Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


IC plastic encapsulant family

Bob Smith

#3909

IC plastic encapsulant family | 5 June, 2000

I am trying to find the plastic family used in manufacturing the bodies of integrated circuits. Usually our product is fully encapsulated in ScotchCast however a new application requires part of a pressure sensor chip to be free of encapsulant. The ScotchCast will not bond to the body of the IC and we are concerned about water intrusion over time as the entire assembly is immersed. I need to know either the plastic family used or a material which will bond to the plastic.

Bob

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#3910

Re: IC plastic encapsulant family | 6 June, 2000

Not as easy as that Bob. But this may help you get started ...

IC packaging materials include: � Silicone - Room temperature vulcanized silicone - Heat curable hydrosilation silicone � Biphenol & multifunctional epoxy glob tops � Polyurethane � Polyimide - Preimidized polyimide - GE Siloxane polyimide � Union Carbide (SGS) Paraline � Dow benzocyclobutane � Hercules siloxane � Mitsubishi bismaleimide triazine � same stuff used in high Tg boards and BGA interposers � BF Goodrich polycyclicolefin

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#3911

Re: IC plastic encapsulant family | 7 June, 2000

Dave - let's not forget Dainippon's Novolac epoxy. This is the stuff that caused us so much grief with IC shortages years ago when their factory was damaged and it turned out they were the world's major supplier of molding compounds. This also spawned many of the competitors you mentioned. John Thorup

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#3912

Re: IC plastic encapsulant family | 7 June, 2000

Point well taken John.

Expanding on epoxies: Novolac is a multifunctional epoxy ... a phenolic resin. Most phenolic resins are made using phenol (P) and formaldehyde (F). They comprise the bulk of IC packaging and are divided into two classes: 1 Novolac (acidic conditions ....F P)

Hey, maybe someone at CBAR can poke their head into Professor CP Wong�s office and see what he would like to add. Aren�t the Georgia Tech people are supposed to be BIG contributors here?

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#3913

Re: IC plastic encapsulant family | 7 June, 2000

Ooooops, I messed that up!!!! It should read:

Point well taken John.

Expanding on epoxies: Novolac is a multifunctional epoxy ... a phenolic resin. Most phenolic resins are made using phenol (P) and formaldehyde (F). They comprise the bulk of IC packaging and are divided into two classes: (1) Novolac (acidic conditions ... F LT P) (2) Resoles (alkaline conditions ... F GT P).

Hey, maybe someone at CBAR can poke their head into Professor CP Wong�s office and see what he would like to add. Aren�t the Georgia Tech people are supposed to be BIG contributors here?

Sorry, but ...

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