SOLUTIONS TO MEET HAND-HELD MARKET'S REQUIREMENT FOR LOW COST ADVANCED REFLOW AND ENVIRONMENTALLY SENSITIVE PACKAGING

摘要

The hand-held consumer products market is driving towards more environmentally preferred packaging in anticipation of the implementation of the WEEE (Waste from Electrical and Electronic Equipment) directive from the European Parliament and it's ban on the use of lead (Pb) by 2008. Concurrently, they also have requirement for lower cost yet more technology driven solutions. This report will discuss evaluations performed at elevated reflow temperatures (250 - 260°C) on Ball Grid Arrays and leaded packages. These studies were conducted while implementing advanced materials for fine pitch wire bonding, increased adhesion of BGA substrate interfaces, and finer substrate geometries. Advance mold compounds with finer fillers are used to insure adequate mold flow and reduce surface tension on silicon. In addition, substrate suppliers are beginning to use chemically etch processing (MEC etch) to improve moisture performance by improving adhesion between substrate interfaces. There are requirements for finer line widths on BGA substrates with lower ball pitch (i.e. down to 0.65/0.5 mm). This creates challenges for packages to withstand higher temperature cycle gradient and higher reflow temperatures without introducing reliability failures such as trace cracking. With new emphasis being placed on cost reduction efforts, this report also looks at polyimide stress buffer elimination & land grid array package solutions and how these alternatives compare to standard reliability test - component and board level. Also discussed is solder joint reliability data on various Pb-free alternatives.