agree with Dave. There are many lead-free solders. Some of them may form
low melting temperature phase when reflowed with leaded solder (quaternary
compounds with lower melting temperature). "OK to use" based on visual
inspection is scary without reliability study... your manufacturing engineer
may be a bit of brave...
jk
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of David Douthit
Sent: Friday, September 10, 2004 11:46 PM
To: [log in to unmask]
Subject: Re: [TN] Lead free
Bill,
There is a possible exception to this blanket "ok to use leaded solder"
statement.
There are possible issues when using SAC/lead-free BGAs or solder bumps.
These need to be liquefied which means higher temperatures, different
fluxes, profile changes, ect...
You are into a lead-free "build" with leaded solder so very careful
qualification/testing is needed.
David A. Douthit
Manager
LoCan LLC
Brooks,Bill wrote:
>I talked with our ME's here and they inform me that the current process of
>using tin/lead solder WILL BE COMPATIBLE with the new 'lead free' parts
that
>are being manufactured... So why change processes if you don't need to deal
>with the EU...?
>
>The ME's say they have real issues with inspecting high temp solder joints
>that do not wet or wick like tin/lead solders... I would expect more
trouble
>with the ductility of other alloys too, so if your surface mount board is
>undergoing thermal excursions and getting stressed at the solder joints due
>to CTE mismatches the other alloys are more likely to crack due to work
>hardening... and less ductility.
>
>How much real research has been done into these alternative alloys? Do you
>want to ride in a Space Shuttle with lead free solder joints? Or put a pace
>maker in your chest that has lead free solder joints? Are they truly
>reliable?
>
>Who's really driving the move to lead free?
>
>I still maintain that leaded car batteries are a much greater threat to the
>environment than cell phones with solder on the small parts they carry
>inside. Look at how many cars there are that have to change their batteries
>every 5 years or less...
>
>
>
>Bill Brooks
>PCB Design Engineer , C.I.D., C.I.I.
>Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510
>http://pcbwizards.com
>
>
>-----Original Message-----
>From: Dehoyos, Ramon [mailto:[log in to unmask]]
>Sent: Wednesday, September 08, 2004 11:13 AM
>To: [log in to unmask]
>Subject: Re: [TN] Lead free
>
> Since Japan is almost 100% lead free, what have they chosen as
their
>best alloy? or Europe?
> Just a thought.
> Ramon
>
>-----Original Message-----
>From: David Bergman [mailto:[log in to unmask]]
>Sent: Wednesday, September 08, 2004 1:28 PM
>To: Dehoyos, Ramon
>Subject: RE: [TN] Lead free
>
>
>Hi Ramon,
>
>It will be interesting to see what Technet response is to this. My
>personal opinion is that the industry is narrowing on the SAC alloy
>(Tin/Silver/Copper). I also believe that the SAC 305 (3% Silver 0.5 %
>copper, balance tin) will be the leading alloy. There is a significant
>amount of R&D work looking at lower temperature alloys including Bismuth
>and Zinc, but none of these are mainstream options yet.
>
>Dave
>
>
>David W. Bergman, CAE
>Vice President, Standards, Technology and International Relations
>IPC
>2215 Sanders Road #250
>Northbrook, IL 60062-6135
>Phone 847-790-5340 Fax 847-504-2340
>Mobile 847-867-1388
>email [log in to unmask] www.ipc.org
>
>
>IPC IS MOVING: On Friday, September 17, IPC will be moving to a new
>office location: 3000 Lakeside Drive, Suite 309 S, Bannockburn, IL,
>60015. All phone, fax, web and e-mail service will be down from the
>close of business on the 16th until Monday, September 20th. The new main
>telephone number will be 1-847-615-7100 and the new main fax number will
>be 1-847-615-7105. Direct phone numbers are not yet available. A
>complete listing of all new direct phone numbers will be available when
>confirmed by the phone company at www.ipc.org/move.
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
>Sent: Wednesday, September 08, 2004 12:15 PM
>To: [log in to unmask]
>Subject: [TN] Lead free
>
> Technetters:
> Last time I checked there were more than a dozen different types
>of lead free solders. Has the industry chosen the best one? Or is it
>still experimenting with different types?
> Regards,
> Ramon
>
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