Hi Tim,
STII, the Soldering Temperature Impact Index, is a combination of Tg(TMA), Td
(5%) and thermal expansion from 50 to 260°C. It is
STII= [Tg+Td]/2 — [TE(50->260°C)%]x10
By direct e-mail, I am sending you an excerpt of my PCB FAB Notes White Paper
that includes a table with these properties and the resulting STII-values.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
-----Original Message-----
Hi, Mr. Engelmaier and other Netters
What does STII stand for?
It looks like a measurement of thermal stability.
I know T260 or T288 but not STII.
I just want to know since I¡¯ve been in this material business for some time.
And I hope I am not the only one who doesn¡¯t know what STII is.
Many thanks in advance.
Tim (Minsu) Lee
Technical Marketing
Doosan Electro-Materials
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Wednesday, August 23, 2006 6:45 AM
To: [log in to unmask]
Subject: Re: [TN] N4000-29 material
Hi Ted,
Here are the pertinent fact about the materials:
Isola IS410 Tg=170, Td=350, TE(50->260)=3.5%, STII=225
Nelco N4000-11 Tg=170, Td=345, TE(50->260)=3.2%, STII=225
Nelco N4000-12 Tg=180, Td=370, TE(50->260)=3.6%, STII=239
N4000-29 Tg=175, Td=350, TE(50->260)=3.0%, STII=232
Generally, the higher the STII the better the material is for LF-soldering
temperatures.
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