JPS62151337A - Printed wiring substrate and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printed wiring board using mica as a base material and a method for manufacturing the same.

[Prior Art 1] A printed wiring board is produced by using a laminated board with excellent electrical insulation performance as an insulating substrate and laminating metal foil on the surface thereof. The insulating substrate made from this laminate is made by stacking multiple sheets of prepreg made by impregnating a base material such as paper with thermosetting U (greasy varnish, etc.) and drying it, then laminating it by heating and pressing. Here, the electrical insulation performance of an insulating substrate is greatly influenced by the resin impregnated into the base material, and is also greatly influenced by the base material itself.Therefore, conventionally, paper is used as the base material. In addition, glass cloth made of woven or nonwoven glass fibers is used as a base material for insulating substrates of printed wiring boards that require particularly high electrical insulation performance.

However, with the recent trend toward higher density mounting of electronic components in printed wiring boards, even higher electrical insulation performance is required of the insulating substrates, and there is a need for a base that can satisfy such high electrical insulation performance. The use of mica, or mica, as a material is attracting attention. Kagaru mica is provided in the form of small scale-like flakes, and when mica is used as a base material, mica paper is produced by making a slurry in which mica scales are dispersed and aggregating the mica scales. It is conceivable to create a mica paper and use this mica paper as a base material.

[Problem to be solved by the invention 1 Here, when creating a prepreg by impregnating a base material with a thermosetting resin face etc. and drying it,
Currently, a long base material is continuously fed through a thermosetting resin face and immersed to impregnate the base material with thermosetting resin varnish. A common manufacturing method is to dry the thermosetting resin face by passing it through the inside and heating it, and then cutting it into regular lengths. This has made it possible to improve the productivity of prepreg.

However, when using mica paper as a base material, when impregnating the mica paper with a thermosetting resin varnish, etc., if the mica paper is immersed in the thermosetting resin face, the thermosetting resin face inside the mica paper will be absorbed. As the mica penetrates, the aggregated mica scales will separate, making it impossible to maintain the paper-like form.Also, it is difficult to soak the thermosetting resin face in the mica paper and send it continuously to the dryer. During this time, tension is applied to the mica paper, but the mica paper, whose mica scales have been separated by the penetration of the thermosetting resin face, cannot withstand this tension and breaks.

Therefore, when using mica paper as a base material, a long mica paper is continuously fed and dipped into a thermosetting resin face, and then a mica paper impregnated with thermosetting resin varnish is continuously fed and immersed in a thermosetting resin face. It is not possible to use methods such as passing the mica paper through a dryer, so for example, a thermosetting resin face is applied to the surface of the mica paper cut into regular lengths by brushing or spraying. It is highly productive, as prepregs have to be created by hand rather than in a continuous process, such as impregnating a face and then drying the mica paper impregnated with this thermosetting resin face one sheet at a time. This means that they have no choice but to rely on low quality work.

Means for Solving Problem E] The present invention has been made for the purpose of solving the above problem, and the printed wiring board according to the present invention has a structure in which mica scales are assembled on the surface of mica paper. A plurality of mica sheets formed by laminating reinforcing sheets into which a resin liquid is permeated become M! by curing the thermosetting resin impregnated into the mica sheets. m*i, and a metal foil is laminated and bonded to the outermost layer of the mica sheet, and the method for producing a printed wiring board according to the present invention is characterized in that the mica sheet is laminated and bonded to the outermost layer of the mica sheet. A mica sheet base material prepreg is created by impregnating a mica sheet with a thermosetting resin liquid and drying the mica sheet, which is formed by laminating a reinforcing sheet into which a resin liquid is permeated onto the surface of mica paper. The method is characterized in that a plurality of base material prepregs are stacked, a metal foil is stacked on the surface of the outermost layer of the mica sheet base material prepreg, and this is heated and press-molded.

In the printed wiring board of the present invention, an insulating board can be formed using mica paper as a base material, in which mica scales are aggregated, and mica's excellent electrical insulation properties provide good electrical properties. In addition, in the method of manufacturing a printed wiring board of the present invention, even when the mica paper is impregnated with the thermosetting resin face, the mica paper has a reinforcing effect due to the reinforcing sheet. When mica paper is used as a base material for insulating substrates of printed wiring boards, it is impregnated with thermosetting resin liquid and dried in a continuous process to create prepreg. This makes it possible to do the following.

The present invention will be explained in detail below.

As mica (mica), either natural mica or synthetic mica can be used, and the types and chemical compositions of mica are shown in Table fpJ1, although they are not particularly limited. These materials can be used alone or in combination.

Table 1 Fluoro-tetra KMg2s (S1o+o)Fz This mica is used in a pulverized state into scales.
The particles are preferably adjusted to 50 meshes or less, preferably 100 meshes or less.

If the particle size is different from 50 meshes, the surface of mica paper made by aggregating mica scales may become rough.

Thus, mica paper can be created by assembling mica scales without using an adhesive or the like, but in the present invention, a reinforcing sheet is laminated on the surface of this mica paper, and the mica paper is reinforced with the reinforcing sheet. It is used as a mica sheet. The reinforcing sheet should be a fibrous material that has the ability to penetrate the resin liquid so as not to impede the impregnation of the thermosetting resin liquid into the mica paper when the mica sheet is used as a base material for an electrical insulating board. For example, paper or plastic fabric made of woven fabric or non-woven fabric of plastic fibers, fabric of other natural fibers or synthetic fibers, asbestos fabric, etc. can be used.

Also, when creating mica sheet 3 by reinforcing mica paper 1 with reinforcing sheet 2, fjt! In addition to laminating the reinforcing sheet 2 on one side of the mica paper 1 as shown in Figure 2(u), reinforcing sheets 2 are laminated on both sides of the mica paper 1 as shown in Figure 12(b). Alternatively, the reinforcing sheet 2 may be sandwiched between the surfaces of two mica papers 1, 1, as shown in FIG. 12(c). Furthermore, a multilayer oval mica sheet 3 can be created by alternately laminating a plurality of mica papers 1 and a plurality of reinforcing sheets 2. In short, mica paper 1 and reinforcing sheet 2
Any combination is not limited in any way and is arbitrary. The reinforcing sheet 2 may be of any thickness as long as it has sufficient thickness to reinforce the mica paper 1.

Here, when creating the mica sheet 3 by laminating the mica paper 1 and the reinforcing sheet 2, it is preferable to laminate the mica paper 1 and the reinforcing sheet 2 without using an adhesive. That is, if the mica paper 1 and the reinforcing sheet 2 are bonded together using an adhesive, the insulation performance of the electrically insulating board may be affected by the type of adhesive. Therefore, in manufacturing the mica sheet 3, the mica paper 1 is produced by aggregating the mica scales by making an aqueous slurry of the mica scales, and at the same time, the mica paper 1 is laminated with the reinforcing sheet 2 to achieve lamination that does not require an adhesive. It is better to FIG. 3 shows an example of a papermaking apparatus. A vat 10 is supplied with a slurry 15 in which fibrous materials such as paper pulp or plus-a miscellaneous materials are dispersed in water. The a4I material remains on the surface of the circular screen 11 and is made into paper, and the paper-made M16 of this fibrous material is transferred to the surface of the endless strip-shaped felt 12. Further, a slurry 17 in which mica scales are dispersed in water is supplied to the vat 13, and this slurry 17 is heated to lI! on the surface of the circular screen 14. The mica scales remain on the surface of the round screen 14 during papermaking, and the papermaking layer 18 of mica scales is transferred to the surface of the papermaking layer 16 of fibrous material attached to the surface of the 7-elt 12. In this way, as shown in FIG. 4, the felt 12 is attached to the surface of the 7L 12 as a paper sheet 19 in which a paper layer 18 of mica scales is laminated on a paper layer 16 of fiber material.
The paper sheet 19 was peeled off from the 7elt 12 and dehydrated by pressing with a roll or the like, and further dried with a drier or the like and then rolled up to dry the paper layer 18 of mica scales. It is possible to obtain a mica sheet 3 in which a mica paper 1 and a reinforcing sheet 2 in which a fabricated layer 16 of fibrous material is dried are laminated. In this way, the mica paper 1 and the reinforcing sheet 2 are laminated during papermaking, so the mica paper 1 and the reinforcing sheet 2 are laminated and integrated to form the mica sheet 3 without the need to use an adhesive. This means that it can be manufactured. In the device shown in Fig. 3, the device shown in Fig. 2 (
Although the mica sheet 3 shown in a) can be manufactured,
By using a pair of vats 10 that supply a slurry 15 of fiber material, the mica sheet 3 shown in FIG. 2(b) is produced.
A mica sheet 3 shown in FIG. 2(C) is produced by using a pair of vats 13 that supply a slurry 17 of mica scales.
can be manufactured respectively.

In addition, in the apparatus shown in FIG. 3, the mica paper 1 and the reinforcing sheet 2 are laminated at the time of papermaking, but in the apparatus shown in FIG. At the same time, a long reinforcing sheet 2 is supplied,
In the vat 13 to which the slurry 17 of mica scales is supplied, a sheet of mica scales N18 is formed on a circular screen 14, and this layer of mica scales 18 is transferred onto the surface of the reinforcing sheet 2. By laminating a paper layer 18 of mica scales on the surface to create a laminated belt 20 as shown in FIG. 6, it is dehydrated by pressing with a roll or the like, further dried with a drier or the like, and then rolled up. It is possible to obtain a mica sheet 3 in which the mica paper 1 in which the paper-formed layer 18 of mica scales has been dried and the reinforcing sheet 2 are bonded to 8 tN. Even in this case, since mica paper 1 and reinforcing sheet 2 are laminated during papermaking, mica paper 1 and reinforcing sheet 2 are laminated 84 and integrated into a mica sheet without using adhesive. 3 can be manufactured. In the apparatus shown in FIG. 5, the mica sheet 3 shown in FIG. 2(a) can be manufactured. By laminating the reinforcing sheets 2, the mica sheet 3 shown in FIG. 2 (Fig.
The mica sheets 3 shown in c) can be obtained.

Note that Fig. 3 and Fig. 5 show a round net type paper making device, but they are separated) 10.13 is a special homer, and a round net 11
, 14 can be replaced with fourdrinier, a fourdrinier type paper making device can also be used.

(Left below) When manufacturing a printed wiring board using the mica sheet 3 manufactured by laminating the mica paper 1 and the reinforcing sheet 2 as described above as a base material, first prepare the prepreg 5 using the mica sheet 3. do. FIG. 7 shows an example of an apparatus for producing the prepreg 5. First, a long mica sheet 3 is continuously fed out and dipped into the thermosetting resin fLA, and then thermoset into the mica sheet 3. impregnated with the synthetic resin e, 4. Here, the thermosetting resin liquid 4 includes epoxy resin, 7 ester resin, area resin, melamine 8 resin, unsaturated polyester resin, polyimide 4 resin, bismaleimide trianone resin, 7 ester resin,
- A face made of any thermosetting resin such as aralkyl resin can be used alone or in combination of two or more kinds. Then, when the mica sheet 3 is immersed in a thermosetting liquid (fertilizer liquid 4), the thermosetting +6 liquid 4 permeates into the mica paper 1 either directly into the mica paper 1 or through the reinforcing sheet 2 formed to be liquid permeable. At this time, as the thermosetting resin liquid 4 penetrates into the mica paper 1, the agglomeration force of the mica scales in the mica paper 1 is weakened, but the mica paper 1 is impregnated with the reinforcing sheet 2. The aggregation force of the mica scales is increased by the lamination of the mica paper 1, and the mica paper 1 is thermosetting (there is no fear that the vapor form will not be maintained due to penetration of the thin liquid 4).

The mica sheet 3 impregnated with the thermosetting resin liquid 4 in this manner is continuously fed and introduced into a dryer 21 such as an oven. When the mica sheet 3 impregnated with the thermosetting resin i4 is sent to the dryer 21, tension is applied to the mica sheet 3, but due to the impregnation with the thermosetting resin liquid 4, the aggregate force of the mica scales is reduced. The mica paper 1 whose strength is weakened is reinforced by the reinforcing sheet 2 as described above, and this tension can be received by the reinforcing sheet 2, so that the mica paper 1 is not torn and the mica sheet 3 is damaged. This means that it can be prevented. Then, the mica sheet 3 is heated by passing it through a dryer 21, and the thermosetting a (fat) impregnated in the mica sheet 3 is dried and semi-cured to obtain a prepreg 5 using the mica sheet 3 as a base material. This prepreg 5 is further cut into a predetermined size by a cutting device 22.

Next, a certain number of prepregs 5 using the mica sheet 3 formed to a predetermined size as a base material are stacked as shown in FIG. By stacking metal foils 6 such as or aluminum foils, placing them between hot platens, and applying heat and pressure to perform lamination molding, the resin in the prepreg 5 melts and hardens, and multiple mica sheets 3 are laminated and bonded. Integrated #! ! A printed wiring board A is obtained in which a laminate of the acid substrate 7 is obtained and a metal foil 6 is laminated on the surface of the insulating substrate 7 using the melted and hardened resin of the prepreg 5 as an adhesive.
) can be obtained as follows. By overlaying metal foils 6 and 6 on the outermost layers of both sides of the prepreg 5, a double-sided metal foil-covered printed wiring board A can be obtained, and by overlaying the metal foil 6 on the outermost layer of one side of the prepreg 5, a single-sided metal foil board A can be obtained. This means that a foil-clad reprinted wiring board A can be obtained.

Here, 31 mica sheets and 1 mica paper
Figure 52 (a) shows several examples of combinations of and reinforcing sheet 2.
As shown in (b) and (C), FIG. 1(a) is a structure in which a plurality of sheets are laminated using only the prepreg 5 using the mica sheet 3 of FIG. 2(a) as a base material. . As shown in Fig. 8(a), multiple sheets of prepreg 5 made of the mica sheet 3 of Fig. 2(b) as a base material can be used to laminate multiple sheets, and as shown in Fig. 8(b), ni f:t
It is also possible to make a plurality of sheets M) using only the prepreg 5 using the mica sheet 3 shown in FIG. 12(c) as a base material. Furthermore, it is also possible to use only the prepreg 5 of the same type of mica sheet 3 as described above, or to use a combination of prepregs 5 of different types of mica sheets 3. FIG. 9(a) shows that the prepreg 5 of the mica sheet 3 of FIG. 2(+1) and FIG. 2(b) is used in combination. ) are Figure 2(a) and 2
FIG. 9(c) shows that the prepreg 5 of each mica sheet 3 shown in FIG. 9(c) is used in combination as shown in FIG. 2(b).
) and the prepreg 5 of the mica sheet 3 shown in FIG. 2(c) are used in combination. Furthermore, as shown in FIG. 9(d), (a) in FIG.
The prepregs 5 of the mica sheets 3 in (b) and (c) can also be used in combination. In the combination shown in FIG. 9, the prepregs 5 of different types of mica sheets 3 can be laminated alternately or randomly, or in any desired manner.

Since the printed wiring boards A formed as described above are formed using the mica sheet 3 as a base material, they can have high electrical insulation properties. Moreover, mica has a scale plate-like form, and mica paper 1 in mica sheet 3
Since this mica is in a layered state, the mica paper 1 has in-plane isotropy and has no warping or twisting after molding, and has excellent dimensional stability, which prevents warping and warping on the printed wiring board A. This means that twisting can be reduced and dimensional stability can be improved. In addition, mica has low hardness, which makes post-processing into printed wiring boards easier. For example, when drilling through-holes, it is possible to suppress heat generation to a small level and reduce the occurrence of smear. It is possible to increase the reliability of

[Example] Next, the present invention will be specifically explained using Examples.

Dog 1" [L 2" - ■Manufacture of mica sheet Slurry 15 containing 25 kg of kraft pulp in water of 100 (N!) is supplied to the vat 10 of the device shown in Fig. Bit, particle size is 200 mesh or less, particle size is 10-150μ)
2 kg of slurry 17 is supplied to the vat 13 of the apparatus shown in FIG. 3, and paper layers 16.18 made from each slurry 15.17 are attached to the surface of the felt 12 in a laminated state as shown in FIG. 4. By drying the paper sheet 19 on which the paper layers 16 and 18 are laminated using a dryer at 100°C, the mica paper 1 and the paper as the reinforcing sheet 2 having the weight shown in Table 2 are laminated together. Mica sheet 3 having the layered structure shown in FIGS. 2(a), (b), and (c)
(Mica sheet No. 2, No. 3) was obtained.

Further, in the apparatus shown in FIG. 5, a glass paper made of glass #1 fibers as a long reinforcing sheet 2 is supplied along the surface of the felt 12, and a slurry 17 of mica scales similar to the above is supplied. Round net 1 in bat 13
By forming a paper layer of mica scales in step 4, transferring it to the surface of the reinforcing sheet 2, and drying it, the mica paper 1 and the glass paper as the reinforcing sheet 2 having the weight shown in table f:IS2 are laminated and integrated. A mica sheet 3 having the layer structure shown in FIG. 2(a) was obtained (Mica Sheet No. 4).

■Manufacture of prepreg The mica sheet 3 thus obtained is impregnated with the resin face shown in Table 3 to a resin content of 55% using the apparatus shown in Fig. 7, and further heated and dried under the conditions shown in Table 3. Mica sheet base material prepreg 5 having mica sheet 3 as a base material was obtained by cutting it into predetermined dimensions (prepreg No. 1 to N).

7).

(Leaving space below) ■Manufacture of copper-clad printed wiring board Six sheets of the obtained prepreg 5 are stacked according to the layer formation shown in Table 4, and the outer surface of the out-of-plane layer of this prepreg 5 is each coated with a thickness of 3.
Electrolytic copper foils 6 having a thickness of 5 μm were stacked and then heated and pressure-molded under the conditions shown in Table 4 to obtain double-sided copper-clad printed wiring boards with a thickness of 1.61 mm (Examples 1 to 6).

Using kraft paper with a scale of ff1164g/■2 as a base material, impregnate it with 7 el/-lum (fatty varnish) shown in Table 3 and dry it to create a paper base prepreg with a thickness of 0.26+oI11. Six sheets of this paper-based prepreg were stacked, and electrolytic copper foil with a thickness of 35 μm was stacked on each outer surface of the outer layer of this paper-based prepreg, and the sheets were molded in the same manner as Example 1 in Table 4, and both sides were covered with copper. A printed wiring board was obtained.

Commercially available glass cloth (WE18 manufactured by Nittobo Co., Ltd.-ZB)
) as a base material, impregnated with the epoxy resin varnish shown in Table 3 and dried to obtain a thickness of 0.27++.
+m plus base material prepreg was created. Six sheets of this glass base material prepreg are stacked, and electrolytic steel foil with a thickness of 35 μm is stacked on the outer surface of each of the outer layers of this glass base material prepreg, and is molded in the same manner as Example 2 in Table 4 to print double-sided copper cladding. A wiring board was obtained.

Commercially available plus cloth (Nitto Boseki Co., Ltd.!! W618-Z
B) was used as a base material, and polyimide If of Table 3 was added to it.
The thickness is reduced to 0.2 by impregnating with fat varnish and drying.
7[11+11] lath base material prepreg was created. This lath base material prepreg is stacked with 6 sheets, and the outer surface of the outer layer of this lath base material prepreg is 3 times thicker.
Electrolytic copper foils having a thickness of 5 μm were stacked and molded in the same manner as in Example 5 in Table 4 to obtain a double-sided steel-clad printed wiring board.

Table 5 shows the results of measuring various properties of the copper-clad printed wiring boards obtained in Examples 1 to 6 and Comparative Examples 1 to 3.

As shown in Table 5, in each example using mica sheet as the base material, as seen in the volume resistivity and surface resistivity items, compared to the comparative example using paper or plastic as the base material. It is confirmed that the electrical insulation properties are significantly improved. Moreover, as can be seen in the terms of dielectric constant and dielectric loss tangent, which are related to high frequency characteristics, it is confirmed that the characteristics of each example are improved over those of each comparative example. Furthermore, it is confirmed that each Example is superior to each Comparative Example in terms of water absorption.

[Effect of the Invention J As described above, the printed wiring board of the present invention includes a plurality of mica sheets formed by laminating reinforcing sheets in which resin liquid is infiltrated on the surface of mica paper in which mica scales are assembled. , because the mica sheet is laminated and bonded by curing of the thermosetting resin impregnated with it, and the metal foil is laminated and bonded to the outermost layer of the mica sheet.
Mica paper can be used as a base material for an insulating substrate of a printed wiring board in a state where it is reinforced with a reinforcing sheet, and the excellent electrical insulation performance of mica in mica paper1 results in a printed wiring board having good electrical properties. There are things you can do. Further, the method for manufacturing a printed wiring board according to the present invention uses mica in which mica scales are aggregated.

A mica sheet base material prepreg is created by impregnating a mica sheet with a thermosetting resin liquid and drying it, which is formed by laminating reinforcing sheets into which the resin liquid permeates the surface of the vapor. Mica paper is made by stacking multiple sheets of prepreg and layering metal foil on the surface of the outermost layer of the mica sheet base prepreg, which is then heated and press-formed.In mica paper, mica scales are assembled by laminating reinforcing sheets. When using a mica sheet as a base material for an insulating substrate of a printed wiring board, even if it is impregnated with thermosetting υI fat blood, the mica paper will no longer retain its vapor form due to the penetration of the thermosetting resin liquid. In addition, the reinforcing sheet can compensate for the drop in tension of the mica paper due to penetration of the thermosetting resin liquid. Soaking and drying can be performed in a series of continuous steps, making it possible to manufacture printed wiring boards with excellent electrical properties using mica as a base material with high productivity.

[Brief explanation of drawings]

Figures 1 (a) and (b) are cross-sectional views of each process of manufacturing a printed wiring board, Figures 2 (, ) (bHc) are front views of various aspects of the mica sheet in the same manner, and Figure 3 is a cross-sectional view of each aspect of the mica sheet. A partial schematic diagram showing an example of a manufacturing device, Figure 1 is a cross-sectional view of a sheet made of felt, and Figure 5 shows another example of a device for manufacturing mica sheets. Some schematic diagrams: Figure 6 is a cross-sectional view of a laminated sheet, Figure 7 is a schematic diagram showing an apparatus for manufacturing prepreg, and Figures 8 (a) and (b) are cross-sections of each step in manufacturing a printed wiring board. Figure 9(a) (
b), (c), and (d) are cross-sectional views showing combinations of prepregs obtained from mica sheets of various embodiments. 1 is a mica paper, 2 is a reinforcing sheet, 3 is a mica sheet, 4 is a thermosetting resin liquid, 5 is a prepreg, and 6 is a metal foil. that's all

Claims (5)

[Claims] (1) Multiple mica sheets are formed by laminating reinforcing sheets into which resin liquid is infiltrated on the surface of mica paper, which is made up of mica scales. In addition to being laminated and bonded,
A printed wiring board characterized by having metal foil laminated and bonded to the outermost layer of a mica sheet. (2) The printed wiring board according to claim 1, wherein the mica sheet is formed by laminating a reinforcing sheet on one side of mica paper. (3) The printed wiring board according to claim 1, wherein the mica sheet is formed by laminating reinforcing sheets on both sides of mica paper. (4) The printed wiring board according to claim 1, wherein the mica sheet is formed by laminating a reinforcing sheet between one side of two mica papers. (5) A mica sheet is formed by laminating a reinforcing sheet in which a resin liquid is infiltrated on the surface of a mica paper on which mica scales are assembled, and then impregnating the mica sheet with a thermosetting resin liquid and drying it. Production of a printed wiring board characterized by creating a material prepreg, stacking a plurality of mica sheet base material prepregs, overlaying a metal foil on the surface of the outermost layer of the mica sheet base material prepreg, and molding this under heat and pressure. Method.