JP2778602B2 - Method and apparatus for detecting solder bridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method and an apparatus for detecting a solder bridge when dip soldering an electronic component mounted on a printed circuit board, and simply and reliably detects a solder bridge without using a special detecting device. An insulation protection sheet having a large number of lead terminal holes corresponding to the lead terminals of an electronic component is brought into close contact with the back surface of the printed circuit board, and the insulation protection sheet is peeled off after soldering. It is configured to detect the location.

[Industrial applications]

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

[Conventional technology]

As the mounting density of electronic components mounted on a printed circuit board increases, the occurrence of solder bridges (solder straddles between adjacent terminals) when dip soldering the lead terminals of the electronic component to the printed circuit board increases. Is coming. Since this solder bridge causes an electrical short, it needs to be found without leakage and removed and repaired.

Conventionally, however, the solder bridge has been checked mainly by visual inspection of an operator or by performing electrical measurement using an instrument such as a tester.

[Problems to be solved by the invention]

Therefore, since the electrical measurement was checked visually or with a meter such as a tester each time to find out where the solder bridge was located, it took a lot of time to perform the inspection. The work was troublesome, and the work reliability was not always satisfactory.

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to reliably and easily detect a solder bridge without the need for a special measuring device such as a tester, and without using a primitive method of visual inspection by an operator.

[Means for solving the problem]

In order to achieve the above object, according to a first aspect of the present invention,
When immersing in a solder bath of a printed circuit board mounted with electronic components with a large number of lead terminals and dip soldering the lead terminals projecting from the back surface to the printed circuit board, a number of lead terminal holes corresponding to the lead terminals are formed. The configuration is characterized in that the insulated protection sheet is brought into close contact with the back surface of the printed circuit board, and after completion of the soldering, the insulated protection sheet is peeled off to detect a solder bridge portion (claim 1).

An apparatus according to a second aspect of the present invention for carrying out the above method has an insulating protection sheet formed with a large number of lead terminal holes corresponding to the lead terminals, and the insulating protection sheet has a lead terminal inserted through the corresponding lead terminal hole. The structure is characterized by being brought into close contact with the back surface of the printed circuit board (claim 2).

Preferably, at least one positioning pin projects from the rear surface of the printed circuit board, and a positioning pin hole corresponding to the positioning pin is formed in the insulating protection sheet.

Further, it is preferable that the lead terminal hole formed in the insulating protection sheet is slightly larger than the diameter of the corresponding lead terminal on the printed circuit board.

[Action]

The insulation protection sheet, on which a number of lead terminal holes corresponding to the lead terminals are formed, is closely adhered to the back surface of the printed circuit board, and the insulation protection sheet is peeled off after the soldering is completed. Because of the sticking, the insulation protection sheet cannot be peeled off. Therefore, the location (solder bridge) can be easily found. Of course, it can be peeled off by pulling with a large force, but since it gets caught at least at the solder bridge,
You can easily find the solder bridge.

The insulating protection sheet may be brought into close contact with the back surface of the printed circuit board either before or after mounting the electronic components on the printed circuit board.

In practicing the present invention, it is only necessary to prepare an insulating protection sheet, and a solder bridge can be found simply by peeling off the insulating protection sheet after the completion of soldering.

By providing positioning pins on the back surface of the printed circuit board and forming positioning pin holes corresponding to the positioning pins on the insulating protection sheet, positioning when the insulating protection sheet is brought into close contact with the back surface of the printed circuit board becomes easy.

By making the lead terminal holes formed in the insulating protection sheet slightly larger than the diameter of the corresponding lead terminals on the printed circuit board, dip soldering can be performed reliably.

〔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 can be generally applied to all electronic components having lead terminals.

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

The printed circuit board 11 on which the IC socket 13 is mounted is immersed in a dip solder bath (not shown) so that the back surface is immersed,
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 a polyester or polyimide-based electrically insulating material in consideration of, for example, heat resistance against the temperature of the solder bath. The thickness t is as thin as possible in consideration of the strength and the like, and is preferably, for example, about 0.1 to 0.2 mm.

The insulating protection sheet 21 has lead terminal holes 25 corresponding to the lead terminals 15 of the IC socket 13, and the lead terminals 15 are inserted into these lead terminal holes 25 on the solder-side surface (back surface) of the printed circuit board 11. It is pushed to the root so that it may adhere.

Attachment of the insulating protection sheet 21 to the printed circuit board 11
Either after the IC socket 13 is mounted on the printed circuit board 11 or before mounting. After the mounting, the lead terminal holes 25 of the insulating protection sheet 21 are inserted into the lead terminals 15 protruding from the back surface of the printed circuit board 11, and conversely, before mounting, the back surface of the printed circuit board 11 is inserted. Printed circuit board in the lead terminal hole 25 of the insulating protection sheet 21 attached to the
11 lead terminals 15 will be inserted.

Preferably, positioning pins 16 are formed on, for example, two diagonal positions on the back surface of the printed circuit board 11, and correspondingly, positioning pin holes 26 are formed on the insulating protection sheet 21 at corresponding positions. Therefore, by matching the positioning pins 16 with the positioning pin holes 26, the insulating protection sheet 21 can be reliably positioned.

Preferably, the diameter D of the lead terminal hole 25 of the insulating protection sheet 21 is slightly smaller than the diameter of the corresponding lead terminal 15, for example, 0.2 mm.
~ 0.3mm larger. By doing so, as shown in FIG. 3, the solder A can flow into the lead terminal 15 satisfactorily, realizing a reliable solder fixing.

When the soldering operation is completed, the insulating protection sheet 21 is peeled downward in FIG. At this time, if the solder bridge S is generated, the insulating protection sheet 21 and the lead terminals 15 are stuck together at that portion, so that the insulating protection sheet 21 cannot be peeled off smoothly. As a result, the solder bridge S can be easily found. In most cases, the solder bridge S can be visually inspected, but the operator can surely find the solder bridge S with a feeling of "snag" when peeling off without relying on visual observation.

The insulating protection sheet 21 may be prepared according to the type of electronic component to be mounted (the arrangement of the lead terminals and the like).

〔The invention's effect〕

As described above, according to the present invention, an insulation protection sheet formed with a number of lead terminal holes corresponding to lead terminals is brought into close contact with the back surface of a printed circuit board, and the insulation protection sheet is peeled off after completion of soldering. Can be easily detected.

In addition, by providing positioning pins on the back surface of the printed circuit board and forming positioning pin holes corresponding to the positioning pins on the insulating protection sheet, positioning when the insulating protection sheet is closely attached to the back surface of the printed circuit board can be easily performed. .

[Brief description of the drawings]

FIG. 1 is a side sectional view of a solder bridge detecting apparatus according to one embodiment of the present invention, FIG. 2 is a plan view of the insulating protective sheet shown in FIG. 1 (also showing the positions of lead terminals), and FIG.
The figure is an enlarged sectional view of a main part of FIG. 11 Printed circuit board, 13 IC socket, 15 lead terminals, 16 positioning pins, 21 insulating protection sheet, 25 lead terminal holes.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H05K 3 / 34,3 / 32 H05K 1 / 16,1 / 18

Claims (4)

(57) [Claims] 1. A printed circuit board (11) on which an electronic component (13) having a plurality of lead terminals (15) is mounted 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. At this time, the insulation protection sheet (2) with many lead terminal holes (25) corresponding to the lead terminals
A method for detecting a solder bridge, comprising the steps of: (1) contacting the back surface of a printed circuit board with a printed circuit board and peeling off the insulating protection sheet after soldering to detect a solder bridge portion. 2. A dip for immersing a printed circuit board (11) on which an electronic component (13) having a plurality of lead terminals (15) is mounted in a solder bath and fixing the lead terminals protruding from the back surface to the printed circuit board by soldering. In the soldering device, the solder bridge detecting device has an insulating protection sheet (21) formed with a number of lead terminal holes (25) corresponding to the lead terminals, and the insulating protection sheet inserts the lead terminals into the corresponding lead terminal holes. A solder bridge detecting device, wherein the device is brought into close contact with the back surface of a printed circuit board. 3. The printed circuit board has at least one positioning pin (16) projecting therefrom, and a positioning pin hole (26) corresponding to the positioning pin formed on the insulating protection sheet. An apparatus for detecting a solder bridge according to claim 2. 4. The solder bridge detecting device according to claim 2, wherein the lead terminal hole formed in the insulating protection sheet is slightly larger than the diameter of the corresponding lead terminal on the printed circuit board.