JPH08213070A - Solder run-up preventive structue of electronic part terminal - Google Patents

Abstract

PURPOSE: To simply and reliably prevent solder run-up when fixing components on a circuit board or the like, and prevent the deterioration of a function and performance by arranging oxide films on local surface parts of terminal parts of plural electronic part terminals fixed to an insulator CONSTITUTION: In an insulator 1 composed of plastic or the like, connectors 2 are installed in a fixing part 22, and contact parts 21 with the other connectors and terminal parts 23 are formed. Next, these terminal parts 23 are inserted into through holes of a circuit boards 3 for connection, and positioned through a stand 4. Next, the terminal parts 23 are fixed on a circuit of the circuit board 3 by solder 5. In that case, oxide films 231 are arrange on local surface parts of the terminal parts 23. These oxide films 231 are preferably arranged over the whole circumference of the terminal parts in a part on the terminal part side reaching an insulator push-in part from a board inserting part, and can be locally formed by heating by irradiation of a laser beam or the like in an oxidizing ambience such as in the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component fixed to the surface of a circuit board with solder, and more particularly to an electronic component having a terminal capable of stopping the solder rising at a predetermined position.

[0002]

2. Description of the Related Art When fixing electronic parts to the surface of a circuit board 3, the terminals of the electronic parts are often connected by soldering. In this case, as the size of the component becomes smaller, the solder is more likely to run up the terminal, often impairing the function and performance of the component. For example, in the case of a connector, if the solder 5 runs unnecessarily from the terminal portion 23 and the solder 5 adheres to the contact portion 21 of the contact 2, the connection reliability of the connector will be impaired. Therefore, various means have been proposed as a measure for preventing the solder 5 from running up, for example: • Sealing with an adhesive Figure 3 (A) • Sealing with insert molding Figure 3 (B) • Sealing with adhesive application Figure 3 (C) etc. can be mentioned.

Sealing with an adhesive is shown in FIG.
As described above, the adhesive 6 is applied to the side where the contact tail of the insulator 1 projects. The gap between the contact 2 and the insulator 1 is filled by applying the adhesive 6. Sealing by insert molding is, as shown in FIG. 3B, that the contact 2 is set in a mold during injection molding of the insulator 1 and the contact 2 is integrally molded with resin. By integrally molding the contact 2 with resin, the gap between the contact 2 and the insulator 1 is eliminated. The sealing by applying the adhesive means that the adhesive 6 and the resist ink are applied to the contact 2 in advance in a band shape as shown in FIG. It is intended to prevent the solder 5 from rising by applying it to the contact 2 in advance by the barrier of the adhesive 6 and the resist ink without the solder 5.

[0004]

However, as shown in FIG.
In the sealing with the adhesive shown in (A), since the contact 2 is fixed to the insulator 1 and then the adhesive 6 is applied,
The applied state of the adhesive 6 is likely to vary, and a gap may occur between the contact 2 and the adhesive 6. If there is a gap between the contact 2 and the adhesive 6, the solder 5 runs up to the contact portion 21 of the contact 2 through the gap. Further, after the insulator 1 and the contact 2 are normally assembled, the adhesive 6 is applied in a later step, which leads to an increase in cost due to an increase in the number of steps.

Further, in the sealing by insert molding shown in FIG. 3 (B), the contact 2 is mounted on the mold and then the resin is filled in the mold, but it is manual work to mount the contact 2 on the mold. Or, it requires a fairly large-scale automatic equipment, which is also a major factor in cost increase.

Further, in the sealing shown in FIG. 3 (C),
Although the adhesive 6 or the resist ink is applied to the tail portion of the contact 2 in advance, contamination of the product by the adhesive when the applicator is not sufficiently maintained, or the adhesive 6
Due to the undesired adhesion to the portion due to the string pulling, an accident that damages the original function (for example, electrical connection with the mating connector) is likely to occur.

Sealing with an adhesive 6 (as shown in FIG. 3A) or sealing with insert molding (see FIG. 3A)
In the sealing method (such as (B)) or by applying the adhesive 6 (such as in FIG. 3C), as described above,
All of them have a problem to be solved that they are likely to lead to cost increase and also impair the function and performance of the connector due to solder rising or solder adhesion.

The present invention has been made in view of the above circumstances, and when the solder is fixed to the circuit board 3 with the solder 5, the solder rising of the terminal portion 23 can be stopped, and the function and performance due to the solder rising are impaired. The purpose is to provide electronic components without

[0009]

The above object of the present invention can be achieved by providing an oxide film 231 on the surface of the terminal portion 23 of the electronic component. Here, the surface local portion refers to the terminal portion 23 of the electronic component terminal, a part or the whole up to the substrate 3, and the entire circumference of the terminal portion 23 of the portion.

[0010]

Since the oxide film 231 provided on the surface of the terminal portion 23 of the contact 2 has a low wettability with respect to solder, the solder 5 running up from the circuit board 3 stops at the oxide film 231 and the contact 2 Does not reach the contact portion 21.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG.
Shows a connector which is one specific example of the present invention. In FIG. 1, 1 is an insulator. The insulator 1 is usually formed in a predetermined shape by an injection molding technique using an electrically insulating plastic material. A required number of contacts 2 are attached and fixed to the insulator 1. The contact 2 is generally composed of a contact portion 21 that comes into contact with a contact of a mating connector, a fixing portion 22 fixed to the insulator 1, and a terminal portion 23 electrically connected to the circuit board 3.

As a general means for mounting or fixing the contact 2, a method of press-fitting the contact 2 into a contact mounting hole provided at a predetermined position of the already molded insulator 1 or a predetermined method when the insulator 1 is molded is used. There is a method of integrally molding the shaped contact 2 with a plastic material. The contact 2 has good conductivity and can be made of a metal material having repulsion elasticity by stamping or other known processing techniques. Examples of the metal material that can be used for the contacts include brass, phosphor bronze, beryllium copper, nickel silver bronze, cadmium copper, and Cu-Ni-Sn alloy.

The terminal portion 23 of the contact 2 projects outward from the insulator 1, and the projecting portion is the circuit board 3
Is inserted into the through hole 31 provided in the. The terminal portion 23 is
At the time of connection with the circuit board 3, solder plating may be applied so as to obtain good solder paste. In the present invention, a strip-shaped oxide film 231 is provided around the surface of the contact 2 terminal portion 23. The position of this strip-shaped oxide film 231 is shown in FIG.
As shown in (A), the connector terminal portion 23 may be located at any position as long as it is closer to the insulator 1 from the position of the surface 31 of the circuit board 3 except for the required soldering length. Generally, it is set near the insulator 1 with a margin in mind.

The width of the band-shaped oxide film 231 should be such that the flow of solder can be prevented, and if it is 500 μm or more, the effect can be sufficiently obtained. Terminal part 2 of contact 2
The band-shaped oxide film 231 of No. 3 can be produced by locally heating a required portion. In this case, if the width of the oxide film 231 is taken into consideration, the heating source is preferably one capable of concentrating heat energy, and the terminal portion 23 is heated by heat.
It is desirable that only the surface can be heated for the purpose of minimizing the deterioration of strength. A laser beam can be cited as an example that satisfies such a requirement.

The heating atmosphere for forming the oxide film is preferably the atmosphere or an oxidizing gas atmosphere such as ozone gas. The oxide film may be formed before or after mounting the contact 2 on the insulator 1. Reference numeral 4 in FIG. 1 denotes a stand protruding from the bottom surface of the insulator 1. The base 4 provides a gap between the connector and the circuit board 3 and is effective in preventing solder wicking.

[0016]

As described above, the present invention has the following unique and remarkable effects. The solder 5 running up from the circuit board 3 is stopped by the oxide film 231 of the terminal portion 23 of the electronic component, and the contact portion 2
Since the number of contacts does not reach 1, the solder 5 does not adhere to the contact portion 21 of the electronic component, and the deterioration of connection reliability due to the solder adhesion cannot occur.

[Brief description of drawings]

FIG. 1 shows a sectional view of a connector according to the present invention.

FIG. 2 is an explanatory view of a strip oxide film portion provided on a contact of the connector according to the present invention.

FIG. 3 is an explanatory view of a conventional measure for preventing solder run-up.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulator 2 Contact 3 Circuit board 4 units 5 Solder 6 Adhesive 21 Contact part 22 Fixing part 23 Terminal part 231 Strip oxide film 31 Through hole

Claims (2)

[Claims] 1. A solder wicking prevention structure for an electronic component terminal comprising a plurality of electronic component terminals and an insulator for accommodating and fixing the electronic component terminals, wherein an oxide film is formed on a local surface of a terminal portion of the electronic component terminal. A structure for preventing solder wicking of electronic component terminals, which is provided. 2. The solder wicking prevention for an electronic component terminal according to claim 1, wherein an oxide film is provided on the entire circumference of the terminal portion on a part of the terminal portion side of the electronic component terminal portion between the board insertion portion and the insulator press-fitting portion. Construction.