Hello Valerie:
Would it be fair to encourage the laminate suppliers to place within their
respective specifications sheets whether the material in question can with
stand the increased solder-float as per UL?
In addition, should not the maximum exposure temp (Td) be higher than 288 to
allow for vagaries of individual processing?
What is your view?
Charlie McMahon
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Valerie St.Cyr
Sent: Monday, December 19, 2005 4:51 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] SV: [TN] Qualification of the Pb-free capable
manufacturers
Inge,
This appears to be a presentation from UL showing what services they
provide to
the electronics industry. Reading between the lines, it appears that they
are saying
that they are increasing their solder float temperature to 288C as a
response to
"industry suggested" - they, UL, did not come up with that number.
There is nothing special about 288C other than it is 550F which is 10%
higher
than 500F, which was the solder float temperature to establish PTH
reliability
in concert with IPC-6012. I don't know the origin of the setting of 500F
value.
So, 288C is 10% higher than 260C, and if you believe that LF assembly
temps will
be up to 260C, then you might want to test to 288C to determine if you
have any
margin in the design/material/fabrication produced PCB.
Werner,
Very few, in fact none so far, of the older or new materials that we have
tested
can get to T288 => 45 minutes; we haven't even tried T320. But unless it
is
polyimide I have a hard time believing it will make =>25 mins. The only
caveat
is that the test is not as "standardized" as having a standard would have
you
believe!
Regards,
Valerie
Ingemar Hernefjord <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
12/14/2005 05:07 PM
Please respond to
TechNet E-Mail Forum <[log in to unmask]>; Please respond to
Ingemar Hernefjord <[log in to unmask]>
To
[log in to unmask]
cc
Subject
[TN] SV: [TN] SV: [TN] Qualification of the Pb-free capable manufacturers
http://www.ul.com/pwb/LeadfreeAndPresentationProceedings.pdf
page 38. what do they point at then?
Inge
-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För Werner Engelmaier
Skickat: den 14 december 2005 20:56
Till: [log in to unmask]
Ämne: Re: [TN] SV: [TN] Qualification of the Pb-free capable
manufacturers
Hi Inge,
I do not know abput UL's proposal, but there are some defined
conditions: T260, T288, T300 & T320 defining temperatures at
which time to delamination is measured up to 45 minutes--I also
do not know who came up with this measure [288°C???]. Standard
FR-4 has a T260 of less thasn 30 minutes and a T288 of less
than 5 minutes, whereas a high Tg/highTd material has a T288
of 45 minutes and a T320 of about 25 minutes.
Werner
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