JPH07115279A - Multilayer board and its manufacture - Google Patents

Abstract

PURPOSE:To provide a multilayer printed wiring board excellent in heatproof impact characteristics having an inner via hole and its manufacturing method. CONSTITUTION:In a board having a structure of electrically connecting with metal foils adhered to both surfaces of an insulated material layer 11 through a filling via hole comprising a conductive powder 12, hardened matter 13a of liquid resin, and reaction matter 13b of solidified resin, a glass transition point of the hardened matter of liquid resin and the reaction matter of the solidified resin constituting the filling via is lower than that of resin hardened matter of the insulated material layer. As for its manufacturing method, the insulated material layer and metal foils containing the filling via are further alternately repeatedly adhered onto one side or both sides of a both-side plate that metal foils of both surfaces are electrically connected through the filling via.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer board having an inner via hole.

[0002]

2. Description of the Related Art With the miniaturization and high functionality of electronic equipment, there is an increasing demand for a multilayer substrate having high wiring density and high reliability. In conventional printed multi-layer boards, interlayer connection by through holes is common. Further, as a higher density substrate, a substrate in which each layer is connected by an inner via hole is proposed. As an example, first, a copper foil is bonded to both sides of an insulating base material such as glass epoxy by thermocompression bonding, a circuit pattern is formed by a method such as etching, and then through holes are drilled at places where the front and back are electrically connected. A two-layer circuit board is manufactured by forming, filling and curing a conductor paste, and a through hole is previously formed in an uncured insulating base material between the two two-layer circuit boards to fill the conductor paste. There is a method for obtaining a four-layer circuit board by sandwiching the above-mentioned intermediate connector and thermocompression bonding. By repeating this method, it is possible to manufacture a multilayer substrate having an arbitrary number of layers by inner via hole connection.

[0003]

However, in a printed circuit board, the coefficient of thermal expansion of the insulating substrate is generally larger than that of the conductor metal. Since the conductor wiring length with respect to the so-called "aspect ratio" is large, the wire may be broken due to thermal shock. This becomes a serious problem as the number of layers increases and the thickness of the substrate increases. In addition, the interlayer connection type multilayer substrate which is the second example described above is considered to be more advantageous than the through hole type substrate from the viewpoint of the aspect ratio, but in the prior patent, after the filled conductive paste is cured, There is no mention of the thermal shock resistance property of. In view of the above, an object of the present invention is to provide a printed multilayer board having an interlayer connection via having excellent thermal shock resistance, paying attention to the structure of the via portion.

[0004]

In order to solve the above-mentioned problems, in the present invention, a multilayer via board is insulated by a filled via hole made of conductive powder, a cured product of a liquid resin, and a reaction product of a solid resin. A double-sided plate in which metal foils adhered to both sides of the material layer are electrically connected, and an insulating material layer including a filling via hole is further repeatedly adhered to one side or both sides, and the metal foil is alternately and repeatedly adhered. To do. Furthermore, it is preferable that the glass transition point of the reaction product of the cured resin of the liquid resin and the solid resin constituting the via is lower than the glass transition point of the cured resin of the insulating material layer, and particularly the liquid resin contains a flexible epoxy resin. It is preferable to use a powder curing agent as the solid resin. The conductive powder can be arbitrarily selected from at least one of silver, copper, and nickel, and the insulating material layer is selected from glass epoxy composite, glass BT resin composite, aramid epoxy composite, and aramid BT resin composite. You can choose. Further, glass and aramid can be used for the substrate of the present invention regardless of whether they are woven cloth or non-woven cloth.

[0005]

With the above-mentioned structure, the solid resin reactant that retains the original skeleton, which is not completely melted during the reaction, can be scattered in the via as the center of the cured network. Since the thermal expansion coefficient is close to that of the insulating layer material, it is possible to reduce the stress caused by the difference in the thermal expansion coefficient between the conductive component and the insulating layer material, and the glass of the cured product of the liquid resin and the reaction product of the solid resin. By setting the transition point to be lower than the glass transition point of the insulating material layer, the via portion can flexibly respond to the thermal expansion and contraction of the substrate, so that it is possible to provide a multilayer substrate excellent in thermal shock resistance.

[0006]

EXAMPLES Examples of the present invention will be described below. First, a method for manufacturing a multilayer substrate in this example will be described.

Via holes are formed in the insulating base material by a laser processing method or the like, and the vias are filled with the conductive paste of the present invention. The insulating base material can be selected from glass epoxy composite, glass BT resin composite, aramid epoxy composite, and aramid BT resin composite. Both sides of the insulating base material filled with the paste are sandwiched between copper foils, and vacuum heat pressing is performed at 180 ° C and 50 kg / cm.
After heated and pressed under the conditions of ^2-hour to form a double-sided plate to form an inner layer circuit pattern. Both sides of this double-sided board,
It is sandwiched between insulating material layers having vias filled with a conductive paste in advance, copper foils are further arranged on both outer sides, and thermocompression bonding is performed under the above conditions to form an outer layer circuit pattern to obtain a substrate having a four-layer structure. By repeating these series of steps, an arbitrary total number of multilayer substrates can be obtained. In the following examples, a four-layer substrate was prepared and evaluated. The method for manufacturing the substrate is common to the following comparative examples having configurations outside the scope of the present invention.

FIG. 1 is a sectional view of a multi-layer substrate having a four-layer structure according to an embodiment of the present invention. The via is filled in the through hole formed in the insulating base material 11. The vias after solidification are composed of the conductive powder 12, the cured product 13a of the liquid resin, and the reaction product 13b of the solid resin, and the inner layer circuit 14 and the outer layer circuit 1 are formed.
5, or the inner layer circuits are electrically connected. The conductive paste used in the present invention is a mixture of conductive powder selected from one or more of silver, copper, and nickel at 50 vol%, epoxy resin at 40 vol%, and powder curing agent at 10 vol%. Can be used. Each conductive powder is spherical powder, silver powder has a central particle diameter of 3.0 microns, BET value of 0.35
m ² / g, copper powder has a central particle size of 2.5 μm, BET value 0.40 m ² / g, nickel powder has 5.0 μm, BE
A T value of 0.30 m ² / g was used. As the epoxy resin, the most common bisphenol A such as bisphenol A (eg; trade name Epicoat 828, 807, 806: made by oiled shell epoxy) and glycidyl ester type (eg; trade name Epicoat 871: oiled shell epoxy) are used. By mixing a flexible epoxy (made by epoxy, Araldite CY184: made by Ciba Geigy), a paste having an appropriate working viscosity can be obtained. By including the flexible epoxy, it is possible to expand the range in which various conductive powders can be pasted. Further, as the powder curing agent, amine-based, imidazole-based, etc. (eg, trade name Amicure MY-2
4, MY-D, MY-H, PN-23, PN-D, PN
-H: Ajinomoto Co., Inc. can be used.

On the other hand, as a paste for a substrate of a comparative example outside the scope of the present invention, 55 parts by weight of a commercially available bisphenol A and an acid anhydride type liquid curing agent (eg; trade name Rikacid M) are used.
H: New Nippon Rika) 44.5 parts by weight and an amine accelerator (eg; riser: Kao) 0.5 parts by weight to a one-part epoxy resin containing 50 vol% of copper and silver. To prepare a mixed paste. FIG. 2 shows a cross section of a four-layer substrate with vias filled with this paste.

The insulating base material 21 can be selected from glass epoxy composite, glass BT resin composite, aramid epoxy composite, and aramid BT resin composite, like the substrate according to the present invention. The substrate according to the present invention and the substrate of the comparative example differ only in the configuration of the via portion. That is, it is composed only of the mesh of the conductive powder 22 and the cured product 23 of the liquid resin, and electrically connects the inner layer circuit 24 and the outer layer circuit 25 or the inner layer circuit.

Table 1 shows the composition of the pastes used in the following examples. The following examples will be described using the paste numbers in (Table 1).

[0012]

[Table 1]

Substrates using various insulating base materials will be described below with reference to specific examples. (Example 1) 140 ° C., 150 ° C., 16 as an insulating base material
Each paste shown in Table 1 was filled into a glass epoxy composite made of three kinds of thermosetting epoxy resins having a glass transition point at 0 ° C. and a glass woven cloth, and a four-layer substrate was manufactured according to the above steps.

30 of the vias included in each of these circuits
For hole 00, hold at -55 ° C and 125 ° C for 30 minutes each 50
The thermal shock test A of 0 cycle was carried out, and the number in which the resistance of the via portion became twice or more as compared with that before the test was regarded as a defect was compared with each other. The results are shown in (Table 2).

[0015]

[Table 2]

Regarding the combination of the glass transition point of the via portion and the base material, substrate Nos. 4 to 15 were selected and the temperature was 26 ° C. at 26 ° C.
The thermal shock test B of 100 cycles held at 0 ° C. for 30 seconds each was carried out, and as in the case of the thermal shock test A, those in which the resistance of the via portion was twice or more compared to that before the test were regarded as defective and the number of them was judged on each substrate. Compared. The results are shown in (Table 3). The glass transition point after curing of each insulating base material and the glass transition point of the resin cured product of each via portion are also shown in Table 3 at the same time.

[0017]

[Table 3]

Example 2 As an insulating base material, 142 ° C., 1
An aramid epoxy composite made of three kinds of thermosetting epoxy resins and aramid nonwoven fabric having glass transition points at 50 ° C. and 163 ° C. was filled with each paste shown in Table 1, and a four-layer substrate was manufactured according to the above steps.

30 of the vias included in each of these circuits
For hole 00, hold at -55 ° C and 125 ° C for 30 minutes each 50
The thermal shock test A of 0 cycle was carried out, and the number in which the resistance of the via portion became twice or more as compared with that before the test was regarded as a defect was compared with each other. The results are shown in (Table 4).

[0020]

[Table 4]

Regarding the combination of the glass transition point of the via portion and the base material, substrate Nos. 28 to 39 were selected and the temperature was 2 ° C.
Thermal shock test B of 100 cycles held at 60 ° C. for 30 seconds each was carried out, and as in the case of thermal shock test A, the one in which the resistance of the via portion was more than double the resistance before the test was regarded as a defect and the number was determined for each substrate. Compared. The results are shown in Table 5. The glass transition point after curing of each insulating base material and the glass transition point of the resin cured product of each via portion are also shown in (Table 5) at the same time.

[0022]

[Table 5]

Example 3 As an insulating base material, 145 ° C., 1
Glass B composed of 3 types of bismaleimide triazines having glass transition points at 55 ° C and 165 ° C and glass nonwoven fabric
The T-resin composite was filled with each paste shown in Table 1, and a four-layer substrate was manufactured according to the above steps.

30 of the vias included in each of these circuits
For hole 00, hold at -55 ° C and 125 ° C for 30 minutes each 50
The thermal shock test A of 0 cycle was carried out, and the number in which the resistance of the via portion became twice or more as compared with that before the test was regarded as a defect was compared with each other. The results are shown in (Table 6).

[0025]

[Table 6]

Regarding the combination of the glass transition point of the via portion and the base material, the substrate Nos. 52 to 63 were selected and the temperature was 2 ° C. and the temperature was 2 ° C.
Thermal shock test B of 100 cycles held at 60 ° C. for 30 seconds each was carried out, and as in the case of thermal shock test A, the one in which the resistance of the via portion was more than double the resistance before the test was regarded as a defect and the number was determined for each substrate. Compared. The results are shown in (Table 7). The glass transition point after curing of each insulating base material and the glass transition point of the cured resin of each via portion are also shown in Table 7 at the same time.

[0027]

[Table 7]

Example 4 As an insulating base material, 143 ° C., 1
Aramid BT made of aramid woven fabric and 3 types of bismalemid triazines having glass transition points at 52 ° C and 167 ° C
The resin composite was filled with each paste shown in (Table 1), and a four-layer substrate was manufactured according to the above steps.

30 of the vias included in each of these circuits
For hole 00, hold at -55 ° C and 125 ° C for 30 minutes each 50
The thermal shock test A of 0 cycle was carried out, and the number in which the resistance of the via portion became twice or more as compared with that before the test was regarded as a defect was compared with each other. The results are shown in (Table 8).

[0030]

[Table 8]

Regarding the combination of the glass transition point of the via portion and the base material, substrate Nos. 76 to 87 were selected and the temperature was 2 ° C. and 2
Thermal shock test B of 100 cycles held at 60 ° C. for 30 seconds each was carried out, and as in the case of thermal shock test A, the one in which the resistance of the via portion was more than double the resistance before the test was regarded as a defect and the number was determined for each substrate. Compared. The results are shown in (Table 9). The glass transition point after curing of each insulating base material and the glass transition point of the cured resin of each via portion are also shown in Table 9 at the same time.

[0032]

[Table 9]

As is clear from the results shown in (Table 2), (Table 4), (Table 6) and (Table 8) of (Example 1) to (Example 4) above, the reaction product of the solid resin is shown. It can be seen that the material containing the in the via has excellent thermal shock resistance characteristics under the temperature conditions of the thermal shock test A. Further, from the results of (Table 3), (Table 5), (Table 7), and (Table 9), heat can be obtained by selecting a combination in which the glass transition point of the resin cured product of the via portion is equal to or lower than the glass transition point of the base material. It can be seen that excellent thermal shock resistance characteristics can be obtained even under a temperature condition in which the glass transition point region is included in the middle of the shock test B.

[0034]

As described above, according to the present invention, it is possible to bring the thermal expansion coefficient of the via portion close to that of the insulating material layer by including the reaction product of the solid resin in the via, and to cure the resin in the via. By making the glass transition temperature of the material lower than that of the insulating layer material, it is possible to provide a multilayer substrate having an inner via hole excellent in thermal shock resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a structure of a multilayer substrate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a conventional multilayer substrate.

[Explanation of symbols]

 11 Insulating Substrate 12 Conductive Powder 13a Liquid Resin Cured Product 13b Solid Resin Reaction Product 14 Inner Layer Circuit 15 Outer Layer Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Togawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Seiichi Nakatani, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (72) Inventor Tamao Kojima 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A double-sided plate in which metal foils bonded to both sides of an insulating material layer are electrically connected by filled via holes made of conductive powder, a cured product of a liquid resin, and a reaction product of a solid resin, The insulating material layer containing the filled via hole and the metal foil are alternately and repeatedly bonded to one side or both sides, and the glass transition point of the cured product of the liquid resin and the reaction product of the solid resin forming the via is the insulating material layer. A multilayer substrate characterized by having a glass transition point lower than that of the resin cured product. 2. The multilayer substrate according to claim 1, wherein the liquid resin contains a flexible epoxy resin. 3. The multilayer substrate according to claim 1, wherein the solid resin is a powder curing agent. 4. The multilayer substrate according to claim 1, wherein the conductive powder is selected from at least one selected from silver, copper and nickel. 5. The multilayer substrate according to claim 1, wherein the insulating material layer is selected from at least one selected from a glass epoxy composite, a glass BT resin composite, an aramid epoxy composite, and an aramid BT resin composite. 6. A step of forming a via hole in an insulating material layer, a step of filling a via with a conductive paste made of conductive powder, a liquid resin and a solid resin, and copper foil on both sides of an insulating base material filled with the conductive paste. Step of sandwiching and thermocompression bonding, forming an inner layer circuit pattern to form a double-sided board, and further thermocompressing an insulating material layer and a copper foil having the above-mentioned filled via holes on both sides or one side of the double-sided board alternately and copper. A method of manufacturing a multi-layer substrate, which comprises a series of steps of patterning a foil to form a circuit to form a multi-layer structure. 7. The method of manufacturing a multilayer substrate according to claim 6, wherein the liquid resin contains a flexible epoxy resin. 8. The method for manufacturing a multilayer substrate according to claim 6, wherein the solid resin is a powder curing agent. 9. The glass transition point of a reaction product of a cured product of a liquid resin and a solid resin constituting a via after thermocompression bonding is lower than a glass transition point of a cured resin product of an insulating material layer. 7. The method for manufacturing a multilayer substrate according to item 6. 10. The method for producing a multilayer substrate according to claim 6, wherein the conductive powder is selected from at least one of silver, copper and nickel. 11. The method for producing a multilayer substrate according to claim 6, wherein the insulating material layer is selected from at least one selected from a glass epoxy composite, a glass BT resin composite, an aramid epoxy composite, and an aramid BT resin composite. Method.