SPECIAL FEATURES FOR EASE OF PRS (PATTERN RECOGNITION SYSTEM) AND MOLD INTERLOCKING MECHANISM X-FLAG DESIGN (TQFP PRODUCTS 160 LEADS)
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-28
In an automatic wirebondiig that utilizes image processing for locating die pads and device leads, the terms of system accuracy and system repeatability are of great importance. Accuracy is a measure of the error between the actual bond locations and the loca- tions where they were taught or the difference between the taught cross-hair position and the actual bond position. As for repeatability, it is the variations of bond locations on the device as measured from one device to another. With the current leadframe design, the wirebond machine always encounters PRS problem (cannot detect the reference points) for the pad location. Current design have stoppages at least once for each of the lead frames indexed in for wire bonding which will force the operator to manually key-in the appropriate placement for the previously selected reference point. This will affect both the productivity (UPH) and the quality of the units bonded. Thus, this specially designed features for both etched and stamped frames will help in increasing the accuracy and the repeatability of the PRS system. In addition, the introduction of this new feature will also help to provide locking mechanism for the mold compound to reduce delamination at the 'tie bar comer' of the lea-e.