JPH0550776U - Printed wiring board - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a printed wiring board that can be easily visually checked by an operator and can be easily checked for a soldering connection without introducing an expensive device. [Structure] QFP (quad flat patch)
In addition to the wiring land on the printed wiring board corresponding to the terminal of e), a similar land not corresponding to the terminal is additionally provided in the vicinity thereof.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a printed wiring board, and more particularly to soldering of surface mount components on the printed wiring board.

[0002]

[Prior Art]

 In the conventional soldering of this type of printed wiring board, for example, a land suitable for a gull wing type terminal of a QFP (quad flat package) is provided on the printed wiring board side, and the land is coated with solder in advance or a cream is applied. After applying solder, the QFP was mounted, and then soldering was performed all at once by means of reflow.

Further, as a means for confirming the soldering of terminals, after reflow, a method such as visual confirmation by a microscope or confirmation of a difference in reflectance by a CCD camera is adopted, and the quality is judged by confirming the fillet shape of the terminal edge. Was there.

[0004]

[Problems to be solved by the device]

 Therefore, the above-mentioned conventional means have drawbacks such as a reduction in work efficiency due to operator fatigue due to inspection check by a microscope and the introduction of expensive equipment.

The object of the present invention is to eliminate the drawbacks of the prior art, to make it easy for the operator to visually check, and to easily check the soldered connection without the need for introducing expensive equipment. To provide a plate.

[0006]

[Means for Solving the Problems]

 In order to solve this problem, in the printed wiring board of the present invention, in addition to the wiring lands on the printed wiring board corresponding to the terminals of the QFP, similar lands not corresponding to the terminals are additionally provided in the vicinity thereof. It has the following structure.

[0007]

[Action]

 If such a printed wiring board is used, the solder on the land on which the QFP terminal is mounted will be consumed for forming the fillet if the soldering connection of the QFP terminal is good at the time of reflow, and on the remaining land. While the solder of No. 3 is thin and flat, the solder on the added land without the Q FP terminal retains its shape after reflow, and the surface remains convex due to the surface tension of the solder. Further, when the solder connection of the QFP terminal is not good, it is not consumed for forming the fillet, so that it remains convex due to the surface tension of the solder. Therefore, there is an advantage that these differences can be confirmed on the same pattern, and the appearance can be easily confirmed by the relative comparison, and that the means does not require a special device.

[0008]

【Example】

 FIG. 1 is an embodiment according to the present invention, in which 1 is a land surface to which terminals are connected, 2 is an additional land surface that does not correspond to a terminal position, and 3 is connected to a sealing portion 4 such as QFP. It is a gull-wing shaped terminal.

FIG. 2 is a structural cross-sectional view taken along the line AA ′ in FIG. 1. Reference numerals 1a and 1b are portions for forming solder fillets with the terminals 3 on the land surface connected to the terminals. Here, 1'is a copper foil land that serves as an underlayer for the surface of the land to which the above-mentioned terminal is connected, and 5 is a base material of the printed wiring board.

FIG. 3 is a structural cross-sectional view of the BB ′ surface of FIG. 1, and 1 ′ and 2 ′ are copper foils that are the bases of the land surface 1 and the land surface 2, respectively.

In such a structure, the land surfaces 1 and 2 are soldered at the stage of the printed wiring board, for example, by a super solder method or a normal solder precoating method. Is generally. After applying a flux (not shown) on this printed wiring board, mount the surface mount component 4 having the gull wing-shaped terminal 3 such as QFP, and apply heat above the solder melting temperature by the reflow process. As a result, the solder is melted and the galling-shaped terminal 3 is connected by soldering. In such soldering, in the portion where the soldering connection with the terminal 3 is good, the shape of the fillet such as the above-mentioned portions 1a and 1b is performed around the terminal 3, so that a large amount of solder is applied there. As a result, the remaining portion of the solder becomes thinner and flatter.

On the other hand, in the portion where the terminal 3 is not mounted, the external appearance of the solder at the pretreatment stage is maintained as in the above-mentioned added land surface 2. Further, if the soldering of the terminal 3 is not good, the fillet such as the portions 1a and 1b is not formed, and as a result, the shape like the surface 2 is maintained.

Therefore, the surface shape of the portion other than the terminal 3 differs depending on the quality of the solder connection, and the quality of the soldering can be easily determined. That is, even if all the soldering is good, the appearance of the terminal without the terminals can be visually recognized at least in the vicinity thereof, so that the operator can easily judge the quality by the relative comparison.

In the present embodiment, an example in which it is provided outside the terminals of the surface mount component is shown, but it is not necessary to limit the position to anything, and it may be used in the middle portion, and the number thereof is also limited. Clearly not. Further, it is clear that the land surfaces 1 and 2 have a similar effect not only by the solder precoating process but also by applying so-called cream solder.

FIG. 4 is a conceptual diagram showing an example of the quality confirmation of soldering on a printed wiring board according to the present invention, 6 is a light control film as one embodiment according to the present invention, and 7 is the above-mentioned. Reflected light from the fillet portion 1a and the surface 2 of the additional land, and 8 is transmitted light that has passed through the light control film 6. In such a configuration, of the reflected light 7, the reflected light is scattered from the fillet portion 1a in the direction perpendicular to the paper surface, but when the light control film 6 has the configuration shown in the figure, the transmitted light is large, while the additional land surface Since the reflected light from 2 is scattered along the paper surface as shown in the figure, the amount of light transmitted through the light control film 6 is greatly reduced, and the transmitted light is small. When this is visually inspected, the part where the fillet is formed is bright, and the part where the additional land and the fillet are not formed is dark.

[0016]

[Effect of the device]

 As described above, according to the present invention, the quality of the solder connection can be easily visually determined by simply adding a land to the printed wiring board, so that the operator is not tired and an expensive device is required. There is an advantage in providing a method of verifying soldered connections.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment according to the present invention.

FIG. 2 is a sectional view taken along the line AA ′ in FIG.

3 is a sectional view taken along line BB ′ of FIG.

FIG. 4 is a schematic view showing a situation of quality judgment of soldering of a printed wiring board according to the present invention.

[Explanation of symbols]

 1 land surface connected to terminals 1a, 1b parts forming solder fillet 1 ', 2'copper foil 2 added land surface 3 terminals 4 encapsulation part (surface mount component) 5 base material of printed wiring board 6 light control Film 7 Reflected light 8 Transmitted light

Claims (1)

[Scope of utility model registration request] 1. In order to easily confirm the connection after soldering a surface-mounted component having a gull-wing terminal shape on a printed wiring board, in the vicinity of a wiring land corresponding to the position of the gull-wing. A printed wiring board, wherein an additional land similar to the wiring land is provided at a position where there is no lead of the surface mount component.