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From: ronc@fai.UUCP (Ronald O. Christian)
Newsgroups: net.micro.mac
Subject: Re: Is the Mac+ socketed?
Message-ID: <72@fai.UUCP>
Date: Tue, 28-Jan-86 14:39:08 EST
Article-I.D.: fai.72
Posted: Tue Jan 28 14:39:08 1986
Date-Received: Sat, 1-Feb-86 05:08:50 EST
References: <1345@mhuxt.UUCP> <479@ssc-vax.UUCP>
Reply-To: ronc@fai.UUCP (Ronald O. Christian)
Organization: Fujitsu America, Inc., San Jose, CA
Lines: 36

>> Are the 256ks socketed? If so are the sockets partially filled sockets
>> (so 1 Megs could be substituted in the future)?
>...The new ram is surface mounted on
>cards that plug into the motherboard.  If you want 4meg, you get new
>surface mount boards.  (anybody got a do it yourself surface mounting
>machine?)
***

Don't know if anyone is *really* interested, but....

I've done surface mounting in an ill-equipped lab.  (Not on a Mac+,
though.)  You can remove the old chip carriers with a heat gun.  You
have to be careful not to fry the board.  There is some kind of white
stuff you can put on the chip that melts at the melting point of
solder, but a little piece of solder works just fine for this.
Get the solder to reflow, then put the board on edge and tap it.
The little suckers just fall off.  Now clean up the board with
wick, apply a little solder paste (available from Kester) to each pad,
apply new chip carriers, then reflow *very carefully* with the
heat gun.  Applying heat whilst putting the new chips on is more
critical than when taking the old ones off.  (More money at stake.)
Double sided boards aren't a problem.  You do one side, turn it
over, do the other side.  The surface tension of the molten solder
will keep the underside parts from falling off.

Anyway, since SMT seems to be the going technique for making things
smaller, we'll all probably have to be experts someday.

			Ron
-- 
--
		Ronald O. Christian (Fujitsu America Inc., San Jose, Calif.)
		ihnp4!pesnta!fai!ronc

Oliver's law of assumed responsibility:
	"If you are seen fixing it, you will be blamed for breaking it."