JPS5841679B2 - How to mount components on a multilayer wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for mounting electronic components on a multilayer wiring board, and particularly to a method for mounting components having a plurality of series of flat leads.

Conventionally, when mounting an electronic component 2 having a large number of leads such as an LSI on a multilayer wiring board and having flat leads 1 arranged in multiple series as shown in FIG. 1, each lead is positioned on a pad coated with solder in advance. A so-called reflow bonding method is generally used, in which the heating chip is pressed against the leads to melt the solder on the pads and bond the pads together after they are placed together.

In this case, each side is normally bonded sequentially using a single heating chip, which takes a long time, and since the pressing and solder melting processes are performed at the same time, the leads may shift from the pads, resulting in short circuits or poor connections between the leads. This may cause problems.

The present invention has been devised to improve this second problem.

For this reason, in the present invention, when an electronic component having a plurality of flat leads is mounted on a multilayer wiring board, the leads on each side of the electronic component are connected to each other by a plurality of heating chips corresponding to each side in a multilayer wiring board. It is characterized in that it is pressed against a pad on a wiring board, and a control circuit is attached to control the supply of electricity to each heating chip, and the heating chips are successively energized and heated, and the leads on each side are joined to the pads in sequence. It is something.

Embodiments of the present invention will be described in detail below based on the accompanying drawings.

In FIG. 2, 2 is an electronic component having flanges on its four sides, and 1 is its lead.

Reference numerals 3 to 6 are heating chips that can each operate independently, and FIG. 3 shows a perspective view of one example.

The heating chips 3 to 6 are configured so that when current is applied from terminal A to B, the lower surface γ generates heat and melts the solder.

Such heating chips 3 to 6 are provided corresponding to the leads on each side of the electronic component 2, and are connected to the control circuit 9 by lead wires 8, respectively.

Further, a power source 10 is connected to the control circuit 9.

Next, a procedure for mounting electronic components using the apparatus configured as described above will be described.

First, the leads 1 of the electronic component 2 are placed on pads at predetermined positions on a multilayer wiring board, and the electronic component 2 is pressed by each of the heating chips 3 to 6.

Next, the control circuit 9 supplies power to the first heating chip, for example chip 3, causing the chip 3 to generate heat and melting the solder previously coated on the pads, and then the supply of power is stopped.

Next, the second heating chip, for example, chip 4, is energized to melt the solder on the pad corresponding to this chip, and then the energization is stopped, and the next third heating chip, for example, chip 5, is energized.

By sequentially supplying current to each separate thermal chip in this manner, the leads on each side can be sequentially joined to pads.

As explained above, the method of the present invention improves work efficiency because it does not require the trouble of moving the chips, which is required when the leads on each side are successively joined by two heating chips, as in the conventional method.

In addition, by sequentially operating multiple heating chips,
The non-operating chip presses and fixes the leads, thereby preventing the pads and the leads from being misaligned.

Note that when a plurality of heating chips are energized at the same time, the elements of the electronic component may be damaged due to leakage current between the chips, but this risk is eliminated by the method of the present invention in which energization is sequentially applied.

[Brief explanation of the drawing]

Figure 1 shows an electronic component with multiple flat leads.
FIG. 2 is an explanatory diagram of a method of mounting electronic components on a multilayer wiring board according to an embodiment of the present invention, and FIG. 3 is a perspective view of an example of a heating chip. 1...Flat lead, 2...Electronic component, 3-6...Heating chip, 9...
control circuit.

Claims (1)

[Claims] 1 When mounting an electronic component having multiple series of flat leads on a multilayer wiring board, the leads on each side of the electronic component are pressed against the pads on the multilayer wiring board by a plurality of heating chips corresponding to each side. A component for a multilayer wiring board, characterized in that the heating chips are heated in sequence through a control circuit that controls energization to each heating chip, and the leads on each side are sequentially bonded to pads. How to implement.