JPS5811736B2 - Hand tie souchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of attaching a semiconductor element to a substrate for a semiconductor device.

The structure of attaching a semiconductor element to a conventional substrate for a semiconductor device will be described using a resin-sealed lead frame for a semiconductor device.

First, a portion of a lead frame made of a metal material such as Kovar on which a semiconductor element is placed (hereinafter referred to as an island) is plated with Au.

The temperature is raised to a temperature at which this lead frame Au-Si alloy piece can be melted (approximately 380°C or higher), and the semiconductor element is brought to the island on which the AuSi alloy piece is placed and rubbed from front to back and from side to side (hereinafter referred to as scrubbing). An alloying reaction occurs between Si, which is a semiconductor element material, the Au-Si alloy piece, and the Au plating part.

As a result, the semiconductor element can be firmly adhered to the island.

Au applied directly on Kovar without using Au-Si alloy pieces
Even if the semiconductor element is scrubbed on the plating, the Au-Si alloying reaction will occur, resulting in the same result as above.

The bonding method using the Au--Si alloying reaction described above is also effective in manufacturing hermetically sealed semiconductor devices whose substrates are made of ceramic or metal materials, and is widely used.

Resin-encapsulated semiconductor devices are widely mass-produced for civilian use, but because the resin materials used are cheaper than ceramic materials, the costs associated with the semiconductor device assembly process are not included in the product cost structure. occupies a large portion.

Naturally, there is a need for automation and labor saving in the assembly process.

Automation of the bonding work process is also required, but automation of this process is not only a simple process, but also has a significant impact on the productivity of the subsequent process, the connection process using thin metal wires (wire bonding process). .

In other words, it is difficult to maintain a constant position when mounting the semiconductor element in the bonding process, so it takes time to align the electrodes of the semiconductor element and the tip of the lead frame in the wire bonding process, which is a later process. This has caused the productivity of the process to be quite low.

This tendency is even more noticeable when wire bonding work is performed using automatic machines, and the current situation is that the capabilities of the machines cannot be fully utilized.

On the other hand, the following can be said about a hermetically sealed semiconductor device whose base is made of a ceramic material.

In order to maintain airtightness of the partial space in which the semiconductor element is placed, sealing requires a seal width of a certain value or more.

However, as the functions of semiconductor devices increase, their scale tends to increase, and even larger islands are required.

Normally, when scrubbing, semiconductor elements are pinched with tweezers or other tools, so in order to obtain good adhesion, it is necessary to attach at least one area between the semiconductor element and the island in the front and back or left and right sides.
．． 0mm, and a gap of 0.5mm or more is required when divided into equal parts.

Some semiconductor devices are so large that even the above-mentioned gap cannot be removed, making it impossible to perform sufficient scrubbing.

If the cohesive aggregation reaction does not proceed sufficiently, the semiconductor element will peel off from the island due to a slight external force.

Furthermore, if the alloying reaction proceeds non-uniformly, it promotes the generation of non-uniform thermal stress, leading to frequent failures such as cracks in semiconductor devices.

The present invention provides an improved structure for mounting semiconductor devices on a substrate that eliminates the above drawbacks.

To achieve this object, the gist of the present invention is to provide a through hole in the island, and at least a part of the side wall of the semiconductor element is inserted into the through hole and bonded, thereby fixing the semiconductor element to the base.

According to the present invention, the gap between the through hole and the semiconductor element is reduced.

Since the amount is within 0.5 mg, the mounting position of the semiconductor element within the island during the bonding process can be kept constant.

Therefore, the alignment time in the currently widely used wire bonding process can be shortened.

This time saving effect is remarkable when an automatic machine is used.

Even when assembling a semiconductor device with two or more semiconductor elements on one island, the positions of the semiconductor elements can be kept constant, which not only ensures reliable assembly but also facilitates freedom of assembly. It can be done.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention applied to a resin-sealed semiconductor device.
An example is shown below.

Island 1 of the base ribbon made of Kovar
has a through hole, and the island portion including the side wall of this through hole is plated with Au.

The base ribbon is supported by a surface-treated stainless steel plate (not shown), and the semiconductor element is inserted into the through hole.

Further, a strip of Au-8i eutectic material is inserted into the gap between the through hole and the semiconductor element, and then placed on the stainless steel plate and the heater block.

When the heater plate is heated to a temperature at which the Au-8i eutectic brazing material 3 melts (approximately 380'C or higher), the semiconductor element and the island undergo an Au-Si alloying reaction and are bonded to each other.

If the alloying reaction is difficult to occur, it is advisable to apply minute amplitude mechanical vibration to the lead frame or island.

When the base ribbon is removed from the stainless steel plate heater block, the Au-8i eutectic brazing material solidifies and the adhesion is completed.

The surface containing the active area of the semi-moving element should preferably not be lower than the island surface, so that the adhesive 3 does not flow onto this surface.

FIG. 2 shows a cut section of the island portion to show the element.

In addition to the AuSi eutectic brazing material mentioned above, the adhesive used is Ac-8u brazing material, thermosetting resin such as epoxy resin, and Au.

An adhesive containing powder such as Ag can be used.

In addition, as a means of heating in the bonding process, in addition to the conventional heating method using a heater block, for example, a strong heat ray such as a laser beam can be used to heat the adhesive material 3 in the gap between the side wall of the through hole of the island and the semiconductor element. It can also be heated by irradiating it with water.

FIG. 2 shows how the laser beam 4 is irradiated from below or above the substrate.

Since the heating by the laser beam 4 is localized, bonding can be performed without impairing the function of the semiconductor element.

Using the above assembly method not only prevents defects such as cracks in the semiconductor element or separation of the semiconductor element from the island due to a slight external force, but also
It is possible to mount a semiconductor element of such a scale that only a gap of 0.5 mm or less is left on the island.

FIG. 3 shows a second embodiment of the present invention applied to a semiconductor device in which two or more semiconductor elements are provided on one island.

Above is the first point. Although the second embodiment has been described, the above embodiment is only a part of the embodiments of the present invention, and it goes without saying that it does not limit the scope of the claims of the present invention.

[Brief explanation of the drawing]

The drawings all show embodiments of the present invention; Fig. 1 is a perspective view of essential parts of the first embodiment, Fig. 2 is a cutaway front view of Fig. 1, and Fig. 3 is a cross-sectional view of the second embodiment. A perspective view of the main parts is shown. In the drawings, 1 is a base island, 2 is a semiconductor element, 3 is an adhesive, and 4 is a laser beam.

Claims (1)

[Claims] 1 A through-hole is provided in the island of the base ribbon, a semiconductor element is inserted into the through-hole, and a surface of the semiconductor element that does not include an active area substantially coincides with one surface of the base ribbon. C. The surface including the active area of the semiconductor element protrudes from the other surface of the base ribbon, and is provided at a distance of 0.5ty or less between the side wall of the through hole and the side wall of the semiconductor element. 1. A semiconductor device, wherein the semiconductor element is fixed to the base ribbon by providing an adhesive in the gap.