TWI Industrial Member Report Summary 616/1997
P M Bartholomew and S B Dunkerton
Cost-effective packaging of electronic devices often relies on polymer encapsulants known as glob top resins. New materials offering stencil printing or UV curing are compared with conventional and modified resin systems across a range of physical, electrical and mechanical tests.
Over recent years, the quality of glob top resins has steadily improved and they are now in widespread use in consumer, industrial and telecommunication products. Multichip modules (MCMs) having a very high ratio of active component area to total substrate area (up to 85%) can benefit considerably. The saving in polymer board (or ceramic, silicon, or metal substrate) area by having a chip mounted and interconnected directly to it, ie chip-on-board (COB), over a conventional packaged device, can be as high as 50-80%.
An earlier report detailed a literature and industry review of current glob top resins and materials in development. It concluded that traditional syringe dispense materials have been largely supplemented by screen printable materials giving advantages in productivity and height control. However, property data are often insufficient.
With respect to new materials, photocurable and UV curable glob top resins are being developed offering potential for room temperature curing.
- To characterise a range of commercially available and novel glob top encapsulants in terms of physical properties and performance in industry standard tests.
- To evaluate methods for determination of the presence of moisture in glob top encapsulants.
- To identify and evaluate a new method to rapidly determine the moisture protection afforded by glob top resins.