TECHNET Archives

August 2000

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 29 Aug 2000 07:10:52 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (188 lines)
Hi Bing! I suggest you determine if the IC leads have a solderability
problem or if your reflow recipe is incorrect. The JSTD-002A contains the
test method you need - the surface mount simulation test (method S). The
reader's digest version of the method is to stencil a solderpaste print of
the IC footprint on a nonsolderable sheet (teflon or stainless steel or
aluminum), place the IC on the print, and run the sheet through the reflow
oven. If the leads are solderable then the solder paste should wet the
leads. If the leads wet then you should review your assembly reflow recipe
for problems - just changing to a more active flux doesn't tell you what
the root cause of the issue is. Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]




Milanie Racuya <[log in to unmask]>@IPC.ORG> on 08/25/2000 10:53:10 PM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Milanie Racuya <[log in to unmask]>

Sent by:  TechNet <[log in to unmask]>


To:   [log in to unmask]
cc:

Subject:  Re: [TN] SIR Interpretation


Hi guys,
Regarding this process of getting rid of oxides on IC leads with the
help of ultra-high activated flux on the solder paste-is this an
effective move? We are experiencing unsoldered joint on our IC leads. We
have adjusted a lot on our reflow profile, within specs solder paste
height and good solder printing but still we experience unsoldered
joints. We are suspecting it on the solder plating of the IC's but we
don't have the means of testing the degree of solder plating.
Should you advice me to change paste? I have tried same paste but with a
higher flux activation level but still unsoldered joint occurs. Even
tried another type and so far, initial results are better. Does this
mean that the paste is not compatible with our existing process??? or
materials???
I need helllppp!!!

Thanks,
Bing

Brunker Ed wrote:

> No it's no coincidence.
> Soldering is a nasty process. High flux activity means low soldering
> defects. The flux is doing a job, breaking up barriers which would
> prevent
> wetting. The more aggressive tyhe flux the better it will break up the
>
> oxides on the surfaces. The issue is what are the implications for the
> long
> term life of the assembly. Many assembly locations don't even consider
> this,
> the DPMO is the bottom line. (Probably aren't monitoring that anyway).
>
> Anyway, life is a balance. These figures fall nicely in the range
> where you
> will have good soldering but still be reasonable for long term
> reliability.
> Who is your customer, what is the application? Do we really need
> XE+10?
> Regards
> Ed Brunker
> Principal Process Engineer
> Sendo
>
> -----Original Message-----
> From: Amanda.Mountain [mailto:[log in to unmask]]
> Sent: Thursday, August 24, 2000 2:41 PM
> To: [log in to unmask]
> Subject: [TN] SIR Interpretation
>
> Hi all.  I'm hoping to pull on the experience on this list...
>
> Performing a flux evaluation, we performed SIR tests with 8 different
> conditions (4 fluxes, 2 temperatures).  The IPC coupons were processed
>
> through our wave soldering/spray fluxing process, doing our best to
> simulate
> regular production.  The fluxes we are evaluating are all VOC free/no
> clean/water soluble/low solids/low residue fluxes.
>
> The test was performed to Bellcore standards.
>
> The SIR results we received were lower than expected - ranging from
> 2.74E+9
> to 4.27E+10.   The pass value assigned by the laboratory is 3.2E+10.
> Only 3
> of 32 samples actually passed this standard.  6 of the 32 samples
> passed the
> Bellcore minimum value (2.0E+10).  What sort of implications can we
> expect
> with selecting a flux with slightly lower SIR results than the minimum
>
> value?  Each of the flux vendors provided their own passing SIR test
> results.
>
> One other thing that was noted was that the boards with the fewest
> defects
> came back with the poorest SIR results, and vice versa.  Is this just
> a
> coincidence, or is there a solid explanation for this?
>
> Thanks in advance,
>
> Amanda Mountain
>
> Amanda Mountain
> Process Engineering
> Leitch Technology International Inc.
> Phone: (416) 445-9640 ext. 3852
> Fax:  (416) 445-7927
> http://www.leitch.com/
>
> ##############################################################
> TechNet Mail List 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 TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional
> information.
> If you need assistance - contact Keach Sasamori at [log in to unmask] or
> 847-509-9700 ext.5315
> ##############################################################
>
> ##############################################################
> TechNet Mail List 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 TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
> additional
> information.
> If you need assistance - contact Keach Sasamori at [log in to unmask] or
> 847-509-9700 ext.5315
> ##############################################################

##############################################################
TechNet Mail List 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 TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################

##############################################################
TechNet Mail List 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 TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################

ATOM RSS1 RSS2