There are many variables involved in the process of sawing wafers. Wafer thickness, the width of the saw streets, the metal composition of the wafer and the die size all have to be considered when formulating the correct saw parameters. Failure to perform the process properly may cause mechanical damage to the die, which is why you should call on the professionals at Chip Supply. We have the expertise and the equipment to ensure the die’s quality remains unscathed.

Due to the fixed cost to produce each wafer, the wafers are designed to hold as many die as possible. This helps in lowering the die production expenses. Each die is segregated by a narrow “street” that is the cut line for singulating the die. Some wafers also have additional monitoring circuits built onto the wafers that take the place of a few die. These circuits are used to measure process controls during wafer fabrication.

Wafer Dicing
Some preparation is needed before beginning the wafer dicing process. First the wafers are mounted on a wafer cutting ring. A piece of filter paper is then centered on the mounting chuck and the wafer is positioned face down on the filter paper and the wafer tape is stretched over the back of it. A roller evenly distributes the tape onto the wafer and excess tape is cut away from the ring. Once completed, the wafers are ready for the dicing process to begin.

During the wafer dicing process, the wafer is divided into single die. The wafer is mounted on a chuck that rotates to align the X and Y axis of the wafer. A diamond stud blade is mounted on a spindle perpendicular to the wafer. It spins at a high speed and travels along the street, cutting the die apart. Usually the blade cuts completely through the wafer and .5 to 1 mil into the tape. The blade can travel either forward or reverse across the wafer. Once all the parallel streets are cut, the chuck rotates 90 degrees and all of the other streets are cut.

Wafer Sort
After the wafer is fully sawn, the individual dies are removed from the wafer tape. There are two methods to accomplish this process. The first method is to manually pick and load the die by peeling them from the tape. The operator then uses a vacuum pencil to transfer the die to the appropriate carrier by positioning the vacuum over the center of the die to lift it. The tool is then moved to the carrier, the vacuum is lowered, the die is released and then falls into the carrier cavity.

The second method of removing die from the wafer tape uses both semi-auto and fully automatic pick and place machines. Both machine types require the tape to be slightly stretched. This is accomplished by loading the wafer onto the machine and clamping it in place. On the semi-automatic machine, XY knobs are used by an operator to center the die in the crosshairs on the monitor. Eject pins push up through the wafer tape to elevate the die and loosen it from the tape. The vacuum driven pick-up tip retrieves the die and deposits it into the carrier located in the discharge fixture on the machine. The automatic machine uses a similar pick up and deposit method but the XY stepping and centering process is done by a pattern recognition system which greatly increases throughput.