John: The 180 Tg point is a sweet spot for obtaining heat resistance, cost effectivly. These high technology boards provide good thermal resistance for wire bonding, direct chip attach, and BGA mounting and rework. Since these boards are harder than 140 Tg boards, plated through holes receive less impact from solder during thermal cycling and less pad lifting and voiding.
Bismaleimide triazine (BT) are 180 Tg epoxy resins systems have a narrower process widow than "standard" 180 Tg epoxies and are used in semiconductor packaging of BGAs and MCMs.
Ta
Dave F
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