JPH0427183Y2 - - Google Patents

Description

[Detailed explanation of the invention] [Industrial application field] This invention is related to the mounting board for circuit components.
In particular, the present invention relates to a mounting board suitable for mounting a surface-mounted circuit component having a plurality of connection terminals formed on two orthogonal side surfaces.

[Summary of the idea]

When attaching a surface-mount type circuit component having a plurality of connection terminals on at least two orthogonal sides to a board, opposing corners of adjacent lands in a portion orthogonal to the connection terminals are cut diagonally, A circuit component mounting board that can prevent bridging from occurring when the surface-mounted circuit component is mounted on the board.

[Conventional technology]

2. Description of the Related Art Recently, the shapes of various circuit components attached to wiring boards are becoming smaller and the number of connection terminals of circuit components is increasing as electronic devices become smaller and more dense.

As a result, the pitch of connection terminals drawn out from circuit components has become shorter, and circuit components without lead terminals have come into widespread use.

For example, in a circuit component (MSP) as shown in Fig. 4a, the connection terminal pulled out from the package P is a short plate-shaped lead frame F, and in the case of Fig. 4b, The tip of this lead frame F is curved inward to further reduce the size. (PLCC type) Also, the one shown in Figure 4c has multiple electrode parts C as connection terminals on the side of the ceramic package.
is formed, and is designed to be directly soldered and attached to the land of the wiring board corresponding to this electrode portion C. (LCC type) The above-mentioned circuit components are generally called surface-mount circuit components, and these surface-mount circuit components are soldered directly to lands formed in the pattern of a wiring board without lead holes. will be attached.

FIG. 5 shows an example of the wiring pattern for installing such surface-mounted circuit components, and the dash-dotted line L
is the area occupied by surface-mounted circuit components, R...,
R _C ... indicates a pattern of lands formed on the substrate.

After the surface mount type circuit components are temporarily fixed with an adhesive or the like on the board B on which the lands R..., R _C ... of such a wiring pattern are formed, the circuit components shown in FIG.
As shown in b, soldering S using cream solder or soldering S using a solder dip tank is applied.

[Problem that the invention attempts to solve]

However, as mentioned above, the spacing between the connection terminals in surface-mounted circuit components is extremely narrow, and for example, if the mounting circuit component is slightly deviated as shown by the two-dot chain line L' in FIG. Due to the misalignment of the land pattern and the connection terminal, bridging occurs between adjacent lands during soldering.

It has been found that such bridges occur frequently, especially in adjacent lands R _C and R _C located at orthogonal positions of the land patterns, causing failures of electronic equipment and deterioration of manufacturing yield.

This invention provides a mounting board for circuit components that can alleviate such problems.

[Means for solving problems]

When mounting a circuit component having a plurality of connection terminals formed on at least orthogonal sides to the mounting board of the present invention, the adjacent lands at the corners of the land pattern formed on the board are The shape is cut diagonally.

[Effect]

Solder failures (bridges) caused by positional errors of mounted circuit components are often caused at corner portions of orthogonal sides, but the land pattern of the mounting board of this invention is Since the facing corners are cut diagonally, the facing distance of these parts is relatively widened, and the occurrence of bridging can be prevented.

〔Example〕

FIG. 1 is a perspective view showing a land pattern of a mounting board showing an embodiment of the present invention, which is intended for a surface-mounted circuit component with connecting terminals drawn out in four directions.

In this figure, R indicates a land portion formed on the printed circuit board, and a chain line indicates an area occupied by a surface-mounted circuit component.

Lands R _C at orthogonal corners have their opposing corners cut diagonally. Therefore, the distance l between the lands R _C and R _C is widened by the conventional land pattern, and even if the set position of the circuit components to be mounted is slightly incorrect, soldering defects due to bridging that are likely to occur at the corner lands can be prevented. It will be possible to prevent this.

Fig. 2 is a perspective view of a land pattern showing another embodiment of the present invention, and when compared with the embodiment shown in Fig. 1, the width t of the land R _C at the corner is
It is characterized in that the width of the land R is larger than the width of the other lands R.

In this way, widening the width of the corner land R _C and cutting the opposing corners diagonally prevents the occurrence of the bridging described above and also improves the initial setting of surface-mount circuit components. When you do
The operator can easily perform temporary soldering by using the widened corner land R _C . . . .

In addition, when soldering other connection terminals after temporary soldering or temporary fixing, the distribution of excess solder is generally distributed in the central part due to surface tension, as shown by the dashed line 1 in Figure 3. The land R _C tends to gather in the center area, which is considered to be a fine pitch, and there is a risk of bridging, but the land at the corner
When R _C is formed to be wider than other lands R, the distribution of surplus solder also moves toward the left and right corners, as shown by the two-dot chain line 2 in FIG. Therefore, the excess solder at each connection terminal is evened out,
It becomes possible to prevent solder defects (templa) that tend to occur when the amount of solder is small and solder defects (bridging) that tend to occur when the amount of solder is large.

In addition, although the above-mentioned embodiment was explained with reference to a surface-mounted circuit component in which a plurality of connection terminals are drawn out in four directions, a circuit component in which a plurality of connection terminals are drawn out from at least two orthogonal sides is also applicable. It goes without saying that the same effect can be obtained by cutting diagonally the opposing corner portions of the lands formed at the corner portions of the land.

[Effect of idea]

As explained above, when soldering a plurality of connection terminals pulled out from orthogonal sides to the circuit component mounting board of the present invention, the opposing corners of the lands at the corners of the land pattern are soldered diagonally. Since the shape is cut in the direction, it is particularly effective in reducing soldering defects even in fine-pitch circuit components where the connection terminal spacing is narrow.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a land pattern formed on a circuit component mounting board of the present invention, Fig. 2 is a perspective view of a land pattern showing another embodiment of the present invention, and Fig. 3 is a distribution of surplus solder. 4A, 4B, and 4C are perspective views showing specific examples of surface mount components, FIG. 5 is a land pattern diagram of the surface mount type, and FIGS. 6A and 6B are explanatory views of soldering. In the figure, R is a land, R _C is an adjacent land, and P
indicates the circuit component package, and F indicates the lead frame (connection terminal).

Claims (1)

[Scope of utility model registration request] When soldering a surface-mount type circuit component having a plurality of connection terminals to at least two orthogonal side surfaces to a printed circuit board, the two orthogonal A circuit component mounting board characterized in that opposing corners of adjacent lands on two sides are cut diagonally.