TWI Industrial Member Report Summary 360/1988
By G L White and B C James
Polymer thick films (PTF) are being developed as alternatives to glass or metal oxide based thick films. They can be used to make resistors and conductors in single and multilayer assemblies and they have the advantage of being low cost and therefore ideally suited to high production applications.
Although not primarily developed with solderability or wire bondability in mind, these requirements are becoming increasingly important. The use of PTF in surface mount technology requires solder joints to be made. Wire bondability needs to be considered as it is anticipated that PTFs will be increasingly used in hybrid-type applications where wire bonding is the major joining process.
Whereas information regarding wire bondability and solderability of glass or metal oxide based thick films in hybrid and copper track printed circuit board applications is available, there is only a limited amount of corresponding data for PTFs.
This report describes an initial feasibility study into the ultrasonic wire bondability of currently available PTFs -both plated and unplated.