JPH069300B2 - 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 by the invention of Japanese Patent Application No. 62-37647, the applicant has been able to carry out the conventional solder resist without any complicated technical work. 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 an insulating silicon and / or fluorine-based material which 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 〃 Benzoyl alkyl ether 4 〃 TiO ₂ (titanium oxide) 5 〃 SiO ₂ (silicon oxide) 3 〃 Diphenyl disulfide 2.0 〃 Pigment (cyanine green) 0.4 〃 Diethylhydroxyamine 0.1 〃 Dimethyl siloxane (anti-foaming agent) 2.0 〃 Silicon polymer resin 2-5 〃 Blending example 2 Epoxy acrylate 28 parts by weight Polyethylene glycol acrylate 72 〃 Benzoyl alkyl ether 4 〃 TiO ₂ (titanium oxide) 5 〃 SiO ₂ (oxidation Silicon) 3 〃 Diphenyldisulfide 2.0 〃 Pigment (Dianine Green) 0.4 〃 Diethylhydroxyamine 0.1 〃 Dimethylsiloxane (Antifoaming agent) 2.0 〃 Fluoro FC-170C Sumitomo 3M Co., Ltd. 2 ~ 5 〃 Mixing example 3 Epoxy acrylate 50 parts by weight Polyureta acrylate 50 〃 Benzoyl methyl ether 4 〃 CaCo ₃ (calcium carbonate) 5 〃 SiO ₂ (silicon oxide) 3 〃 Cyanine green 0.4 〃 Benzothiazole 0.05 〃 Bezophenone 2.6 〃 Dimethyl siloxane Silicon-based polymer resin 2-5 〃 Blending example 4 Epoxy acrylate 50 parts by weight Polyureta acrylate 50 〃 Benzoyl methyl ether 4 〃 CaCo ₃ (calcium carbonate) 5 〃 SiO ₂ (silicon oxide) 3 〃 Cyanine green 0.4 〃 Benzothiazole 0.05 〃 Bezophenone 2.6 〃 Dimethylsiloxane 1.5 〃 Silicon polymer resin 2-5 〃 Fluoro surfactant (Florado FC-430 manufactured by Sumitomo 3M Limited) 3-5 〃 In addition, the silicone-based compounds in the above formulation examples And fluorine resin ingredients A body example is shown below.

Silicon Polon L, Polon T, KF96, KS-700, KS-701, KS-707, KS
-705F, KS-706, KS-709, KS-709S, KS-711, KSX-712, K
S-62F 、 KS-62M 、 KS-64 、 Silicolube G-430 、 Silicolube
G-540, Siliconube 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 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. 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 on the entire surface of the insulating substrate 1. However, it is possible to form the solder resist coatings 6 and 7 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 a peripheral portion.

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 between circuit terminals, improving product accuracy 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

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] The 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 a circuit pattern of the printed wiring board is formed. On the upper side of the substrate, a concave portion for a flux pool portion, which is not coated with the solder resist coating, is provided, and a flux absorptive coating portion is provided in the concave portion.

[Function] 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 solder resist coating is provided on an upper side of a substrate on which a circuit pattern of the printed wiring board is formed. A concave portion for the flux pool that is not adhered is provided and a flux absorptive coating is provided in this recess. Thus, the spot phenomenon of flux on the upper surface of the solder resist film due to the cissing action of the solder resist film can be eliminated.

[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 vertical 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 on which the circuit pattern 2 is formed without coating the same 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. Therefore, a plurality of them are arranged at positions required to prevent the spot phenomenon from occurring.

Reference numeral 10 denotes a flux absorptive coating portion which is buried in the flux pool recess portion 8. The absorptive coating portion 10 is capable of positively adsorbing the flux, for example, carbon or the like is formed by a means such as coating. To do.

In addition, about the other structure, it consists of the same structure as the printed wiring board shown in FIG.

Now, in the printed wiring board having such a configuration,
In addition to obtaining the above-described effects of the printed wiring board having the configuration shown in FIG. 2, the flux (not shown) applied to the upper surface 1a of the insulating substrate 1 on which the circuit pattern 2 is formed is solder resist. The flux is repelled by the action of the coating film 6 and flows into the recess portion 8 for the flux accumulation portion arranged in the same portion, and at the same time, the flux can be adsorbed to the adsorptive coating portion 10 of the recess portion 8 to escape, and the flux can be released from the solder resist coating film 6 Prevents remaining spots on the upper surface.

Therefore, it is possible to provide an expected printed wiring board which eliminates the adverse effect of unevenness on the printed wiring board itself due to the spot phenomenon of flux, does not impair the appearance of the printed wiring board, and has no problem in quality, accuracy, etc. It is a thing.

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

In particular, the desired action and effect of the present invention can be optimized by the adsorption action of the flux absorptive coating portion provided in the recess in addition to the flux pool recess.

[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. DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... Circuit pattern 3 ... Connection land 4 ... Through hole 6,7 ... Solder resist film 8 ... Flux pool recessed part 10 ... Flux adsorptive film part

Front Page Continuation (72) Inventor Hirotaka Konogi 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Prefecture Japan CMC Co., Ltd. ) Inventor Norihi Mukai 1106 Fujikubo, Miyoshi-cho, Iruma-gun, Saitama Japan CMC Co., Ltd. (56) Reference JP-A-60-10692 (JP, A) JP-A-60-10694 (JP, A)

Claims (1)

[Claims] 1. A printed wiring board provided with a solder resist coating containing silicon and / or a fluorine-based resin, wherein a flux which does not adhere to the solder resist coating is provided on the upper side of the substrate on which the circuit pattern of the printed wiring board is formed. A printed wiring board comprising a recess for a reservoir and a flux adsorbing coating on the recess.