JPH0614587B2 - Printed wiring board - Google Patents

Description

TECHNICAL FIELD The present invention relates to a printed wiring board.

[Prior Art] Generally, a printed wiring board is formed by forming a required circuit pattern on an insulating substrate via a conductor and incorporating required electronic parts into the circuit pattern.

Then, assembling the electronic components into the printed wiring board is performed by immersing the circuit pattern surface of the printed wiring board in a molten solder bath or a jet solder bath while the electronic components are mounted on the printed wiring board. This is carried out by attaching solder to and electrically and mechanically connecting the lead of the electronic component and the circuit pattern.

Further, the soldering of the circuit pattern and the lead of the electronic component is performed by solder resist on the entire surface of the circuit pattern except for the land portion to be soldered so that the solder may be attached only to the coupling component of both in advance. However, with the miniaturization of the circuit pattern, the interval between the adjacent circuits becomes narrower, and the interval between the connection lands to the leads of the electronic component also becomes narrower, so that the original function of the solder resist is impaired. There was a case where a bridging phenomenon occurred between lands due to soldering, and correction work or the like was required.

Therefore, in order to prevent such bridging of solder, in particular, in order to prevent bridging of solder in a portion having a small land interval, in manufacturing the printed wiring board, a conductor pattern is printed on an insulating substrate. In order to prevent bridging of solder, the first layer of soldering resistance layer is formed on the entire surface leaving the land to be soldered on the surface on which the conductor pattern is formed, and also to prevent the bridging of solder at least in the portion where the land interval is narrow. The method of forming the soldering resistance layer on the first layer of the soldering resistance layer is adopted, and such a method is also disclosed in Japanese Patent Publication No. 54-41162.

Accordingly, the method of forming the soldering resistance layer of the first layer and then forming the soldering resistance layer for bridging prevention on the soldering resistance layer of the first layer is as follows. Since the resistive layer is formed on the entire surface leaving the land to be soldered on the surface on which the conductor pattern is formed, high accuracy is required for the alignment accuracy for leaving the land to be soldered, and the solder of the first layer is also required. Since the soldering resistance layer for preventing bridging is formed on the soldering resistance layer of the first layer after formation on the soldering resistance layer, in addition to the matching accuracy for leaving the land to be soldered, It has a drawback that the solder resist ink is bleeding due to screen printing when the soldering resistance layer is formed on the land portion to be applied.

Therefore, in view of the above-mentioned drawbacks of the conventional printed wiring board, the applicant previously proposed the invention of Japanese Patent Application No. 62-37647 without any troublesome technical work for implementing the conventional solder resist. It has just disclosed a printed wiring board provided with a solder resist coating capable of obtaining an original effect as a solder resist.

That is, the solder resist coating of the printed wiring board has the function of positively preventing the adhesion of flux or solder due to the characteristics of the silicon and / or fluorine resin contained in the printed wiring board. By forming a film on the other surface of the printed wiring board with a pattern using the solder resist printing ink, it is possible to positively infiltrate flux or solder from the through holes or component insertion holes provided in the printed wiring board. It has a function that can be prevented.

FIG. 2 is a partially enlarged sectional view showing a printed wiring board provided with the solder resist coating. In FIG. 2, 1 is an insulating substrate and 2 is a copper foil as a conductor formed on one surface 1 a of the insulating substrate 1. Formed by this, 3 is a connection land in this circuit pattern 2, 4 is a through hole opened in the connection land 3, 6 is a solder resist film coated on the surface of the circuit pattern 2, and 7 is the other surface of the insulating substrate 1. It is a solder resist film coated on 1b.

The solder resist coating 6 is formed by leaving the connection lands 3 in the circuit pattern 2 and is made of insulating silicon and / or fluorine-based material that can prevent the flux and solder from adhering together with the solder resist coating 7. It is formed by coating with a printing ink containing a resin by means such as silk printing.

In addition, a formulation example of the solder resist printing ink used for forming the solder resist coatings 6 and 7 will be specifically shown below.

Formulation Example 1 Epoxy acrylate 28 parts by weight Polyethylene glycol acrylate 72 〃 Benzoin alkyl ether 4 〃 TiO (titanium oxide) 5 〃 SiO (silicon oxide) 3 〃 Diferdisulfide 2.0 〃 Pigment (cyanine green) 0.4 〃 Diethylhydroxyamine 0.1 〃 Dimethyl siloxane (antifoaming agent) 2.0 〃 Silicon polymer resin 2-5 〃 Blending example 2 Epoxy acrylate 28 parts by weight Polyethylene glycol acrylate 72 〃 Benzoin alkyl ether 4 〃 TiO (titanium oxide) 5 〃 SiO (silicon oxide) 3 〃 Diffel Sulfide 2.0〃 Pigment (Cyanine Green) 0.4〃 Diethylhydroxyamine 0.1〃 Dimethylsiloxane (Antifoaming agent) 2.0〃 Fluorosurfactant (Florad FC-170C Sumitomo 3M Co., Ltd.) 2-5〃 3 epoxy Crylate 50 parts by weight Polyureta acrylate 50 〃 Benzoin methyl ether 4 〃 CaCo (calcium carbonate) 5 〃 SiO (silicon oxide) 3 〃 Cyanine green 0.4 〃 Benzothiazole 0.05 〃 Bezophenone 2.6 〃 Dimethylsiloxane 1.5 〃 Silicon-based polymer resin 2-5 〃 Formulation example 4 Epoxy acrylate 50 parts by weight Polyureta acrylate 50 〃 Benzoin methyl ether 4 〃 CaCo (calcium carbonate) 5 〃 SiO (silicon oxide) 3 〃 Cyanine green 0.4 〃 Benzithiazole 0.05 〃 Bezophenone 2.6 〃 Dimethyl siloxane 1.5 High silicon 〃 Molecular resin 2-5 〃 Fluoro-based surfactant (Fluoro FC-430 manufactured by Sumitomo 3M Co., Ltd.) 3-5 〃 Specific examples of the silicone-based and fluorine-based resins in the above-mentioned respective formulation examples are shown below.

Silicon type Polon L, Polon T, KF96, KS-700, KS-701, KS-707,
KS-705F, KS-706, KS-709, KS-709S, KS-711, KS
X-712, KS-62F, KS-62M, KS-64, Siliconube G-430, Si
licolube G-540, Silicolube G-541 or above SH-200, SH-210, SH-1109, SH-3109 manufactured by Shin-Etsu Chemical Co., Ltd. SH-3107, SH-801
1, FS-1265, Syli-off23, DC pan Glaze620 or more Toray Silicon Co., Ltd. Fluoro-based Daifuri-MS-443, MS-543, MS-743, MS-043, ME-413, ME-
810 or more Daikin Industries Ltd. Fluoride FC-93, FC-95, FC-98, FC-129, FC-134, FC-43
0, FC-431, FC-721 or more Sumitomo 3M Co., Ltd. Sumiflunon FP-81, FP-81R, FP-82, FP-84C, FP-84R, FP-86 or more Sumitomo Chemical Co., Ltd. Surflon SR- 100, SR-100X or above Made by Kiyomi Chemical Co., Ltd. Also, in each of the compounding examples, the case where the silicon-based or fluorine-based polymer resin is compounded alone is shown, but both the silicon-based and fluorine-based polymer resins are compounded. It has been found that the desired effect can be obtained by blending 2 to 5 parts by weight with respect to the blending amount, and an increase in the blending amount causes a problem of economical efficiency, but is not suitable. It goes without saying that a certain effect can be expected.

Further, it was found that the contact angle of the conventional solder resist ink is 60 to 70 °, whereas the contact angle of the solder resist ink according to the above formulation example is 90 ° or more.

Now, according to the printed wiring board having such a structure, the solder resist coatings 6, 6 formed on both surfaces of the insulating substrate 1 are formed.
7 is formed by coating a printing ink containing silicon and / or a fluorine-based resin, and therefore, depending on the characteristics of the silicon and the fluorine-based resin, it repels flux or solder to electrically connect the connection land 3 and the like. It is possible to positively prevent the adhesion of the flux or the solder to portions other than the portion, and it is possible to prevent the occurrence of the bridging phenomenon between the adjacent parts due to the high density of the circuit pattern 2.

Moreover, the solder resist coatings 6 and 7 can be formed by coating by means such as silk printing, which has the advantage that they can be performed in the same operation as conventional solder resist coatings.

Further, the other surface 1b of the insulating substrate 1 provided with the circuit pattern 2
Further, by providing the solder resist coating 7, it is possible to prevent the flux or the solder from entering through the through holes 4 provided in the printed wiring board.

In the above-mentioned embodiment, the case where the circuit pattern 2 is formed only on the one surface 1a of the insulating substrate 1 is shown. However, the circuit pattern 2 is formed on both surfaces, or only the solder resist coating 6 on the circuit pattern 2 side of the one surface 1a of the insulating substrate 1 is shown. Of course, it is possible to form the solder resist coatings 6 and 7 shown in the figure, and the solder resist coatings 6 and 7 are formed on the entire surface of the insulating substrate 1. It is also possible to form and implement it only on a local portion such as the peripheral portion of 4.

According to the printed wiring board described above, the solder resist coating itself can exert the effect of preventing flux or solder wetting, and mounting of components on the printed wiring board
The effect of preventing bridging between circuits or between component terminals by performing soldering work when connecting circuit terminals, improving the product system and eliminating the need for bridge correction work, and improving workability Have.

[Problems to be Solved by the Invention] However, according to a printed wiring board provided with a solder resist coating containing the above-mentioned silicon and / or fluorine-based resin, due to the action of the solder resist coating of the printed wiring board, When flux is applied to the surface of the solder resist coating, the flux becomes spots on the surface of the solder resist coating, and this has the drawback of impairing the product accuracy and appearance of the printed wiring board. It was

That is, the flux repelled by the cissing action of the solder resist film remains on the surface of the solder resist film in a scattered state, and this remains as spots on the upper surface of the printed wiring board, resulting in the appearance of the printed wiring board as a product. It was something that inhibited.

In addition, since the main component of the flux is composed of pine resin and a solvent (alcohol-based), pine resin has an adhesive property, so that the printed wiring board is a final product (for example, an electric product such as a television). When used by being incorporated into a product, dust in the air adheres to the residual flux scattered and scattered on the surface of the printed wiring board, and this adheres between the circuits of the printed wiring or between the components mounted between the printed wirings. It also causes insulation deterioration and short circuit.

Further, the pine resin itself in the main component of the flux has a chemically hydrophilic group (-COOH, -OH), and causes a phenomenon of absorbing water with respect to humidity. Therefore, between circuits of printed wiring or between components. May cause insulation deterioration and short circuit of
This was a drawback in terms of product accuracy.

Therefore, the present invention has been made in view of the drawbacks in a printed wiring board provided with a solder resist coating containing the above-mentioned silicon and / or fluorine-based resin, and spots of flux are generated on the surface of the solder resist coating. An object of the present invention is to provide a printed wiring board that can prevent the above.

[Means for Solving Problems] A printed wiring board of the present invention is a printed wiring board provided with a solder resist coating containing silicon and / or fluorine resin, and is formed on the upper side of the substrate of the printed wiring board. In addition, a plurality of recesses for the flux accumulation portion for accumulating the flux repelled by the solder resist coating are randomly arranged in a space other than the printed wiring pattern.

[Operation] The printed wiring board of the present invention is a printed wiring board provided with a solder resist coating containing silicon and / or a fluorine-based resin, wherein the printed wiring board is randomly formed in a space other than the printed wiring pattern formed on the upper side of the substrate. A plurality of fluxes repelled by the cissing action of the solder resist coating in the recesses for the flux accumulation portion for accumulating the flux repelled by the solder resist coating disposed in the printed wiring board. Prevents scattered and remaining on the surface of the plate.

[Embodiment] An embodiment of the printed wiring board of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially enlarged sectional side view showing an embodiment of the printed wiring board of the present invention.

In the figure, 8 is the solder resist coating 6
Insulating substrate 1 at the same time when forming by silk printing
Is a recess for a flux pool provided on the upper surface 1a of the same without depositing the solder resist ink.

In the illustrated case, the concave portion 8 is provided only at one place, but when viewed from the plane, the flux repelling action of the flux of the coating film 6 is made to correspond to the area to which the solder resist coating film 6 is applied. Thus, a plurality of random spots are arranged at positions required to prevent the spot phenomenon from occurring.

As a specific position, a space other than the printed wiring pattern, that is, a space between the printed wirings in the printed wiring pattern, or a part of the conductor portion of the printed wiring when the conductor width is wide, and other printed wiring patterns Install in a space other than.

Further, the recesses 8 for the pools of the respective fluxes are formed as recesses 8 having a diameter sufficient to allow the flux repelled by the repelling action of the solder resist coating 6 to flow in, for example, about 2 mmφ.

In addition, about the other structure, it consists of the same structure as the printed wiring board of 2nd illustration, the same code | symbol is attached | subjected to the same structure part, and the description is abbreviate | omitted.

Now, in the printed wiring board having such a configuration,
In addition to the fact that the working effects of the printed wiring board having the above-described second configuration are obtained as they are, the flux applied to the upper surface 1a of the insulating substrate 1 can be obtained in addition to the working effects of the insulating substrate. (Not shown) is repelled by the action on the solder resist coating 6 and can flow into the recess 8 for the pool of the flux disposed in the same to escape and remain as spots on the upper surface of the solder resist coating 6. Prevent from doing.

Therefore, the adverse effect of the unevenness generated on the printed wiring board itself due to the spot phenomenon of the flux is eliminated, and the appearance of the printed wiring board is not impaired, and the flux is the recessed portion 8 for the reservoir portion arranged in the space other than the printed wiring pattern. Since it is stored inside, the defects of the appearance due to the scattering of the flux are eliminated, and the problems such as product quality and accuracy due to the dust adhesion caused by the scattering of the flux or the water absorption function are minimized. It is possible to provide an intended printed wiring board that can be manufactured.

[Effects of the Invention] According to the printed wiring board of the present invention, the intended effect of the solder resist coating itself is
It can be exhibited without causing problems in accuracy and the like.

[Brief description of drawings]

FIG. 1 is a partially enlarged vertical side view showing an embodiment of the printed wiring board of the present invention, and FIG. 2 is a partially enlarged sectional view showing a printed wiring board provided with a cissing solder resist coating. 1 ... Insulating substrate 2 ... Circuit pattern 3 ... Connection land 4 ... Through hole 6,7 ... Solder resist coating 8 ... Recess for recess of flux

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Satoshi Haruyama 1106 Fujikubo Fujiyoshibo, Miyoshi-cho, Iruma-gun, Saitama Prefecture, Japan MK Corporation (72) Inventor Hirotaka Konogi 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Japan CMK Corporation (72) Inventor Katsutomo Nikaido 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture Japan CMC Co., Ltd. (72) In-house author Norito Mukai 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Japan CMK Corporation (56) Reference References JP-A-59-151491 (JP, A) JP-A-51-100270 (JP, A) Actually open Sho-60-76064 (JP, U) Actual-open Sho-61-111177 (JP, U)

Claims (1)

[Claims] 1. A printed wiring board provided with a solder resist coating containing silicon and / or a fluorine-based resin for preventing the adhesion of flux or solder, wherein the printed wiring is formed on the upper side of the substrate of the printed wiring board. A printed wiring board in which a plurality of recesses for a pool of flux for accumulating the flux repelled by the solder resist coating are randomly arranged in a space other than the pattern.