, the direction of the bumps is reversed between the single-sided wiring board substrate M1A and the other single-sided wiring board substrate (M1). In addition, an electroconductive base material (L) can also be used instead of another single-sided wiring board base material (M1). In this case, a multilayer printed wiring board in which the conductive substrate (L) is disposed on both outer sides is obtained.

(3) Pressing Thereafter, temporary bonding is performed within a temperature range in which the adhesive layer is not completely cured. Furthermore, these are pressed (pressurized) and heated together by a vacuum press. FIG. 7c is a cross-sectional view of the laminate after the lamination press. The conductor bumps and the adhesive layer flow during the laminating press to fill the gaps between the bumps and the through-holes and the steps of the circuit formed on the single-sided wiring board substrate (M1) or the double-sided wiring board substrate M2A. ing. Since the pressurization is continued while cooling after completion of heating, almost no warping or the like occurs.

(4) Patterning After completion of the lamination press, the multilayer printed wiring board of the present invention is obtained by masking the copper foil of the conductive base material (L) and performing patterning by appropriate wet etching. FIG. 7d is a cross-sectional view of the multilayer printed wiring board thus obtained.

  8 uses a double-sided wiring board substrate M2B having bumps instead of the double-sided wiring board substrate M2A in the multilayer printed wiring board of the example of FIG. 7, and the wiring board instead of the outer single-sided wiring board substrate (M1). This is an example using the base material M3. That is, the conductive substrate (L), the adhesive sheet layer O2, the single-sided wiring board substrate (M1), the adhesive sheet layer O2, the double-sided wiring board base material M2B, the adhesive sheet layer O2, and the wiring board base material M3. It is process drawing which shows the process of carrying out the lamination | stacking lamination press in order, and manufacturing a multilayer printed wiring board.

  Also in the example of FIG. 8, superposition, pressing, and patterning are performed in the same manner as in the examples of FIGS. FIG. 8a is a cross-sectional view showing the superimposed state. FIG. 8b is a cross-sectional view of the multilayer printed wiring board after lamination pressing and patterning. In place of the wiring board substrate M3, a single-sided wiring board substrate (M1) or a double-sided wiring board substrate (M2) is used, and another single-sided wiring board substrate (M1) or the like is overlapped to obtain a multilayer. It is also possible to manufacture a printed wiring board with high productivity by a batch laminating press.

It is process drawing which shows the manufacturing process of the electroconductive base material (L) used for this invention. It is process drawing which shows the manufacturing process of the adhesive sheet layer (O) used for this invention. It is process drawing which shows the manufacturing process of the single-sided wiring board base material (M1) used for this invention. It is process drawing which shows the manufacturing process of the double-sided wiring board base material (M2) used for this invention. It is process drawing which shows the manufacturing process of the wiring board base material used for this invention. It is process drawing which shows the lamination press process of an example of this invention. It is process drawing which shows the lamination press process of the other example of this invention. It is process drawing which shows the lamination press process of the other example of this invention.

Claims (7)

A conductive base material (L) in which conductor bumps are formed at predetermined positions on the main surface;
An insulating substrate, a circuit provided on one surface of the insulating substrate, and a via hole formed in the insulating substrate so as to reach the circuit and open on the other surface is filled with a conductive material, and a conductor is provided on the via hole. A single-sided wiring board substrate (M1) obtained by forming bumps, an insulating substrate, and a circuit on both surfaces of the insulating substrate, and a conductive material filled in holes penetrating the insulating substrate. Double-sided wiring board substrate (M2) in which the upper circuits are connected and, if necessary, conductor bumps are formed on the circuits
A wiring board substrate (M) selected from the group consisting of: an adhesive sheet layer (O) having a through-hole having a diameter larger than the diameter of the bump at a position corresponding to the bump;
The total number of the conductive substrate (L) and the wiring board substrate (M) is 3 or more,
The conductive base material (L) is arranged on one or both outsides, and the adhesive sheet layer (O) is placed between the conductive base material (L) and the wiring board base material (M) or two or more wirings. A method for producing a multilayer printed wiring board, wherein the bumps are sandwiched and overlapped so as to be inserted into the through-holes between the board substrates (M), and these are collectively laminated and pressed.   The method for producing a multilayer printed wiring board according to claim 1, wherein the diameter of the through hole of the adhesive sheet layer (O) is 1.5 to 5 times the diameter of the corresponding bump. .   The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the adhesive sheet layer (O) has a three-layer structure of adhesive layer / insulating film layer / adhesive layer.   The method for producing a multilayer printed wiring board according to claim 3, wherein the insulating film layer constituting the adhesive sheet layer (O) is a resin film mainly composed of polyimide.   The insulating resin layer is provided on the surface of the circuit board (M) having a circuit that does not come into contact with the conductor bump after lamination pressing and has an opposing circuit. The manufacturing method of the multilayer printed wiring board in any one.   The method for producing a multilayer printed wiring board according to claim 5, wherein the insulating resin layer is made of a resin mainly composed of polyimide. A multilayer printed wiring board manufactured by the method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 6.

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