Yes 42 alloy is just a [cheap] version of Kovar which is a trade name
variant of Invar. I suppose your concern is solderability and so far
as I know the only other metals with appropriate TCE are even worse eg
moly. Having said that lid sealing onto 42 alloy rings is pretty
standard stuff and can be accomplished routinely. I think some where I
have response on this to a similar problem posted some Moons ago. If
it helps I can dig it out

Mike Fenner

 T: +44 1295 722992
 F: +44 1295 720937
Visit: www.lasercuttingco.com
----- Original Message -----
From: "Earl Moon" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, November 17, 2000 2:12 AM
Subject: Re: [TN] Ceramic to metal and other seals


> Mike,
>
> Based on what we all know as certain "truths" concerning Alloy 42
solder
> wettability, I'm looking for an alternative to that metal - first.
Knowing
> what we all know concerning the TCE matching characteristics between
this
> alloy and ceramic, are there alternatives, other than Kovar and/or
Invar,
> exhibiting better solderability characteristics as well. I cannot
think of
> any.
>
> My application requires receiving typical, pre-tinned (soldered) TCE
> matching "lids" for ceramic mating to ensure hermetic sealing during
and
> after a reflow process. This is assuming a similar metallization is
made to
> the ceramic that too is solderable.
>
> Simply, I don't know the latest and greatest ceramic/metal seal.
Moreover,
> is there one?
>
> Earl
>
> --------------------------------------------------------------------
-------------
> Technet Mail List provided as a free service by IPC using LISTSERV
1.8d
> To unsubscribe, send a message to [log in to unmask] with following
text in
> the BODY (NOT the subject field): SIGNOFF Technet
> Search previous postings at: www.ipc.org > On-Line Resources &
Databases > E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
> --------------------------------------------------------------------
-------------
>

---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------