JPH0410491A - Method and device for detecting solder bridge - Google Patents

Abstract

PURPOSE:To detect the area of a solder bridge by adhering an insulating protection sheet, of which many lead terminal holes corresponding to lead terminals are formed, on the back of a printed board and peeling off the insulating protection sheet after soldering when soaking a printed board in a solder tank and fixing the lead terminals projecting from the back of the printed board on the printed board by dip-soldering. CONSTITUTION:An insulating protection sheet 21 is formed by the polyester of polyimide electrically insulating material, for example, taking the heat resistivity of a solder tank into account. The sheet has lead terminal holes 25 corresponding to the lead terminals 15 of an IC socket 13, the sheet is pushed furthest so as to adhere to the soldering side (back) of a printed board 11 under the condition that the lead terminals 15 are inserted into the lead terminal holes 25, then, dip-soldered. When soldering is completed, the insulating protection sheet 21 is peeled down. At that time, if a solder bridge S is generated, the sheet be peeled smoothly.

Description

[Detailed Description of the Invention] [Summary] A method and apparatus for detecting solder bridges when dip-soldering electronic components mounted on a printed circuit board, which easily and reliably detects solder bridges without using special detection equipment. With the aim of making this possible, solder bridges can be created by attaching an insulating protection sheet with a large number of lead terminal holes corresponding to the lead terminals of electronic components to the back of the printed circuit board, and peeling off the insulating protection sheet after soldering is completed. Configure to detect locations.

[Industrial application field]

The present invention relates to a method and apparatus for detecting solder bridges when dip-soldering electronic components mounted on a printed circuit board from the back side thereof.

[Conventional technology]

As the mounting density of electronic components mounted on printed circuit boards increases, solder bridges (solder straddles adjacent terminals) occur more frequently when dip soldering electronic component lead terminals to printed circuit boards. It's coming. Since this solder bridge causes an electrical short, it is necessary to discover, remove, and repair it without leaking.

However, conventionally, the solder bridges have been checked mainly by relying on the visual inspection of the operator or by making electrical measurements using instruments such as testers.

[Problem to be solved by the invention] Therefore, in order to discover where there is a solder bridge, it is necessary to conduct an electrical measurement each time visually or with an instrument such as a tester, which requires a large amount of time for inspection. Not only is the process time-consuming, the work is troublesome, and the reliability of the work is not always satisfactory.

An object of the present invention is to enable solder bridges to be detected reliably and easily without the need for special measuring equipment such as a tester, and without relying on the primitive method of visual inspection by an operator.

[Means to solve the problem]

In order to achieve the above object, according to the first invention, a printed circuit board on which electronic components having a large number of lead terminals are mounted is immersed in a solder tank, and the lead terminals protruding from the back surface of the printed circuit board are immersed in a solder tank. When dip soldering is carried out, a protective insulation sheet with a large number of lead terminal holes corresponding to the lead terminals is closely attached to the back of the printed circuit board, and after soldering is completed, the insulation protective sheet is peeled off to detect the solder bridge location. This is a structural feature (Claim 1).

A device according to a second aspect of the present invention for carrying out the above method has a protective insulation sheet in which a large number of lead terminal holes corresponding to the lead terminals are formed, and the insulation protection sheet inserts the lead terminals into the corresponding lead terminal holes. The structure is characterized in that it is brought into close contact with the back surface of the printed circuit board (claim 2).

Preferably, at least one positioning pin is provided protruding from the back surface of the printed circuit board, and a positioning pin hole corresponding to the positioning pin is formed in the insulation protection sheet (Claim 3).
).

Further, it is preferable that the diameter of the lead terminal hole formed in the insulation protection sheet is slightly larger than the diameter of the corresponding lead terminal of the printed circuit board (claim 4).

[Effect]

By adhering a protective insulation sheet with a large number of lead terminal holes corresponding to the lead terminals to the back of the printed circuit board, and peeling off the protective insulation sheet after soldering, if there is a solder bridge, that location can be removed with solder. The insulation protection sheet cannot be removed because it is stuck together. Therefore,
The location (solder bridge) can be easily found. Of course, you can peel it off if you pull it with a lot of force, but at least it gets caught at the solder bridge, so you can easily find the solder bridge.

The insulating protection sheet may be attached to the back surface of the printed circuit board either before or after electronic components are mounted on the printed circuit board.

In carrying out the present invention, it is only necessary to prepare an insulation protection sheet, and the solder bridge can be found by simply peeling off this insulation protection sheet after soldering is completed.

By providing positioning pins on the back surface of the printed circuit board and forming positioning pin holes corresponding to the positioning pins in the insulation protection sheet, positioning when closely adhering the insulation protection sheet to the back surface of the printed circuit board becomes easy.

Dip soldering can be performed reliably by making the lead terminal holes formed in the insulation protection sheet slightly larger in diameter than the corresponding lead terminals on the printed circuit board.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the following embodiments, an IC socket will be described as an example of an electronic component, but the present invention is generally applicable to all electronic components having lead terminals.

In FIG. 1, an IC socket 13 is mounted on the top surface of a printed circuit board 11. As shown in FIG. A large number of lead terminals (socket leads) 15 are formed in the IC socket 13 and extend through corresponding holes 17 of the printed circuit board 11 to the back surface.

The printed circuit board 11 on which the IC socket 13 is mounted is immersed in a dip solder tank (not shown) so that the back side thereof is immersed, and the lead terminals 15 are fixed to the printed circuit board 11 by soldering.

Here, according to the present invention, an insulating protection sheet 21 as shown in FIG. 2 is used. The insulating protection sheet 21 is formed of an electrically insulating material such as polyester or polyimide in consideration of heat resistance against the temperature of the solder bath, for example. Further, the wall thickness t is preferably as thin as possible in consideration of strength and the like, for example, about 0.1 to 0.2 mm.

The insulation protection sheet 21 is the lead terminal 1 of the IC socket 13
5, and with the lead terminals 15 inserted into these lead terminal holes 25, the lead terminals 15 are pushed into the solder side surface (back surface) of the printed circuit board 11 to the root thereof.

The insulation protection sheet 21 may be attached to the printed circuit board 11 either after or before mounting the IC socket 13 on the printed circuit board 11. After mounting, the lead terminal holes 25 of the insulation protection sheet 21 are inserted into the lead terminals 15 protruding from the back surface of the printed circuit board 11;
The lead terminals 15 of the printed circuit board 11 are inserted into the lead terminal holes 25 of the insulation protection sheet 21 attached to the back surface of the printed circuit board 11.

Preferably, positioning pins 16 are formed on the back surface of the printed circuit board 11, for example, at two diagonal positions, and correspondingly, positioning pin holes 26 are formed on the insulation protection sheet 21 at corresponding positions.

Therefore, these positioning pins 16 and positioning pin holes 26
By matching these, the positioning of the insulation protection sheet 21 can be performed reliably.

Preferably, the diameter of the lead terminal hole 25 of the insulation protection sheet 21 is slightly larger than the diameter of the corresponding lead terminal 15, for example, by 0.2 to 0.3 mm. By doing so, as shown in FIG. 3, the solder A can smoothly flow to the base of the lead terminal 15, thereby achieving reliable solder fixation.

When the soldering work is completed, the insulation protection sheet 21 is peeled off downward in FIG. At this time, if a solder bridge S occurs, the insulation protection sheet 21 and the lead terminal 15 are stuck together at that portion, making it impossible to peel off the insulation protection sheet 21 smoothly. As a result, the solder bridge S can be easily found. In most cases, this solder bridge S can be visually observed, but even if the solder bridge S is not visually observed, the operator can surely detect it by the feeling of "getting caught" when peeling it off.

The insulation protection sheet 21 may be prepared depending on the type of electronic component to be mounted (the arrangement of lead terminals, etc.).

〔Effect of the invention〕

As described above, according to the present invention, an insulating protective sheet in which a large number of lead terminal holes corresponding to lead terminals are formed is brought into close contact with the back surface of a printed circuit board, and the insulating protective sheet is peeled off after soldering is completed, thereby forming a solder bridge. The presence of can be easily detected.

In addition, by providing positioning pins on the back of the printed circuit board and forming positioning holes corresponding to the positioning pins in the insulation protection sheet, it is possible to easily position the insulation protection sheet when it is closely attached to the back of the printed circuit board. .

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a solder bridge detection device according to an embodiment of the present invention, FIG. 2 is a plan view of the insulation protection sheet shown in FIG. 1 (also showing the positions of the lead terminals), and FIG.
The figure is an enlarged sectional view of the main part of FIG. Printed circuit board, IC socket, lead terminal, positioning pin, insulation protection sheet, lead terminal hole. Figure 2 △

Claims (4)

[Claims] 1. Electronic component (13) having multiple lead terminals (15)
) mounted on the printed circuit board (11) is immersed in a solder bath and the lead terminals protruding from the back surface are fixed to the printed circuit board by dip soldering, a number of lead terminal holes (25) corresponding to the lead terminals are formed. Insulation protection sheet (2
1) A method for detecting solder bridges, which comprises: detecting solder bridge locations by closely contacting 1) to the back surface of a printed circuit board and peeling off the insulation protection sheet after soldering is completed. 2. Electronic component (13) having multiple lead terminals (15)
) In a dip soldering device that immerses a printed circuit board (11) equipped with a solder in a solder tank and solders the lead terminals protruding from the back side of the printed circuit board (11) to the printed circuit board, the solder bridge detection device detects a large number of leads corresponding to the lead terminals. Terminal hole (
A solder bridge detection device characterized in that it has an insulating protection sheet (21) formed with an insulating protection sheet (25), and the insulating protection sheet is brought into close contact with the back surface of a printed circuit board by inserting a lead terminal into a corresponding lead terminal hole. 3. According to claim 2, wherein at least one positioning pin (16) is protruded from the back surface of the printed circuit board, and a positioning pin hole (26) corresponding to the positioning pin is formed in the insulation protection sheet. solder bridge detection device. 4. 4. The solder bridge detection device according to claim 2, wherein the lead terminal hole formed in the insulation protection sheet has a diameter slightly larger than the diameter of the corresponding lead terminal of the printed circuit board.