JP2000244114A - Manufacture of build-up multilayer wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To implement a method of manufacturing a build-up multilayer wiring board, which facilitates the formation of fine circuits, owing not only to the good filling property of an insulating resin into spaces between the fine circuits but also to the fact that an insulating resin layer can be formed uniformly and with a high degree of surface smoothness. SOLUTION: A liquid insulating resin is applied to the surface of a circuit board 2 on which circuits 1 are formed and is heated to thereby form a half- cured insulating resin layer 3, whose minimum melting viscosity is 100-30,000 ps at 130 deg.C. Then, a sheet material 4 is superposed on the layer 3, and the resulting board 2 is molded by thermal compression. When the liquid insulating resin is applied, spaces between the circuits 1 can easily be mode to fill with the insulating resin, and the spaces between the circuits 1 can be easily filled with the insulating resin also by taking advantage of the flow of the resin, when the half-cured layer 3 is molded by thermal compression. Moreover, the thermal compression molding via the material 4 allows the layer 3 to be formed uniformly and with high degree of surface smoothness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer wiring board by a build-up method.

[0002]

2. Description of the Related Art Electronic devices and electric devices have been reduced in size and weight as represented by mobile phones and personal digital assistants (PDAs). And as the multilayer wiring board used for these, the density is increased by the build-up multilayer wiring board,
Miniaturization and thinning have been promoted.

Various methods have been developed for producing a build-up multilayer wiring board. For example, using a resin-coated metal foil formed by providing a semi-cured thermosetting resin on one side of a metal foil such as a copper foil, and applying the resin-coated metal foil to the surface of a circuit board having a circuit formed on the surface. Then, after laminating by heating and pressing, the metal foil is etched to form a circuit, and this is repeated as necessary to further form a multiplex circuit. Further, a thermosetting liquid insulating resin is applied to the surface of a circuit board having a circuit formed on the surface as described in Japanese Patent Application Laid-Open No. 9-260841, and this is heated and cured to form an insulating resin layer. Is formed, a circuit is formed on the cured insulating resin layer by electroless plating and electrolytic plating, and this is repeated as necessary to further form a multiple circuit.

[0004]

However, in the former method using a metal foil with a resin, since the resin provided on the metal foil is in a semi-cured state, the fluidity at the time of heat and pressure molding is low, and the fineness is small. There is a problem that the filling between circuits is poor, and the resin provided on the metal foil has a constant thickness,
It is difficult to adjust the film thickness of the insulating resin layer formed on the surface of the circuit board with the resin by a circuit on the surface of the circuit board. However, there is a problem that it is difficult to form a fine circuit by the above method. In the latter method of applying and curing a liquid insulating resin on the surface of a circuit board, unevenness occurs in the thickness applied by the circuit on the surface of the circuit board, and the unevenness occurs on the surface of the formed insulating resin layer. Thus, there is a problem that it is difficult to form a fine circuit by plating on the surface of the insulating resin layer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a high filling property of insulating resin between fine circuits, and can form an insulating resin layer uniformly and with high surface smoothness. It is an object of the present invention to provide a method for manufacturing a build-up multilayer wiring board in which a circuit can be easily formed.

[0006]

According to a method of manufacturing a build-up multilayer wiring board according to the present invention, a liquid insulating resin is applied to the surface of a circuit board 2 having a circuit 1 formed on the surface and heated to 130.degree. The minimum melt viscosity at 100ps-30
It is characterized in that a semi-hardened insulating resin layer 3 of 000 ps is formed, and then a sheet material 4 is superimposed on the insulating resin layer 3 and is subjected to heat and pressure molding.

According to a second aspect of the present invention, a liquid insulating resin having a viscosity of 10 cps to 1000 ps is used.

According to a third aspect of the present invention, in the semi-cured state of the insulating resin layer 3, the curing time at 170 ° C. is from 1 minute and 00 seconds.
10 minutes and 00 seconds.

According to a fourth aspect of the present invention, the method for applying the liquid insulating resin is selected from a curtain coater, a die coater, a dip, a roll coater, and a screen printing method.

[0010]

Embodiments of the present invention will be described below.

As the circuit board 2, a board having an electrically insulating resin laminate such as a glass cloth base epoxy resin laminate as the board 5 can be used.
As shown in FIG. 1 (a), a circuit 1 is formed on the surface by etching metal foils such as laminated copper foils and metal plating such as electroless copper plating and electrolytic copper plating.

First, a liquid insulating resin 3a is applied to the surface of the circuit board 2 on which the circuit 1 is formed, as shown in FIG. 1 (b). The liquid insulating resin 3a is not particularly limited, but a varnish of a thermosetting resin such as an epoxy resin can be used. As a method for applying the liquid insulating resin 3a, a method having good uniformity of the coating film thickness is preferable, and a method using a flow coater, a method using a die coater, a dip method, a method using a roll coater, a screen, Printing methods can be employed. By applying the liquid insulating resin 3a by these methods, uniform application of the liquid insulating resin 3a is facilitated and fine adjustment of the film thickness of the insulating resin layer 3 formed by the liquid insulating resin 3a is also facilitated. It becomes something.

The liquid insulating resin 3a easily flows into the minute gaps of the circuit 1 due to its fluidity, so that the filling property between the fine circuits is high. Here, the liquid insulating resin 3
It is preferable to use a having a viscosity of 10 cps to 1000 ps during coating. The viscosity of the liquid insulating resin 3a is 10c
If it is less than ps, the filling property between the fine circuits 1 is high,
The flow becomes too large and it becomes difficult to adjust the thickness of the insulating resin layer 3 formed. Conversely, the viscosity of the liquid insulating resin 3a is 1
If the flow rate exceeds 000 ps, the fluidity becomes poor and the fine circuit 1
The space filling property is reduced, and a space is generated between the insulating resin layer 3 formed by the liquid insulating resin 3a and the circuit 1, and voids are easily generated. When the liquid insulating resin 3a is applied by screen printing, the viscosity of the liquid insulating resin 3a is preferably in the range of 50 ps to 1000 ps.

After the liquid insulating resin 3a is applied to the surface of the circuit board 2 as described above, the liquid insulating resin 3a is heated and heated.
Is semi-cured to form an insulating resin layer 3 on the surface of the circuit board 2. By adjusting the heating temperature and the heating time, the semi-cured state is such that the minimum melt viscosity at 130 ° C. is 1
It is set to be 00 ps to 30000 ps. Here, the minimum melt viscosity at 130 ° C.
When the resin is heated at 130 ° C., the melt viscosity changes with time. The melt viscosity is the lowest value among the melt viscosities. And the semi-cured state of the insulating resin layer 3 is
If the minimum melt viscosity at 130 ° C. exceeds 30,000 ps, the fluidity of the resin at the time of hot press molding described below deteriorates, the filling property between the fine circuits 1 decreases, and the liquid insulating resin 3a causes A space is formed between the formed insulating resin layer 3 and the circuit 1 to easily cause voids, and the surface flatness of the cured insulating resin layer 3 after the heat and pressure molding is reduced. Furthermore, the minimum melt viscosity at 130 ° C. is 3
When the thickness exceeds 0000 ps, the semi-curing of the insulating resin layer 3 is excessively advanced, and when the metal foil 4a is laminated on the insulating resin layer 3 using a metal foil such as a copper foil as the sheet material 4 as described later, There is a possibility that the adhesion between the foil 4a and the insulating resin layer 3 may be reduced. The semi-cured state of the insulating resin layer 3 is
If the minimum melt viscosity at 130 ° C. is less than 100 ps, the progress of semi-curing is insufficient, and the resin flow becomes too large during the heat-press molding described below, making it difficult to adjust the thickness of the insulating resin layer 3. become.

The semi-cured state of the insulating resin layer 3 is 17
The curing time at 0 ° C. is preferably from 1 minute 00 seconds to 10 minutes 00 seconds. Here, the curing time at 170 ° C. is measured based on JIS C 6521. When the semi-cured state of the insulating resin layer 3 is less than 1 minute 00 seconds at 170 ° C., the semi-cured state of the insulating resin layer 3 is excessively advanced, and the fluidity of the resin at the time of heat and pressure molding is increased. Of the insulating resin layer 3 formed by the liquid insulating resin 3a
A space is formed between the circuit board 1 and the circuit 1 so that voids are easily generated, and the flatness of the surface of the cured insulating resin layer 3 after the heat and pressure molding is lowered. Further, when the metal foil 4a is laminated on the insulating resin layer 3 using a metal foil such as a copper foil as the sheet material 4 as described later, the adhesion between the metal foil 4a and the insulating resin layer 3 may be reduced. . Further, when the semi-cured state of the insulating resin layer 3 is such that the curing time at 170 ° C. exceeds 10 minutes 00 seconds, the progress of the semi-curing is insufficient, and the resin flow during the heating / pressing molding described below may be reduced. It becomes too large, and it becomes difficult to adjust the thickness of the insulating resin layer 3.

As described above, the insulating resin liquid 3a is applied and heated to form a semi-cured insulating resin layer 3 on the surface of the circuit board 2. Then, as shown in FIG. 3
The sheet material 4 is overlaid on the surface of the sheet, and is heated and pressed using a flat plate press or the like (the pressed state is indicated by an arrow). The conditions for the heat and pressure molding are not particularly limited.
It is preferable to set the temperature in the range of 0 to 50 kgf / cm ² , the temperature of 150 to 200 ° C., and the time of 1.5 to 3 hours. By performing the heat and pressure molding in this manner, the semi-cured insulating resin layer 3 is melted and cured, and the cured insulating resin layer 3 is cured.
The sheet material 4 can be laminated on the surface of the circuit board 2 as shown in FIG. Here, the circuit board 2
When the insulating resin layer 3 in a semi-cured state is formed by coating and heating the liquid insulating resin 3a on the surface of the substrate, the insulating resin layer 3 swells at a portion where the circuit 1 exists, and the thickness of the insulating resin layer 3 (from the surface of the substrate 5). Is not uniform as shown in FIGS. 1 (b) and 1 (c), but by performing the heat and pressure molding in this way, as shown in FIG. 1 (d), the film thickness becomes uniform and the surface becomes uniform. A smooth cured insulating resin layer 3 can be obtained.

When a metal foil 4a such as a copper foil is used as the sheet material 4, the metal foil 4a can be laminated on the surface of the circuit board 2 via the cured insulating resin layer 3. By performing patterning by etching or the like of the metal foil 4a, a circuit can be formed on the surface of the insulating resin layer 3 and a build-up multilayer wiring board provided with multilayer circuits can be obtained. is there. Further, by repeating the above operation, it is possible to obtain a build-up multilayer wiring board having a further multiplex circuit configuration.

In the case where a release sheet is used as the sheet material 4, the release sheet is peeled off from the cured surface of the insulating resin layer 3 after the heat and pressure molding, and the surface of the cured insulating resin layer 3 is removed. By applying electroless copper plating, electrolytic copper plating, or the like, a circuit can be formed on the surface of the insulating resin layer 3 and a build-up multilayer wiring board having multiple circuits can be obtained. Further, by repeating the above operation, it is possible to obtain a build-up multilayer wiring board having a further multiplex circuit configuration.

In forming a circuit on the surface of the insulating resin layer 3 as described above, the insulating resin layer 3 has a uniform film thickness and a smooth surface. Is easier.

[0020]

The present invention will be described below in detail with reference to examples.

(Example 1) Using an epoxy resin glass substrate laminate ("R1766T" manufactured by Matsushita Electric Works Co., Ltd.) having a copper foil having a thickness of 12 µm on both sides, the copper foils on both sides were entirely etched and then semi-additive. A circuit board 2 was prepared by providing a circuit 1 of copper plating with a thickness of 35 μm on both sides by the method. The circuit 1 has a conductor width of 500 μm and a conductor interval of 50 μm.
It was formed into a 0 μm comb. First, this circuit board 2 is coated with an organic acid-based etching solution (“CZ-
5452 "), and the surface of the circuit 1 was roughened by performing soft etching for etching the surface of the circuit 1 by 2 μm.

Next, a liquid insulating resin 3a was applied to one surface of the circuit board 1 by extrusion from a die coater to a thickness of 80 μm (see FIG. 1B). Here, as the liquid insulating resin 3a, 50 parts by weight of a polyfunctional epoxy resin (“VG3101M80” manufactured by Mitsui Chemicals, Inc.) and a brominated epoxy resin (“VF2803M80” manufactured by Mitsui Chemicals, Inc.)
150 parts by weight, 40 parts by weight of a brominated bisphenol A type epoxy resin (“YDB400” manufactured by Toto Kasei Co., Ltd.)
40 parts by weight of a curing agent (“Cure Hard MED” manufactured by Ihara Chemical Industry Co., Ltd.), 0.5 parts by weight of a curing accelerator (“2E4MZ-CN” manufactured by Shikoku Chemicals Co., Ltd.), a fluorine-based surfactant (Sumitomo 3M Limited) "FC430"
0.5 parts by weight, 70 parts by weight of N, N-dimethylformamide as a solvent, 1,2-methoxypropanol 20
An epoxy resin varnish in a weight part mixture was used. The viscosity of the liquid insulating resin 3a was 150 cps. After the liquid insulating resin 3a is coated on one surface of the circuit board 1 by a die coater and dried at 110 ° C. for 20 minutes, the liquid insulating resin 3a is further coated on the other surface of the circuit board 1.
Was similarly coated and dried. Then, the circuit board 1 is heated to 140 ° C
For 21 minutes to form a semi-cured insulating resin layer 3 on the surface of the circuit board 1. The semi-cured state of the insulating resin layer 3 has a minimum melt viscosity at 130 ° C. of 1
000 ps and a curing time at 170 ° C. of 4 minutes 0
It was 0 seconds.

Next, a copper foil 3a having a thickness of 12 μm (“GT-S” manufactured by Furukawa Circuit Foil Co., Ltd.) is overlaid on the surface of the semi-cured insulating resin layer 3 at 170 ° C. and 30 kg.
The resin was molded under heat and pressure by a vacuum press under the conditions of 90 cm / cm ² and 90 minutes to cure the insulating resin layer 3 and laminate the copper foil 3a (see FIG. 1D). After completion of the molding, in order to further completely cure the insulating resin layer 3, the insulating resin layer 3 was heated for 120 minutes by a drier at 200 ° C.

(Example 2) By adjusting the heating temperature and the heating time after the application of the liquid insulating resin 3a,
The semi-cured insulating resin layer 3 was formed in such a manner that the minimum melt viscosity in the above was in a semi-cured state of 100 ps. This insulating resin layer 3 had a curing time at 170 ° C. of 7 minutes and 30 seconds. Others were the same as Example 1.

Example 3 The heating temperature and the heating time after the application of the liquid insulating resin 3a were adjusted to 130 ° C.
The semi-cured insulating resin layer 3 was formed in such a manner that the minimum melt viscosity in Example 1 was in a semi-cured state of 10,000 ps. This insulating resin layer 3 has a hardening time at 170 ° C. of 2 minutes 0 minutes.
It was 0 seconds. Others were the same as Example 1.

Example 4 The heating temperature and the heating time after the application of the liquid insulating resin 3a were adjusted to 130 ° C.
The semi-cured insulating resin layer 3 was formed in such a manner that the minimum melt viscosity in the semi-cured state was 30,000 ps. This insulating resin layer 3 has a curing time at 170 ° C. of 1 minute 1 minute.
5 seconds. Others were the same as Example 1.

(Embodiment 5) Instead of the copper foil 3a, a thickness of 25
Example 1 except that a μm release sheet (“Therapy Q-1” manufactured by Toyo Metallizing Co., Ltd.) was used.
Same as.

(Comparative Example 1) The same circuit board 2 as in Example 1 was used.
a was applied using a die coater in the same manner as in Example 1. This was heated at 150 ° C. for 50 minutes to be in a semi-cured state, and further heated at 170 ° C. for 120 minutes to form a completely cured insulating resin layer.

(Comparative Example 2) A resin-coated copper foil (Matsushita Electric Works) using the same circuit board 2 as in Example 1 and providing a semi-cured resin layer of 80 μm thick epoxy resin on one side of a 12 μm thick copper foil “R-0880” manufactured by Co., Ltd.) was used. Then, a copper foil with resin was laminated on the surface of the circuit board 2 on the resin side, and this was heated and pressed under the conditions of 170 ° C., 30 kg / cm ² and 90 minutes, and the copper foil was laminated on the circuit board 2.

(Comparative Example 3) The heating temperature and the heating time after the application of the liquid insulating resin 3a were adjusted to 130 ° C.
The semi-cured insulating resin layer 3 was formed such that the minimum melt viscosity in the above was in a semi-cured state of 50 ps. The curing time of this insulating resin layer 3 at 170 ° C. was 11 minutes and 00 seconds. Others were the same as Example 1.

(Comparative Example 4) The heating temperature and the heating time after application of the liquid insulating resin 3a were adjusted to 130 ° C.
The semi-cured insulating resin layer 3 was formed in such a manner that the minimum melt viscosity in the above was in a semi-cured state of 50,000 ps. This insulating resin layer 3 has a curing time at 170 ° C. of 0 minutes 4
5 seconds. Others were the same as Example 1.

As described above, Examples 1 to 5 and Comparative Examples 1 to
With respect to the build-up multilayer wiring board obtained in 4, the “filling property”, “flatness”, and “minimum resin thickness” were measured. For these measurements, the insulating resin layer was exposed by etching and removing the copper foil on the surface for Examples 1 to 4 and Comparative Examples 2 to 4, and for Example 5,
Remove the release sheet to expose the insulating resin layer
Comparative Example 1 in which the insulating resin layer was exposed was performed as it was. The “filling property” is used to evaluate the filling property of the resin between the circuits. The cross section of the insulating resin layer at the circuit portion is visually observed with a SEM microscope, and those without voids are marked with “○”, Some were judged as "x".
"Flatness" is to evaluate the smoothness of the surface of the insulating resin layer, and those having no irregularities with a radius of 15 μm or more on the surface were judged as “○”, and those having irregularities with a radius of 15 μm or more were judged as “X”. . The “minimum resin thickness” is used to evaluate the flowability of the resin at the time of heat and pressure molding, and it is assumed that the insulating resin layer on the circuit has a thickness of 40 μm or more necessary to maintain electrical insulation. "O", those less than 40 m were judged as "x". Table 1 shows the results.

[0033]

[Table 1]

As shown in Table 1, the semi-cured insulating resin layer had a minimum melt viscosity at 130 ° C. of 1000 to 300.
In each of the examples set to be 00 ps, the “filling property”, the “flatness”, and the “minimum resin thickness” were all good. In Comparative Example 4 having a high minimum melt viscosity, there was a problem in "resin thickness", and there was a problem in "fillability" and "flatness".
In Comparative Example 1 in which a liquid insulating resin is applied and completely cured, a problem occurs in “flatness”, and in Comparative Example 2 using a copper foil with a resin, problems occur in “filling property” and “flatness”. there were.

[0035]

As described above, according to the present invention, a liquid insulating resin is applied to the surface of a circuit board having a circuit formed on the surface and heated to obtain a minimum melt viscosity at 130 ° C. of 100 ps.
Form a semi-cured insulating resin layer of ~ 30000ps,
Next, since the sheet material is stacked on this insulating resin layer and heated and pressed, the insulating resin can be easily filled between the fine circuits when applying the liquid insulating resin, and it is in a semi-cured state. The insulating resin layer can be easily filled between the fine circuits by the flow of the resin when the insulating resin layer is heated and pressed, and the filling property of the insulating resin between the fine circuits is high. The insulating resin layer can be formed uniformly and with high surface smoothness by the heat and pressure molding through the substrate, and the formation of a fine circuit on the surface of the insulating resin layer becomes easy.

According to the second aspect of the present invention, since the liquid insulating resin having a viscosity of 10 cps to 1000 ps is used, the liquid insulating resin can be used between the circuits without difficulty in adjusting the thickness of the insulating resin layer. It can be easily filled.

According to a third aspect of the present invention, in the semi-cured state of the insulating resin layer, the curing time at 170 ° C. is from 1 minute 00 seconds to 1 minute.
Since the time is 0 minutes and 00 seconds, the resin can be satisfactorily flowed at the time of the heating and pressing molding without difficulty in adjusting the thickness of the insulating resin layer, and can be easily filled between the circuits.

According to the fourth aspect of the present invention, since the method of applying the liquid insulating resin is a method using a curtain coater, a die coater, a dip, a roll coater, and screen printing, coating can be performed with a uniform film thickness. Things.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention,
(A)-(d) are sectional views, respectively.

[Explanation of symbols]

 Reference Signs List 1 circuit 2 circuit board 3 insulating resin layer 4 sheet material

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Shoichi Fujimori 1048 Kazuma Kadoma, Kadoma, Osaka Prefecture Inside the Matsushita Electric Works Co., Ltd. (72) Inventor Yoshiaki Ezaki 1048 Kadoma Kadoma, Kadoma City, Osaka Pref. F-term (reference) 5E346 AA06 AA12 AA15 AA38 BB01 CC08 DD02 DD03 EE31 EE35 GG27 GG28 HH11 HH26

Claims (4)

[Claims] 1. A semi-cured insulating resin layer having a minimum melt viscosity at 130 ° C. of 100 ps to 30000 ps is formed by coating a liquid insulating resin on a surface of a circuit board having a circuit formed on the surface and heating the liquid insulating resin. Next, a sheet material is superimposed on the insulating resin layer and heated and pressed to form a multi-layer wiring board. 2. A liquid insulating resin having a viscosity of 10 cps or more.
2. The method according to claim 1, wherein said one of 1000 ps is used.
3. The method for producing a build-up multilayer wiring board according to 1.). 3. The build-up multilayer wiring board according to claim 1, wherein the semi-cured state of the insulating resin layer is a curing time at 170 ° C. of 1 minute to 10 minutes. Production method. 4. The build-up according to claim 1, wherein the method of applying the liquid insulating resin is selected from a method using a curtain coater, a die coater, a dip, a roll coater, and screen printing. A method for manufacturing a multilayer wiring board.