JPH07335693A - Semiconductor device mounting method and semiconductor device - Google Patents

Abstract

(57) [Summary] [Purpose] The base and tip are fixed by a film base.
A bonding strength of a TAB having supported leads can be effectively improved. Constitution: a step of setting the width of the lead 15 relatively narrower than the width of the pad 21 and allowing the lead 15 to stand on the pad 21; and a laser beam focused to at least the width of the pad 21 or less. And a step of scanning while illuminating. The lead 15 having the base portion 15b and the tip portion 15a fixed and supported by the film base material 12 is soldered to the pad 21 on the mounting substrate 20. A high solder joint strength between the lead 15 and the pad 21 is secured, and the joint state can be easily and surely confirmed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is, for example, a TAB (Tape
Automated Bonding), especially LCD (Liquid Crystal Dis
The present invention relates to a semiconductor device mounting method suitable for a play TAB and a semiconductor device using the LCD TAB.

[0002]

2. Description of the Related Art In a TAB in which a semiconductor chip is mounted on a film carrier, a plurality of (many) leads patterned on a film base material are provided, and the semiconductor chip is connected to the inner lead side of the lead in a device hole.・
It is mounted and connected to a predetermined mounting substrate on the outer lead side.

When mounting the TAB on the substrate, a heating tool, for example, a hot bar method such as pulse heating is used, and the hot bar method has been the mainstream in the past. In the hot bar method, there is a problem that a short circuit due to solder easily occurs as the lead pitch becomes narrower, and in that case, it becomes difficult to increase the yield.

By the way, a method of mounting a TAB on a substrate using a laser beam is being developed. In this case, the laser light is condensed to a width approximately equal to the lead width, and the reflow of the solder is performed pin by pin by the irradiation of the laser light. Therefore, according to the mounting method using the laser light, problems such as solder shorts occur There is no

For example, in a QFP (Quad Flat Pack) type TAB, the lead (outer lead) tip is divided, and the laser light is emitted from the lead tip, so that the solder on the mounting substrate leads. The tip portion and the lead extend around to the rising portion from the substrate, and so-called front fillet and back fillet are formed in these portions. In the semiconductor device thus mounted, the bonding strength with respect to the mounting substrate is generally high, and the appearance inspection for confirming the solder bonding state and the like can be easily performed.

On the other hand, TAB is introduced for driving a liquid crystal panel used in a liquid crystal television.
In the TAB for D or the like, the leading end and the base of the lead are fixed and supported by a polyimide film substrate 1 as shown in FIG. 6, for example. In other words, lead 2 (outer lead)
The tip portions 2a of the are connected to each other via this polyimide. Further, the lead 2 is not formed into a special shape (for example, a gull wing shape) but is bonded to the pad 4 of the substrate 3 while being flat and mounted.

[0007]

By the way, such LC
In the TAB for D, when the lead 2 and the pad 4 of the substrate 3 are joined, it is possible to join them by using laser light. However, in the conventional mounting method, TA for LCD is used.
As described above, the lead 2 in B is mounted on the substrate in a flat shape with its tip 2a connected as described above. Therefore, as shown in FIG. 6, especially when the lead 2 and the pad 4 have the same width. Even if scanning is performed while irradiating the laser beam 100, the solder bonding is performed only in the lower surface region of the lead 2.
That is, the front or back fillet is not effectively formed, and therefore the solder joint strength is unavoidable. Further, since the pad 4 to be connected to the lead 2 is completely hidden under the lead 2, it becomes extremely difficult to confirm the bonding state between the two.

In view of the above situation, the present invention is a semiconductor device mounting method and a semiconductor device capable of effectively improving the bonding strength of a TAB having a lead whose base and tip are fixed and supported by a film base material. The purpose is to provide.

[0009]

A method of mounting a semiconductor device according to the present invention is a mounting method in which a lead having a base portion and a tip portion fixed and supported by a film base material is soldered to a pad on a mounting substrate. A step of setting the width of the lead relatively narrower than the width of the pad, and leaving the lead still on the pad, and irradiating a laser beam focused at least below the width of the pad along the lead. While scanning, the leads are soldered to the pads.

Further, a semiconductor device according to the present invention is mounted on a film carrier having a patterned lead and a film base material for fixing and supporting a base portion and a tip end portion of the lead, and is mounted at a predetermined position on the film carrier. A semiconductor chip connected to the leads; and a mounting board having a large number of pads solder-bonded in the vicinity of the tips of the leads, wherein the width of the leads is set relatively narrower than the width of the pads. This lead is soldered to the pad.

[0011]

According to the method of the present invention, the lead of the film carrier is soldered to the pad on the mounting substrate, and the width of the lead is set relatively narrower than the width of the pad. Then, the solder is reflowed by irradiating the laser light focused to the pad width or less along the lead. By this reflow, the side fillet is formed not only in the lower surface region of the lead but especially on the side portion of the lead. Therefore, a high solder joint strength can be obtained, and the appearance inspection can be performed very easily.

According to the semiconductor device of the present invention, the lead width is set to be relatively narrower than the pad width of the substrate, especially in the TAB for LCD in which the base portion and the tip portion of the lead are fixed and supported by the film base material. As a result, a side fillet is formed especially on the lead side portion, and high solder joint strength can be realized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a semiconductor device mounting method and a semiconductor device according to the present invention will be described below with reference to FIGS.

1 and 2 show the overall structure of a semiconductor device according to this embodiment. This semiconductor device is an LCD
It is assumed that the TAB 10 for LCD and the mounting substrate 20 for mounting the TAB 10 for LCD are used. LCD
In the TAB 10 for use, the film carrier 11 has a film base material 12 formed of a material such as polyimide and a plurality of leads 13 patterned on the film base material 12. Each lead 13 is composed of an inner lead 14 and an outer lead 15. The inner lead 14 protruding into the device hole 16 connects and mounts the semiconductor chip 18 via the bump 17. The semiconductor chip 18 is sealed with potting resin 19 or the like.

As shown in FIG. 3, the lead 13, especially the tip portion 15a and the base portion 15b of the outer lead 15, are
Basically, it is fixed and supported by the film substrate 12 as in the case of the conventional example described above. That is, outer lead 1
The front end portions 15a of the film 5 are connected to each other via the end portions 12a of the film base material 12 (see FIG. 1).

As shown in FIGS. 2 and 3, a plurality of pads 21 corresponding to the outer leads 15 are arranged at a predetermined pitch on the mounting board 20. Each pad 21
Has a constant length and a constant width along the outer lead 15. In particular, the outer lead 15 and the pad 2
In the relationship of 1, the outer lead 15 (inner lead 1
4 is the same), as shown in FIG. 4, is set relatively narrower than the width of the pad 21.
In other words, the width of the outer lead 15 is narrower than that of the conventional one, but at the same time, the outer lead 15 is set to the extent that electrical conductivity and strength of the outer lead 15 can be sufficiently secured. The outer lead 15 and the pad 21 are bonded to each other through the solder 22, and therefore the semiconductor chip 18
Are electrically connected to the mounting substrate 20.

Next, a method of mounting the semiconductor device having the above structure will be described. According to the method of the present invention, the lead 1
3, that is, the outer lead 15 is soldered to the pad 21 on the mounting substrate 20, but as described above, the outer lead 1
The width of 5 is set relatively narrower than the width of the pad 21.
Then, the outer lead 15 is allowed to stand still on the pad 21. In this case, the outer lead 15 is arranged at the substantially central portion (width direction) of the pad 21 as shown in FIG.
By setting the width of the outer lead 15 to be narrow as described above, the solder 22 pre-coated exists outside the side surface of the outer lead 15.

Next, as shown in FIG. 4, the laser beam 10 is preferably focused to the same size as the width of the pad 21.
The outer lead 15 is irradiated with 0. The pad 21
The laser beam 100 'condensed to a size equal to or smaller than the width may be irradiated. Then, the laser beam 100 is scanned so that the entire region of the pad 21 including the outer lead 15 is irradiated with the laser beam 100. In addition, when the laser light 100 ′ is irradiated, it is assumed that the laser light 100 ′ is irradiated so as to include at least the region of the outer lead 15.

Laser light 100 or laser light 100 '
When irradiating, the scanning is performed in a direction (see arrow A) from the tip portion 15a of the outer lead 15 to the base portion 15b thereof, as shown in FIG. The scanning direction of the laser light 100 or the like may be set opposite to the above, that is, the direction from the base portion 15b of the outer lead 15 toward the tip portion 15a. In either case, pad 2
Laser light 100 or 100 ′ so that the entire area of 1 or at least the area of the outer lead 15 is irradiated.
To scan.

In the above case, the laser beam 100 or the laser beam 100 'is emitted from a laser generator (not shown). In consideration of the above, it can be set and controlled arbitrarily and suitably.

By irradiating the laser beam 100 or 100 ', the solder 22 is reflowed to bond the outer lead 15 and the pad 21. According to this solder bonding, not only the lower surface area of the outer lead 15 but also the outer lead 15 is formed. The side fillet 22a is formed at the side portion.
By thus setting the width of the outer lead 15 to be relatively narrower than the width of the pad 21, a high solder joint strength can be obtained and the appearance inspection thereof can be extremely easily performed.

Here, the TAB 10 for LCD is mounted on the mounting substrate 2
When mounting on 0, the outer lead 15 is assumed to be pad 2
Consider a case in which it is not arranged in the central portion with respect to 1, that is, it is arranged so as to be biased to either the left or right side. In this case as well, the side fillet 22a is formed at least on the right or left side of the outer lead 15, so that a high solder joint strength can always be obtained in such a case.

[0023]

As described above, according to the present invention, particularly in the TAB for LCD, the width of the lead is set relatively narrower than the width of the pad, and the laser beam condensed to the width of the pad or less is scanned. As a result, the side fillet is effectively formed on the lead side portion. As a result, there are advantages that a high solder joint strength can be obtained and the appearance inspection can be performed very easily.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged cross-sectional view of section III of FIG.

FIG. 4 is a main part plan view of a semiconductor device according to an embodiment of the present invention.

FIG. 5 is a perspective view showing an example of a laser irradiation method according to an embodiment of the present invention.

FIG. 6 is a plan view of a main part of a semiconductor device according to a conventional mounting method.

[Explanation of symbols]

 10 TAB for LCD 11 film carrier 12 film base material 12a end part 13 lead 14 inner lead 15 outer lead 15a tip part 15b base part 16 device hole 17 bump 18 semiconductor chip 19 potting resin 20 mounting substrate 21 pad 22 solder 22a side fillet 100 laser

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Yamaguchi 5-10-1 Fuchinobe, Sagamihara City Electronics Research Laboratories, Nippon Steel Co., Ltd. (72) Masahiro Daimon 5-10-1, Fuchinobe, Sagamihara Electronics Co., Ltd. Electronics Research Laboratory

Claims (2)

[Claims] 1. A method of mounting a semiconductor device, wherein a lead having a base portion and a tip portion fixed and supported by a film base material is solder-bonded to a pad on a mounting substrate, wherein a width of the lead is relatively greater than a width of the pad. A step of setting the lead narrowly on the pad, and leaving the lead still on the pad; and a step of scanning while irradiating the lead with a laser beam focused at least equal to or less than the width of the pad, A method of mounting a semiconductor device, wherein a lead is soldered to the pad. 2. A film carrier having a patterned lead and a film base material for fixing and supporting a base portion and a tip portion of the lead, and a semiconductor mounted at a predetermined position of the film carrier and connected to the lead. A chip; and a mounting board having a large number of pads solder-bonded in the vicinity of the tips of the leads, wherein the width of the leads is set to be relatively narrower than the width of the pads. A semiconductor device that is soldered to a pad.