JPH0645743A - Circuit board and soldering thereof - Google Patents

Abstract

PURPOSE:To achieve a soldering of a metallic sealed case to an electrode land on the circuit board of an electronic equipment in a state that one part of the metallic sealed case is fitted in a slit orifice in the circuit board in high quality and stably. CONSTITUTION:In a method of soldering 5 a projected part 2, which is made to fit in a slit orifice 6 provided in a circuit board 1, of a metallic sealed case to an electrode land 3 on the board 1, a synthetic resin film 4, which contains metal powder and has a wettability with solder, or a metal film is formed on the wall surface of the slit orifice and thereafter, the board 1 is dipped in a molten solder bath in a state that the part 2 of the metallic sealed case is made to fit in the slit orifice 6 and the part 2 is soldered to the land 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering a circuit board of an electronic device, a component lead, a shield case and the like.

[0002]

2. Description of the Related Art A conventional soldering method will be described with reference to FIG.

As a method of soldering the component lead 2 or the shield case to the circuit board 1, the component lead 2 and a part of the protrusions of the shield case are brought close to the electrode pattern 3 of the circuit board 1 individually. It is common to attach solder.

Further, a hole 6 is provided in the circuit board, and the protruding portion 2 of the shield case is immersed in the molten solder bath while being fitted in the hole 6, and the electrode pattern 3 adjacent to the hole 6 is formed at a plurality of positions. A method of soldering at the same time is generally performed.

[0005]

In the conventional case, if the gap between the protrusion 2 of the shield case and the electrode pattern 3 of the circuit board 1 is 0.2 mm or more, the fillet formation with solder cannot be satisfactorily performed, and the soldering failure will occur. However, there are some drawbacks, such as the possibility that the soldering will be increased and the correction of the soldering finish is not small.

In this case, it was possible to make up for this drawback by forming a through-hole metal film layer by copper plating or the like on the wall surface of the hole 6, but there was a drawback in that it was expensive. .

[0007]

DISCLOSURE OF THE INVENTION The present invention is a projection of a shield case that is easily fitted into a slit hole of a circuit board at a low cost without using a complicated and costly method such as copper through hole plating. In order to ideally form a soldered fillet with, a paste liquid composed of a resin containing a predetermined amount of metal powder, a solvent, etc. is applied in advance to the board insertion hole, dried and solidified, and then a component lead or By inserting a metal protrusion such as a shield case, immersing it in a molten solder bath and soldering it, ideally between the electrode pattern around the circuit board hole and the metal protrusion such as the component lead or shield case. It is an invention relating to a soldering method characterized in that various solder fillet formation is achieved.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] By forming a resin coating film containing a predetermined amount of metal powder on the wall of the insertion hole to impart solder wettability to the wall of the insertion hole, it is melted between the projection and the projection of the shield case By having a stable solder layer between the hole wall and the component lead or metallic protrusion by the same phenomenon as the capillary phenomenon of solder, fillet due to the cohesive force of the solder itself when the solder cools and solidifies from the molten state. The formation obstruction factor is removed to prevent the solder from separating and adhering to each of the soldered electrode portion and the shield case protrusion of the substrate.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

An insertion hole 6 is provided in a part of the circuit board, and an electrode land 3 for soldering is provided around the insertion hole 6. Next, a synthetic resin liquid 4 containing 60% or more (weight ratio) of copper powder and having wettability with respect to the solder 5 is applied to the wall surface of the insertion hole, and then dried and cured.

As a coating method, screen printing or a needle-shaped material is coated with the synthetic resin liquid in advance,
After the synthetic resin liquid is transferred to the pore walls, it is dried and solidified.

After that, the protrusions 2 of the shield case are inserted and fitted into the holes 6, and then immersed in a molten solder bath, and the synthetic resin film 4, the solder 5, the metallic protrusions 2 and the substrate 1 are further inserted.
The purpose of the present method is achieved by integrating the soldered electrode (land) 3 of 1.

In this case, the same effect can be obtained by forming a solder wettable metal film in the range of 30% to 100% of the hole wall surface area instead of the solder wettable synthetic resin film 4. The metal film can be formed by, for example, a method such as electroless plating, and the film thickness, surface condition, adhesion, etc. are not limited as long as the metal has solder wettability.

[0014]

[Effect] The present invention has no drawback in soldering the soldered land of the substrate and the component lead or the shield case, and
It is a method of stable reproduction, and it achieves its purpose at low cost in terms of member costs and processing man-hours.

[Brief description of drawings]

FIG. 1 is a substrate cross-sectional view showing a soldering method of the present invention.

FIG. 2 is a substrate cross-sectional view showing a defective state in the case of a conventional soldering method.

FIG. 3 is a sectional perspective view showing a state of a soldering method according to the present invention.

[Explanation of symbols]

 1 Circuit board 2 Shield case protrusion (board slit hole fitting part) 3 Solder electrode land 4 Resin film containing metal powder on slit hole wall 5 Solder fillet 6 Insert hole

Claims (2)

[Claims] 1. A method of soldering a metal lead such as a component lead and a shield case to be fitted into a hole provided in a circuit board and an electrode land of the circuit board,
After forming a synthetic resin coating containing solder powder on the wall surface of the hole and having a solder fouling property, immersing in a molten solder bath with the component leads and the metallic projections fitted together for soldering. The characteristic soldering method. 2. The soldering method according to claim 1, wherein a metal film is formed on the wall surface of the hole instead of the solder-wettable synthetic resin film containing metal powder.