JPS598391A - Solder plate for mounting planarly - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solder plate for planar mounting that connects terminals of a planar mounting component to a wiring board in a two-dimensional manner without using through holes.

In recent years, many methods have been adopted in which the terminals of electronic components are soldered directly to the terminal butt portions of the circuit board without using through holes, improving the packaging density. However, planar mounting, which enables high-density mounting, differs from conventional through-hole mounting in that it is necessary to apply solder to the terminal portions of the component mounting surface in advance. As a workaround, solder paste was printed on the terminals of the board using techniques such as silk screen printing, but this required a new screen printing mask, which increased costs. Even when part of the conventional through-hole mounting is realized by planar mounting, the number of steps will be significantly increased.

The present invention solves the above-mentioned problems, and provides a solder board for flat mounting for soldering flat mounted components to a board, which has a plurality of terminal parts corresponding to the terminal parts of the flat mounted parts to be connected to the terminal parts of the board. The device is characterized in that the terminal portions are connected by a narrow-diameter bridge portion.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a conventional method for soldering flat-mount components such as leadless chip carriers. Terminal portion 2 of leadless chip carrier 1 as a plane mount component
are metalized and can be used as solder connection terminals.
Ru. On the other hand, solder 4 is attached to the terminal portion 5 on the board side of the board 6 by screen printing. In this state, the leadless chip carrier 1 and the board 6 are aligned to match the corresponding terminals 2 on the carrier side and terminals 5 on the board side, and then the solder 4 is melted by reflow to make a solder connection. It is. Further, 6 is a via hole 1 connected to the terminal 5 of the substrate 3. In such a conventional method, a screen printing process is first required, which requires equipment and mask costs. Second, when modifying or repairing a package, it is impossible to partially screen print solder on the board, and using conventional methods, it is very difficult to solder after assembly.

Therefore, as shown in FIGS. 2 and 3, a solder plate 4' for planar mounting according to the present invention for soldering planar mounting components such as leadless chips or flat pack ICs to a board is as follows:
It has a plurality of terminal parts 4a' corresponding to the terminal parts 2 of the flat mount component 1 to be connected to the terminal parts 5 of the board B, and a narrow diameter bridging part 4b' is provided between the terminal parts 4a'. It is combined with . The solder plate 4' has a large amount of solder in the terminal portions 4a', and the bridge portion 4b' connecting these terminal portions 4a' is formed to have a small diameter in order to reduce the amount of solder.

By the way, in order to perform soldering using the solder plate 4' according to the present invention, the chip carrier 1 and the solder plate 4 must be placed so that the positions of the leadless chip carrier 1, the solder plate 4', and the board 3 are in a predetermined relationship. After aligning the solder plate 4' with the substrate 6, the solder plate 4' is aligned with the substrate 6, or conversely, the solder plate 4' is first aligned with the substrate 6, and then the chip plate 1 is aligned therewith. After the three parts have been accurately positioned, the solder is melted by reflow, and the chip carrier terminal part 2 and the board terminal part 5 are connected by the terminal part 4a' of the solder plate 4'. On the other hand, the bridge portion 4 of the solder plate 4'
Since the b' beam melts into a liquid state due to the flow, it is separated by the action of its surface tension and absorbed into the terminal portion 4a', and does not remain as a bridge.

FIG. 6 shows an embodiment of the solder plate 4' according to the present invention, and FIG. 3 shows a planar mounting of a component consisting of 16 4×4 terminals. The thickness of the solder plate 4 and the terminal portion 4
The outer shape YXQ of a' and the outer shape XXR of the bridge portion 4b' are particularly important for soldering characteristics. The amount of solder on the terminal portion 4a' affects the amount of solder build-up and the height control of soldering, and the soldering greatly influences the subsequent reliability.

However, the amount of solder in the bridging portion 4b' greatly affects the ease of handling the solder plate and the prevention of bridging during soldering.

In the embodiment of the present invention, a solder plate with a thickness of 0.6 mm, a pitch between terminals Z = 1.27 rug, and a chip carrier with 16 terminals are soldered, and the solder plate terminal portion 4a'
The external shape of Q = 0.9-1.0 fin, Y = 0.7-0.
The outer shape of the bridging part 4b is R = 0.5~
Good soldering characteristics were obtained by setting 0.351JINX = about 0.5 to 0.551JI.

Figures 4 and 5 compare the soldering process in flat mounting using the conventional method and the method according to the present invention. Show the process.

In FIG. 4, as shown in FIG. 4(a), paste solder 4 is first applied to a screen 8 by screen printing.
As shown in (b), the terminal portion 5 of the substrate 5 is screen printed. As shown in FIG. 4(c), a plane mount component 1 such as a chip carrier is placed on the printed paste-like solder 4 so that its terminal portion 2 rests on the solder 4, and using an appropriate flow. The solder is melted using solder 4, and the terminal portion 2 of the component and the terminal portion 5 of the board are connected with solder 4 as shown in FIG. 4(d).

On the other hand, in FIG. 5, the soldering according to the present invention is a process, and there is no screen printing process. That is, Fig. 5 (a
) is a planar mounting component 1 such as a chip carrier, and a solder plate 4.
' and the positional relationship of the substrate 3. In this diagram, part 1
The solder plate 4' is attached using flux 9, but
Alternatively, it is also possible to align the solder plate 4' with the board 6 and then install the component 1.

For positioning, use solder flanks or an adhesive that is harmless to soldering. FIG. 5(b) shows how the three parts are aligned and then soldered using a heat source A such as infrared rays or vapor. In the figure, the bridge portion 4b' of the solder plate 4' is shown in a state before it is fused away. FIG. 5(c) shows the state after soldering, in which the terminal portion 2 of the component and the terminal portion 5 of the board are connected by soldering. The bridging portion 4b' of the connecting plate 4' melts away and is absorbed by the terminal portion 4a' due to surface tension.

As described above, the solder plate according to the present invention has terminal portions corresponding to the terminal portions of the flat mount component, and the terminal portions are connected by a narrow bridge portion, so that it is suitable for screen printing. It is possible to solder and solder flat-mounted components at low cost without using necessary equipment or masks, and the amount of solder can be accurately controlled, and it can also be used for retrofitting work such as repairs. It is effective.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram of planar mounting according to the conventional method, Fig. 2 is a conceptual diagram of planar mounting according to the present invention, Fig. 6 is a configuration diagram showing an example of the solder plate according to the present invention, and Fig. 4 is a conventional method. FIG. 5 is a diagram showing the process of one embodiment of the planar mounting according to the present invention. 1... Leadless chip carrier (plane mount component) 2
...Terminal part 3 of leadless chip carrier (plane mount component)... Board 4'... Ender board 4a'
...Terminal part 4b' of solder board...Bridging part of solder board Patent applicant NEC Corporation Representative Patent attorney Naka Kanno:j]・I゛,',
,,n,,,,・Figure 3 X5

Claims (1)

[Claims] +1+ Leadless chip or flat pack IC
A solder board for flat mounting, which is used to solder flat mounted components such as A solder plate for flat surface mounting characterized by being joined at a bridge portion.