JP2001036243A - Laminated board with interlayer circuit and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rear-burning even when board thickness is thin, about 0.2-0.6 mm, in a laminated board with interlayer circuit formed by combining forming material of an interlayer circuit and a prepreg for heat-molding. SOLUTION: In a laminated board with interlayer circuit formed by combining a forming material of an interlayer circuit and a prepreg for heat-molding, the prepreg is formed by impregnating glass woven fabric matrix with varnish wherein black system coloring agent is compounded by 0.1-20.0 pts.wt. to 100 pts.wt. of resin solid component, and drying it. In a method for manufacturing it, the prepreg formed by impregnating glass woven fabric matrix with varnish wherein black system coloring agent is compounded by 0.1-20.0 pts.wt. to 100 pts.wt. of resin solid component, and drying it, is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated board having an inner circuit suitable for producing a multilayer printed wiring board having solder resist patterns formed on both sides thereof by a double-sided simultaneous exposure method, and a method for producing the same.

[0002]

2. Description of the Related Art It is a common practice to combine a material for forming an inner layer circuit and a prepreg, form them by heating and integrate them into a laminated board containing an inner layer circuit, and process the laminated board to produce a multilayer printed wiring board. .

In a printed wiring board including a multilayer printed wiring board, a solder resist is usually formed on the outermost conductive circuit in order to prevent a solder bridge between conductors at the time of soldering or to permanently protect the conductive circuit. . This solder resist has conventionally been formed from a thermosetting resin by screen printing or the like, but is now formed by a photographic printing method using a photosensitive resin for the purpose of improving pattern accuracy. In addition, photosensitive resin (photoresist ink) is applied to both sides of the laminate after circuit formation for workability.
And simultaneous double-sided exposure (baking) has been performed. However, when such double-sided simultaneous exposure is performed, the ultraviolet light transmitted through the photoresist ink at the time of exposure further passes through the inside of the laminated board, and also exposes the photoresist inks on the opposite sides to each other. There is an increasing demand for improvement in so-called back burn, in which a pattern is not formed.

As a countermeasure, pigments such as phthalocyanine blue, phthalocyanine green and titanium white, dyes such as methyl violet and victoria pure blue, ultraviolet absorbers such as orthohydroxybenzophenones, potassium carbonate, clay and silica are used as light shielding substances. A method for preventing the transmission of ultraviolet light by including a filler such as acid salts in a laminate (Japanese Patent Application Laid-Open No. 54-32769), or a method in which a glass fiber base material is coated on a thermosetting resin with a fluorescent dye (coumarin, etc.) ) Or a method of using a prepreg impregnated and dried in a varnish containing a tetrafunctional epoxy resin.

[0005]

However, these conventional methods cannot completely prevent backburn when the thickness of the laminate is as thin as about 0.6 mm or less. The improvement is desired.

[0006] In the case of a laminated board containing an inner layer circuit formed by combining an inner layer circuit forming material and a prepreg and heat molding, it is necessary that both the inner layer circuit forming material and the prepreg contain a light shielding material or the like. However, such an inner layer circuit forming material or prepreg containing a light-shielding substance or the like becomes expensive, so if only one of the materials contains the light-shielding substance or the like, the backburn phenomenon may occur. There is also a demand for the development of technologies that can prevent this.

[0007] The present invention, in response to such a need in the art, combines an inner layer circuit forming material and a prepreg,
Provided is a laminated board containing an inner circuit formed by heat molding, wherein the laminated board containing an inner layer circuit which can prevent back burn even when the thickness is as thin as about 0.2 mm to 0.6 mm, and a method for producing the same. That is the task.

It is another object of the present invention to provide a laminated board with an inner circuit, which can provide a multilayer printed wiring board free from back burn without containing a light shielding material or the like in the inner layer circuit forming material. However, when applying the developed means, there is no particular limitation on the inner layer circuit forming material.

[0009]

Means for Solving the Problems In order to achieve the above object, an invention according to claim 1 is directed to a laminated board with an inner layer circuit formed by combining an inner layer circuit forming material and a prepreg and heating and forming the prepreg. It is a prepreg obtained by impregnating and drying a glass woven fabric base material in a varnish prepared by mixing 0.1 to 20.0 parts by weight of a black colorant with respect to 100 parts by weight of a resin solid component. As described above, since the prepreg contains the black colorant at a predetermined ratio, even when the thickness of the laminated board with the inner layer circuit is as thin as about 0.2 mm to 0.6 mm, the photoresist ink is used at the time of simultaneous exposure on both sides. The transmitted ultraviolet light further passes through the laminated board with the inner layer circuit, and also exposes the photoresist ink on the opposite surface, so that a back burn phenomenon that a normal solder resist pattern is not formed is less likely to occur. The material for forming the inner layer circuit is not limited, and the material may or may not contain a light shielding material or the like. However, in terms of cost, it is advantageous to use a material that does not contain a light-shielding substance or the like.

Since it has not been known that a black colorant has a higher backburn preventing effect than other light-shielding substances, a black colorant is exemplified as a light-shielding substance in the prior art. Never. The present inventors have found that a black colorant has a higher backburn preventing effect than other light-shielding substances, and have reached the present invention.

The invention of claim 2 is characterized in that, in the invention of claim 1, the black colorant is carbon black or aniline black. In this case, since the type of the black colorant is specified as carbon black or aniline black, which is a black pigment, the selection thereof is ensured.

The invention of claim 3 is characterized in that, in the invention of claim 1, the black colorant is spirit black. In this case, since the black colorant is specified as spirit black, which is a black dye, the selection is ensured.

According to a fourth aspect of the present invention, there is provided a method of manufacturing a laminated board having an inner layer circuit in which an inner layer circuit forming material and a prepreg are combined and then heat molded to be integrated. A prepreg obtained by impregnating and drying a woven glass substrate with a varnish prepared by mixing 0.1 to 20.0 parts by weight of a black colorant with respect to 100 parts by weight, It is a manufacturing method. Thus, at least one of the prepregs used
Since the sheet contains the black colorant at a predetermined ratio, the manufactured laminated board with the inner layer circuit has a thickness of 0.2 mm to 0.6 mm.
Even when the board thickness is as thin as possible, the ultraviolet light that has passed through the photoresist ink during simultaneous exposure on both sides passes through the laminated board containing the inner layer circuit, and also exposes the photoresist ink on the opposite side, resulting in normal soldering. The back-burn phenomenon that a resist pattern is not formed hardly occurs. Also in the present invention, there is no limitation on the material for forming the inner layer circuit, and it is applicable whether the material contains a light shielding material or the like or not. However, in terms of cost, it is advantageous to use a material that does not contain a light-shielding substance or the like.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Claims 1, 2, and 3
As an embodiment of the present invention, as shown in the conceptual diagram of FIG. 1, an inner layer circuit forming material 2 having an inner layer circuit 1 formed on both surfaces thereof is provided.
And prepreg 3 containing a black colorant,
Further, there is a laminated board with an inner layer circuit, which is formed by arranging copper foils 4 on both outer sides thereof and then heat-molding them. As another embodiment of the present invention, as shown in FIG. 1, an inner layer circuit forming material 2 having an inner layer circuit 1 formed on both surfaces thereof is also provided.
And prepreg 3 containing a black colorant,
Furthermore, there is a method of manufacturing a laminated board with an inner layer circuit by arranging copper foils 4 on both outer sides thereof and then heat-molding and integrating them.

In the first to fourth aspects of the present invention, as the inner layer circuit forming material, for example, a glass cloth base epoxy resin copper-clad laminate on which a circuit is formed can be used. It is not necessary to include a light-shielding substance such as a black colorant in the material, and a copper-clad laminate made of a material containing no ordinary colorant can be used.

Regarding the prepreg, at least one varnish prepared by mixing 0.1 to 20.0 parts by weight of a black colorant with 100 parts by weight of a resin solid component is impregnated with a glass woven fabric substrate and dried. Use a prepreg. There is no particular limitation on the type of resin constituting the varnish, and a thermosetting resin such as an epoxy resin or a polyimide resin can be used. The black colorant is preferably a black pigment or a black dye, and specifically, is preferably carbon black, aniline black, or spirit black.

The mixing ratio of the black colorant in the varnish used in producing the prepreg is limited to the range of 0.1 to 20.0 parts by weight based on 100 parts by weight of the resin solid component. If the amount is less than 0.1 part by weight, it may not be possible to achieve the prevention of backburn, which is the object of the present invention. Even if the amount is more than 20.0 parts by weight, no further improvement in the effect can be expected, and there is a possibility that it will be wasted. Because it is expensive.

The method for combining the inner layer circuit forming material and the prepreg is not particularly limited. For example, as shown in FIG.
Further, it is also possible to combine copper foils 4 on both outer sides. The heat molding conditions after the combination of the inner layer circuit forming material and the prepreg are not particularly limited, and optimal conditions may be selected according to the type of resin constituting the varnish.

[0019]

EXAMPLE 1 100 parts by weight of an epoxy resin (brominated bisphenol A type epoxy resin manufactured by Toto Kasei: YDB500), 2.5 parts by weight of dicyandiamide, and 0.2 parts by weight of 2-ethyl-4-methylimidazole were converted to methyl. It was dissolved in a mixed solvent of cellosolve and methyl ethyl ketone to prepare an epoxy resin varnish stock solution having a resin solid component ratio of 65% by weight based on the whole. To this varnish stock solution, carbon black, which is an inorganic black pigment, is added and mixed to form a resin solid component 10
A varnish containing a black colorant containing 0.1 parts by weight of carbon black with respect to 0 parts by weight was prepared.

The obtained varnish containing a black colorant was coated on a glass woven fabric substrate having a thickness of 0.1 mm (product number WE manufactured by Nitto Boseki).
A2116-S136) and dried to a resin content of 5
A prepreg of 0% by weight was obtained.

Inner layer circuit formed by processing an FR-4 type double-sided copper-clad laminate (substrate thickness 0.2 mm, copper foil thickness 18 μm, containing no light-shielding substance) and forming inner layer circuits on both sides thereof A forming material was prepared. Next, one prepreg 3 obtained as described above and one copper foil 4 having a thickness of 18 μm were combined above and below the inner layer circuit forming material 2 as shown in FIG. Temperature 170 ° C, pressure 30kgf /
It was heated and pressed at 90 cm 2 for 90 minutes to form a laminated board having an inner circuit having a thickness of 0.4 mm.

The copper foil on the surface of the obtained laminated board with the inner layer circuit was removed by etching, and the obtained substrate was
Using a V transmittance measurement device [ORC UV illuminometer manufactured by Oak Manufacturing Co., Ltd., sensor spectral wavelength 241 to 271 nm], the UV transmittance when the light from the exposure machine was irradiated on the substrate was measured. The results obtained are shown in Table 1. Further, the copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was coated with a photoresist ink on both sides and dried. Next, light from an exposure machine was irradiated from one side of the substrate for 30 seconds, and the presence or absence of back burn of the resist ink was examined. The obtained results are shown in Table 1.

Example 2 FR-4 type double-sided copper-clad laminate (substrate thickness 1.2 m)
m, a copper foil thickness of 18 μm, and no light-shielding substance contained) were processed to prepare an inner-layer circuit-forming material having an inner-layer circuit formed on both surfaces thereof. Next, two prepregs 3 obtained in Example 1 were combined on the upper and lower sides of the prepared inner layer circuit forming material 2, and one copper foil 4 with a thickness of 18 μm was combined on the upper and lower sides as shown in FIG. 2. After that, heating temperature 170 ° C, pressure 30kgf / c
A laminate having an inner layer circuit having a thickness of 1.6 mm was prepared by heating and pressing at m2 for 90 minutes.

The copper foil on the surface of the obtained laminated board with an inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 1 shows the obtained results. Thus, the present invention can be applied to a case where the thickness is as thick as 1.6 mm.

Example 3 To an epoxy resin varnish stock solution prepared in Example 1, aniline black as an organic black pigment was added and mixed.
A varnish containing a black colorant containing 0.1 part by weight of aniline black based on 100 parts by weight of the resin solid component was prepared. A laminated board with an inner layer circuit having a thickness of 0.4 mm was prepared in the same manner as in Example 1 except that a varnish containing a black colorant containing 0.1 part by weight of aniline black was used.

The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 1 shows the obtained results.

Example 4 Spirit black (manufactured by Chuo Gosei Kagaku, trade name: Spirit Black CA) was added to the stock solution of epoxy resin varnish prepared in Example 1 and mixed to obtain 100 parts by weight of a resin solid component. Parts with aniline black.
A varnish containing a black colorant containing 1 part by weight was prepared.

A laminated board having an inner layer circuit having a thickness of 0.4 mm was prepared in the same manner as in Example 1 except that a varnish containing a black colorant containing 0.1 part by weight of the spirit black was used. did.

The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 1 shows the obtained results.

Comparative Example 1 The procedure of Example 1 was repeated, except that the varnish containing a black colorant of Example 1 was used.
A prepreg and a laminated board with an inner layer circuit having a thickness of 0.4 mm were prepared in the same manner as in Example 1, except that the stock solution of epoxy resin varnish prepared in was used. The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was treated in the same manner as in Example 1.
Investigate UV transparency and the presence or absence of back burn of the resist ink,
The results obtained are shown in Table 1.

Comparative Example 2 An FR-4 type double-sided copper-clad laminate (substrate thickness: 1.2 mm, copper foil thickness: 18 μm, containing no light-shielding substance) was processed in the same manner as in Example 2 to form an inner layer. An inner layer circuit forming material having circuits formed on both surfaces thereof was prepared. Next, a 1.6 mm-thick laminated board with an inner circuit was prepared in the same manner as in Example 2 except that the prepreg obtained in Comparative Example 1 was used.

The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 1 shows the obtained results.

Comparative Example 3, Comparative Example 4, Comparative Example 5 A black colorant was added to the stock solution of epoxy resin varnish prepared in Example 1, mixed, and the black colorant was added to 100 parts by weight of the resin solid component. A varnish containing a black colorant containing 0.05 part by weight of the agent was prepared. As the black colorant in that case, carbon black as an inorganic black pigment in Comparative Example 3, aniline black as an organic black pigment in Comparative Example 4, and spirit black as a black dye in Comparative Example 5 (manufactured by Chuo Gosei Kagaku) And trade name: Spirit Black CA).

An inner layer circuit having a thickness of 0.4 mm was prepared in the same manner as in Example 1 except that a varnish containing a black colorant containing 0.05 parts by weight of the black colorant obtained above was used. A laminated board was prepared.

The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 2 shows the obtained results.

Comparative Example 6 A tetrafunctional epoxy resin was added to the stock solution of epoxy resin varnish prepared in Example 1, mixed, and 4.0 parts by weight of the tetrafunctional epoxy resin was added to 100 parts by weight of the resin solid component. A varnish containing parts was prepared. A prepreg and a laminated board with an inner layer circuit having a thickness of 0.4 mm were prepared in the same manner as in Example 1 except that a prepreg was prepared using this varnish.

The copper foil on the surface of the obtained laminate containing the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 2 shows the obtained results.

Comparative Example 7 Coumarin was added to the stock solution of epoxy resin varnish prepared in Example 1 and mixed to prepare a varnish containing 0.5 parts by weight of coumarin with respect to 100 parts by weight of the resin solid component. A prepreg and a laminated board with an inner layer circuit having a thickness of 0.4 mm were prepared in the same manner as in Example 1 except that a prepreg was prepared using this varnish.

The copper foil on the surface of the obtained laminated board with the inner layer circuit was removed by etching, and the obtained substrate was examined for UV transmittance and the presence or absence of back burn of the resist ink in the same manner as in Example 1. Table 2 shows the obtained results.

[0040]

[Table 1]

[0041]

[Table 2]

As is evident from the results in Tables 1 and 2, it was confirmed that in Examples 1 to 4, UV transmittance was lower than that of Comparative Examples 1 to 7, and no back burn of the resist ink occurred. Was done.

[0043]

According to the invention of claims 1 to 3, the prepreg contains a black colorant in a predetermined ratio,
Even when the thickness of the laminated board containing the inner layer circuit is small, there is an effect that the backburn phenomenon is less likely to occur when performing double-sided simultaneous exposure.

According to the fourth aspect of the present invention, since at least one of the prepregs used contains a black colorant at a predetermined ratio, even if the thickness of the laminated board containing the inner layer circuit is small, simultaneous exposure on both sides is possible. It becomes possible to manufacture a laminated board with an inner layer circuit in which the backburn phenomenon during the process is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an embodiment according to claims 1, 2, 3 and 4.

FIG. 2 is a conceptual diagram illustrating a combination state according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner layer circuit 2 Inner layer circuit forming material 3 Prepreg 4 Copper foil

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Hiroshi Noguchi 1048, Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Works, Ltd. (Reference) 5E346 AA05 AA06 AA12 AA15 BB01 CC04 CC08 CC09 CC16 DD02 DD12 DD32 EE02 EE06 EE09 GG02 GG22 HH33

Claims (4)

[Claims] 1. A laminate containing an inner layer circuit formed by combining an inner layer circuit forming material and a prepreg and heat molding, wherein the prepreg contains 0.1 to 100 parts by weight of a resin solid component with a black colorant. A prepreg obtained by impregnating and drying a varnish mixed with 20.0 parts by weight of a glass woven fabric base material, wherein the laminate has an inner layer circuit. 2. The laminate according to claim 1, wherein the black colorant is carbon black or aniline black. 3. The laminate according to claim 1, wherein the black colorant is spirit black. 4. A method for producing a laminated board with an inner layer circuit, comprising combining an inner layer circuit forming material and a prepreg, followed by heat molding and integrating, wherein at least one of the prepregs is based on 100 parts by weight of a resin solid component. A varnish containing 0.1 to 20.0 parts by weight of a black colorant and a prepreg obtained by impregnating and drying a glass woven fabric substrate.