Factors affecting welding in vacuum eutectic furnace

When interconnecting chips, components, etc. with carriers (such as substrate, tube shell, etc.), the main methods are conductive adhesive bonding and eutectic welding. The utility model has the advantages of high microwave power, low thermal resistance and low reliability caused by high-end microwave welding. So what are the factors affecting vacuum eutectic furnace welding? Here is a brief introduction.

1、 Vacuum degree and protective atmosphere during welding in vacuum eutectic furnace

Vacuum degree and protective atmosphere are important factors affecting the quality of vacuum eutectic furnace. In the process of eutectic welding, if the vacuum is too low, the gas around the welding area and the gas released during welding of solder and welded devices are easy to form cavities after welding, so as to increase the thermal resistance of devices, reduce the reliability of devices and expand the possibility of IC fracture. However, if the vacuum degree is too high, the conductive medium becomes less in the heating process, which is easy to produce the phenomenon that the eutectic solder reaches the melting point but has not melted yet. Generally, the vacuum degree during eutectic welding is 5pa ~ 10Pa, but for some devices requiring vacuum degree internally, the vacuum degree is often higher, generally up to 5 × 10-2 Pa～5 × 10-3pa, even higher.

2、 Setting of temperature curve during welding in vacuum eutectic furnace

Another important influencing factor in vacuum eutectic furnace welding is the setting of temperature curve. In the process of eutectic welding, the temperature curve generally includes temperature rise curve and insulation curve. Temperature rise curve and thermal insulation curve can be set as one or more sections according to product characteristics. The setting of temperature curve includes the temperature rise temperature and time of temperature rise curve; Insulation temperature and time of insulation curve.

3、 Pressure during welding in vacuum eutectic furnace

The pressure applied above the vacuum furnace directly affects the welding quality of the chip. When using vacuum eutectic furnace for eutectic, a device is often added on the heated graphite fixture to pressurize. According to different products, the pressure is also different. The pressure range is usually 1g ~ 50g, which is realized by the self weight of the pressing block. For some special fixtures, special pressurization methods will be used, such as spring pressurization.