gee, why Jason sign off? skip few e-mails, I guess I missed all the fun.
just to throw few oldies of mine (posted on TechNet before Y2K), may be
Jason can jump back on and agree or disagree all over again ...hehehe...;-)
jk
"it was long long time ago (early 90s), some of us (eng. and r&d chaps) were
interested in the same topic (leadfree). After realize the limitation in
the world
supply of elements, lead free was considered as a difficult goal to acheive
for the near future (approx. 10 years at the time of chat).
All the elements can be used to replace lead, with the production quantity
and avaliability in the world, are limited. In, Sb, As, Au are not very
common elements on the earth.... Ag is the one can be widely used as Pb (but
the mechanical properties!). The price of many elements at current stage
are not that expansive, however, the price is likely to go sky rocket when
the demand heats up. particularly, with those elements only has limited
avaliability on the earth (someone managed to get a world metal production
overview or resource map to get the point cross very effectively, at least
convince me). At the time, some of us agreed that the best way is to reduce
Pb usage (we some what gave up the Pb free idea, after the discussion got
into the power circuit requirement and reducing feature size, etc. Pb is
very ductile material. It is a concern about mechanical properties of fine
pitch joint characteristics, electrical and mechanical, over the temp
range)...Here are few of the 2 cents flying around at the time
(non-official):
(1) integrate as many device as possible to the chip level = reduce I/O,
reduce lead usage. MCM or others method may be useful.
(2) recycle the lead. Limited Pb usage for 2nd level package (mostly Pb
usage are on the 2nd level package - module to PWB). problem is that
recycle Pb will be more expansive than the fresh supply of Pb... no
resolution there...
(3) epoxy or other methods (sockets, wire bond, etc.)were discussed.
However, it was believed that conductive epoxy and others may be useful to
commercial (office environment) products, it may be difficult for extream
environment. (At the time, Z-axis conductive adhesive is limited for LCD
only. some of the conductive adhesives are still in the early develop
stage. Surface finishing of the device is the other issue.... You need a
bondable surface....Normally, the device surface finishing are either
solderable, or bondable, but not both...)..Supply of the bondable surface
device is very limited at the time.
Things changed a lot since the discussion we had long long time ago... With
many conductive adhesives and alloys on the market now, it may be look
rather different (promising) than a group of us sat down had few drinks.
Sorry to say that, at the time of discussion, Pb free things were not look
very promising even after few drinks. Hopefully, the UK chaps will give us
some good news, such as some ground breaking technology advances. (every 3
to 5 years is so called a "generation"... I feel very old).
jk"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of George Patrick
Sent: Wednesday, June 15, 2005 2:33 PM
To: [log in to unmask]
Subject: Re: [TN] Lead-Free, Why?
Didn't Steve Gregory start this :)
--
George Patrick
Tektronix, Inc.
Central Engineering, PCB Design Group
P.O. Box 500, M/S 39-512
Beaverton, OR 97077-0001
Phone: 503-627-5272 Fax: 503-627-5587
http://www.tektronix.com http://www.pcb-designer.com
It's my opinion, not Tektronix'
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard
Sent: Wednesday, June 15, 2005 11:22
To: [log in to unmask]
Subject: Re: [TN] Lead-Free, Why?
I agree with everything you are all saying, and I also heartily agree
that the forum's sole purpose is the exchange of opinions as well as
ideas.
In order for the forum to be effective, if someone has an opinion or an
idea, they must feel free to share it.
But don't criticize those who do, either because you have no interest in
the topic, or don't like what was said.
Jason Gregory used the forum to instigate discussion today. Some
criticized the topic, others criticized his opinions.
But guess what? He got more people discussing other aspects of the
lead-free impact that many others had not thought of.
We don't need the negative stuff, such as people telling others to go
have a glass of water or decaf. They should simply respond with their
opinions.
My hat is off to Jason.
Hope you sign back on, Jason.
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
