JPH067274U - Printed board - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the formation of solder bridges between the heat dissipation terminals and the lead terminals during solder dipping. [Structure] A plurality of conductive protrusions or protrusions are formed on a heat dissipation terminal land for soldering a heat dissipation terminal of an electronic component to a printed circuit board. When the electronic component separates from the molten solder layer, the molten solder that adheres to the heat dissipation terminal is guided to and moves in the direction of the multiple conductive protrusions or protrusions provided on the heat dissipation terminal land, and The amount of molten solder that adheres is reduced, and as a result, it is possible to prevent a solder bridge that occurs between the heat dissipation terminal portion and the lead terminal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a printed circuit board to which an electronic component such as an IC having a heat dissipation terminal portion near a lead terminal is soldered by a dip method.

[0002]

[Prior art]

 There is a dip method as a method for soldering electronic components to a printed circuit board. As is well known, this dip method involves mounting a plurality of electronic components on one or both sides of a printed circuit board, transporting the printed circuit board in a substantially horizontal state in this state, and immersing the one side in the surface of the molten metal , The lead terminals of electronic components are soldered to the conductive patterns on the printed circuit board. According to this method, a large number of electronic components mounted on the printed circuit board can be soldered at one time, which saves time and costs.

[0003]

[Problems to be solved by the device]

 In the above-mentioned dip method, the printed circuit board is transported almost horizontally and one surface of the printed circuit board is immersed in the surface of the molten solder layer.Therefore, when the printed circuit board separates from the solder layer, the lead terminals of the electronic components mounted on the printed circuit board are removed. Solder that adheres to the solder will separate from the molten solder layer. At this time, in some cases, the rear end of the adhered solder may flow and adhere to the rear lead terminal, which may cause a so-called solder bridge. This solder bridge is more likely to occur as the lead terminal spacing (pitch) is narrower.

By the way, when a completed printed circuit board is incorporated into an apparatus for use, a large amount of heat is generated in an electronic component provided with a heat dissipation terminal portion 12 as shown in FIG. Since the heat release terminal portion 12 is generally provided at the center of the main body of the electronic component 1, it is arranged between the lead terminals 11.

FIG. 6 shows a state in which such an electronic component 1 is placed on the printed circuit board 2 and shows a state before the soldering process is performed. In this figure, the lead terminal lands 21 and the heat radiating terminal land 22 are provided on the printed board 2 in correspondence with the mounting positions H 1 of the lead terminals 11 and the heat radiating terminal portion 12 of the electronic component 1, respectively. ing.

Each lead terminal land 21 is for soldering the electronic component 1 to the printed circuit board 2, and a portion other than the land 21, that is, a portion indicated by a broken line of the conductive pattern 20 is coated with a resist. ing. The electronic component 1 is electrically connected to the printed board 2 via the land 21.

The heat-dissipating terminal portion land 22 is for soldering the heat-dissipating terminal portion 12 of the electronic component 1 onto the printed board 2, and has an appropriate land area for improving the heat-dissipating effect. However, a resist is applied to the other part shown by the broken line, and it is connected to, for example, an earth pattern. In the state before the soldering process shown in FIG. 6, the electronic component 1 is temporarily fixed to the printed board 2 with an adhesive or the like.

In this state, when the electronic component 1 is soldered to the printed board 2 by the dip method, a large amount of solder adheres to the heat dissipation terminal portion 12 having a larger area than the lead terminal 11. When this separates from the molten solder layer, it flows backward with respect to the conveyance direction of the printed circuit board 2 and adheres to the lead terminal 11 at the rear, so that a solder bridge often occurs. When such a solder bridge occurs, the heat radiating terminal portion 12 and the lead terminal 11 are short-circuited, and the electronic component 1 may be damaged in some cases.

In view of the above, the present invention solves the above-described problems, and in a printed board to which an electronic component having a heat dissipation terminal near a lead terminal is soldered by a dip method, We propose a printed circuit board that can prevent solder bridging between lead terminals.

[0010]

[Means for Solving the Problems]

 In order to solve the above-mentioned problems, in the present invention, in a printed circuit board to which an electronic component having a heat dissipation terminal portion near a lead terminal is soldered by a dip method, the heat dissipation terminal portion of the electronic component is soldered to the printed circuit board. A plurality of conductive protrusions or protrusions are provided on the land for the heat dissipation terminal portion.

[0011]

[Action]

 1 to 3, when the electronic component 1 is separated from the molten solder layer, the molten solder adhered to the heat dissipation terminal portion 12 has a plurality of conductive protrusions 23, 24 or convex portions provided on the heat dissipation terminal portion land 22. By being guided and moved in the arrangement direction of 25, the amount of molten solder adhering to the heat dissipation terminal portion 12 is reduced, and as a result, the solder bridge generated between the heat dissipation terminal portion 12 and the lead terminal 11 is prevented. It becomes possible to do.

[0012]

【Example】

 Next, an embodiment of the printed circuit board according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a first embodiment of a printed circuit board according to the present invention. As shown in FIG. 2A, the heat dissipation terminal land 22 of the printed circuit board 2 is formed so as to cross the heat dissipation terminal land 22 substantially in parallel with the lead terminals 11 and the heat dissipation terminal 12 of the electronic component 1. A number of lead-shaped projections 23 are planted. The height h of the lead-shaped protrusion 23 is set to be at least higher than the thickness t of the heat dissipation terminal portion 12, as shown in FIG. It should be noted that the conductive pattern portion of the portion where the resist is applied is omitted in the drawing.

In this printed circuit board 2, since a plurality of lead-shaped projections 23 are provided on the heat dissipation terminal portion land 22, when the printed circuit board 2 is separated from the molten solder layer during solder dipping, the heat dissipation terminal portion 12 is exposed. Since the adhered solder is guided and moves to the side of the plurality of lead-shaped protrusions 23 that are erected on the heat dissipation terminal land 22, the amount of solder adhered to the heat dissipation terminal 12 is reduced. Therefore, the amount of solder flowing from the heat radiating terminal portion 12 to the rear lead terminal 11 is reduced, and it is possible to prevent the generation of a bridge between the heat radiating terminal portion 12 and the lead terminal 11.

FIG. 2 shows a second embodiment. Conductive needle-like protrusions 24 are provided on the radiating terminal land 22 of the printed circuit board 2. It should be noted that the conductive pattern portion of the resisted portion is omitted in the drawing as in FIG.

FIG. 3 shows a third embodiment. A large number of conductive protrusions 25 are provided on the heat dissipation terminal land 22 of the printed circuit board 2. The conductive pattern portion of the resisted portion is omitted in the drawing.

FIG. 4 shows a third embodiment. The radiating terminal portion land 22 of the printed circuit board 2 is provided with a conductive rectangular parallelepiped body 26 connected to the radiating terminal portion 12 in a direction orthogonal to the dip direction indicated by the arrow of the printed circuit board 2. .

In each of the embodiments shown in FIGS. 2 to 4, as in the first embodiment shown in FIG. 1 described above, the conductive needle-like protrusions 24 and the protrusions 25 are formed on the radiating terminal land 22. Since the rectangular parallelepiped 26 is provided, the solder adhering to the heat radiating terminal portion 12 is guided and moved to the conductive needle-like projections 24 or the convex portions 25. Is reduced. Therefore, the amount of solder flowing from the heat radiating terminal portion 12 to the rear lead terminal 11 is reduced, and it is possible to prevent the generation of a solder bridge between the heat radiating terminal portion 12 and the lead terminal 11.

The present invention is not limited to the above-described embodiment, and in short, a plurality of conductive protrusions or projections are formed on the land for the heat radiating terminal as a means for reducing the amount of molten solder attached to the heat radiating terminal. Etc. should be provided.

[0020]

[Effect of device]

 As described above, the present invention provides a plurality of conductive protrusions or projections on the land for the heat dissipation terminal. Therefore, according to the present invention, the solder adhered to the heat dissipation terminal is moved by being guided by the conductive protrusions or the protrusions, so that the amount of solder adhered to the heat dissipation terminal is reduced, which allows the heat dissipation terminal and the lead terminal to be soldered. It is possible to prevent solder bridging that occurs during this period.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a first embodiment of a printed circuit board according to the present invention.

FIG. 2 is an explanatory view illustrating a second embodiment of the printed circuit board according to the present invention.

FIG. 3 is an explanatory view illustrating a third embodiment of the printed circuit board according to the present invention.

FIG. 4 is an explanatory view illustrating a fourth embodiment of the printed circuit board according to the present invention.

FIG. 5 is an explanatory diagram illustrating an electronic component in a conventional example.

FIG. 6 is an explanatory diagram illustrating a state in which an electronic component is temporarily fixed to a printed circuit board in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic component 2 Printed circuit board 11 Lead terminal 12 Heat dissipation terminal portion 20 Conductive pattern 21 Lead terminal land 22 Heat dissipation terminal portion land 23 Lead-like protrusion 24 Conductive protrusion 25 Conductive convex portion

Claims (2)

[Scope of utility model registration request] 1. A printed circuit board to which an electronic component having a heat radiating terminal portion near a lead terminal is soldered by a dip method, for a heat radiating terminal portion for soldering the heat radiating terminal portion of the electronic component to the printed circuit board. A printed circuit board having conductive protrusions or projections on the land. 2. The printed circuit board according to claim 1, wherein the conductive protrusions or protrusions are at least thicker than the lead terminals and the heat dissipation terminal portions.