Die Bonders Information
Die bonders are specialized semi- or fully-automatic high-precision machine tools used in semiconductor device fabrications. Die bonders fix the semiconductor chip, or die, to the substrate, package, or lead frame, using an adhesive glue, eutectic material or solder. Usually the chip or die is a 25 mm square and comes in wafer trays. Die bonding machines have to be accurate down to the micron level.
Semi-automatic die bonders are used for small scale applications. Fully-automated industrial versions are for large-scale mass production. They are all computer-controlled with digital camera vision sensors, and are high precision machines.
There are three technologies that are used for bonding a chip or die to a substrate or package.
A eutectic bonding is the joining of a die and substrate by melting a preform consisting of a mixture or alloy of two or more dissimilar metals in the joint between the die and substrate. By heating the package above the eutectic temperature and placing die on it a bond is formed between the die and package.
Epoxy bonding is formed by attaching the die to the substrate with the use of epoxy glue. Epoxy is dispensed on the package and the die placed on top of it. The package is heated to cure the epoxy properly. This process uses adhesives such as polyimide, epoxy and silver-filled glass as die attach material to mount the die on the die pad. Advantages of epoxy bonding is low curing temperature, can be used for a wide range of die sizes and can be reworked easily.
Solder attachment involves the fluxing of the components, applying heat and reflowing the solder material. Solder is the most preferably type of die bonding because of the better thermal conductivity of the solder material. Solder provides good mechanical strength, high thermal conductivity and good electrical conductivity.