JP2614190B2 - Prepreg for multilayer board, laminated board, multilayer printed circuit board and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg for a multi-layer board, a multi-layer board, a multi-layer printed circuit board, and a method of manufacturing the same, which constitute a low-k laminate used as, for example, a high-frequency printed circuit board.

[0002]

2. Description of the Related Art Conventionally, prepregs of the above-mentioned example are disclosed in, for example, JP-A-63-47127 and JP-A-5-69442.
And Japanese Patent Application Laid-Open No. 2-261830, both of which have a basic structure in which a base material such as a glass cloth is impregnated and held with a PTFE resin.

The above-mentioned PTFE (polytetrafluoroethylene, tetrafluoroethylene resin) has a very high viscosity (for example, 10 ¹¹ poise at 380 ° C.) even in a molten state, and the viscosity of another fluorine resin (for example, PFA) is low. 380
℃ even compared to 10 ⁴ to 10 ⁵ poises) at its melt viscosity is large. For this reason, if the press molding is not performed for a long time under the condition of high temperature and high pressure, sufficient adhesion to the above-mentioned glass cloth base material cannot be ensured.

On the other hand, during the secondary molding of the multilayer board provided with the above-mentioned prepreg, if the press molding is performed for a long time under the condition of high temperature and high pressure, the displacement of the wiring circuit made of the Cu foil formed beforehand and the completion of the completed circuit are completed. The multilayer board undergoes dimensional changes and warpage, making it difficult to use it as a wiring board (high-frequency printed wiring board) for applying high frequency. The dimensional tolerance in the processing of the circuit wiring is 10 GHz (10 × 10 ⁹ Hz)
Is 50 μm or less.

Further, when press molding is performed under low-temperature and low-pressure conditions in order to avoid the above-described displacement of the wiring circuit and dimensional change of the wiring board, the viscosity of PTFE is lower than that of other fluororesins. Since it is extremely high, sufficient adhesion to the glass cloth base material cannot be obtained, and voids may remain in the PTFE resin held by the prepreg, and these phenomena are caused by the glass cloth base material and the PTFE resin. The plating solution and moisture may enter the gaps and the porous portion of the resin, leading to a decrease in solder heat resistance and non-uniform insulation resistance. And a fatal defect as a high-frequency printed wiring board.

[0006]

SUMMARY OF THE INVENTION The invention according to claim 1 of the present invention relates to an unsintered PTFE on a substrate such as a glass cloth.
The PTFE resin is impregnated with 60 to 96 vol% of the entire prepreg and the porosity of the PTFE resin is 3 to 15 vol%, so that the moving distance of the PTFE resin in a gelled state at the melting temperature is as small as possible. It is possible to hold down the heating and pressurizing state during press molding in a short time,
An object of the present invention is to provide a prepreg for a multilayer board which can ensure good dimensional accuracy under pressing conditions in a low-temperature and low-pressure state and can eliminate a deviation of a wiring circuit when applied to a laminated board or a multilayer printed circuit board.

According to a second aspect of the present invention, a low dielectric constant is achieved by disposing a metal foil on one or both sides of at least one layer of the prepreg for a multilayer board according to the first aspect.
A large amount of unsintered PTFE resin described above in order to ensure
Despite impregnated held, Ki out to ensure good adhesion of the metal foil at the same resin effect, the circuit board
Proper insulation resistance and uniform dielectric properties.
The purpose is to provide a laminated board that can be cut .

According to a third aspect of the present invention, there is provided a multilayer printed circuit board using the laminated board according to the second aspect, that is, the laminated board in which the resin layer located immediately below the metal foil is only PTFE as an inner layer board. By doing so, it is possible to prevent a swimming phenomenon (movement) of the wiring circuit during the secondary molding, reduce a dimensional change, and provide a highly accurate multilayer printed circuit board.

According to a fourth aspect of the present invention, there is provided a prepreg according to the first aspect, wherein a PTFE particle having an average particle size of 0.2 to 0.5 μm is formed on a substrate such as a glass cloth.
And dried under a low temperature condition with respect to the melting point (327 ° C.) of the PTFE resin. Such impregnation and drying are repeated to obtain a large amount of 60-96 vol% resin. By setting the holding amount, the porosity can be kept at 3 to 10 vol%,
When applied to laminated boards and multilayer printed circuit boards, the thickness accuracy is high, the coefficient of linear expansion in the thickness direction is small, the solder heat resistance is excellent, foreign matter is less mixed, and mud cracks are temporarily generated. It is also possible to provide a method for manufacturing a prepreg for a multilayer board, which can fill the mud cracks at the next impregnation, eliminate the influence of the cracks, and achieve a low dielectric constant by securing a necessary resin amount. Aim.

According to a fifth aspect of the present invention, in the production of a prepreg disposed above and below the inner layer plate, the prepreg is formed of a first layer of PTFE, a second layer of PTFE, and a third layer of PFA. And the PTFE second layer is dried under a low temperature condition without sintering to obtain a PFA
By maintaining the third layer in good condition and forming the PFA third layer not by a film interposed structure but by dispersion impregnation, drying and baking, it can be applied to a laminated board or a multilayer printed circuit board. By applying pressure under the conditions of high temperature and higher than the melting points of PTFE and PFA at the time of laminating press, thickness accuracy is high, thickness variation is small, linear expansion coefficient in the thickness direction is small, and metal Strong adhesion between foil and prepreg, high solder heat resistance and high resistance to thermal shock, and no penetration of chemicals
An object of the present invention is to provide a method for producing a prepreg that can achieve a low dielectric constant.

According to a sixth aspect of the present invention, a large amount of resin held by the manufacturing method according to the fourth aspect is reduced.
The prepreg with the inner layer plate, above and below this inner layer plate,
After arranging a fluororesin film such as PFA or FEP or a prepreg manufactured by the manufacturing method of claim 5 and further arranging a metal foil on the outermost layer, press molding at a temperature higher than the melting point of PTFE and in a high pressure state. It is an object of the present invention to provide a method for manufacturing a multilayer printed circuit board having high adhesion to a substrate, having uniform physical properties, and further having excellent properties of water absorption, dimensional change, and solder heat resistance.

[0012]

According to the first aspect of the present invention, a base material such as a glass cloth is impregnated with an unsintered PTFE resin in an amount of 60 to 96 vol% of the entire prepreg .
It is a prepreg for a multilayer board in which the porosity of the PTFE resin is 3 to 10 vol%.

According to a second aspect of the present invention, there is provided a laminated plate in which a metal foil is disposed on one or both sides of the prepreg for a multilayer board of at least one layer according to the first aspect.

According to a third aspect of the present invention, there is provided the laminated board according to the second aspect as an inner layer plate, and a fluororesin film such as PFA or FEP, or a PTFE resin as a base material, above and below the inner layer plate. And a prepreg impregnated and held with PFA or FEP on both outer layers, and a multi-layer printed circuit board on which a metal foil is arranged on the outermost layer.

According to a fourth aspect of the present invention, there is provided a method for producing a prepreg for a multilayer board according to the first aspect,
Substrate such as glass cloth has an average particle size of 0.2 to 0.5 μm
Impregnated with a PTFE resin dispersion composed of PTFE particles , dried under a low-temperature condition with respect to the melting point of the PTFE resin, and the above-described impregnation and drying were repeated.
It is a method for producing a prepreg for a multilayer board having a resin holding amount of 0 to 96 vol%.

According to a fifth aspect of the present invention, there is provided the method for producing a prepreg according to the third aspect, wherein
After impregnated with TFE dispersion and dried, PT
Baking under a condition higher than the melting point of FE, repeating the above-described impregnation, drying and baking to form a first layer having a required resin holding amount; and impregnating the surface of the first layer with a PTFE dispersion. A second step of drying under a condition lower than the melting point of PTFE and repeating the above-described impregnation and drying to form a second layer having a required resin holding amount;
After impregnated with the FA dispersion and dried, the PF
A and baked under the condition of higher temperature than the melting point of PTFE,
A method for producing a prepreg, comprising the steps of: forming a third layer having a required resin holding amount by repeating the above-described impregnation, drying, and firing, and a third step of forming a prepreg.

According to a sixth aspect of the present invention, there is provided a prepreg produced by the production method according to the fourth aspect as an inner layer plate, and a fluororesin film such as PFA or FEP or a fluororesin film formed on the upper and lower sides of the inner layer plate. Item 5. A method for manufacturing a multilayer printed circuit board, comprising: arranging a prepreg manufactured by the manufacturing method of Item 5, further arranging a metal foil on an outermost layer, and press-molding at a temperature higher than the melting point of PTFE and at a high pressure. There is a feature.

[0018]

According to the first aspect of the present invention, the base material such as a glass cloth or the like is coated with 6 parts of the entire prepreg.
Unsintered PTF impregnated and held at a rate of 0 to 96 vol%
Since the porosity of the E resin is 3 to 10 vol%,
The moving distance in a state where the resin is gelled at its melting temperature (gelled at about 330 ° C.) can be made as small as possible, so that the heating and pressurizing state during press molding can be suppressed in a short time. In addition to being able to do so, the gap between the base material and the initial P
The PTFE gel can penetrate into the gaps between the TFE particles, filling the gaps with the base material during molding, and reducing the water absorption. If water is absorbed into the base material, the circuit will be short-circuited due to the infiltration of the plating solution etc. along the space in the base material, and the gas inside the space will expand rapidly at the solder temperature, causing destruction inside the base material. This causes disconnection and deterioration of electrical characteristics, but the present invention can prevent them.

As described above, by setting the above porosity, PT
By minimizing the travel distance of the FE resin in the gelled state at its melting temperature, the same dimensional accuracy as conventional products can be ensured even in press molding under low-temperature and low-pressure conditions.
There is no deviation of the wiring circuit when applied to a laminated board or a multilayer printed circuit board, and in addition, when forming a multilayer printed circuit board using the prepreg for the multilayer board, by performing press molding in a high temperature and high pressure state, There is an effect that a multilayer printed circuit board having high adhesion to a base material and uniform physical property values can be obtained.

If the porosity exceeds 10 vol%, the moving distance of the gelled PTFE becomes large, making it difficult to completely eliminate the voids during the manufacture of the substrate. When the porosity is less than 3 vol%, it becomes impossible to manufacture a substrate having various physical properties.
The TFE particles are excessively adhered to each other, and it is difficult to sufficiently remove a dispersant such as a surfactant incorporated in the PTFE dispersion even in a deep part in a drying process.
This dispersant is immediately carbonized under pressing conditions exceeding 300 ° C., and the substrate becomes rich in carbon content, leading to a decrease in insulation resistance, making it impossible to secure an indispensable resistance value as an insulating plate. Not only that, the dielectric constant also increases, making it unusable as a high-frequency circuit board.

According to the second aspect of the present invention,
Since the laminated plate is formed by arranging metal foil on one or both surfaces of the prepreg for at least one layer according to claim 1 , a large amount of the prepreg is required to secure a low dielectric constant. Despite impregnating and holding sintered PTFE resin
It not, by the effect of the resin can be ensured good adhesion of the metal foil, a suitable insulation resistance and uniform as a circuit board
There is an effect that the dielectric properties can be secured .

According to the third aspect of the present invention,
The multilayer board according to claim 2, that is, the resin layer located immediately below the metal foil constitutes a multilayer printed circuit board by using the laminate having only PTFE as an inner layer board. High-precision multi-layer printing by preventing the swimming phenomenon (movement) of the printed circuit board and reducing the dimensional change of the completed multi-layer printed circuit board
There is an effect that a circuit board can be obtained .

According to the invention described in claim 4 of the present invention,
2. A PTF having an average particle size of 0.2 to 0.5 .mu.m on a substrate such as a glass cloth when producing the prepreg according to claim 1.
Impregnated with a PTFE resin dispersion composed of E particles , dried under a low temperature condition with respect to the melting point of the PTFE resin of 327 ° C., and the above impregnation and drying were repeated to obtain a large amount of resin retention of 60 to 96 vol%. , The porosity can be kept at 3 to 10 vol%.
Therefore , when this prepreg is applied to a laminated board or a multilayer printed circuit board, the thickness accuracy is high, the coefficient of linear expansion in the thickness direction is small, and the solder heat resistance is excellent, and there is little foreign matter contamination. Even if mud cracks occur, the mud cracks can be filled during the next impregnation,
The effect of cracks can be eliminated, and the resin holding amount is 6
As large as 0 to 96 vol%, there is an effect that a low dielectric constant can be achieved. In addition, since the prepreg manufacturing process does not include a sintering process, it is unlikely that the substrate has wavy deformation.

According to the invention described in claim 5 of the present invention,
In manufacturing a prepreg arranged above and below the inner layer plate, the prepreg is combined with a first layer of PTFE and a PTF.
E has a three-layer structure of a second layer of P and a third layer of PFA,
The FE second layer is dried under a condition lower than the melting point of PTFE without sintering to improve the holding of the PFA third layer, and the PFA third layer is not a film interposition means but a PF.
Since the prepreg is formed by impregnation, drying and baking of the A dispersion, high-temperature and high-pressure pressing at the time of lamination is possible when the prepreg is applied to a laminate or a multilayer printed circuit board.

In addition, PTFE and P
By applying pressure under high temperature and higher temperature than the melting point of FA, the thickness accuracy is high, the thickness variation is small, the coefficient of linear expansion in the thickness direction is small, and the adhesive force between the metal foil and the prepreg is low. It is strong, has high solder heat resistance and high resistance to thermal shock, has no effect of infiltration of a chemical solution, and has the effect of achieving a low dielectric constant.

Further, when a laminated board and a multilayer printed circuit board are manufactured by the high-temperature and high-pressure press as described above, there is no void (small hole) between the layers, sufficient bonding between the layers, and no resin unevenness of the prepreg itself. This has the effect of preventing swelling of the metal foil during solder bonding, interlayer cracking and interlayer delamination.

According to the invention described in claim 6 of the present invention,
A large amount of resin preservative produced by the production method according to claim 4.
A prepreg having a holding capacity is used as an inner layer plate, and a fluororesin film such as PFA or FEP or a prepreg manufactured by the manufacturing method according to claim 5 is arranged above and below the inner layer plate, and a metal foil is further formed on the outermost layer. After placing, PTF
Since the multilayer printed circuit board is manufactured by press molding at a temperature higher than the melting point of E and at a high pressure, the adhesiveness between the glass cloth base material and the PTFE resin is high and the uniform physical property values are obtained in the completed multilayer printed circuit board. In addition, there is an effect that a multilayer printed circuit board excellent in various characteristics of water absorption, dimensional change, and solder heat resistance can be obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. First Embodiment FIGS. 1 to 4 show a prepreg for a multilayer board and a laminated board according to the present invention and a method for manufacturing the same. As shown in FIG. 1, as shown in FIG. A PTFE resin dispersion having a concentration of 60% is formed using..., And the above-mentioned PTFE resin dispersion is impregnated into a glass cloth substrate 2 having a basis weight of 48 g / m ² shown in FIGS.
Drying is performed under a condition of 305 ° C., which is lower than the melting point of 327 ° C. of the TFE resin 3, and the unsintered resin is held on the glass cloth substrate 2.

By repeating such impregnation and drying under low-temperature conditions, the prepreg 4 having a resin holding amount in the range of 60 to 96 vol%, for example, 76 vol% (hereinafter, for convenience of explanation, this prepreg 4 is used as the first prepreg 4 ). Leg). The porosity of the resin layer of the first prepreg 4 thus formed was 3 to 10 vol%.

Next, as shown in FIG.
Are laminated in a plurality of layers, for example, four layers, and as shown in FIG. 4, the melting point of the PTFE resin 2 is 327 ° C. The laminate 6 was formed by laminating under a higher temperature condition of 380 ° C., under a laminating condition of 50 kgf / cm ² and a pressing time of about 60 minutes.

The first prepreg 4 of the first embodiment (FIG. 2)
And PTFE particles having an average particle size of 0.1 to 0.5 μm, and all other conditions were set to be the same as those of the first example for the purpose of comparing various characteristics with the laminated plate 6. With the laminate 50 of Example 1 (see FIG. 5), the average particle size is 0.3 to
The laminated plate 60 of Comparative Example 2 (FIG. 6) in which 0.7 μm PTFE particles were used and all other conditions were set to be the same as in the first embodiment.
), The porosity of the prepreg, the dielectric constant of the laminate, and the water absorption after the PCT (pressure cooker test) (wt.
%) The results of measuring and comparing the solder heat resistance after PCT are shown in the following [Table 1].

[0032]

[Table 1]

Here, PCT (pressure cooker test)
The water absorption rate after the measurement is a result of measuring the water absorption rate after immersion in water at 121 ° C. and 1.8 atm for 30 minutes. The solder heat resistance after PCT is immersed in a molten solder bath at 260 ° C. for 60 seconds, and the surface is pulled up. While observing the white spots, the white spots were visually counted, those with zero white spots were regarded as excellent, those with 1 to 5 white spots as good, those with 6 to 10 white spots as acceptable, 11 or more or those with blisters were not allowed.

As is clear from Table 1 above, the first embodiment can obtain better results in both water absorption and solder heat resistance as compared with Comparative Examples 1 and 2. Was. In particular, in the case of Comparative Example 1, since the average particle size of PTFE is excessively small in the range of 0.1 to 0.5 μm, lumps are generated, good dispersion cannot be obtained, and the porosity is 10 to 15 vol%, which is out of the predetermined range. Became.

(Second Embodiment) FIG. 7 shows a multilayer printed circuit board and a method of manufacturing the same according to the present invention. The laminated plate 6 obtained in the first embodiment is used as an inner layer plate, and the thicknesses above and below this inner layer plate 6 are shown. The PFA films 7, 7 having a thickness of 25 μm are arranged, and the above-mentioned PFA films 7, 7 are further arranged.
The upper and lower outer plates 8, 8 are arranged at 350 ° C., which is higher than the melting point of 327 ° C. of the PTFE resin 2, and have a surface pressure of 15 ° C.
A multilayer printed circuit board was manufactured by heating and pressing at kgf / cm ² for 10 minutes. Here, the above-mentioned outer layer plate 8 is obtained by removing the electrolytic Cu foil 5 on the inner layer plate side shown in FIG. 7 from the laminated plate 6 shown in FIG. 4 by etching means.

(Third Embodiment) FIG. 8 shows a multilayer printed circuit board and a method of manufacturing the same according to the present invention. The laminated plate 6 obtained in the first embodiment is used as an inner layer plate, The second prepregs 9 described later are stacked three by three, and the upper and lower outermost layers have a thickness of 18 μm.
m electrolytic Cu foils 10, 10 are arranged and laminated, and PTFE
Under the condition of 350 ° C. higher than the melting point of 327 ° C. of the resin 2,
Heating and pressurizing was performed at a surface pressure of 15 kgf / cm ² for 10 minutes to produce a multilayer printed circuit board. Here, the configuration and manufacturing method of the above-described second prepreg 9 are as follows.

That is, in the first step S1 shown in FIG. 9, PT is applied to the glass cloth base material 11 (see FIG. 10) having a basis weight of 48 g / m ² .
After impregnated with FE dispersion and dried, PT
Baking (sintering) at 380 ° C, which is higher than the melting point of FE, 327 ° C
The above-mentioned impregnation, drying and sintering are repeated until the resin content of 70 vol% as the required resin holding amount is reached, and the PTFE is repeated.
The first layer 12 is formed.

Next, in the second step S2 shown in FIG.
After the upper and lower surfaces of the TFE first layer 12 are impregnated with the PTFE dispersion, the PTFE is dried at 305 ° C., which is lower than the melting point of 327 ° C., until the resin content becomes 76 vol% as a required resin holding amount. The drying is repeated to form the PTFE second layer 13.

Next, in the third step S3 shown in FIG.
After the upper and lower surfaces of the TFE second layers 13 and 13 are impregnated with the PFA dispersion and dried, the melting point of PFA 3
It is fired (sintered) at 10 ° C. and 380 ° C., which is higher than the above-mentioned melting point of PTFE of 327 ° C., and the above-mentioned impregnation, drying and sintering are repeated until the resin content of 80 vol% as a required resin holding amount is reached. The third layer 14 is formed to form the second prepreg 9 described above. In the drawings other than FIG. 10, for convenience of illustration, the PTFE second layer 1 is used.
Illustration of 3 and 13 is omitted. This second prepreg 9
Does not require a film or the like for bonding, it is easy to handle, there is no change in the dielectric constant of the insulating layer, and in addition, the adhesive layer is formed of a coating layer and the resin has no directionality. Dimensional change due to subsequent molding is small.

(Fourth Embodiment) FIG. 11 shows a multilayer printed circuit board and a method of manufacturing the same according to the present invention. The laminated board 6 obtained in the first embodiment is used as an inner board, and The second prepregs 9 are arranged one by one, and outer layer plates 8, 8 having the same configuration as in FIG. 7 are arranged above and below the second prepregs 9, 9.
Under a condition of 350 ° C. higher than the melting point of 327 ° C. and a surface pressure of 15 kgf / cm ² for 10 minutes to produce a multilayer printed circuit board.

(Fifth Embodiment) FIG. 12 shows a multilayer printed circuit board according to the present invention and a method of manufacturing the same. The laminated board 6 obtained in the first embodiment is used as an inner board. On the other hand, one second prepreg 9 inside,
Two first prepregs 4 and 4 on the outside, and a thickness of 1
8 μm electrolytic Cu foils 15 are arranged, and 380
After heating and pressing at 15 ° C. and 15 kgf / cm ² for 60 minutes, an outer layer plate 16 is formed by removing only the electrolytic Cu foil 15 on the second prepreg 9 side by etching means.

Then, outer plates 16, 16 are arranged above and below the inner layer plate 6 so that the second prepreg 9 side faces the inner layer plate 6, and the melting point 32 of the PTFE resin 2 is reduced.
Under conditions of 350 ° C higher than 7 ° C and surface pressure of 15kgf /
The substrate was heated and pressed at 10 cm ² for 10 minutes to produce a multilayer printed circuit board.

Comparative Example 3 FIG. 13 shows a comparative example manufactured for comparing various characteristics with the second, third, fourth and fifth embodiments of the present invention. The obtained laminated plate 6 is used as an inner layer plate. On the other hand, a base material 61 is impregnated with a PTFE resin 62, and a fired prepreg 63 heated and pressed at a temperature higher than a melting point of 327 ° C. of the PTFE resin 62 is provided.

A thickness of 25 is formed above and below the laminated plate 6.
μm PFA film 7, fired prepreg 63, PFA
A film 7, a fired prepreg 63, a PFA film 7 and an electrolytic Cu foil 64 having a thickness of 18 μm are arranged in this order, and PTF
Under the condition of 350 ° C. higher than the melting point of 327 ° C. of the E resin,
Further, heating and pressing were performed at a surface pressure of 15 kgf / cm ² for 10 minutes to produce a multilayer printed circuit board as a comparative example.

Comparative Example 4 FIG. 14 shows a comparative example manufactured to compare various characteristics with the second, third, fourth and fifth embodiments of the present invention. The above-mentioned second prepregs 9 and 9 are respectively arranged on both sides of the obtained one prepreg 4, and electrolytic Cu foils 71 and 71 having a thickness of 35 μm are arranged on the outermost layer.
A laminated plate is formed by pressure molding at a temperature of 380 ° C., which is higher than the melting point of PTFE of 327 ° C., and a surface pressure of 50 kgf / cm ² for 60 minutes. Further, the electrolytic Cu foil on the inner layer plate 72 side of the first prepreg 4 is removed by etching means, and a laminated plate having the electrolytic Cu foil 73 only in the outer layer is formed.

Then, an outer layer plate 74 is arranged above and below the inner layer plate 72 with one second prepreg 9 interposed therebetween to form a PTFE.
A multilayer printed circuit board as a comparative example was manufactured by heating and pressing under a condition of 350 ° C. higher than the melting point of the resin at 327 ° C. and a surface pressure of 15 kgf / cm ² for 10 minutes.

The water absorption (wt%), the dimensional change (%), and the solder heat resistance of the multilayer printed circuit boards of the second, third, fourth and fifth embodiments and Comparative Examples 3 and 4 are described. Are shown in the following [Table 2].

[0048]

[Table 2]

Here, the conditions for measuring the water absorption rate and the solder heat resistance are the same as those described above. The dimensional change rate is obtained by measuring the change rate of the distance between the marks written on the inner layer. That is, the result of measuring the distance between the four corners of a plate having a length of 340 × width 340 mm using a three-dimensional measuring device is shown.

As is clear from Table 2 above,
It is apparent that the third, fourth and fifth examples are superior to the comparative examples 3 and 4 in the overall properties of water absorption, dimensional change and solder heat resistance. In particular, in the case of Comparative Example 3, solder heat resistance was not possible, and in the case of Comparative Example 4, the dimensional change rate was large. In addition, the circuit of Comparative Example 4 has a PFA layer immediately below the electrolytic Cu foil 71 of the inner layer plate 72, so that the circuit formed by the electrolytic Cu foil 71 when pressed at 350 ° C. with a melting point of 310 ° C. or more of PFA is used. The pattern shifted and a swimming phenomenon occurred.

In short, according to the first aspect of the present invention, the entire prepreg is applied to the substrate 2 such as a glass cloth.
Since the porosity of the unsintered PTFE resin 3 to be impregnated and held at a rate of 60 to 96 vol% of the body was set to 3 to 10 vol%,
The moving distance in a state where the PTFE resin 3 is gelled at the melting temperature can be made as small as possible, so that the heating and pressurizing state at the time of press molding can be suppressed in a short time and the PTFE can be melted. Even when the temperature is near the lowest temperature (that is, in the low-temperature heating state), the gap between the
The PTFE gel can penetrate into the gaps between them.

As described above, by setting the above porosity, PT
By minimizing the movement distance of the FE resin 2 in the gelled state at its melting temperature, the same dimensional accuracy as that of the conventional product can be ensured even in press molding under low-temperature and low-pressure conditions. There is no deviation of the wiring circuit when applied to a printed circuit board.
When a multi-layer printed circuit board is formed by using, by performing press molding in a high temperature and high pressure state, it is possible to obtain a multi-layer printed circuit board having high adhesion to the base material 2 and uniform physical property values. is there.

If the above porosity exceeds 10 vol%, the moving distance of the gelled PTFE becomes large, making it difficult to completely eliminate the void portion during the production of the substrate. It becomes impossible to manufacture a substrate having physical properties. Conversely, if the porosity is less than 3 vol%, P
The TFE particles are excessively adhered to each other, and it is difficult to sufficiently remove a dispersant such as a surfactant incorporated in the PTFE dispersion even in a deep part in a drying process.
This dispersant is immediately carbonized under pressing conditions exceeding 300 ° C., and the substrate becomes rich in carbon content, leading to a decrease in insulation resistance, making it impossible to secure an indispensable resistance value as an insulating plate. Not only that, the dielectric constant also increases, making it unusable as a high-frequency circuit board.

According to the second aspect of the present invention,
2. The at least one layer of the first prepreg according to claim 1.
A metal foil (see electrolytic Cu foil 5) is disposed on one or both sides of each of
As described above, in order to secure a low dielectric constant ,
For holding such a large amount of unsintered PTFE resin
Regardless, Ri effect there can be secured a good adhesion of the metal foil by the effect of the resin, suitable as a circuit board
High insulation resistance and uniform dielectric properties
You .

According to the third aspect of the present invention,
The multilayer board according to claim 2, that is, the resin layer located immediately below the metal foil constitutes a multilayer printed circuit board by using the above-described laminate of only PTFE as an inner layer board, so that wiring during secondary molding (during pressing) is performed. A swimming phenomenon (movement) of the circuit can be prevented, and as is clear from the above-mentioned [Table 2], a dimensional change of the completed multilayer printed circuit board is reduced to achieve a highly accurate multilayer printed circuit board. There is an effect that can be obtained .

According to the invention described in claim 4 of the present invention,
In producing the first prepreg 4 according to claim 1,
Substrate 2 such as glass cloth has an average particle size of 0.2 to 0.5 μm
Impregnated with a PTFE resin dispersion composed of the PTFE particles described above, and the melting point of the PTFE resin 3 is 327 ° C.
In this method, the resin is dried under a low temperature condition, and the above impregnation and drying are repeated to obtain a resin holding amount of 60 to 96 vol%, so that the porosity can be kept at 3 to 10 vol%.
When the first prepreg 4 is applied to a laminated board or a multilayer printed circuit board, the thickness accuracy is high, the linear expansion coefficient in the thickness direction is small, the solder heat resistance is excellent, and the foreign matter is less mixed. Further, even if a mud crack is generated, the mud crack can be filled in the next impregnation, the influence of the crack can be eliminated, the resin holding amount is as large as 60 to 96 vol%, and the dielectric constant can be reduced. There are effects that can be achieved. Further, since the manufacturing process of the first prepreg 4 does not include the sintering process, the substrate 2 cannot be deformed in a wavy shape.

According to the fifth aspect of the present invention,
When manufacturing the second prepreg 9 disposed above and below the inner layer plate 6, the second prepreg 9 is replaced with the first PTFE
Layer 12, a second layer 13 of PTFE, and a third layer 1 of PFA
4, the PTFE second layer 13 is dried without being sintered at a temperature lower than the melting point of PTFE,
Since the holding of the PFA third layer 14 is good and the PFA third layer 14 is formed by impregnation, drying, and baking of the PFA dispersion instead of the film interposing means, the second prepreg 9 is used as a laminate, a multilayer printed circuit. When applied to a substrate, high-temperature and high-pressure pressing during lamination is possible.

In addition, PTFE and P
Pressing under the conditions of higher temperature and higher pressure than the melting point of FA provides high thickness accuracy, small thickness variation, small coefficient of linear expansion in the thickness direction, and metal foil (see electrolytic Cu foil)
And the second prepreg 9 have a strong adhesive force, high solder heat resistance and high resistance to thermal shock, and further have no effect of infiltration of a chemical solution and have an effect of achieving a low dielectric constant.

Further, when the laminated board and the multilayer printed circuit board are manufactured by the high-temperature and high-pressure press as described above, there are no voids (small holes) between the layers, the bonding between the layers is sufficient, and the resin unevenness of the second prepreg 9 itself is also reduced. In addition to this, there is an effect that swelling of the metal foil, cracks between layers, and delamination between the layers at the time of solder bonding or the like can be prevented.

According to the invention of claim 6 of the present invention,
A large amount of resin preservative produced by the production method according to claim 4.
The first prepreg 4 having a holding capacity (60 to 96 vol%) is used as an inner layer plate 6, and a fluororesin film 7 such as PFA or FEP is formed on the upper and lower sides of the inner layer plate 6 or the manufacturing method according to claim 5 above. After arranging the second prepreg 9 and further arranging the metal foil on the outermost layer, the multi-layer printed circuit board is manufactured by press molding at a temperature higher than the melting point of PTFE and at a high pressure. There is an effect that a multilayer printed circuit board having high adhesion between the base material and the PTFE resin, having uniform physical property values, and further having excellent properties of water absorption, dimensional change, and solder heat resistance can be obtained. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between a glass cloth substrate and PTFE particles.

FIG. 2 is a sectional view showing a single-layer structure of a prepreg for a multilayer board of the present invention.

FIG. 3 is a sectional view showing a three-layer structure of a prepreg for a multilayer board of the present invention.

FIG. 4 is a cross-sectional view showing a laminate of the present invention.

FIG. 5 is a cross-sectional view showing a laminate of Comparative Example 1.

FIG. 6 is a cross-sectional view showing a laminate of Comparative Example 2.

FIG. 7 is an exploded sectional view showing the multilayer printed circuit board of the present invention.

FIG. 8 is an exploded sectional view showing another embodiment of the multilayer printed circuit board of the present invention.

FIG. 9 is a process chart showing a method for producing a second prepreg.

FIG. 10 is a sectional view of a second prepreg.

FIG. 11 is an exploded sectional view showing still another embodiment of the multilayer printed circuit board of the present invention.

FIG. 12 is an exploded sectional view showing still another embodiment of the multilayer printed circuit board of the present invention.

FIG. 13 is an exploded cross-sectional view illustrating a multilayer printed circuit board of Comparative Example 3.

FIG. 14 is an exploded cross-sectional view illustrating a multilayer printed circuit board of Comparative Example 4.

[Explanation of symbols]

2 ... Glass cloth base material 3 ... PTFE
Resin 4: First prepreg 5: Electrolytic Cu
Foil 6 Laminated plate (inner layer plate) 7 PFA film 9 Second prepreg 10, 15
Electrolytic Cu foil 11: Base material 12: PTF
E first layer 13: PTFE second layer 14: PTF
E third layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H05K 3/46 H05K 3/46 T

Claims (6)

(57) [Claims] An unsintered PTFE is applied to a substrate such as a glass cloth.
A prepreg for a multilayer board in which a resin is impregnated and held at 60 to 96 vol% of the entire prepreg, and the porosity of the PTFE resin is 3 to 10 vol%. 2. A laminate in which a metal foil is disposed on one or both sides of the prepreg for a multilayer board of at least one layer according to claim 1. 3. A laminate according to claim 2, wherein the laminate is an inner plate, and a fluororesin film such as PFA or FEP, or a PTFE resin is impregnated and held on a base material on the upper and lower sides of the inner plate, and PFA is formed on both outer layers. Alternatively, a multi-layer printed circuit board in which a prepreg impregnated with FEP is disposed and a metal foil is disposed on the outermost layer. 4. The method for producing a prepreg for a multilayer board according to claim 1, wherein the base material such as glass cloth has an average particle size of 0.2 to 0.5 μm.
Impregnated with a PTFE resin dispersion composed of PTFE particles , dried under a low-temperature condition with respect to the melting point of the PTFE resin, and the above-described impregnation and drying were repeated.
A method for producing a prepreg for a multilayer board having a resin holding amount of 0 to 96 vol%. 5. The method for producing a prepreg according to claim 3, wherein the substrate is impregnated with a PTFE dispersion and dried, and then calcined under a condition higher than the melting point of PTFE. A first step of forming a first layer having a required resin holding amount by repeating baking; and impregnating the surface of the first layer with a PTFE dispersion, followed by drying at a temperature lower than the melting point of the PTFE, and performing the impregnation and drying. A second step of forming a second layer having a required resin holding amount by repeating the above, and after impregnating the surface of the second layer with a PFA dispersion and drying, under a condition higher than the melting points of the PFA and the PTFE, Baking, repeating the above-described impregnation, drying and baking to form a third layer having a required resin holding amount, and a third step of forming a prepreg. 6. A prepreg manufactured by the manufacturing method according to claim 4 is used as an inner layer plate, and a fluororesin film such as PFA or FEP or a manufacturing method according to claim 5 is formed above and below the inner layer plate. A method for manufacturing a multilayer printed circuit board, comprising: arranging a prepreg, further arranging a metal foil on the outermost layer, and press-molding the prepreg at a temperature higher than the melting point of PTFE and at a high pressure.