LEADFREE Archives

July 1999

Leadfree@IPC.ORG

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Subject:
From:
"Bernier, Dennis" <[log in to unmask]>
Reply To:
Leadfree Electronics Assembly E-Mail Forum.
Date:
Fri, 23 Jul 1999 09:50:03 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (142 lines)
Basically, the problem is that fluxes have been designed to work with the
higher melting SnPb alloys, i.e., the melting point of abietic acid (the
working ingredient of rosin) is about 175°C.  So, the activators employed
usually melt or decompose about that temperature.  Even the zinc-ammonium
chloride fluxes melt about 176°C.  Everything is designed around Sn63Pb37
melting at 183°C.  Mostly every flux will work with the lead-free alloys
other than the SnBi because high temperature stability/activity is not a
problem.

Most of the no-clean fluxes used in electronics contain non-water-soluble
organic acids that melt above 150°C to work with Sn-Pb solder alloys. The
high melting is necessary to be able to pass insulation resistance tests.
So, what does that leave?    Water-soluble fluxes, especially those that are
alcohol-based can be used for soldering with low-temperature solder alloys.
However, the residues must be removed because they are corrosive.

There are many RMA fluxes developed since MIL-F-14256 was issued in 1956.
Though most of the RMA fluxes have evolved to activate about 175°C, there
are some that use activators that BEGIN to activate about 145°C.  

-----Original Message-----
From: Brooks, Peter [mailto:[log in to unmask]]
Sent: Thursday, July 22, 1999 7:46 PM
To: [log in to unmask]
Subject: Re: [LF] No Messages


It has been reported in a technical paper that standard fluxes (e.g RMA) are
not
fully activated when used with low temperature solders such as SnBi (Tliq =
138
C). Thus the reflow temperature must be increased to about 190 degrees.

Does anyone know if non standard fluxes have been successfully used which
allow
lower reflow temperatures (say 160 C)?

Pete Brooks
Harris Semiconductor

        -----Original Message-----
        From:   Paul Klasek [SMTP:[log in to unmask]]
        Sent:   Thursday, July 22, 1999 7:54 PM
        To:     [log in to unmask]
        Subject:        Re: [LF] No Messages

        Lead-free is in hibernation Sherry (must be holidays) ;
        Technet is displaying just touch better signs of life .

        paul

        PS
        you should get this twice , to confirm server

        -----Original Message-----
        From: Sherry Goodell [mailto:[log in to unmask]]
        Sent: Friday, 23 July 1999 3:18
        To: [log in to unmask]
        Subject: Re: [LF] No Messages


        Hello everyone,

        I have not received any mail for a few days now.  Is anyone else
getting
        mail or is there a server problem?

        Thanks
        Sherry

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        Leadfree E-Mail Forum provided as a free service by IPC using
LISTSERV
1.8c
        ################################################################
        To subscribe/unsubscribe, send a message to [log in to unmask]
        with following text in the body:
        To subscribe:   SUBSCRIBE Leadfree <your full name>
        To unsubscribe:   SIGNOFF Leadfree
        ################################################################
        IPCWorks -October 25-28 featuring an International Summit on
Lead-Free
Electronic
        Assemblies.
        Please visit IPC's Center for Lead-Free Electronics Assembly
        (http://www.ipc.org/html/leadfree.htm ) for additional information.
        For technical support contact Gayatri Sardeshpande [log in to unmask] or
847-790-5365.
        ################################################################

################################################################
Leadfree E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask]
with following text in the body:
To subscribe:   SUBSCRIBE Leadfree <your full name>
To unsubscribe:   SIGNOFF Leadfree
################################################################
IPCWorks -October 25-28 featuring an International Summit on Lead-Free
Electronic
Assemblies.
Please visit IPC's Center for Lead-Free Electronics Assembly
(http://www.ipc.org/html/leadfree.htm ) for additional information.
For technical support contact Gayatri Sardeshpande [log in to unmask] or
847-790-5365.
################################################################

################################################################
Leadfree E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask]
with following text in the body:
To subscribe:   SUBSCRIBE Leadfree <your full name>
To unsubscribe:   SIGNOFF Leadfree
################################################################
IPCWorks -October 25-28 featuring an International Summit on Lead-Free Electronic
Assemblies.
Please visit IPC's Center for Lead-Free Electronics Assembly
(http://www.ipc.org/html/leadfree.htm ) for additional information.
For technical support contact Gayatri Sardeshpande [log in to unmask] or 847-790-5365.
################################################################

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