22 May
2002
22 May
'02
5:41 a.m.
If anyone's interested, here are the paths to the four
additional photos that have been taken. I think they came out pretty
good, though a little on the large side. I actually reduced them in
size a little so the quality isn't as good as they were. A coworker
took these with a Nikon D1X digital camera.
http://www.geocities.com/siliconvalley/lakes/6757/images/be044_back.jpg
http://www.geocities.com/siliconvalley/lakes/6757/images/be044_front.jpg
http://www.geocities.com/siliconvalley/lakes/6757/images/be044_inside.jpg
http://www.geocities.com/siliconvalley/lakes/6757/images/be044_inside_close…
Jeff
--
Home of the TRS-80 Model 2000 FAQ File
http://www.cchaven.com
http://www.geocities.com/siliconvalley/lakes/6757
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22 May
22 May
1:35 p.m.
On Wed, 22 May 2002, Jeff Hellige wrote:
If anyone's interested, here are the paths to the
four additional
photos that have been taken. I think they came out pretty good,
though a little on the large side. I actually reduced them in size a
little so the quality isn't as good as they were. A coworker took
these with a Nikon D1X digital camera.
Is that an exposed chip die I see in the closeup photo? If so, you should
be very careful with that. It should have had a metal or ceramic cover
taped over it if it was a prototype chip, but it might have come off.
-Toth
1:41 p.m.
2:44 p.m.
On Wed, 22 May 2002, Jeff Hellige wrote:
They are very delicate, and even dust can damage exposed chip dies. The
bonding wires are another concern, since they are a very fine gold or
silver wire. If a bonding wire gets broken, it can be replaced, but not
without access to an expensive machine. What size QFP is that chip? I
doubt I have any covers that fit it, but I'll keep a look out.
-Toth
http://www.geocities.com/siliconvalley/lakes/6757/images/be044_inside_close…
Is that an exposed chip die I see in the closeup photo? If so, you should
be very careful with that. It should have had a metal or ceramic cover
taped over it if it was a prototype chip, but it might have come off.
Yes, that's what it looks like. There was nothing loose in the case
though. I've been very careful not to get too close to that chip.
It's pretty interesting looking up close. It was the main reason we
took the closeup and I thought the cables had been pulled back enough
so it wouldn't be blocked. 
3:19 p.m.
I would be sort of surprised if the machine ran for very long without a
cover on the chip. Sure there isn't a glass sheet over it? I've seen that
several times at IBM and VLSI.
--John
-----Original Message-----
From: cctalk-admin(a)classiccmp.org [mailto:cctalk-admin@classiccmp.org]On
Behalf Of Tothwolf
Sent: Wednesday, May 22, 2002 19:45
To: cctalk(a)classiccmp.org
Subject: Re: [CCTECH] more Hobbit photos
On Wed, 22 May 2002, Jeff Hellige wrote:
.jpg
They are very delicate, and even dust can damage exposed chip dies. The
bonding wires are another concern, since they are a very fine gold or
silver wire. If a bonding wire gets broken, it can be replaced, but not
without access to an expensive machine. What size QFP is that chip? I
doubt I have any covers that fit it, but I'll keep a look out.
-Toth
Is that an exposed chip die I see in the closeup photo? If so, you should
be very careful with that. It should have had a metal or ceramic cover
taped over it if it was a prototype chip, but it might have come off.
Yes, that's what it looks like. There was nothing loose in the case
though. I've been very careful not to get too close to that chip.
It's pretty interesting looking up close. It was the main reason we
took the closeup and I thought the cables had been pulled back enough
so it wouldn't be blocked.
3:33 p.m.
I would be sort of surprised if the machine ran for
very long without a
cover on the chip. Sure there isn't a glass sheet over it? I've seen that
several times at IBM and VLSI.
John,
Now that you mentioned that, I took a closer look at it and
it indeed has a clear cover over the die. The white 'ring' around
the die in the picture is the seal/gasket between it and the clear
cover.
As stated before, the machine does run...it's just not
terribly useful due to how early a version of the OS is installed.
Jeff
--
Home of the TRS-80 Model 2000 FAQ File
http://www.cchaven.com
http://www.geocities.com/siliconvalley/lakes/6757
4:57 p.m.
On Wed, 22 May 2002, Jeff Hellige wrote:
Now that you mentioned that, I took a closer look at
it and it indeed
has a clear cover over the die. The white 'ring' around the die in
the picture is the seal/gasket between it and the clear cover.
I was starting to wonder how they might have installed that QFP without a
cover. It would be possible to hand solder such a chip, instead of using
an automated hot air system, but hand soldering that size of QFP would not
be an easy task, and there would be a serious risk of flux contamination
of the die. I really haven't seen too many chips that used a clear cover,
and I'd guess they were still debugging/testing that particular chip.
-Toth
23 May
23 May
12:08 a.m.
I was starting to wonder how they might have installed
that QFP without a
cover. It would be possible to hand solder such a chip, instead of using
an automated hot air system, but hand soldering that size of QFP would not
be an easy task, and there would be a serious risk of flux contamination
of the die. I really haven't seen too many chips that used a clear cover,
and I'd guess they were still debugging/testing that particular chip.
I really had to turn the system slowly in the light to see
that there was something covering the whole chip. It was very
difficult to spot.
Jeff
--
Home of the TRS-80 Model 2000 FAQ File
http://www.cchaven.com
http://www.geocities.com/siliconvalley/lakes/6757
10:46 a.m.
On Thu, 23 May 2002, Jeff Hellige wrote:
The cover is probably removable, thought I'd certainly not try removing
it... The reason they'd use a removable cover is so the whole board could
be put in a stand, under a micro-manipulator, and tiny probes could be
used to probe at different spots on the chip's die.
-Toth
I was starting
to wonder how they might have installed that QFP without a
cover. It would be possible to hand solder such a chip, instead of using
an automated hot air system, but hand soldering that size of QFP would not
be an easy task, and there would be a serious risk of flux contamination
of the die. I really haven't seen too many chips that used a clear cover,
and I'd guess they were still debugging/testing that particular chip.
I really had to turn the system slowly in the light to see that there
was something covering the whole chip. It was very difficult to spot.
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