JPH0737332Y2 - Printed board - Google Patents

Description

[Detailed Description of the Invention] [Outline] A printed circuit board having a discard pattern for solder attachment that is independent of a wiring pattern, and prevents unstable solder attachment to a member exposed on the soldering surface and having weak solder attachment force. The purpose is to form a wiring pattern on an insulating substrate and solder part of the circuit component to the component land connected to the pattern. The wiring is provided with a discarding pattern for attaching solder around a positioning hole into which a positioning member having a weak solder adhesion force for positioning the component exposed on the mounting surface is inserted, or around the soldering surface side of a substrate end portion. The pattern is formed independently of the pattern.

[Industrial application field]

The present invention relates to a printed circuit board having a soldering discard pattern independent of a wiring pattern.

When soldering a printed circuit board to a printed circuit board, dipping using a solder bath is generally used, so not only the component land of the circuit board and the lead parts of the circuit component are melted during this soldering, but also the parts that do not need to be melted. Contact with solder. There is no problem if this unsoldered part is a material that can be metallized with solder, or a material that does not attach solder at all,
If a material such as aluminum that adheres solder halfway (no metal compound) adheres to the surface with a weak bonding force, the mass of solder adheres to it, causing it to drop due to subsequent vibrations, etc., causing a short-circuit accident. .

[Conventional technology]

FIG. 4 is an example of a conventional printed circuit board, (a) is a side view and (b) is a partially enlarged view thereof. In the figure, 10 is a printed circuit board, on the surface of which various circuit components are mounted.
20 is one of them, which is a heat-generating circuit component (for example, a power transistor). 30 is a heat sink and 31 is the fixing screw. The circuit component 20 is mounted on this heat sink 30 and leads
21 is soldered on the lower surface of the substrate 10. Wiring patterns and component lands are formed on this surface, but they are omitted in the drawing.

Numeral 11 is a through hole for positioning which penetrates through the substrate 10, into which the positioning portion 32 of the heat dissipation plate 30 is inserted for positioning. Since soldering is performed by dipping the lower surface of the substrate 10 into a solder bath, the solder 40 adheres not only to the leads 21 but also to the periphery of the tip of the screw 31. There is no problem because all of these are metal compounds.
However, since the tip of the positioning portion 32 of the heat dissipation plate 30 (generally an aluminum material) also contacts the solder liquid surface, the solder attached at the time of pulling is solidified into a ball-shaped solder mass 41.

[Problems to be solved by the device]

Since the solder mass 41 described above has a weak adhesive force, it is likely to drop due to vibration, and if it contacts a part of the wiring pattern, it causes a short circuit accident. It is difficult to inspect each of the mass-produced printed circuit boards 10 for the presence or absence of such a solder mass 41.

Masking with a tape or the like is generally effective to prevent solder from being attached to the positioning portion 32 at all, but the masking method has a drawback that the number of steps increases.

Contrary to the idea of masking described above, the present invention forms a discard pattern having a strong solder adhesive force in the vicinity of a portion having a weak solder adhesive force, and firmly adheres the solder to the pattern, thereby forming an unstable solder mass. It is intended to prevent the occurrence.

[Means for Solving the Problems]

FIG. 1 is a principle view of the present invention. 10 is a printed circuit board, 11 is a through hole for positioning, 12 is a discard pattern, 32 is a member having a weak solder adhesion force (for example, the above-mentioned positioning portion), and 40 is solder. .

In (a), the discard pattern 12 is an annular plane pattern. On the other hand, (c) is a through pattern of the discard pattern 12. (B) is an intermediate of these, and has both a plane pattern and a semi-cylindrical pattern.
Such a discard pattern is formed by copper plating or the like and is formed in the same process as the wiring pattern or the like.

[Action]

If the positioning portion 32 is short as shown in FIG. 1 (a), the solder 40 adheres to the planar waste pattern 12 to form a fillet. Therefore, solder balls or the like do not adhere to the positioning portion 32. However, if the diameter of the through hole 11 is large, a through hole is formed in the central portion of the solder 40, leaving a possibility that solder balls or the like will adhere to the positioning portion 32. In this case, the solder 40 is attached to the semi-cylindrical portion of the discarding pattern 12 as shown in (b) to prevent the solder from attaching to the positioning portion 32. If this semi-cylindrical portion is not easy to manufacture, if the discard pattern 12 is made into a through hole as shown in (c), it can be formed simultaneously with the original through hole connected to the wiring pattern, and the positioning portion 32 is long. Also, the solder 40 can be reliably attached.

〔Example〕

FIG. 2 is a block diagram showing an embodiment of the present invention, which is an example of the through-hole type shown in FIG. 1 (c). Reference numeral 32 is a positioning portion of the heat sink 30. Since the inner wall surface of the positioning through hole 11 of the printed circuit board 10 is covered with a through-hole-shaped waste pattern, the solder 40 is sucked up to the inside of the through hole 11 as shown in FIG. To cover and to solidify. Since the adhesive force of the solder 40 is mainly due to metal compounding with the discard pattern 12, the solder 40 firmly adheres and is not easily separated.

FIG. 3 shows another embodiment of the present invention using a planar discard pattern. When the positioning portion 32 of the heat dissipation plate 30 made of sheet metal is bent and fixed on the lower surface of the substrate 10 as shown in the drawing, molten solder is often scooped by the positioning portion 32 to form an unstable solder mass. In this example, the solder is attached to the discard pattern 12 formed in the vicinity of the positioning portion 32 to prevent the generation of this kind of solder lump.

(A) is a positioning part in a through hole formed in a part of the substrate 10.
This is an example in which 32 is inserted and bent, and (b) is an example in which the positioning portion 32 is applied to the end of the substrate 10 and bent. In the case of the end part, a square discard pattern 12 may be used as shown in (c),
In the case of a through hole, the discard pattern 12 is formed in an annular shape as shown in (d).

[Effect of device]

As described above, according to the present invention, it is possible to prevent unstable solder adhesion to a portion having a weak solder adhesion. Therefore, it is possible to prevent a short-circuit accident or the like due to the dropping of the solder balls or the like. Moreover, since the discard pattern for this can be formed in the same process as the wiring pattern and the land, there is an advantage that no special manufacturing process or working process is required.

[Brief description of drawings]

1 is a principle diagram of the present invention, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a configuration diagram showing another embodiment of the present invention, and FIG. 4 is a conventional printed circuit board. It is a block diagram. In the figure, 10 is a printed circuit board, 12 is a discard pattern, 32 is a positioning portion (a member having a weak soldering force), and 40 is solder.

Claims (1)

[Scope of utility model registration request] 1. A printed circuit board in which a wiring pattern is formed on an insulative substrate and a part of a circuit component is soldered to a component land connected to the pattern, the solder protruding from the component mounted on the substrate. Attach solder (40) around the soldering surface side of the positioning hole or the end of the board where the positioning member (32) with weak solder adhesion for positioning the component exposed on the soldering surface is inserted. A printed circuit board, characterized in that the discarded pattern (12) is formed independently of the wiring pattern.