Path: utzoo!utgpu!watserv1!watmath!att!tut.cis.ohio-state.edu!mailrus!ncar!mephisto!mcnc!rti!bcw
From: bcw@rti.rti.org (Bruce Wright)
Newsgroups: comp.sys.ibm.pc.misc
Subject: Re: Packard Bell doesn't really exist (long)
Summary: Soldering RAM into the motherboard
Message-ID: <4057@rtifs1.UUCP>
Date: 9 Sep 90 16:59:34 GMT
References: <1990Sep6.154721.12322@iwarp.intel.com> <35112@eerie.acsu.Buffalo.EDU>
Organization: Research Triangle Institute, RTP, NC
Lines: 42

In article <35112@eerie.acsu.Buffalo.EDU>, v116kzmd@ubvmsd.cc.buffalo.edu (Dave Archer) writes:
> (about Packard Bell ...)
> >2.  Is it true that you can't so much as replace a RAM chip on one of
> >these boards?  And if it's true, why would anyone design a board that
> >way?  
> 
> Anything is possible.  Even if a ram chip is soldered right to the board, it
> CAN be removed.  I've done things like this plenty of times.  The problem is
> that modern computer motherboards with their extremely thin traces and
> multi-multi-layering, are not the type of board that you want to be 
> unsoldering chips from. [...]
> 
> As for why they'd do it..  Probably has to do with cost.  They might claim it
> makes for a more reliable system, but that's fairly silly.  Even the cost 
> issue is silly, since sockets are not exactly that expensive.

The most common problem with socketed chips is that the pins get bent
and don't make good contact with the socket;  it is somewhat less
common that the chip itself goes bad.  So it probably _does_ increase
reliability, but at the cost that if something _does_ go wrong, it's
much harder to fix.  IMHO, socketed chips are better since neither of
these types of failures is all that common, and a bent pin is usually
fairly easy to fix.  Pins don't usually get bent unless someone has
his hands in the machine;  users who have no experience dealing with
chip sockets shouldn't be messing with the machine's innards at that
level.

Cost is certainly a consideration for cheap machines, but the issue is 
NOT the cost of the sockets (which as you note is pretty small), but the
cost of putting the RAM chips into the sockets, which requires either
fairly expensive additional equipment or a human assembly line worker.
Directly soldered chips don't have quite as much of a cost problem 
because essentially all motherboards are soldered with wave solder
machines, and it's quite automated.  (It's quite true that wave solder
machines are themselves expensive, but they can stamp out boards
pretty fast and reliably, and are considered cheaper than manual
assembly for any significant number of boards.  Chips can be placed
on the boards by automated equipment, but equipment to put chips
into sockets is going to be different and cost more than just putting
the chips directly into the boards).

						Bruce C. Wright