Heraeus speeds production with new SMD adhesive

Citation

(1999), "Heraeus speeds production with new SMD adhesive", Soldering & Surface Mount Technology, Vol. 11 No. 1. https://doi.org/10.1108/ssmt.1999.21911aad.011

Heraeus speeds production with new SMD adhesive

Heraeus speeds production with new SMD adhesive

Keywords Adhesives, Heraeus, Surface mount device

Heraeus Materials is announcing the introduction of PD955PY, the industry's most advanced solvent-free, thermosetting single-component, polymer adhesive. Developed specifically to make the production process faster, by allowing the operator to successfully print variable heights of adhesive dots in just one print cycle, PD955PY is suitable for all SMT applications. It can also be used on bare substrates.

Stencil printing is every day practice in the electronics industry, but its use for applying surface mount adhesive (SMA) onto PCBs has not, until now, been completely successful. By making it possible to successfully print variable heights of adhesive dots in the same print cycle, Heraeus has made the production process faster and more efficient ­ as it is obviously quicker to screen print a PCB than it is to dispense dots. In fact, in one print cycle PD955PY can produce 5,000 dots in 30 seconds.

In response to the industry's ever demanding needs of smaller and more densely populated PCBs, Heraeus has developed this SMA to offer the widest process window. The combination of advanced rheology and adhesive drag on the hole walls allows the new adhesive to print dots of various heights (from 0.25mm to 1.3mm) with metal stencils giving diameters up to 2.2mm. With plastic stencils dot heights of 1.98mm and diameters of 3mm have been achieved, thus making it suitable for all SMDs, regardless of component size or shape.

PD955PY continuously delivers excellent adhesion (as it has a high surface insulation resistance) on both standard and difficult to glue components. It also prevents movement of components during placement due to its very high green strength, and always forms stable glue dots. Cured adhesion strength is typically greater than or equal to 25N per sq. mm. It has been tested to show no dendritic growth and no E-corrosion. Tests also show that defective SMDs can be removed and repaired without damage.

The adhesive has very low humidity absorption, which allows for steep temperature increases and very short curing times without the risk of air bubbles forming or the loss of adhesion occurring. The manufacturer recommends a standard curing time of three minutes at 125°C. Maximum curing temperature is 200°C.

To clean uncured adhesive, Heraeus recommends Zestron SD300 ­ a cleaner specially designed not to attack the stencil frame adhesive.

PD955PY can be stored for up to six months in a refrigerator, at a temperature of 5-12°C.

For further information please contact: Quentin Reynolds, Heraeus Materials Ltd, 1 Craven Court, Canada Road, Weybridge, Surrey KT14 7JL, UK. Tel: +44 (0) 1932 349315; Fax:+44 (0) 1932 347904.