JP4821276B2 - Multilayer printed wiring board manufacturing method and multilayer printed wiring board - Google Patents

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 technology that enables high-density mounting of components and can connect the components in the shortest distance (meaning that they are electrically connected. Hereinafter, simply referred to as “connection”). Yes. 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.

  A method for manufacturing a multilayer printed wiring board by IVH is described in, for example, Japanese Patent Application Laid-Open No. 2004-95963 (Patent Document 1). In this manufacturing method, after bonding an insulating base material provided with a conductive layer on one side and an adhesive layer, a bottomed via hole is formed in the insulating base material and the adhesive layer, and a conductive paste composition is formed in the via hole. And a bump is formed on the opening side to obtain a wiring board substrate, and a plurality of the wiring board substrates are laminated and pressed so that the bumps are in contact with conductive layers of other wiring board substrates. Printed wiring boards are manufactured.

  Here, the formation of the bottomed via hole (via opening process) does not cause a decrease in connection reliability, and therefore requires a precise process that does not damage the conductive layer made of copper foil or the like. Therefore, in this processing, it is necessary to perform drilling using an expensive laser, which complicates the process and causes an increase in cost.

  In addition, this method requires two heating steps in the bonding step with the adhesive layer and in the interlaminar bonding step, and each temperature must be changed. This also causes an increase in cost.

Therefore, development of a method for producing a multilayer printed wiring board capable of producing a multilayer printed wiring board having excellent connection reliability with a simple process and low cost has been desired.
JP 2004-95963 A

  The present invention provides a multilayer printed wiring board excellent in connection reliability, a manufacturing method of a highly productive multilayer printed wiring board that can be manufactured at a low cost and a simple process, and is manufactured by the manufacturing method and excellent in connection reliability. It is an object to provide a multilayer printed wiring board.

  As a result of the study, the inventor comprises an insulating substrate, a conductive layer provided on one surface thereof, a conductive portion formed by filling a conductive paste composition into a hole penetrating the insulating layer, and a conductive paste composition. Using a wiring board substrate having a bump having a diameter larger than the diameter of the conductive part, an adhesive sheet in which a through hole having a diameter larger than the bump is formed between the wiring board substrate and another wiring board substrate. A multilayer printed wiring board with excellent connection reliability can be easily obtained by stacking and pressing together so that the bumps of the wiring board substrate are inserted into the through-holes of the adhesive sheet. The present invention has been completed by finding that it can be produced at a low cost and with a simple process.

The present invention according to claim 1,
A wiring board substrate having an insulating substrate, a conductive layer provided on at least one surface thereof, and a conductive portion formed by filling a conductive paste composition A in a hole penetrating the insulating substrate and the conductive layer. A wiring board substrate a in which bumps having a diameter larger than the diameter of the conductive portion are formed of the conductive paste composition B in contact with both ends of the conductive portion;
An adhesive sheet in which a through hole having a larger diameter than the bump is formed at a position corresponding to the bump, and an insulating substrate and a wiring board substrate having a conductive layer provided on the surface thereof, Other wiring board substrate b having a conductive layer or a portion conducting to the conductive layer at a position corresponding to the bump
At least three layers of
A step of laminating and pressing the adhesive sheet between the insulating substrate of the wiring board base material a and the wiring board base material b and inserting the bumps into the through holes of the adhesive sheet. A method for producing a multilayer printed wiring board is provided.

  Here, as the insulating substrate constituting the wiring board base a, an insulating resin film can be used. A resin film mainly composed of PET or polyimide is exemplified, but considering the heat resistance during reflow, etc., it is preferable to use a resin film mainly composed of polyimide.

  A conductive layer is a circuit made of a conductor formed on the surface of an insulating substrate. When the conductive layer is the outermost layer of a multilayer printed wiring board, an element such as a semiconductor, an electronic component, etc. Is implemented. An insulating substrate having a conductive layer on one surface uses, for example, an insulating substrate having a conductive layer such as a metal foil attached to one surface, and the conductive layer is etched to form a conductive layer. Obtainable. Etching involves forming a resist layer circuit pattern on the conductive layer, then immersing the conductive layer in an etchant that corrodes, removing portions other than the circuit pattern, and then removing the resist layer (wet etching). Is exemplified.

  The material of the metal foil is preferably a material mainly composed of copper from the viewpoint of conductivity, durability, availability, etc., and examples thereof include copper or an alloy mainly composed of copper. In addition to copper, silver, aluminum, nickel, or the like may be used. 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 with which copper foil was affixed on the single side | surface is illustrated.

  An insulating substrate having a conductive layer on one surface can be obtained by applying a conductive paste composition on one surface of the insulating substrate so as to form a circuit pattern. Here, examples of the conductive paste composition include those obtained by kneading conductive particles, for example, metal fine particles, metal fillers, carbon fine particles, and the like into a resin that is easily plastically deformed. Specifically, a silver paste, a silver-coated copper filler, a copper filler or a carbon mixture paste, and the like are exemplified, and are applied onto the insulating substrate by means such as screen printing.

  In this way, after an insulating substrate having a conductive layer on one surface is obtained, a hole penetrating the conductive layer and the insulating substrate is formed at a predetermined position, that is, a position where an interlayer connection of the conductive layer is made. . Formation of this hole does not require expensive laser drilling, and a method of mechanically drilling using a drill or the like can be employed. Therefore, the production cost can be reduced as compared with the conventional method that requires the formation of a bottomed via hole.

  After forming a hole penetrating the conductive layer and the insulating substrate, the conductive paste composition is filled in the hole to form a conductive portion. This conductive paste composition is referred to as “conductive paste composition A”. Although the filling method of the electrically conductive paste composition A is not specifically limited, For example, the method of filling by screen printing is mentioned. As the conductive paste composition A, similar to the conductive paste composition used for forming the conductive layer, a mixture of metal fine particles, metal filler, carbon fine particles, etc., in a resin that can be easily plastically deformed. Specific examples include silver paste, silver-coated copper filler, copper filler and carbon mixture paste.

  After forming the conductive portion, bumps made of a conductive paste composition are formed in contact with both ends of the conductive portion, that is, on the surface of the insulating substrate and the conductive layer and at a position where the conductive portion is conducted. The wiring board base material a used for the manufacturing method of this invention is obtained. The conductive paste composition for forming the bumps is referred to as a conductive paste composition B.

  A bump made of a conductive paste composition is a protrusion of the conductive paste composition, and its formation method is not particularly limited. For example, a release layer made of polyethylene terephthalate (PET) or the like is formed on an insulating substrate. Then, a method of forming a projecting portion by forming a via hole penetrating the insulating substrate and the release layer, filling the via hole with a conductive paste composition, and peeling the release layer is exemplified. As another method for forming the bumps of the conductive paste composition, a method of filling the via paste with the conductive paste composition and then applying the conductive paste composition onto the via hole by screen printing is also included.

  The conductive paste composition B may be the same material as the conductive paste composition A. In consideration of the adhesiveness between the conductive portion and the bump, the same material is preferable. Therefore, as the material of the conductive paste composition B, the same materials as those exemplified for the conductive paste composition A are exemplified.

  The bump has a diameter larger than that of the conductive portion. By making the bump diameter larger than the diameter of the conductive part, the conductive layer and the bump come into contact with each other over a wide area. Therefore, the connection between the conductive layer and the bump and also between the conductive part is reliable. Thus, the connection reliability of the multilayer printed wiring board can be improved. Since the contact area between the conductive layer and the conductive portion is small, sufficient connection reliability cannot be obtained when the bump diameter is smaller than the diameter of the conductive portion.

  Preferably, the bump diameter is 1.2 times or more the diameter of the conductive portion. Claim 2 corresponds to this preferable mode. By setting it to 1.2 times or more, the connection reliability of the multilayer printed wiring board can be further increased, and excellent connection reliability that can withstand reflow conditions using Pb-free solder is obtained.

  The height of the bump is preferably in the range of 0.5 to 3.0 times the thickness of the adhesive sheet. If it is 0.5 or less, the connection with the other conductive layer portion may be poor. Yes, when it is 3.0 times or more, there is a problem that the flatness of the conductive layer portion is deteriorated due to insufficient crushing at the time of lamination pressing.

  The adhesive sheet used in the production method of the present invention is an adhesive such as a thermoplastic polyimide resin, a resin mainly composed of thermoplastic polyimide and partly having a thermosetting function, and a thermosetting resin such as an epoxy resin or an imide resin. It is a sheet | seat which has as a main component. As the adhesive that constitutes the adhesive sheet, a resin that has a thermosetting function, mainly a thermoplastic polyimide, a thermosetting epoxy resin, and a thermosetting imide resin, ensure sufficient adhesion after heat curing. This is preferable.

  In the adhesive sheet, through holes having a larger diameter than the bumps are formed at positions corresponding to the bumps. The position corresponding to the bump means a position overlapping with the bump, that is, a position where the bump is inserted in the lamination press.

  The method for forming the through hole is not particularly limited, and a method of mechanically drilling using a drill or the like can be employed.

  The diameter of the through hole is larger than the bump diameter. When the diameter of the through hole is smaller than the bump diameter, alignment when the adhesive sheet layer and the wiring board substrate are overlapped is not easy, and the bump may not be inserted into the through hole of the adhesive sheet layer.

  On the other hand, the diameter of the through hole is preferably not more than 5 times the diameter of the bump. If 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. That is, the diameter of the through hole is preferably 1.0 to 5.0 times the bump diameter. Claim 3 corresponds to this preferable mode.

  In the production method of the present invention, at least three layers of the wiring board base material a, the adhesive sheet, and the other wiring board base material b are combined with the insulating substrate of the wiring board base material a and the wiring board base material b. The adhesive sheet is sandwiched therebetween, and the bumps, that is, the bumps formed on the insulating substrate of the wiring board base material a are laminated and pressed so as to be inserted into the through holes of the adhesive sheet.

  The other wiring board base material b is a wiring board base material having an insulating substrate and a conductive layer provided on the surface thereof. Examples of the material for forming the insulating substrate and the conductive layer include the same materials as those exemplified as the material for forming the insulating substrate and the conductive layer of the wiring board base material a. Moreover, the formation method of the insulating board | substrate and conductive layer of the wiring board base material b can also employ | adopt the same method as the case of the wiring board base material a. The conductive layer of the wiring board base b may be provided on both surfaces of the insulating substrate.

  Further, the wiring board substrate b has a conductive layer or a portion that conducts with the conductive layer at a position corresponding to the bump of the wiring board substrate a. As a result, the bumps of the wiring board substrate a and the conductive layer or the conductive layer of the wiring board substrate b are connected by a laminating press described later, and the conductive properties of the wiring board substrate a and the wiring board substrate b are connected. The layers are interconnected.

  The lamination press is performed by sandwiching an adhesive sheet between the insulating substrate of the wiring board base material a and the wiring board base material b. The lamination press is performed so that the bumps are inserted into the through holes of the adhesive sheet. That is, the wiring board substrate and the adhesive sheet are arranged so that the opening of the through hole of the adhesive sheet includes the bump. The lamination press can be performed by heating and pressurizing using a cure press or the like.

  By the lamination press, the adhesive constituting the adhesive sheet spreads in the through hole, and the bump also plastically deforms and spreads, so that the conductive paste composition of the bump and the adhesive come into contact with each other, and the through hole and the bump The gap between them is eliminated. Moreover, since this bump, ie, the bump of the wiring board base material a, is plastically deformed and comes into contact with the conductive layer or the conductive layer of the wiring board base material b, the conductive layer-wiring board base of the wiring board base material a The conductive part of the material a-the conductive part in the adhesive sheet formed by the bump-the conductive layer of the wiring board base b or the conductive layer connected to the conductive layer is connected, and the wiring board base a and the wiring board base b Conductive layers are interconnected.

  In the production method of the present invention, at least three layers of the wiring board base material a, the wiring board base material b, and the adhesive sheet are laminated and pressed. If necessary, the wiring board base material a and the wiring board base material are used. A wiring board substrate other than b, which has a conductive bump provided on the surface thereof, may be laminated and pressed at the same time. Even when a wiring board substrate other than the wiring board substrate a and the wiring board substrate b is used, an adhesive sheet similar to the above is sandwiched between the wiring board substrates, and bumps are inserted into the through holes of the adhesive sheet. Are stacked and stacked and pressed together. Thus, since the multilayer printed wiring board of this invention can be manufactured by one lamination press, high productivity is obtained.

  As the wiring board base b, for example, an insulating substrate, a conductive layer provided on one surface thereof, and a hole penetrating the insulating substrate and having the conductive layer as a bottom are filled with a conductive paste composition. The wiring board base material which has the electrically conductive part formed in the position corresponding to the said bump can be mentioned. This conductive paste composition is referred to as “conductive paste composition C”. Claim 4 corresponds to an embodiment using this wiring board substrate.

  In this case, the end on the insulating substrate side of the conductive portion formed by filling the hole having the conductive layer at the bottom through the insulating substrate with the conductive paste composition (that is, the portion corresponding to the opening of the hole) This corresponds to the portion that is electrically connected to the conductive layer. In the laminating press, the layers are laminated so that the insulating substrate is on the adhesive sheet side, and the portion that is electrically connected to the conductive layer is in the through hole of the adhesive sheet.

  Examples of the material for forming the conductive paste composition C include the same materials as those exemplified as the material for the conductive paste composition A. The conductive paste composition C may be the same composition as the conductive paste composition A and the conductive paste composition B. In addition, as a method for obtaining an insulating substrate and a conductive layer provided on one surface thereof, and a method for filling a hole with a conductive paste composition, the same method as in the case of the wiring board base material a is exemplified. be able to. As a method of forming the hole penetrating the insulating substrate and having the conductive layer as the bottom, a method using a laser can be exemplified.

  As the wiring board base b, an insulating substrate, a conductive layer provided on one surface thereof, and a hole penetrating the insulating substrate and the conductive layer are filled with the conductive paste composition C. The wiring board base material which has a conductive part in the position corresponding to the said bump can also be illustrated. Claim 5 corresponds to an embodiment using this wiring board substrate.

  In this case, the end on the insulating substrate side of the conductive portion formed by filling the hole penetrating the insulating substrate and the conductive layer with the conductive paste composition (that is, the portion corresponding to the opening on the insulating substrate side of the hole). Corresponds to the portion that is electrically connected to the conductive layer. In the laminating press, the layers are laminated so that the insulating substrate is on the adhesive sheet side, and the portion that is electrically connected to the conductive layer is in the through hole of the adhesive sheet.

  The wiring described above can also be used as a method for obtaining an insulating substrate and a conductive layer provided on one surface thereof, a method for forming a hole penetrating the insulating substrate and the conductive layer, and a method for filling the hole with a conductive paste composition. The same method as the case of the board | substrate base a can be mentioned.

  As the wiring board base b, those in which bumps made of a conductive paste composition are formed in contact with the insulating substrate side end of the conductive portion of the above-described wiring board base b can also be used. The conductive paste composition used for forming the bumps is referred to as a conductive paste composition D. Claim 6 corresponds to an embodiment using this wiring board substrate.

  In this case, the bumps of the wiring board substrate b correspond to the portions that are electrically connected to the conductive layer. In the lamination press, the bumps are laminated so that the insulating substrate is on the adhesive sheet side and the bumps are inserted into the through holes of the adhesive sheet.

  Examples of the material forming the conductive paste composition D include the same materials as those exemplified as the material of the conductive paste composition A. The conductive paste composition D may be the same composition as the conductive paste compositions A to C. In addition, as a method for forming the bump, the same method as in the case of the wiring board substrate a can be used.

  The present invention further provides a multilayer printed wiring board manufactured by the method for manufacturing a multilayer printed wiring board. This multilayer printed wiring board is a wiring board that enables high-density wiring with a high degree of freedom, and has excellent connection reliability, and is suitably used for manufacturing electronic products such as digital cameras and mobile phones. It is done.

  According to the method for producing a multilayer printed wiring board of the present invention, a multilayer printed wiring board having excellent connection reliability can be produced with a simple process, low cost, and high productivity. In addition, the multilayer printed wiring board manufactured by this manufacturing method is a wiring board that enables high-density wiring with a high degree of freedom, and that can achieve an excellent reflow good product rate and has excellent connection reliability. It is.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings. It should be noted that the scope of the present invention is not limited to this form or the examples described later, and can be changed to other forms as long as the gist of the present invention is not impaired.

  FIG. 1 is a schematic cross-sectional view of a wiring board substrate a constituting the multilayer printed wiring board of the present invention. In FIG. 1, reference numeral 101 denotes a wiring board base material. The wiring board base material 101 is provided with a conductive layer 21 on one surface of a polyimide film 11 which is an insulating substrate, and further includes a polyimide film 11 and a conductive layer 21. A through-hole 31 (diameter: R1) is provided, and the conductive portion is formed in the hole 31 by being filled with the conductive paste composition A. Bumps 41 and 41 ′ (diameter: R 2) are formed on both sides of the hole 31 using the conductive paste composition B. As shown in FIG. 1, the bump diameter R2 is larger than the via hole diameter R1 (R2 / R1> 1.2).

  FIG. 2 is a schematic cross-sectional view showing an example of the multilayer printed wiring board of the present invention. The multilayer printed wiring board of this example is a combination of the wiring board substrate 101 (wiring board substrate a), the adhesive sheet 51 and the wiring board substrate 102 which is another wiring board substrate b shown in FIG. is there. However, the wiring board substrate 102 used in this example is a wiring board substrate having the same configuration as the wiring board substrate 101.

  This multilayer printed wiring board includes a wiring board substrate 101 comprising a polyimide film 11 and a conductive layer 21 formed thereon, and a wiring board substrate comprising a polyimide film 12 and a conductive layer 22 formed thereon. The material 102 is obtained by laminating and pressing the material 102 with a cure press or the like while sandwiching the adhesive sheet 51.

  FIG. 3 shows the positional relationship between the wiring board substrate 101, the adhesive sheet 51, and the wiring board substrate 102 before the lamination press. As shown in FIG. 3, the adhesive sheet 51 is disposed between the polyimide film 11 and the polyimide film 12 which are insulating substrates, and the bumps 41 ′ and the bumps 42 ′ are openings of the through holes 61 of the adhesive sheet 51. It is arranged to be included in the department. Since the diameter of the through hole 61 is larger than the bump diameter R2, a gap is generated between the through hole 61, the bump 41 ', and the bump 42' before the lamination press.

  After being arranged in this way, by laminating and pressing them, the polyimide film 11 and the polyimide film 12 are bonded by the adhesive of the adhesive sheet 51, and the adhesive and the bump 41 ′ and the bump 42 ′ are plastic. Due to the deformation, the gaps between the through holes 61 and the bumps 41 ′ and 42 ′ are eliminated, and the multilayer printed wiring board shown in FIG.

  As shown in FIG. 2, a hole extending from the conductive layer 21 to the conductive layer 22 and penetrating the polyimide film 11, the polyimide film 12, and the adhesive sheet 51 is formed in the laminated body 151. The conductive paste composition is filled, and the inter-circuit conductive portion 71 is formed. As a result, the conductive layer 21 and the conductive layer 22 are connected. Further, the bump 41 and the bump 42 cover the surfaces of the conductive layer 21 and the conductive layer 22, respectively, and are in contact with these over a wide area, so that excellent connection reliability can be obtained.

  4 shows a wiring board substrate 103 in which a conductive layer 23 is formed on a polyimide film 13 and a wiring board in which a conductive layer 24 is formed on a polyimide film 14 on both outer sides of the laminate 151 in FIG. The laminated body 152 obtained by laminating | stacking the base material 104 is shown, This laminated body 152 is another example of the multilayer printed wiring board of this invention.

  The multilayer printed wiring board made of the laminate 152 also uses adhesive sheets 52 and 53 that are the same adhesive sheets as the adhesive sheet 51, and the adhesive sheet is provided between the wiring board base 101 and the wiring board base 102. 51, the adhesive sheet 52 is sandwiched between the wiring board base material 101 and the wiring board base material 103, and the adhesive sheet 53 is sandwiched between the wiring board base material 102 and the wiring board base material 104. Manufactured by laminating press. Therefore, it can be manufactured with high productivity.

  The hole in which the hole 33 in the polyimide film 13 and the through hole 62 in the adhesive sheet 52 are connected is filled with a conductive paste composition, and an inter-circuit conductive portion 72 is formed. Similarly, a conductive paste composition is filled in the hole in which the hole 34 in the polyimide film 14 and the through hole 63 in the adhesive sheet 53 are connected, and an inter-circuit conductive portion 73 is formed. . The conductive layers 21, 22, 23, and 24 are interlayer-connected by the inter-circuit conductive portions 72 and 73 and the inter-circuit conductive portion 71 described above to form a multilayer printed wiring board. Hereinafter, similarly, a multilayer printed wiring board having a larger number of conductive layers is formed by laminating wiring board substrates.

  FIG. 5 shows an insulating substrate, a conductive layer provided on one surface thereof, and a hole penetrating the insulating substrate and having the conductive layer as a bottom instead of the wiring board substrate 102 in FIG. The laminated body 153 obtained by using the wiring board substrate 105 having conductive portions filled with the conductive paste composition C at positions corresponding to the bumps is shown. It is another example of the multilayer printed wiring board of invention (the aspect of Claims 4 and 6).

  The wiring board substrate 105 is formed by forming the conductive layer 25 on the polyimide film 15 and is provided with a bottomed hole 35 (via hole) with the conductive layer 25 as a bottom, and the conductive paste composition is formed in the hole 35. Is filled. Furthermore, the opening side of the bottomed hole 35 has a bump made of a conductive paste composition. The other configuration is the same as that of FIG. 2, and the following description is omitted.

  6 shows an insulating substrate, a conductive layer provided on one surface thereof, and the conductive layer penetrating through the insulating substrate, instead of the wiring board bases 103 and 104 in the example of FIG. A laminated body 154 obtained by using the wiring board base materials 106 and 107 having conductive portions formed by filling the conductive paste composition C in the holes with bottoms at positions corresponding to the bumps. This laminate 154 is another example of the multilayer printed wiring board of the present invention. The other points are basically the same as those in FIG. 4, and the following description is omitted.

  Examples will be described in more detail below.

[Production of wiring board substrate]
A single-sided copper-clad substrate (PI: 25 μm, copper thickness: 18 μm) bonded to one side of a polyimide film (PI) without using an adhesive, with a drill, a through hole (opening diameter 100 μm) Was opened and wet desmearing was performed with alkali and potassium permanganate. A total of 8 holes were formed.

  In each hole, a silver paste in which silver particles are dispersed in an epoxy resin (70 parts by weight of a bisphenol A type epoxy resin having an epoxy equivalent of 7000-8500 and 30 parts by weight of a bisphenol F type epoxy resin having an epoxy equivalent of 160-170) It is obtained by adding 12 parts of an imidazole-based latent curing agent to a solution in which the resin is dissolved in butyl carbitol acetate, and further adding and dispersing silver particles so that the total solid content is 55% by volume. In addition, the same silver paste was screen-printed thereon to form a total of 8 bumps. At this time, the diameter of the bump was 200 μm and the height was 50 μm.

[Preparation of adhesive sheet]
An adhesive made of an epoxy resin and having an elastic modulus at 30 ° C. of the cured product as shown in Table 1 (manufactured by Yodogawa Paper, TLF-Y30) was molded into a sheet having a thickness of 25 μm. A through-hole having a diameter of 300 μm was formed at a predetermined position (a position corresponding to the bump) of this sheet using a drill to obtain an adhesive sheet. This adhesive sheet is referred to as BS1.

[Lamination press]
Two of the above-mentioned wiring board base materials and the adhesive sheet are superposed so as to insert the bumps into the through holes of the adhesive sheet, and then heat-pressed by a vacuum press. Then, a circuit was formed so as to form a daisy chain, and a printed wiring board was produced. The circuit was formed by forming a circuit pattern of the resist layer and chemical etching. The structure at this time is as shown in FIG.

  A multilayer printed wiring board was produced in the same manner as in Example 1 except that the structure was as shown in FIG. At this time, the diameter of the bump was 200 μm.

  In Example 1, a multilayer printed wiring board having the structure shown in FIG. 5 was similarly obtained except that one wiring board base material was changed to a wiring board base material having a bottomed via instead of the through hole. Obtained.

  A multilayer printed wiring board having the structure shown in FIG. 6 was obtained in the same manner as in Example 2, except that the outermost two layers were changed to a wiring board substrate having a bottomed via instead of the through hole.

(Example 5)
In Example 1, the same thing was produced except that the diameter of the bump was 500 μm and the opening diameter of the interlayer adhesive was 600 μm.

  As mentioned above, about the multilayer printed wiring board obtained in Examples 1-5, the reflow non-defective rate and ion migration were evaluated by the method shown below, and the result was shown in Table 1.

[Reflow good product rate]
The multilayer printed wiring board is heated at a temperature of 260 ° C. for 5 seconds at a peak time for a total heating time of 300 seconds, and the ratio of the multilayer printed wiring board whose resistance change measured by the above method is within 10% is determined to be non-defective. The ratio (%) was obtained.

[Ion migration]
Eight interlayer connection parts are used as positive electrodes, and a circuit adjacent thereto is used as a negative electrode. The circuit interval between the positive electrode and the negative electrode was 70 μm. After applying a voltage of 50V to this circuit and leaving it to stand at a temperature of 85 ° C. and a humidity of 85% for 1000 hours, a multilayer printed wiring board having a resistance of 10 ⁸ Ω or more is regarded as a non-defective product. The results are shown in Table 1.

  In the examples of the present invention shown in the examples, a drill is used instead of a laser in the drilling process, and as a result, the productivity is improved. As shown in Table 1, the reflow non-defective product rate is excellent. A multilayer printed wiring board without migration is obtained.

It is a schematic cross section which shows an example of the wiring board base material in the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention. It is a schematic cross section which shows 1 process of the manufacturing method of the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention. It is a schematic cross section which shows an example of the multilayer printed wiring board of this invention.

Explanation of symbols

11, 12, 13, 14, 15 Polyimide films 21, 22, 23, 24, 25 Conductive layers 31, 32, 33, 34, 35 Holes 41, 41 ′ Bumps 51, 52, 53 Adhesive sheets 61, 62, 63 Through holes 71, 72, 73 Inter-circuit conductive portions 101, 102, 103, 104, 105, 106, 107 Wiring board base materials 151, 152, 153, 154 Laminate

Claims (7)

A wiring board substrate having an insulating substrate, a conductive layer provided on at least one surface thereof, and a conductive portion formed by filling a conductive paste composition A in a hole penetrating the insulating substrate and the conductive layer. A wiring board substrate a in which bumps having a diameter larger than the diameter of the conductive portion are formed of the conductive paste composition B in contact with both ends of the conductive portion;
An adhesive sheet in which a through hole having a larger diameter than the bump is formed at a position corresponding to the bump, and an insulating substrate and a wiring board substrate having a conductive layer provided on the surface thereof, Other wiring board substrate b having a conductive layer or a portion conducting to the conductive layer at a position corresponding to the bump
At least three layers of
A step of laminating and pressing the adhesive sheet between the insulating substrate of the wiring board base material a and the wiring board base material b and inserting the bumps into the through holes of the adhesive sheet. A method for producing a multilayer printed wiring board, comprising:   The method for manufacturing a multilayer printed wiring board according to claim 1, wherein a diameter of the bump is 1.2 times or more of a diameter of the conductive portion. The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the diameter of the through hole of the adhesive sheet is 1.5 to 3.0 times the diameter of the bump.   The wiring board base b is filled with the conductive paste composition C in an insulating substrate, a conductive layer provided on one surface thereof, and a hole penetrating the insulating substrate and having the conductive layer as a bottom. A wiring board substrate having a conductive portion at a position corresponding to the bump, and sandwiching the adhesive sheet between an insulating substrate of the wiring board substrate a and an insulating substrate of the wiring board substrate b The method for producing a multilayer printed wiring board according to any one of claims 1 to 3, wherein:   A wiring board base b includes an insulating substrate, a conductive layer provided on one surface thereof, and a conductive portion formed by filling a conductive paste composition C in a hole penetrating the insulating substrate and the conductive layer. A wiring board substrate having a position corresponding to the bump, wherein the adhesive sheet is sandwiched between an insulating substrate of the wiring board substrate a and an insulating substrate of the wiring board substrate b. A method for producing a multilayer printed wiring board according to any one of claims 1 to 3.   6. The multilayer print according to claim 4, wherein a bump made of the conductive paste composition D is formed in contact with an end of the conductive portion of the wiring board base b on the insulating substrate side. A method for manufacturing a wiring board. 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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