12 Aug
2006
12 Aug
'06
4:37 p.m.
Date: Fri, 11 Aug 2006 15:58:16 -0600
From: "e.stiebler" <emu at e-bbes.com>
Chuck Guzis wrote:
BGA components have a specification for the clearance between the
chip package and the circuit board after soldering. I don't think
you could meet that just by putting the thing in the oven.
However, it might be interesting to get some feeler guages the same
thickness as the clearance that that specification calls for, place
the feeler guages around the edges of the chip between the chip and
the board and then heat the chip and board until the chip presses
down on the feeler guages. That *should* give the proper clearance
and therefore the appropriate solder ball "squish".
I don't know how one reballs BGA components though. Anyone care to explain?
Jeff Walther
On 8/11/2006 at 4:37 PM shoppa_classiccmp at
trailing-edge.com wrote:
I suspect that the legacy DIP stuff will get
harder to buy new through
"normal" channels, given RoHS. In the long run, I suppose we'd all
better
get used to working with surface mount. :(
Yup, get ready to solder .2 mm balls on 800 balls BGA.
Get your toaster-oven ready ;-) 
12 Aug
12 Aug
7:06 p.m.
If we were gonna do a homebrew CPU, I'd sure like to see it done with
something akin to AMD 2901's. Why not build a retro cpu out of a retro
technology?
Jay
13 Aug
13 Aug
1:06 a.m.
Jay West wrote:
If we were gonna do a homebrew CPU, I'd sure like
to see it done with
something akin to AMD 2901's. Why not build a retro cpu out of a retro
technology?
Hey until I could find out I could get PROMs burned,
SSI was the way to for me. That is why I have not built
a computer yet. :(
Jay
I am starting to grumble at all the better
computer systems
that the PEE-CEE wiped out! I was just looking at a bit on
the PREQ.
2:28 a.m.
On Sat, 12 Aug 2006, Don wrote:
Jay West wrote:
It came to me tonight that maybe a TTL-based 8086 would be fun with all
the busses, registers, and other things were brought out to a front panel.
The Magic-1 runs at 4MHz, so maybe an discrete-built 8086 would be fast
enough. It would be a fun thing to hack FreeDOS with.
--
David Griffith
dgriffi at cs.csubak.edu
A: Because it fouls the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?
If we were gonna do a homebrew CPU, I'd sure
like to see it done with
something akin to AMD 2901's. Why not build a retro cpu out of a retro
technology?
Makes sense. But, do you try to design some "classic"
processor or just some "classic 2901 design"? 
12:08 a.m.
On Sat, 12 Aug 2006, Jeff Walther wrote:
Thats entirely determined by the package weight and surface tension (assuming
the solder balls are all melted), If you do it by hand you can see the BGA
package 'sink' when all the balls are melted. So you can do it with an oven, a
simple hot air gun or probably even a propane torch if you are skilled enough.
I have done many successful BGA protos with nothing more than a $59.00 Granger
hot air gun.
and actually the commercial SMT equipment bears a large resemblence to a
glorified toaster oven...
BGA's are not all that hard to do with simple hand tools.
Date: Fri, 11
Aug 2006 15:58:16 -0600
From: "e.stiebler" <emu at e-bbes.com>
Chuck Guzis wrote:
BGA components have a specification for the clearance between the chip
package and the circuit board after soldering. I don't think you could meet
that just by putting the thing in the oven. On 8/11/2006 at 4:37 PM shoppa_classiccmp at
trailing-edge.com wrote:
I suspect that the legacy DIP stuff will get
harder to buy new through
"normal" channels, given RoHS. In the long run, I suppose we'd all
better
get used to working with surface mount. :(
Yup, get ready to solder .2 mm balls on 800 balls BGA.
Get your toaster-oven ready ;-)
However, it might be interesting to get some feeler guages the same thickness
as the clearance that that specification calls for, place the feeler guages
around the edges of the chip between the chip and the board and then heat the
chip and board until the chip presses down on the feeler guages. That
*should* give the proper clearance and therefore the appropriate solder ball
"squish".
I don't know how one reballs BGA components though. Anyone care to explain?
Jeff Walther
Peter Wallace
Mesa Electronics
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
10:09 a.m.
On Aug 12, 2006, at 4:37 PM, Jeff Walther wrote:
Very true...but I've looked far & wide for a reason for that
specification to exist, and have found none. The only thing I can
think of is the possible flattening out of the balls causing them to
short against adjacent ones...but is that really possible? Not sure.
Yup, get ready
to solder .2 mm balls on 800 balls BGA.
Get your toaster-oven ready ;-)
BGA components have a specification for the clearance between the chip
package and the circuit board after soldering. I don't think you
could meet that just by putting the thing in the oven. I don't know how one reballs BGA components
though. Anyone care to
explain?
One "reballing" kit that I've seen has very thin metal "masks"
which
you place over the chip, and you slather solder paste through that with
something that looks like a squeegee. It's similar to applying paste
solder to a PCB with a stencil. I don't know how effective that method
is.
-Dave
--
Dave McGuire
Cape Coral, FL
10:35 p.m.
Very true...but I've looked far & wide for
a reason for that
specification to exist, and have found none. The only thing I can
think of is the possible flattening out of the balls causing them to
short against adjacent ones...but is that really possible? Not sure.
I suspect the spec may be due to what IBM found with SLT developement
in 1963 (which was basically BGA on a small scale) - having some
height allowed for a small moment arm, which was good for absorbing
the flexes due to thermal expansion as the chip heats up.
--
Will
6558
days inactive
6560
days old
7 comments
8 participants
participants (8)
-
bfranchuk＠jetnet.ab.ca -
dgriffi＠cs.csubak.edu -
jwest＠classiccmp.org -
mcguire＠neurotica.com -
pcw＠mesanet.com -
THX1138＠dakotacom.net -
trag＠io.com -
wdonzelli＠gmail.com