JPS6030195A - Method of connecting lead - 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 [Technical Field] The present invention relates to a single-layer or multi-layer wiring board on which wiring conductors are patterned [solder used in outer lead bonding of a tape carrier device using a reflow method]. This relates to a lead connection method.

<Prior art> About the basic structure of bonding the outer leads of electronic components such as circuit elements onto a component mounting board having wiring conductors g! ;Explained with Figure 1.

The inner lead-bonded tape carrier device 1 is cut from the conveying tape in the seventh state with the outer leads 2 attached to form an outer lead.

2 is formed (molded) to form a bonding portion at the end of the outer lead 2 that is substantially flush with the bottom surface (mounting surface) of the tape carrier device l. Next, a bonding punt 4 forming a part of the wiring conductor on the wiring board 3
The tape carrier device 1 is mounted on the wiring board 3 by bonding the two with the bonding portions of the outer leads 2 facing each other on the upper side. Outer lead bonding of the tape carrier device is thus performed. In addition, the reflow one-way method means that when performing outer lead bonding, a solder paste containing a solder material and a solvent is layered in a divided area where band-shaped bonding panods 4 are arranged in parallel, and this solder paste is heated in a heating furnace. Alternatively, by melting the solder with infrared irradiation and evaporating the solvent, the solder can be focused by surface tension onto each bonding pad 4 of a metal film with affinity, and the bonding pad can be bonded without using a bonding tool. 4 and a plurality of outer leads 2 facing the outer leads 2 are connected simultaneously. This reflow one-type method has the following advantages: (1) Solder can be easily applied using a printing method, and (2) Outer leads 2 are automatically and accurately placed on each honting pad 4 due to the self-alignment effect caused by the surface tension of the solder. (3) It is possible to bond a large number of devices at the same time.
This is a very useful technology for mounting various circuit elements such as C and LSI on wiring boards.

However, as shown in FIG. 2, if each of the seven minks of a plurality of outer leads 2 arranged in a row exhibits uneven distribution in the vertical direction, the outer leads 2 will not be pressed by a bonding tool or the like. Since the outer lead 2 is bonded onto the bonding pad 4, the outer lead 2 and the solder paste 5 on the bonding pad 4 cannot come into contact with each other, resulting in an open failure. significantly reduces production yield.

<Object of the Invention> In view of the above-mentioned problems, the present invention provides a new and useful lead connection for a component mounting board that can reliably perform outer lead bonding of a tape carrier device that uses a reflow one-way method without causing open defects. The purpose is to provide a method.

<Embodiment> FIG. 3 is a configuration diagram of a lead bonding section explaining one embodiment of the present invention. FIG. ) shows the state after the tape carrier device 1 is pressed by the device holding tool 7.

A metal lead 2 bonded to an external connection electrode of a tape carrier device 1 such as a transistor, a resistor element, an integrated circuit element, etc. is bent on the outside of the tape carrier device 1, and a substrate 3 of metal or ceramic is formed. The tape carrier device 1 is mounted on the substrate 3 and electrically connected to the conductive trace by being adhered to the bonding pad 4 of the conductive trace patterned thereon.

The bonding portion of the outer lead 2 contacts the ponting pad 4 several tens of microns below the bottom surface (mounting surface) of the tape carrier device 1 (i.e., d = several tens of microns).
The surface on which the tape carrier device 1 is mounted on the substrate 3 (() is coated with adhesive 6. In addition, the adhesive 6 maintains a relatively high viscosity at room temperature, but increases in viscosity as the temperature rises. It has the characteristic of decreasing.

By pressing the tape carrier device 1 with the device holding tool 7, the tape carrier device 1 placed on the substrate 3 is pressed onto the substrate 3, and as a result, the tape carrier device 1 is The outer leads 2 which were not in contact with the H solder paste 5 before being pressed are also pressed onto the hang paste 5. Further, even after the device holding tool 7 is raised, the tape carrier device I remains stuck to the substrate 3 due to the adhesive force of the adhesive 6, so the outer lead 2 also remains pressed against the solder paste 5''. In this state, it is inserted into a heating furnace or heated by infrared irradiation or the like.

(Solder paste as temperature rises) 61-1: As the solvent evaporates, it becomes molten solder and is transferred onto each bonding pad 4 by surface tension. At this time, the viscosity of the adhesive 6 also decreases, and the adhesive force between the tape carrier device I and the substrate 3 becomes weak (so that even if there is a positional shift between the outer lead 2 and the punch ink butt 4, it is due to the surface tension of the solder). Due to the self-alignment effect, the outer lead 2 is accurately placed on the bonding pad 4.Then, the melted solder solidifies to firmly bond the outer lead 2 and the bonding pad 4, and open defects are prevented. Does not occur.

In the above embodiment, the method of lead-bonding the O'' tape carrier ten-ice alone using the reflow method was explained. The present invention is also applicable.

In addition, the outer leads can be bonded without forming the leads by immersing the circuit elements into the board, and the outer leads can be mounted on the board with the surface facing downward (face down) on the tape carrier device. It is also possible to do so.

<Effects of the Invention> As explained in detail above, the present invention can be applied to outer lead bonding using a binder paste or the like or a flow type one-type outer lead bonding.
This eliminates forming defects in the outer lead and makes use of the self-alignment effect caused by the surface tension of the solder, dramatically improving reliability and production yield.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the basic configuration for bonding the outer leads of a circuit element to a wiring board. FIG. 2 is a front view showing the state in which the deno-chair is mounted when the outer lead varies in the vertical direction in the conventional one-way flow type. FIG. 3 (F) is a lead bonding configuration diagram for explaining one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Tape carrier device, 2 - Outer lead, 3... Wiring board, 4... Pumping tube 1
5...Solder paste layer, 6...Adhesive, 7.
7'/\chair holding tool. Agent Patent Attorney Aihiko Fukushi (and 2 others) 1B 2nd Diagram 3

Claims (1)

[Claims] 1. After applying an adhesive whose viscosity decreases as the temperature rises to the device mounting surface of the board, place each lead of the device face-to-face on a bonding pad coated with solder paste on the board, and apply the adhesive A lead connection method 0 characterized in that the temperature is raised while the device is adsorbed onto the substrate with an agent, and lead bonding is performed by a reflow method.