Dear Harvey,
My response to your question about whether I "would you fly in an airplane
whose black boxes are lead-free or use a pacemaker (that is lead-free)"
would
be, "Certainly".
The laboratory results indicate that the Sn-Ag-Cu system (and the Sn-Cu)
system is stronger in all respects than the Sn-Pb alloys they replace and
the
experience with commercial products that have been in the field for nearly
two years seems to confirm that. This is particularly the case in regard
to thermal fatigue, possibly the main cause of failure in electronic
circuitry, where the lead-free alloys have a much longer life.
In regard to the possible consequences of an encounter between the Sn-Cu
binary eutectic alloy and the Sn-Ag-Cu ternary eutectic alloy I would say
that the worst that could happen is that you would get an alloy that lay
somewhere along the "valley" on the liquidus surface of the
three-dimensional
ternary phase diagram, between these two eutectics. The resulting mixture
would have a melting point somewhere between 217C and 227C and its
mechanical
properties should be somewhere in between also, which means they are going
to
be generally better than those of a Sn-Pb alloy.
In regard to whether lead-free solders are being used, as I have already
mentioned in another recent contribution to this forum, my company's
lead-free solders are being used in commercial production at some 30 sites
around Japan and Asia with some lines having been running for nearly two
years. There are more than 14 million individual electronic products
manufactured with our solders out in the market with more added every day.
As to whether any solder makers are making any money, the solder industry
has
made a massive investment in research and development over the past ten
years
since the possibility of a change to lead-free was first mooted. Whether
they will ever make a net profit on that investment will depend on whether
the solder users will be prepared to pay a fair price for the lead-free
solders. Most of the increased price for lead-free solders compared with
tin-lead solders is to cover the increased cost of replacing cheap lead with
expensive tin and (in some cases) silver.
Certainly the manufacturers of reflow ovens should do well selling machines
that can provide the more sophisticated thermal profiles required for reflow
of lead-free solders at minimum peak temperatures. And all soldering
machine manufacturers should benefit from their customers' need for tighter
process control when using lead-free materials.
Regards
Tetsuro Nishimura
Executive Director
Nihon Superior Co Ltd
******************************************
西村哲郎 Tetsuro Nishimura
取 役 Executive Director
㈱日本スペリア社 Nihon Superior Co.,Ltd.
〒564‐0063 吹田市江坂町1‐16‐15
16-15, Esakacho 1chome, Suita, Osaka, 564-0063
TEL : +81-(0)6-6380-1121
FAX : +81-(0)6-6380-1262
E-mail : [log in to unmask]
HP : http://www.nihonsuperior.co.jp
******************************************
----- Original Message -----
From: "Harvey Miller" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 01, 2001 4:18 AM
Subject: Re: [LF] Eutectic alloys?????
> Andrew and Doug
> How does one maintain the binary Sn 3.5Ag or Sn 0.7Cu at those precise
> eutectic compositions? And I note that the pasty zones are very large
when
> compositions deviate. What happens when the ternary SnAgCu alloy in SMT
paste
> meets and joins the SnCu alloy used in wave soldering?
>
> How do you think the consumers of the world will like the reduced product
> lives. And the product liability suits for failed ICs, turned into sieves
> by lead-free melting temps-- can't wait.
>
> Would you fly in an airplane whose black boxes are lead-free or use a
> pacemaker....
>
> So how much lead-free is being used today? Is any one making money from
> lead-free? How many lead-free-ready ovens have BTU or Vitrronics or
Cookson
> sold?
>
> Lead-free is a bad, expensive joke, and not even Green.
>
> Harvey Miller
>
> --------------------------------------------------------------------------
-------
> Leadfee Mail List provided as a free service by IPC using LISTSERV 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Leadfree
> To temporarily stop delivery of Leadree for vacation breaks send: SET
Leadfree NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
> --------------------------------------------------------------------------
-------
>
---------------------------------------------------------------------------------
Leadfee Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Leadfree
To temporarily stop delivery of Leadree for vacation breaks send: SET Leadfree NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
