JPH0955577A - Production of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a printed wiring board comprising a step for forming an insulation layer on a conductor wiring pattern in which the reliability of insulation layer is enhanced by making uniform the thickness. SOLUTION: A build-up method for forming an insulation layer comprises step B for applying a photosensitive insulation material 14a for first layer onto an insulation board 11 including conductor wiring patterns 12, 13, step D for developing and removing the insulation layer on the conductor wiring patterns 12, 13, and step E for smoothing the surface by mechanical polishing. Subsequently, a photosensitive insulation material for second layer is applied, photovias are made, and the surface is polished to obtain a printed wiring board. Since the photosensitive insulation material for second layer can be applied smoothly while filling the gap between patterns, polishing pressure difference caused by coarseness of wiring pattern is eliminated resulting in smooth polishing.

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 printed wiring board, and more particularly to a method for manufacturing a printed wiring board having a circuit pattern of fine pitch.

[0002]

2. Description of the Related Art In recent years, as ICs, LSIs, etc. have been highly integrated and speeded up very rapidly, it has become necessary to increase the density of printed wiring boards on which they are mounted. ing.

As one of the methods for increasing the density of a printed wiring board, a method for manufacturing a multilayer printed wiring board by buildup is known. Here, a conventional build-up insulating layer forming method (hereinafter referred to as “conventional method”) will be described with reference to FIG. 3A to 3C are cross-sectional views in order of the processes including Processes A to E for explaining the conventional method in the process of manufacturing a multilayer printed wiring board by buildup.

In the conventional method, as shown in FIG. 3, step A (wiring pattern forming step) → step B (photosensitive material applying step) → step C (photovia exposing step) → step D (photovia) Developing step) → step E (photosensitive material polishing step)
It is composed of

The conventional method will be described in more detail. In this method, as shown in step A of FIG.
Conductor wiring pattern such as GV pattern depending on the conductor material
After forming a conductor wiring pattern 33 such as 32 and a signal circuit pattern, as shown in the same process B, a photosensitive insulating material 34 is formed.
Is coated on the insulating substrate 31 by a known screen method or a curtain coating method. Subsequently, as shown in Step C to Step D of FIG. 3, a photo via 36 for connecting the layers is formed by a known photo printing method using the mask film 35.

Thereafter, in order to remove the excessively photopolymerized portion of the surface layer of the photosensitive insulating material 34 and to obtain a desired insulating layer thickness, as shown in FIG.
The surface layer 34 is polished by a mechanical means such as a belt sander to obtain a printed wiring board 37.

By the way, in the insulating layer forming step according to the above-mentioned conventional method, since the surface of the insulating substrate 31 is uneven due to the thickness of the conductor layer itself forming the conductor wiring patterns 32 and 33, defective printing may occur. There was a problem that it was likely to occur.

As a means for solving the above problems, a method of smoothing an insulating layer by double coating (hereinafter referred to as "known example") has been proposed (see JP-A-61-242095). This known example will be described with reference to FIG. In addition, in FIG.
FIG. 7A is a sectional view in order of the steps, for illustrating the formation of an insulating layer according to a known example that employs a double-coating means, including step A (wiring pattern).
Forming step) → step B (first photosensitive material coating step) → step C (first photosensitive material polishing step) → step D
(Second photosensitive material coating step) → step E (photovia exposure step) → step F (second photosensitive material polishing step)
It is composed of

That is, in the known example, as shown in FIG. 4A, the conductor wiring pattern 4 is formed on the insulating substrate 41 by the conductor material.
After the formation of the second and the same 43, as shown in the same step B, the first layer of the photosensitive insulating material having a thickness equal to or larger than the conductor thickness of the conductor wiring patterns 42 and 43 by a known screen method. 44a
Is applied on the insulating substrate 41. Next, as shown in step C of FIG. 4, the surface of the photosensitive insulating material 44a of the first layer, which is raised above the conductor thickness, is removed by mechanical polishing means to smooth the surface.

Subsequently, as shown in FIG. 4D, the photosensitive insulating material 44b of the second layer is again formed by the known screen method.
Is applied. Next, as shown in FIG. 4E, a photo via 46 is formed using the mask film 45 to connect the layers by a known photo printing method.

Thereafter, in order to remove the excessively photopolymerized portion existing on the surface layer of the second layer photosensitive insulating material 44b,
Further, in order to obtain a desired insulating layer thickness, as shown in FIG. 4F, the surface layer of the second layer of photosensitive insulating material 44b is polished by a mechanical means such as a belt sander to form the printed wiring board 47. obtain.

[0012]

By the way, in the above-mentioned conventional method, in mechanically polishing the insulating layer on the wiring pattern in the step E shown in FIG. For example, a GV pattern part which is a solid pattern for supplying power and grounding, or a part where the signal circuit pattern is extremely crowded), and a part where the wiring pattern is rough ( For example, since the polishing pressure is different between the portion where the signal circuit pattern exists independently or the portion where the wiring pattern does not exist), the insulating layer cannot be uniformly polished, and the wiring pattern cannot be polished. There is a problem that the thickness of the insulating layer on the screen varies.

As a method for solving the above-mentioned problems, as described above, a method of forming an insulating layer by a publicly known example that employs a double coating means has been proposed, but even in the method by this publicly known example, the first time Since mechanical polishing is used when the insulating layer is polished (see step C in FIG. 4 described above), the same drawbacks as those of the above-described conventional method occur, the surface cannot be uniformly smoothed, and finally the insulating layer thickness is reduced. It will be scattered.

That is, as shown in, for example, FIG. 3E or FIG. 4C, the signal circuit pattern (conductor wiring patterns 33, 43) has no wiring pattern. Although the polishing is performed with substantially the same polishing pressure as the above, the GV pattern (conductor wiring patterns 32, 42) is a solid pattern, so it is harder to polish than other portions, and this conductor wiring pattern is less likely to be polished. -The thickness of the insulating layer on the horns (32, 42) becomes thicker. As a result, the thickness of the insulating layer on the wiring pattern is unbalanced on the same layer surface, which has a drawback that defects such as insulation characteristics and moisture resistance characteristics are likely to occur.

The present invention has been made in view of the above-mentioned conventional problems and drawbacks, and an object of the present invention is to improve the uniformity of the insulating layer thickness and improve the reliability of the insulating layer. A method for manufacturing a wiring board is provided.

[0016]

In order to solve the above-mentioned problems and drawbacks of the prior art and to achieve the above object, the present invention adopts a double coating means as in the above-mentioned known example. In particular, a photosensitive insulating material is used as the insulating layer, and the photosensitive material of this insulating material is used to chemically remove the insulating material on the conductor wiring pattern and then perform mechanical polishing. The present invention provides a method for manufacturing a printed wiring board that improves the uniformity of the insulating layer thickness and improves the reliability of the insulating layer.

That is, according to the present invention, "In the method for manufacturing a printed wiring board, when the insulating layer is formed on the upper surface and the lower surface of the printed wiring board having the conductor wiring pattern formed on the insulating substrate, (1)
At least a step of applying an insulating layer equal to or higher than the height of the conductor wiring pattern, (2) a step of developing and removing only the insulating layer on the conductor wiring pattern, (3) a conductor wiring pattern by a mechanical polishing means. Smoothing the insulating layer and the insulating layer, (4) heating and curing the insulating layer remaining between the conductor wiring patterns, (5) roughening the copper surface of the exposed conductor wiring pattern, 6) a step of re-applying an insulating layer having a desired thickness, (7) a step of forming a desired insulating layer pattern by exposure to development, (8) a photopolymerization portion of the surface of the insulating layer generated by the exposure. And a step of polishing and removing by a mechanical polishing means. (Claim 1) is the gist.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a photosensitive insulating material is particularly used as the insulating layer in the above step (1). By exposing and developing ", the insulating material on the conductor wiring pattern is chemically removed. This allows the space between the conductor wiring patterns to be filled with an insulating layer, and the height of the insulating layer and the conductor wiring pattern can be increased. -The height can be the same.

In the present invention, as the photosensitive insulating material, any negative or positive type photosensitive insulating material can be used, and it is not particularly limited in the present invention. Further, the insulating layer in the step (1) and that in the step (6) can use the same photosensitive insulating material, and
Different materials are possible and all are included in the present invention.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a printed wiring board according to the present invention will be described below with reference to FIGS. 1 and 2 are views for explaining an embodiment of a method for manufacturing a printed wiring board according to the present invention, in which FIG.
FIG. 2 is a sectional view of a process sequence including step E, and FIG. 2 is a sectional view of a process sequence including steps F to K subsequent to the step E of FIG. 1. The printed wiring board in the following embodiments is a double-sided board or a multilayer board, but only one surface will be described for the sake of simplicity.

In this embodiment, step A (wiring pattern) of FIG.
Forming step) → the same step B (first photosensitive material applying step) → the same step C (first photosensitive material exposing step) → the same step D (first photosensitive material developing step) -> The same process E (polishing process of the first photosensitive material) is included. Further subsequently, step F of FIG. 2 (step of roughening the surface of the wiring pattern) →
Same process G (second photosensitive material coating process) → same process H
This is a method of manufacturing a printed wiring board in the order of (exposure step of photo via) → the same step J (developing step of photo via) → the same step K (polishing step of second photosensitive material).

That is, in this embodiment, first, as shown in FIG. 1A, the conductor wiring patterns 12, 13 are formed on the insulating substrate 11.
(Consists of conductor wiring pattern 12 consisting of "GV pattern that plays a role of power supply or ground", conductor wiring pattern 13 consisting of "signal circuit pattern", etc.) It is made of a material. In addition, these conductor wiring patterns
As the means for forming 12 and 13, for example, a subtractive method or an additive method can be used.

Next, as shown in step B of FIG. 1, the insulating wiring board 11 including the conductor wiring patterns 12 and 13 is completely covered and the thickness of the conductor wiring patterns 12 and 13 is about 30 μm. The first layer of photosensitive insulating material 14a (for example, Probima-52 manufactured by Ciba-Geigy Co., Ltd.) is applied with a thickness of 30 μm to 40 μm, which is equal to or more than the same. As the application method at that time,
For example, a screen method or a curtain coating method can be used.

Subsequently, as shown in step C of FIG. 1, the conductor wiring patterns 12, 13 are formed in order to remove a portion of the photosensitive insulating material 14a of the first layer which is thicker than the wiring pattern thickness.
The insulating material other than the above portion is exposed by contact using the mask film 15a and photopolymerized.

Thereafter, as shown in step D of FIG. 1, a photosensitive insulating material which is not photopolymerized (that is, the conductor wiring pattern 12,
The photosensitive insulating material 14a) on 13 is developed and removed with a 1% aqueous sodium carbonate solution. In this embodiment, the negative type photosensitive insulating material 14a is used, but a positive type photosensitive insulating material may be used to photo-decompose and remove the portion raised above the wiring pattern thickness by development. it can.

Since the photosensitive insulating material 14a after development has a slight bulge at the conductor edge portions of the conductor wiring patterns 12 and 13 (see step D in FIG. 1), as shown in step E in FIG. The portion is removed by mechanical polishing means to smooth the surface. As the polishing means, for example, a belt sander polishing machine may be used, and a polishing material having high flatness, for example, "resin cross belt RAXB" manufactured by Sankyo Rikagaku Co., Ltd.
By using "AA # 600", it is possible to realize a smooth surface sufficient to apply the second layer of photosensitive insulating material 14b (see step G in FIG. 2 described later) to be applied next smoothly.

Thereafter, in order to increase the hardness of the photosensitive insulating material 14a of the first layer having the same thickness as that of the conductor wiring patterns 12 and 13, thermal curing (for example, baking for 90 minutes at a temperature of 130 ° C.) is performed. Heat cure) or UV cure (for example, UV cure by exposure to UV light with an exposure dose of 600 mj / cm ² )
Perform post cure.

Further, as shown in step F of FIG. 2, for the purpose of improving the degree of adhesion between the surface of the second layer of photosensitive insulating material 14b applied in the next step G and the conductor wiring patterns 12 and 13. ,
The surfaces of the conductor wiring patterns 12 and 13 are roughened with a chemical such as potassium persulfate to form fine irregularities having a depth of about 0.1 to 1 μm on the surfaces of the wiring patterns 12 and 13.

Next, as shown in step G of FIG. 2, a second layer of photosensitive insulating material, which is the same material as the first layer of photosensitive insulating material 14a, is formed so as to obtain a desired insulating layer thickness. Material 14
b is applied by a screen method or a curtain coating method. At this time, it is necessary to apply the insulating layer in consideration of the thickness to be removed by polishing after photopolymerization. For example,
If you want to set the insulating layer thickness on the conductor wiring patterns 12 and 13 to 50 μm, the height of the first insulating layer (the first layer of the photosensitive insulating material 14a) and the conductor wiring patterns 12 and 13 must be high. Since the height is the same, the thickness of the insulation layer on the desired wiring pattern is
The photosensitive insulating material having a thickness of 60 μm, which is obtained by adding 10 μm which is removed by polishing to 50 μm, is used as the photosensitive insulating material 14b for the second layer.
It may be applied as.

Next, a photo via 16 for connecting the layers
2H, as shown in FIG. 2H, contact exposure is carried out using a mask film 15b for forming photo vias, and the second layer of photosensitive insulating material 14b other than the photo vias 16 is photopolymerized. Subsequently, as shown in Step J of FIG. 2, the photo-polymerized portion is developed and removed with a 1% sodium carbonate aqueous solution to form a photo via 16.

Then, as shown in step K of FIG. 2, the excessively photopolymerized portion (thickness of about 10 μm) of the surface layer of the second layer of photosensitive insulating material 14b is removed by polishing by mechanical means. The printed wiring board 17 is obtained. As the polishing means, for example, a belt sander polishing machine or the like may be used,
An abrasive having high flatness, for example, "resin cross belt RAXB""AA#600" manufactured by Sankyo Rikagaku Co., Ltd. is used.

In the conventional method, the polishing amount varies due to the influence of the wiring pattern density, but according to this embodiment, the conductor wiring patterns 12 and 13 are formed by the first layer photosensitive insulating material 14a. Since it is filled and is smooth (see step E in FIG. 1 above), it is possible to perform uniform polishing in the polishing step (FIG. 2 step K) of the second layer photosensitive insulating material 14b,
The printed wiring board 17 having a uniform insulating layer thickness can be obtained.

Although one embodiment of the method for manufacturing a printed wiring board according to the present invention has been described above in detail, the present invention is not limited to the above-mentioned embodiment, and is within the scope of the present invention described above. Various modifications are possible, and these are also included in the present invention.

[0034]

As described in detail above, the present invention is a method for manufacturing a printed wiring board including a step of forming an insulating layer on a conductor wiring pattern, wherein a photosensitive insulating material is used as the insulating layer, Utilizing the fact that the insulating material is photosensitive, the insulating material on the conductor wiring pattern is chemically removed, and mechanical polishing is performed on the insulating material. The space can be filled with an insulating layer, and the height of the insulating layer and the height of the wiring pattern can be made the same. ・ When applying the insulating material of the second layer, smooth application is possible and the space between the patterns is Since it is filled with the insulating layer, the polishing pressure difference due to the density of the wiring pattern does not occur, and the effect that uniform polishing can be achieved is obtained. As a result, To provide a method for manufacturing a printed wiring board that can improve the reliability of printed circuit boards Can effect occurs.

According to the method of the present invention, conventionally, in a portion having a high circuit density (for example, a GV pattern or a high-density circuit pattern portion represented by line / space = 100/150 μm). The polishing amount is as small as about 5 to 10 μm, and the polishing amount is large at about 15 to 25 μm in a portion where the circuit density is rough (for example, a single circuit pattern portion), so the insulation layer thickness accuracy on the wiring pattern is high. Was about ± 10 μm, but since it was possible to polish it uniformly regardless of the circuit density, there is an effect that the accuracy of the insulating layer thickness on the pattern can be controlled to ± 5 μm.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of a method for manufacturing a printed wiring board according to the present invention, which is a cross-sectional view in order of steps A to E.

2A to 2C are sectional views in order of the processes, including the processes F to K following the process E in FIG.

FIG. 3 is a cross-sectional view in order of the processes, which includes processes A to E for explaining a conventional method in a process for manufacturing a multilayer printed wiring board by buildup.

4A to 4C are cross-sectional views in order of steps including steps A to F for explaining formation of an insulating layer according to a known example that adopts a double coating means.

[Explanation of symbols]

 11 Insulating Substrate 12 Conductor Wiring Pattern (GV Pattern) 13 Conductor Wiring Pattern (Signal Circuit Pattern) 14a First Photosensitive Insulating Material 14b Second Layer Photosensitive Insulating Material 15a Mask Film 15b Mask film (for photo via formation) 16 Photo via 17 Printed wiring board 31 Insulating substrate 32, 33 Conductor wiring pattern 34 Photosensitive insulating material 35 Mask film 36 Photo via 37 Printed wiring board 41 Insulating substrate 42, 43 Conductor wiring pattern 44a First layer photosensitive insulating material 44b Second layer photosensitive insulating material 45 Mask film 46 Photovia 47 Printed wiring board

Claims (2)

[Claims] 1. A method for manufacturing a printed wiring board, wherein when forming an insulating layer on the upper surface and the lower surface of a printed wiring board having a conductor wiring pattern formed on an insulating substrate, (1) at least a conductor wiring pattern The step of applying an insulating layer equal to or higher than the height of
(2) Step of developing and removing only the insulating layer on the conductor wiring pattern, (3) Step of smoothing the conductor wiring pattern and the insulating layer by mechanical polishing means, (4) Between conductor wiring patterns Step of heating and curing the remaining insulating layer, (5) Step of roughening the copper surface of the exposed conductor wiring pattern, (6) Step of re-applying an insulating layer of a desired thickness, (7) Desired Printed wiring, which comprises a step of forming an insulating layer pattern of (1) by exposure to development, and (8) a step of polishing and removing a photopolymerized portion of the surface of the insulating layer generated by exposure by mechanical polishing means. Method of manufacturing a plate. 2. The method for manufacturing a printed wiring board according to claim 1, wherein the insulating layer in the steps (1) and (6) of claim 1 is made of a photosensitive insulating material.