TWI Frequently asked questions
by Simon Mason
Pin transfer is a very simple, fast method for the application of adhesive onto a substrate. An entire board can be treated in one go and adhesive volume can be tailored for each dot. The main variables are:
- Pin diameter. This determines the adhesive dot volume and is important as different packages have different sizes and stand-off heights and thus require different amounts of adhesive. The dot profile is determined by the stand-off of the pin from the board. The stand-off can be guaranteed by using pins designed with a mechanical foot, which has a height equal to the pin stand-off required.
- Depth of adhesive layer in the reservoir. This also affects the adhesive dot volume and is controlled by the design of the vessel.
- Temperature. This affects the rheology of the adhesive and again determines dot volume. There will be an optimum temperature range for the process, outside of which, dot volume onto the pin, dot slump and the release characteristics when the pin is pulled away will be inappropriate for the application.
