JPH02224362A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the tip of a lead in positional accuracy at bonding and to enable the flattening of a thinned lead by a method wherein the electrode of a semiconductor element and the tips, which are, at least, connected together through a bridge section, of the leads are connected to each other through bonding wires, and the bridge section is cut off by the irradiation with a laser beam. CONSTITUTION:A semiconductor element 5 is fixed to the center of a rectangular insulating ceramic board through a solder 6. Electrodes formed on the upper periphery of the element 5 are connected to the tips 9 of leads respectively through bonding wires 4. Then, a bridge section 7 of the tips 9 of the leads is cut off with a laser beam, and a ceramic cap 10 is bonded through a glass of low melting point to seal up the semiconductor element 5 and others. Next, a tie bar and a lead frame outer frame 8 are cut off. By this setup, a lead pattern, which is provided with leads that are thinned to deal with an element provided with many pins and excellent in evenness and positional accuracy, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device suitable for manufacturing a multi-pin semiconductor device having thinned leads.

[Prior Art] Conventionally, semiconductor devices in which electrodes and leads of a semiconductor element are connected by bonding wires have been manufactured by the method described below.

In the case of a semiconductor device such as a circumquat package, first, a thin metal plate of 42 alloy or the like is processed and formed using a pressing or etching technique to obtain a lead frame. This lead frame has a plurality of leads whose tips are separated from each other.

Next, a semiconductor element is placed and fixed in the center of this lead frame. Then, the electrodes formed on the peripheral edge of the upper surface of the semiconductor element and the tips of the leads are electrically connected by wire bonding. Next, the semiconductor element, bonding wires, etc. are sealed.

This completes the semiconductor device.

In the case of a semiconductor device in a laminated ceramic package, first, a pattern such as a lead is formed around a semiconductor element mounting area in the center of a ceramic substrate using screen printing technology. Next, this pattern is subjected to metallization treatment to obtain a metal film (metallized) pattern of tungsten or the like. Next, the semiconductor element is fixed in the mounting area, and the electrodes of the semiconductor element and the tips of the metalized leads are electrically connected by wire bonding.

After that, the semiconductor element, bonding wires, etc. are sealed. This completes the semiconductor device.

In this way, in the conventional semiconductor device manufacturing method,
A semiconductor device is manufactured by connecting the tip of a lead whose tip has been separated and an electrode of a semiconductor element with a bonding wire, and then sealing the semiconductor element, the tip of the lead, the bonding wire, and the like.

[Problems to be Solved by the Invention] In recent years, the number of bins in semiconductor devices has been promoted, and in order to cope with this, it is necessary to make the leads thinner. However, when the leads are thinned, the following problems arise in the conventional manufacturing method.

In the former method of using a lead frame, the strength of the leads is insufficient because the width thereof is narrow, and the tips of the leads in particular are easily deformed when external force is applied. If this happens, the lead tips will come off the predetermined position during wire bonding, making it impossible to perform wire bonding.

Furthermore, in the case of leads formed using the latter metallized pattern, when a fine pattern is formed by screen printing, the upper surface of the pattern becomes an arcuate curved surface due to the surface tension of the applied coating liquid.

Even after the metallization process, the flatness of the lead tip required for wire bonding cannot be obtained. For this reason, the reliability of wire bonding is significantly reduced.

The present invention has been made in view of such problems, and includes:
To provide a method for manufacturing a semiconductor device capable of manufacturing a semiconductor device having thinned leads corresponding to a large number of bins, excellent in flatness of the leads, and capable of obtaining a lead pattern with high positional accuracy. With the goal.

[Means for Solving the Problems] A method for manufacturing a semiconductor device according to the present invention connects the tips of a plurality of leads, at least the tips of which are interconnected by a bridge portion, and an electrode of a semiconductor element using a bonding wire. and a step of cutting the bridge portion by laser beam irradiation.

[Operations] In the present invention, first, the tips of the leads, whose tips are mutually connected by the bridge portion, and the electrodes of the semiconductor element are connected by bonding wires. in this way,
During wire bonding, the tips of the leads are connected to each other by a bridge section, which significantly improves the strength of the tips of the leads on the lead frame, making it possible to avoid deformation of the tips of the leads even when external pressure is applied. . Therefore, the positioning accuracy of the lead tip during bonding is improved,
The reliability of wire bonding is significantly improved. on the other hand,
In the case of leads formed by screen printing, the shape of the top surface of the lead tip depends not on the width of the lead but on the width of the bridge portion. Therefore, even if the lead is extremely narrow, by setting the width of the bridge portion to an appropriate dimension, a lead with excellent top surface smoothness can be obtained.

Thereby, highly reliable wire bonding can be performed.

Thereafter, in both the lead frame and the metallized pattern, at least the bridge portion at the tip of the lead is cut by laser beam irradiation.

As a result, each lead is electrically isolated, and each electrode of the semiconductor element is individually connected to, for example, wiring on a wiring board.

[Embodiments] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a plan view showing the method of the first embodiment of the present invention, and FIG.
The figure is an enlarged view of the area indicated by the arrow ■ in FIG. 1, and FIG.
FIG. 4 is an enlarged perspective view of the area indicated by the arrow ■ in FIG.

In this embodiment, a lead frame is used for manufacturing a semiconductor device. As shown in FIG. 1, this lead frame is formed from a thin metal plate, and has a rectangular opening in the center.

A plurality of leads 1 are arranged and formed around this opening. This lead 1 is formed such that its tip end on the opening side is connected to the adjacent lead 1 by a bridge portion 7. The central parts of the leads 1 are connected to each other by tie bars, and the other ends are connected to the lead frame outer frame 8.

In the method for manufacturing a semiconductor device according to this embodiment, first, a semiconductor rectifier 5 is fixed to the center of an insulating ceramic substrate 2 having a rectangular shape with a brazing material 6. In this case, the above-mentioned lead frame is bonded onto the ceramic substrate 2 with the low melting point glass 3 so that the opening fits into the semiconductor element 5.

Next, the electrodes formed on the peripheral edge of the upper surface of the semiconductor element 5 and the tips 9 of each lead are connected by bonding wires 4.

Next, the bridge portion 7 (shaded area in FIG. 2) between the lead tips 9 is cut with a laser beam.

Next, as shown in FIG. 3, the ceramic cap 10 is bonded with low melting point glass 3 to seal the semiconductor element 5 and the like. Thereafter, the tie bars and lead frame outer frame 8 are cut to complete the semiconductor device. In this case, the lead tip portion 9 and the bonding wire 4 are sealed while maintaining a proper bonding state at all times, as shown in FIG.

As mentioned above, in this embodiment, during wire bonding, the lead tips 9 are connected to each other by the bridge part 7, so the strength of the lead tips 9 is extremely high. Therefore, even if the lead 1 has a narrow width, Since deformation of the lead tip 9 can be avoided, bonding defects such as lead drop can be prevented.

FIG. 5 is a plan view showing the second embodiment method of the present invention, and FIG.
The figure is an enlarged view of the area indicated by the arrow ■ in FIG. 5, and FIG.
FIG. 8 is an enlarged perspective view of the area indicated by the arrow ■ in FIG. 7.

In this embodiment, a semiconductor device is manufactured using an insulating ceramic substrate 12 on which a metallized pattern is formed.

This ceramic substrate 12 is composed of a plurality of ceramic layers. The central portion of this substrate 12 is a mounting area for a semiconductor element 15, and a pattern of metalized leads 11 and a bridge portion 17 is formed around this mounting area.

Note that each lead 11 has its tip 19 connected to the bridge portion 17.
are interconnected by.

In this embodiment, the semiconductor element 1 is placed in the center of the ceramic substrate 12 on which the metallized pattern is formed as described above.
Fix 5. Then, the electrodes of the semiconductor element 15 and the lead tips 19 are connected by bonding wires 14, respectively.

Next, each lead 11 is electrically separated by cutting the bridge portion 17 (shaded area in FIG. 6) between each lead tip 19 using a laser device.

Next, as shown in FIG. 7, a metal cap 20 is bonded onto the ceramic substrate 12 with a sealing brazing material 21 to seal the semiconductor element 15 and the like.

As described above, in this embodiment, the tips 19 of each lead 11 are connected to each other by the bridge portion 17. Therefore, the flatness of the top surface of the lead tip does not depend on the width of the lead, so even if the lead is for a semiconductor device with a large number of pins, the flatness of the top surface is excellent. Thereby, as shown in FIG. 8, good bonding can always be performed.

[Effects of the Invention] As explained above, according to the present invention, after connecting the electrode of a semiconductor element and the tip end of the lead whose tip end portions are mutually connected by the bridge portion with a bonding wire, Since the portion is cut by laser beam irradiation, in a semiconductor device using a lead frame, the strength of the lead tip portion is improved, its deformation is prevented, and the positional accuracy of the lead tip portion during bonding is improved. Therefore, an extremely high bonding yield can be ensured even with thinned leads for multi-bin semiconductor devices. Furthermore, in a semiconductor device having metalized leads, the flatness of the top surface of the lead tip does not depend on the width of the lead, so even if the lead is thin, the top surface is flat. For this reason,
Bonding properties at the lead tips are significantly improved.

Therefore, according to the present invention, wire bonding can be performed on thinned leads in good condition, and a highly reliable semiconductor device can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the method of the first embodiment of the present invention, and FIG.
The figure is an enlarged view of the area indicated by the arrow ■ in Figure 1, and Figure 3 is an enlarged view of the area indicated by the arrow ■ in Figure 1.
FIG. 4 is an enlarged perspective view of the area indicated by the arrow ■ in FIG. 3;
FIG. 5 is a plan view showing the second embodiment method of the present invention, and FIG.
The figure is an enlarged view of the area indicated by the arrow ■ in Figure 5, and Figure 7 is an enlarged view of the area indicated by the arrow ■ in Figure 5.
FIG. 8 is an enlarged perspective view of the area indicated by the arrow ▪ in FIG. 7. FIG.

Claims (1)

[Claims] (1) A step of electrically connecting the tips of a plurality of leads, at least the tips of which are connected to each other by a bridge portion, and an electrode of a semiconductor element using a bonding wire, and irradiating the bridge portion with a laser beam. 1. A method of manufacturing a semiconductor device, comprising: a step of cutting the semiconductor device.