JPS60192352A - Method for sealing integrated circuit devices - 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 method for hermetically sealing lead wires, and particularly to a method for hermetically sealing lead wires in the manufacture of semiconductor integrated circuit devices.

As is well known, a dual in-line type glass-sealed semiconductor device has better moisture resistance (airtightness) than a resin-sealed semiconductor device, and is also superior in device reliability.

However, in this glass-sealed semiconductor device, the lead wires are supported by glass, so if an external force is applied to the lead wires, the fragile glass may easily crack. As a result, the device becomes less airtight and less reliable. Therefore, in the manufacturing process of semiconductor devices, leads or lead frames are used in which predetermined portions of the lead wires are bent in advance at the time of glass sealing.

However, such a bent lead frame lacks rigidity, so it has the disadvantage that it is easily distorted when external force is applied. Therefore, after heating the ceramic paste and softening the glass, lead frames and semiconductor pellets (pellets) are produced.
Even in the assembly process of embedding pellets in glass, the positional relationship between the pellet and each lead wire of the lead frame is often disrupted due to distortion of the lead frame. For this reason, when automating (mechanizing) the wire bonding work that connects the electrode part of the pellet and the lead with a wire, the wire is not fixed at the appropriate electrode position or lead position, making it impossible to perform the desired wire bonding. be.

Therefore, by using a rigid plate-shaped (flat) bent frame, we can improve the relative positional accuracy between the pellet and the lead, improve the yield of automatic wire bonding work, and create semiconductor devices with good airtightness. As a method for providing this, the applicant temporarily seals a lead wire in a softening temperature range where crystallization does not occur using crystalline glass or non-crystalline glass, and then bends the lead wire. After the glass layer is reheated to soften it and eliminate any cracks that may have occurred within the glass layer or at the boundary with the lead wire when the lead wire is bent, main sealing is performed to assimilate or crystallize the lead wire. We have already proposed a method to achieve hermetic sealing.

By the way, it has become clear that in the main sealing step of this method, if the entire process is performed inside the furnace body, the following disadvantages will occur. That is, depending on the type of silicon semiconductor element, if it is repeatedly exposed to high temperature conditions, its characteristics may be adversely affected. For example, through gold paste pellets (
In a structure that fixes semiconductor elements (semiconductor elements), gold diffuses into silicon, changing the lifetime.

In addition, since the entire glass layer is heated inside the furnace, the entire glass layer softens, and the leads move due to vibrations generated from various parts of the sealing device during sealing work, causing the correlation between each lead to collapse.
It will not meet the standards.

Further, as the lead moves, the thin wire connecting the lead tip and the electrode of the pellet changes and moves, and comes into contact with adjacent leads, wires, etc., causing a short circuit. Additionally, if the lead moves too much, the wire may break.

On the other hand, it has also been found that the cracks are relatively shallow in the lead bending process after the temporary sealing, and that the cracks disappear in a short time by partially heating the glass layer from the outside.

Therefore, an object of the present invention is to provide a method for hermetically sealing lead wires with glass without causing deterioration of characteristics.

Another object of the present invention is to provide a method for hermetically sealing lead wires with glass, which can perform glass hermetic sealing without causing any deviation in the spacing between the lead wires.

In order to achieve this purpose, one embodiment of the present invention is as follows:
When performing main sealing, hot air or laser beams are applied to areas of the glass layer that have cracks or are not properly sealed.

By applying infrared rays or the like, it is possible to carry out the main sealing without heating the semiconductor element.The present invention will be specifically explained below with reference to Examples.

FIGS. 1 and 2 show an embodiment of the method for hermetically sealing a lead wire in glass according to the present invention. FIG. 1 is a flowchart showing the manufacturing process of a dual in-line type glass-sealed semiconductor package, and FIGS. 2(a) to 2(f) are process charts showing the state of the product corresponding to the flowchart.

As shown in FIG. 2(a), a base 1 made of ceramic is prepared. On the upper surface of this base 1, a low melting point amorphous glass layer (glass layer) 2 is formed. next,
This base 1 is heated in a nitrogen atmosphere to form the glass layer 2.
As shown in the same figure (b), lead frame 3 is melted.
and attach pellet 4. Thereafter, after cooling to room temperature, the electrode part of the pellet 4 and the corresponding inner end of the lead 5 are connected to aluminum (A
They are connected with a thin wire 6 made of a wire or the like. After that, the same figure (d)
As shown in , a cap 7 made of ceramic is inserted into a pellet 4. Base 1 so as to cover the inner end of lead 5 and wire 6
This is placed on top and exposed again to a nitrogen atmosphere. Then, the amorphous glass layer 8 provided on the periphery of the lower surface of the cap 7 and the glass layer 2 on the paste 1 are softened and melted into each other. Therefore, the temperature is lowered to room temperature again and the base 1 and the cap 7 are integrally sealed (referred to as temporary sealing). Next, as shown in FIG. Further, in this semiconductor device 9, since a bending force acts on the leads 5 in the step of bending the leads, the leads 5
Cracks occur in the integrated glass layer 10 that holds the glass layer 10, or the boundary between the glass layer 10 and the board 5 peels off.

Therefore, the glass layer portion where the peeling or cracking has occurred is partially heated using a heating tool called a hot jet 11 that blows out hot air, and the glass is temporarily softened and melted again (referred to as main sealing). Close the peeled parts or fill in the cracks to eliminate them. At this time, use Hontojet 1
The tip of the nozzle 12 is moved relatively along the glass layer 10 to heat it. Therefore, the upper and lower parts of the base 1 and the cap 7 are not heated.

According to this embodiment, the glass layer is partially softened and melted in the main sealing step. Further, this softened and melted portion gradually moves as the nozzle 12 of the hot jet 11 moves. Furthermore, if the moving speed is increased, the outer surface of the glass layer will be softened and melted, and if it is slowed down, the glass layer will be softened and melted deep inside. Therefore, even with this method, cracks, distortions, etc. in the glass layer are completely eliminated. Therefore, a semiconductor device with excellent airtightness can be manufactured.

Further, in this embodiment, the entire semiconductor device is not heated in the main sealing process. In addition, since partial heating is performed using hot jets, the internal pellets do not reach high temperatures and their properties do not deteriorate.

Further, in this embodiment, the softened and melted portion of the glass in the main sealing step is localized, and this softened and melted portion moves for a while. For this reason, the entire surrounding glass, which serves to hold each lead extending within the glass layer, will not melt at the same time, so even if a semiconductor device moves between hot jets, the leads may be damaged by vibration, etc. It does not move relative to the glass layer. Therefore, the spacing (arrangement) between each lead is always constant, resulting in a product that passes the standards.

Note that the present invention is not limited to the above embodiments. That is,
Partial heating of the glass layer in this sealing step may be performed by irradiation with infrared rays, laser beams, or the like.

Further, although amorphous glass was used as the glass in the above embodiments, crystalline glass may also be used.

In this case, the temporary sealing process must be performed at a temperature in the softening temperature range at which the glass does not crystallize.

Furthermore, in the present invention, the material forming the adhesive layer is not necessarily limited to glass.

As described above, according to the glass hermetic sealing method for lead wires of the present invention, high heat is not applied to the pellet during actual sealing, so there is no deterioration of characteristics and highly reliable sealing is achieved. can be done.

Further, according to the present invention, since each lead wire does not move during the final sealing, a constant lead wire interval can be maintained at all times, and yield can be improved.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing each step of an embodiment of the glass hermetic sealing method for lead wires of the present invention, and FIG. 2(a)
-(f) are process diagrams showing the assembly state of each process corresponding to the flowchart. DESCRIPTION OF SYMBOLS 1...Base, 2...Amorphous glass layer, 3...
Lead frame, 4... pellet, 5... lead,
6... Wire, 7... Camp, 8... Glass layer, 9... Semiconductor device, 10... Glass layer, 11...
・Hot jet, 12...nozzle. Figure 1 Figure 2 (me)

Claims (1)

[Claims] 1. A method for sealing an integrated circuit device using heat, which is characterized in that the heat for sealing is concentrated on a portion that requires it.