JP2009038191A - Multilayer wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of manufacturing the multilayer wiring board of high quality by eliminating a liquid process after lamination and dissolving the problems on manufacture by plating and the thickness increase of a conductor circuit. <P>SOLUTION: In the manufacturing method of the multilayer wiring board, two double-sided wiring boards for which formation of the means of an inter-layer conducting structure and circuit formation for wiring are performed beforehand, an insulating layer composed of a resin for which a thermoplastic resin or a thermoplastic adhesive is formed on both surfaces and provided with through-holes perforated at appropriate parts, and copper balls are prepared. Then, copper balls are inserted to the through-holes of the insulating layer to attain an intermediate layer, the intermediate layer is clamped between the two double-sided wiring boards, they are pressurized, heated and laminated, and the two double-sided wiring boards are attached through the intermediate layer. Also, metal bonding is formed between the crushed copper balls inside the through-holes of the intermediate layer and a wiring pattern in contact with them to form inter-layer conduction, and the multilayer wiring board is manufactured without executing a process by a liquid line even after the final lamination. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer wiring board and a method for manufacturing the same, which have improved the problems related to the lamination of printed wiring boards using a conventional build-up method.

In recent years, with the advancement of electronic technology, the density and speed of electronic devices have been increased, and multilayer printed wiring boards are often used to meet the demand.
Conventionally, as this manufacturing method, a build-up method in which conductor circuits and organic insulator layers are alternately stacked is often used, and the conductor circuits form via holes to perform interlayer conduction. In addition, in the case of stacking by the build-up method, if there is a void in the through hole, it causes a dent in the stacking process. Therefore, as disclosed in Patent Document 1, interlayer conduction is required after stacking. There has also been proposed a method of forming a via fill plating by forming a hole reaching a conductor circuit below the portion of the conductor circuit and the insulating layer and filling the hole by plating. However, when this method is used, the gap is filled by plating, so that a long plating time is required, and the conductor circuit other than the portion forming the interlayer conduction is also plated, and the thickness of the conductor circuit is increased. Therefore, it is difficult to form a fine circuit by a subtractive method or the like. Further, in the build-up method, it is necessary to perform circuit formation after forming interlayer conduction by plating, and it is necessary to perform these for each layer to be laminated.

  As a method for solving this problem, as disclosed in Patent Document 2, an interlayer conduction method using a copper ball has been proposed. In this method, a hole is formed in advance in a portion of the insulating layer where interlayer conduction is formed, a copper ball is inserted therein, a copper foil is disposed on the front surface and the back surface, and these are heated and pressed to obtain a copper. The ball is deformed and pressed against the copper foil, a new surface is generated, a metal bond is obtained, and interlayer conduction can be formed without using plating. Hereinafter, this method for forming interlayer conduction using copper balls is referred to as CBIC (Copper Ball Interconnection Co-laminated).

FIG. 1 is a cross-sectional view showing a method of manufacturing a filled via double-sided substrate using CBIC technology in the order of steps. In this method, first, an insulating layer 1 in which a thermoplastic resin or an adhesive is applied on both sides of a thermoplastic resin or an insulating material serving as a base material is prepared, and this is coated with a drill, a YAG laser, a CO ₂ laser, or the like. A through hole 5 for fitting the ball 2 is formed (see FIG. 1A). Next, air is sucked from one side of the insulating layer 1 and the copper ball 2 is fitted into the through hole 5 from the opposite side (see FIG. 1B). Thereafter, the insulating layer 1 is sandwiched between two copper foils 3 and 4 (see FIG. 1C), and heated and pressurized by a vacuum press. As a result, the through-hole 5 of the insulating layer is filled with the copper ball 2, and the copper ball 2 and the copper foils 3 and 4 are connected to each other by a metal bond to have the interlayer conduction shown in FIG. A double-sided substrate is obtained.

In Patent Document 2, as a method for realizing a multilayer substrate by applying the CBIC technology, an insulator is opened in a portion where one wants to obtain interlayer conduction on one substrate produced in advance, a copper ball is disposed, and a circuit is provided. A method is disclosed in which the other substrate formed is stacked and heated under pressure. Patent Document 3 discloses a method of laminating substrates produced using the CBIC technology through an insulating layer.
JP-A-5-343854 JP 2006-179833 A JP 2006-294725 A

  In the method using the build-up method, which is a method for manufacturing a multilayer printed wiring board described in the prior art, as described above, it is necessary to form a circuit after forming an interlayer conductor by plating using a liquid line. is there. In addition, in order to form a circuit, many liquid line processes such as development of a photoresist, etching of a conductor layer, and stripping of the photoresist are required, which must be performed every time one layer is laminated. For example, in order to form a multilayer printed wiring board, since it has been put into a process that is several times the number of layers, the process using the liquid line is passed many times, and there is a high possibility that defects will occur. Become. Also, if a defect occurs after stacking several layers, everything stacked up to that point is wasted. Thus, in the manufacturing method that passes through the liquid line process for plating and circuit formation after laminating, a single defect in the liquid line greatly affects the defect as a product. Of course, in order to keep the state of the chemicals in the liquid process constant, it is necessary to constantly monitor and manage daily, so it should be replaced with a separate process that does not require daily monitoring even partially. .

  In addition, as disclosed in Patent Document 2, an insulating layer is opened and a copper ball is disposed only in a portion where interlayer conduction on one substrate prepared in advance by applying CBIC technology is desired, and a circuit is provided. In the method of obtaining a multilayer substrate by stacking the other substrate that has been formed and laminating under pressure and heating, the bonding strength due to the metal bond between the conductor layers can be obtained as a mechanical bond between the substrates, but copper It is difficult to stably obtain the mechanical bonding strength between the insulating layer of the substrate on which the ball is disposed and the other substrate. This is because, after forming an insulating layer on the substrate on the side where the copper ball is to be placed in advance, it is necessary to place the copper ball by opening only the portion where conduction is required. The insulating layer of the layer on which the ball is disposed is desirably a thermoplastic resin having adhesiveness. However, if the thermoplastic resin is used for the insulating layer by the method as in Prior Art Document 2, when the insulating layer is formed on the substrate prepared in advance, the pressure is applied when the thermoplastic resin is bonded to the substrate. Once it is done, it will be pressurized and heated again when it is stacked with the other substrate by CBIC technology, so the insulating layer thickness and adhesive strength can be realized stably even if the thermal history is applied multiple times. Must select a suitable thermoplastic resin. Of course, a method of joining by using a method other than pressure heating when forming an insulating layer on the substrate in advance is also conceivable, but as a material used for the insulating layer, in addition to the adhesive function by thermoplastic, another adhesive function can be used. Need to have.

  Patent Document 3 also discloses a technique for laminating a substrate manufactured using the CBIC technique, but the laminating is performed using an insulating adhesive, and interlayer conduction between the laminated substrates is performed. Means are not shown.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method capable of manufacturing a high-quality multilayer wiring board by eliminating the need for a liquid process after stacking and eliminating the problems of manufacturing by plating and the increase in the thickness of a conductor circuit. And

  In order to achieve the above object, the present invention provides two double-sided wiring boards that have been previously formed with means for interlayer conduction structure and circuit formation for wiring, and a thermoplastic resin or a thermoplastic adhesive formed on both sides. An insulating layer having a through hole formed in a proper position and a copper ball, and then inserting the copper ball into the through hole of the insulating layer to form an intermediate layer. This intermediate layer is sandwiched between the wiring boards, these are heated and laminated, and the two double-sided wiring boards are bonded via the intermediate layer, and the crushed copper ball in the through hole of the intermediate layer is in contact with it. Provided is a method for manufacturing a multilayer wiring board, wherein a metal bond is formed between the wiring pattern and an interlayer continuity is formed, and a multilayer wiring board is manufactured without performing a liquid line process after the final lamination. To do.

  In the method for manufacturing a multilayer wiring board of the present invention, the two double-sided wiring boards are double-sided wiring boards each having a wiring pattern on both the front and back surfaces, and a multilayer wiring having a four-layer wiring pattern that is interlayer-conductive after final lamination It is preferable to manufacture a substrate.

  In the method for manufacturing a multilayer wiring board according to the present invention, each of the two double-sided wiring boards is a multilayer wiring board having a four-layer wiring pattern, and the multilayer wiring having an eight-layer wiring pattern in which the layers are electrically connected after final lamination A substrate can also be manufactured.

  In the method for manufacturing a multilayer wiring board of the present invention, one of the two double-sided wiring boards is a multilayer wiring board having an odd-numbered wiring pattern of three or more layers, and the odd-numbered wiring that is interlayer-conductive after the final lamination A multilayer wiring board having a pattern can also be manufactured.

  Moreover, this invention provides the multilayer wiring board manufactured by the manufacturing method of the multilayer wiring board which concerns on this invention mentioned above.

Since the present invention uses a wiring board on which a circuit has already been formed, there is no need to pass a liquid process after lamination, and there is no need for plating even in interlayer conduction. Does not occur, does not hinder the formation of a fine circuit by the subtractive method, and does not require management of chemicals. In this way, the number of steps using the liquid is small and the possibility of occurrence of defects can be reduced, and the yield of products can be improved.
In addition, in a multilayer wiring board based on a build-up method in which circuit formation or plating is performed after lamination, if a defect occurs after lamination, all the boards laminated so far are wasted. In the present invention, a double-sided wiring board is formed. Even if a failure occurs at this time, if the double-sided wiring board is recreated, only two layers of losses are required, so that the manufacturing cost can be reduced.

  In the present invention, by using the CBIC technology, the metal bond in the interlayer conduction between the laminated substrates and the adhesive strength between the copper foil and the insulating layer can be stably obtained by using the CBIC technique. It will be solved. That is, at least four layers with an insulating layer containing at least an organic resin, a multi-layer conductor circuit made of metal formed on and inside the insulating layer, and a via conductor portion for connecting the multi-layer conductor circuit As a method of forming the multilayer wiring board, in the present invention, two or more substrates on which circuits are formed in advance are prepared, and holes are drilled at predetermined positions as layers for realizing interlayer conduction while bonding them together. For example, a thermoplastic insulating layer is arranged, and an intermediate layer substrate is prepared in which a copper ball is inserted into the hole and temporarily mounted, and the double-sided substrates prepared above and below this layer are placed up and down. It is characterized in that it is aligned and heated and pressed in the arranged state to form a multilayer wiring structure having four or more layers.

  In the manufacturing method of the present invention, the copper ball is crushed by one pressurization and heating, and a new surface is exposed, and metal bonding is performed with the copper foil of the circuit pattern facing the copper ball, thereby providing interlayer conduction between the bonded substrates. At the same time, it is possible to bond the insulating layer provided with copper balls and the upper and lower substrates. Therefore, unlike the conventional technique, an insulating layer is formed once on the surface of one substrate by some bonding method, and then the opening is made and a copper ball is arranged and then bonded to the other substrate. Since the process is sufficient, the insulating layer on which the copper balls are arranged may be selected from those that can be joined by one pressurization and heating, and the construction method can be simplified.

FIG. 2 is a cross-sectional view showing an embodiment of a method for manufacturing a multilayer wiring board according to the present invention in the order of steps.
In the present embodiment, as shown in FIG. 2 (a), two double-sided wiring boards 6, 7 in which circuit patterns made of a conductor such as copper are formed on both sides of an insulating layer made of polyimide film or the like. An insulating layer made of a resin in which a thermoplastic resin or a thermoplastic adhesive is formed on both surfaces and having through holes formed at appropriate positions, and copper balls 9a and 9b are prepared.

  Next, as shown in FIG. 2 (b), copper balls 9a and 9b are inserted into the through holes of the insulating layer to form the intermediate layer 8, and then, as shown in FIG. 2 (c), two double-sided wiring boards The intermediate layer 8 is sandwiched between the layers 6 and 7 and laminated by pressurizing and heating, and the two double-sided wiring boards 6 and 7 are bonded together via the intermediate layer 8, and in the through hole of the intermediate layer 8. A metal bond is formed between the crushed copper ball and the wiring pattern in contact therewith to form interlayer conduction. After this final lamination, no liquid line process is performed, as shown in FIG. A multilayer wiring board having a wiring pattern of layers is manufactured.

  In this embodiment, after forming a circuit on the two double-sided wiring boards 6 and 7 manufactured using the CBIC technique, the copper balls 9a and 9b are fitted into the through holes opened at arbitrary positions in the insulating layer. It is completed by sandwiching the intermediate layer 8 and heating and pressing with a vacuum press. In this construction method, since double-sided wiring boards 6 and 7 that have already been circuit-formed are used, a process using a liquid is not performed after lamination, and further, there is no need for plating even in interlayer conduction, so there is little possibility of occurrence of defects, Even if a defect occurs when the double-sided wiring boards 6 and 7 are formed, if the double-sided wiring boards 6 and 7 are remade, only two layers of losses are required.

  In the present embodiment, two double-sided wiring boards 6 and 7 having circuit patterns provided on the front and back are used, and after final lamination, a multilayer wiring board having a four-layer circuit pattern as shown in FIG. However, the present invention is not limited to this example, and the number of wiring patterns formed on each of two double-sided wiring boards may be two or more. As shown, a multilayer wiring board having an eight-layer wiring pattern can be manufactured by using two double-sided wiring boards 10 and 10 'each having a four-layer circuit pattern, or as shown in FIG. Of the two double-sided wiring boards 13 and 14, a double-sided wiring board 14 having an odd-numbered wiring pattern (three layers in FIG. 4) is used as one double-sided wiring board 14, and a multilayer having an odd-numbered wiring pattern. A wiring board can also be manufactured.

In the present embodiment, the case where two double-sided wiring boards 6 and 7 manufactured using the CBIC technique are illustrated, but the double-sided wiring board used in the present invention is limited to this. Instead, it is also possible to use a double-sided wiring board in which a circuit pattern or interlayer conduction is formed using a plating method.
Further, it goes without saying that the steps (a) to (d) in FIG. 2 can be repeated not only once.
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the following examples are merely illustrative of the present invention, and the present invention is not limited only to these descriptions.

In this example, a multilayer wiring board having a four-layer circuit pattern was manufactured according to steps (a) to (d) shown in FIG.
First, the upper and lower double-sided wiring boards 6 and 7 to be bonded together were produced. These were made using CBIC technology. As an insulating material, a polyimide sheet having a thickness of 50 μm having a thermoplastic adhesive layer formed on both the front and back surfaces was prepared, and a through hole having a thickness of, for example, 90 μm was formed by a laser at a place where interlayer conduction was required. Next, a copper ball having a diameter of 100 μm is placed in the through hole, press-fitted, and a copper foil having a thickness of, for example, 12.5 μm is placed on the upper and lower sides, and heated in a pressurized state with a press to insulate Two copper foils were bonded through the material. Next, a resist for forming a circuit pattern was formed on the front and back copper foils, and a circuit pattern was formed on the front and back surfaces by a subtractive method to produce two double-sided wiring boards 6 and 7 shown in FIG. .

  On the other hand, an intermediate layer 8 for bonding the double-sided wiring boards 6 and 7 was prepared separately from these. As an insulating material for the intermediate layer 8, a polyimide sheet having a thickness of 50 μm in which a thermoplastic adhesive was formed on both the front and back surfaces was used. For example, a 90 μm through hole was formed in this sheet by a laser at a location where interlayer conduction was required. Next, copper balls 9a and 9b having a diameter of 100 μm were placed in the through holes and press-fitted to produce the intermediate layer 8 shown in FIG.

  After the two double-sided wiring boards 6 and 7 and the intermediate layer 8 are prepared, as shown in FIG. 2 (c), the double-sided wiring board 6 is provided on the upper surface of the intermediate layer 8, and the double-sided board 7 is provided on the lower surface. After arranging and aligning, these were set in a press and heated in a pressurized state for lamination (final lamination). After heating and pressing, the finished product was taken out from the press. Thereby, as shown in FIG. 2D, a multilayer wiring board having a four-layer wiring pattern was obtained.

  In this embodiment, the multilayer wiring board is manufactured through the steps of FIGS. 2A to 2D, so that the copper balls 9a and 9b of the intermediate layer 8 are formed on the circuit pattern on the lower surface of the upper double-sided wiring board 6. In addition to metal bonding, a metal pattern is formed with the circuit pattern on the upper surface of the lower double-sided wiring board 7, and further, the thermoplastic adhesive of the intermediate layer 8 and the interlayer conduction between the double-sided wiring boards 6 and 7 are not formed. Interlayer adhesion can be realized at the same time, and a four-layer laminated substrate can be formed on a substrate on which a circuit has been correctly formed in advance.

(Another example of Example 1: Production example of a four-layer wiring board using a double-sided board by an interlayer conduction method other than CBIC)
Although the substrate configuration itself is the same as that in FIG. 2, the double-sided wiring boards 6 and 7 to be used may not be those using the CBIC technology. For example, a double-sided copper-clad laminate having an insulating layer thickness of 25 μm and a copper foil layer thickness of 12.5 μm can be used. In that case, a through-hole is formed with a laser etc. in a required location, interlayer conduction is formed by via fill plating, and a double-sided wiring board is manufactured.

  On the other hand, an intermediate layer 8 for bonding the double-sided substrates 6 and 7 is prepared separately. As an insulating material for the intermediate layer substrate, a polyimide sheet having a thickness of 50 μm in which a thermoplastic adhesive layer is formed on both front and back surfaces is used. A through hole of, for example, 90 μm is formed in this sheet with a laser at a location where interlayer conduction is required. Next, a copper ball having a diameter of 100 μm is placed in the through hole and press-fitted to produce the intermediate layer 8.

  After these substrates are prepared, one double-sided board 6 is arranged on the upper surface and the other double-sided wiring board 7 is arranged on the lower surface with respect to the intermediate layer. Thus, as shown in FIG. 2D, a multilayer wiring board having a four-layer wiring pattern is obtained.

  By doing so, the copper balls 9a and 9b of the intermediate layer 8 are metal-bonded to the circuit on the lower surface of the upper double-sided wiring board 6 and the upper surface of the lower double-sided board 7 is the same as in the first embodiment. It is possible to form a metal bond with the circuit, and further realize interlayer adhesion at the portion where the interlayer adhesive is not formed between the thermoplastic adhesive of the intermediate layer 8 and the double-sided wiring boards 6 and 7.

In this example, a multilayer wiring board having an eight-layer circuit pattern was produced according to the steps (a) to (b) shown in FIG.
In this embodiment, two multilayer wiring boards having the four-layer wiring pattern manufactured in the first embodiment described above are used as the double-sided wiring boards 10 and 10 ', and these are used in the same manner as in the first embodiment. Are stacked through the intermediate layer 11 fitted with (FIG. 3A), these are set in a press machine, and heated in a pressurized state for lamination (final lamination). After heating and pressing, the finished product was taken out from the press. As a result, as shown in FIG. 3B, a multilayer wiring board having an eight-layer wiring pattern was obtained.

In this example, a multilayer wiring board having an odd-numbered circuit pattern was fabricated according to the steps (a) to (b) shown in FIG.
In this example, a double-sided wiring board 13 having a two-layer wiring pattern, a double-sided wiring board 14 having a three-layer wiring pattern, and an intermediate layer 15 similar to those used in Examples 1 and 2 were used. . The intermediate layer 15 is sandwiched between two double-sided wiring boards 13 and 14 (FIG. 4 (a)), and these are set in a press machine and heated in a pressurized state for lamination (final lamination). It was. After heating and pressing, the finished product was taken out from the press. As a result, as shown in FIG. 4B, a multilayer wiring board having a five-layer wiring pattern was obtained.

It is sectional drawing which illustrates the manufacturing method of the double-sided board by a CBIC construction method in order of a process. It is sectional drawing which shows the manufacturing method of the multilayer wiring board in Example 1 which concerns on this invention in process order. It is sectional drawing which shows the manufacturing method of the multilayer wiring board in Example 2 which concerns on this invention in process order. It is sectional drawing which shows the manufacturing method of the multilayer wiring board in Example 3 which concerns on this invention to process order.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Insulation layer, 2 ... Copper ball, 3, 4 ... Copper foil, 5 ... Through hole, 6, 7, 10, 10 ', 13, 14 ... Double-sided wiring board, 8, 11, 15 ... Intermediate layer, 9a, 9b, 12, 16 ... Copper balls.

Claims (5)

  It consists of two double-sided wiring boards that have been previously formed with interlayer conduction structure means and circuits for wiring, and a resin that is formed on both sides with a thermoplastic resin or thermoplastic adhesive. A perforated insulating layer and a copper ball are prepared. Then, the copper ball is inserted into a through hole of the insulating layer to form an intermediate layer, and the intermediate layer is sandwiched between two double-sided wiring boards. Are laminated by pressing and heating, and two double-sided wiring boards are bonded via an intermediate layer, and a metal bond is formed between the crushed copper ball in the through hole of the intermediate layer and the wiring pattern in contact therewith. A method of manufacturing a multilayer wiring board, comprising: forming interlayer conduction, and manufacturing the multilayer wiring board without performing a liquid line process after the final lamination.   The two double-sided wiring boards are each a double-sided wiring board having wiring patterns on both front and back surfaces, and a multi-layer wiring board having four-layer wiring patterns in which interlayer conduction is performed after final lamination is manufactured. 2. A method for producing a multilayer wiring board according to 1.   The two double-sided wiring boards are multilayer wiring boards each having a four-layer wiring pattern, and a multi-layer wiring board having an eight-layer wiring pattern in which interlayer conduction is performed after final lamination is manufactured. 2. A method for producing a multilayer wiring board according to 1.   One of the two double-sided wiring boards is a multilayer wiring board having an odd-numbered wiring pattern of three or more layers, and after the final lamination, manufacturing a multilayer wiring board having an odd-numbered wiring pattern that is interlayer-connected. The method for producing a multilayer wiring board according to claim 1, wherein:   The multilayer wiring board manufactured by the manufacturing method of the multilayer wiring board in any one of Claims 1-4.

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