Hi Alvin,
Colin Lea in the UK did quite a bit of work on this in the late 80's--a good
deal of it can be found in his book "A Scientific Guide to Surface Mount
Technology," Electrochemical Publications, 1988.
It is a time/temperature issue--how long before the IMCs grow through the
surface and affect solderability. Yo my knowledge, little has been done in this
regard with LF-solders.
I will touch on some of this in my workshops that I will be giving in
Singapore May 4 & 5--for more detail on this please contact Chua Eng Guan at
www.upstar.com.sg.
Regards,
Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL 32174 USA
Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904
E-mail: [log in to unmask], Website: www.engelmaier.com
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Message-ID: <[log in to unmask]>
Date: Thu, 6 Jan 2005 18:24:24 +0100
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
Daan Terstegge <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
From: Daan Terstegge <[log in to unmask]>
Subject: Re: [TN] HASL solder thickness impact on solderability...
X-To: [log in to unmask]
To: [log in to unmask]
Precedence: list
Hello Alvin,
Lots of good info about HASL can be found via my website at
http://www.smtinfo.net
Just click on the link named "HASL".
Best Regards,
Daan Terstegge
PCB Assembly Department
Thales Land&Joint Systems
Tel: +31(0)35 524 8297
Fax: +31(0)35 524 8181
Unclassified Email
>>> [log in to unmask] 01/06/05 02:06am >>>
hi,
the full title of this msg is: "HASL (hot air solder levelling) solder
thickness impact on solderability with SnPb and Pb-free solder"
i am currently in my 3rd year in a local university in singapore. the
above
named issue is a project that i am supposed to do. due to my lack of
knowledge in this field, i would like to seek the opinions, advice or
help
from the people with expertise here.
the project objectives are as follows:
1) To study the extent of inter-metallic layer on thin HASL coating
thickness and the influence on assembly solderability.
2) To study any implication of lead free HASL as a surface finishing
3) To compare solderability of thick and thin HASL solder thickness
with
both SnPb and PB free solder
i would appreciate any facts, info or links to relevant
articles/reports/journals/magazines pertaining to my scope of the
project.
many thanks!
regards,
alvin
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From: Roger Stoops <[log in to unmask]>
Subject: [TN] Solder Joint Failures after Short-term Vibration
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Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin PQFP processor, after short-term vibration. The board layout and mechanical mounting apparatus were designed with vibration in mind, and have passed vibration testing in the past. The same processor is used on a dozen other assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and heel fillet. The heel fillet is unusually large, and the top of the PQFP lead has a grainy appearance instead of a matte or shiny appearance. Some leads can be pushed off the solder joint with very little pressure. Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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Message-ID: <[log in to unmask]>
Date: Thu, 6 Jan 2005 11:24:07 -0700
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
"Blomberg, Rainer (FL51)" <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
From: "Blomberg, Rainer (FL51)" <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
X-To: TechNet E-Mail Forum <[log in to unmask]>,
Roger Stoops <[log in to unmask]>
To: [log in to unmask]
Precedence: list
Sounds like a brittle joint. Are the leads pre-tinned to remove excess
gold to avoid "gold embrittlement"?
> Rainer G. Blomberg
> Staff Production Engineer
> Space Systems - Clearwater
> Honeywell International, Inc.
> * Phone (727) 539-5534
> * Fax (727) 539-4469
> * Email [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger Stoops
Sent: Thursday, January 06, 2005 1:19 PM
To: [log in to unmask]
Subject: [TN] Solder Joint Failures after Short-term Vibration
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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Date: Thu, 6 Jan 2005 12:27:31 -0600
Reply-To: TechNet E-Mail Forum <[log in to unmask]>, [log in to unmask]
Sender: TechNet <[log in to unmask]>
From: Cheryl Tulkoff <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
X-To: TechNet E-Mail Forum <[log in to unmask]>,
Roger Stoops <[log in to unmask]>
To: [log in to unmask]
In-Reply-To: <[log in to unmask]>
Precedence: list
Roger -
Does this board go through the wave solder process after SMT? You could be
seeing secondary reflow of the SMT joint at the wave. This happens when the
temperature of the wave process is sufficient to remelt topside joints. It
usually happens only on fine pitch QFPs(smaller joints with less solder
volume). To avoid this, most people will run the wave solder temperature
lower (240-250 C rather than 260C) and the conveyor faster (5.5 ft/min or
higher).
I can send more info if you're interested in checking it out.
Thanks,
Cheryl Tulkoff
Phone:(512) 683-8586
Fax: (512) 683-8847
National Instruments
11500 N. Mopac Expressway
Building A
Austin, TX 78759-3504
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
01/06/2005 12:19 [TN] Solder Joint Failures after
PM Short-term Vibration
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM>
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
---------------------------------------------------
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847-615-7100 ext.2815
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Message-ID: <[log in to unmask]>
Date: Thu, 6 Jan 2005 13:33:24 -0500
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
Roger Stoops <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
From: Roger Stoops <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
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No Au, appears to be SnPb (have seen these failures on parts dated from 2001-2002).
Roger
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Blomberg, Rainer
(FL51)
Sent: Thursday, January 06, 2005 1:24 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
Sounds like a brittle joint. Are the leads pre-tinned to remove excess
gold to avoid "gold embrittlement"?
> Rainer G. Blomberg
> Staff Production Engineer
> Space Systems - Clearwater
> Honeywell International, Inc.
> * Phone (727) 539-5534
> * Fax (727) 539-4469
> * Email [log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger Stoops
Sent: Thursday, January 06, 2005 1:19 PM
To: [log in to unmask]
Subject: [TN] Solder Joint Failures after Short-term Vibration
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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From: Louis Dallara <[log in to unmask]>
Organization: Cad Labz
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Does any one know what platforms Mentor Boardstation runs on.
I know it use to be Unix based, but wonder if they have ported it to
Windows?
I could find the info on there web site
TIA
Lou Dallara CID
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Sender: TechNet <[log in to unmask]>
From: "David D. Hillman" <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
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Hi Roger! I recommend having a cross-section completed so you can get a
look at the solder joint/component lead interface to determine the quality
of the solder joint interface/structure. Good Luck.
Dave Hillman
Rockwell Collins
[log in to unmask]
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
01/06/2005 12:19 [TN] Solder Joint Failures after
PM Short-term Vibration
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Roger Stoops
<Roger_Stoops@TRI
MBLE.COM>
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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From [log in to unmask] Thu Jan 6 10:45:07 2005
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Date: Thu, 6 Jan 2005 12:40:04 -0600
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
Kelly Morris <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
From: Kelly Morris <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
To: [log in to unmask]
Precedence: list
Cheryl's point on 2ndary reflow is a good one. I"ve seen this a couple of
times. Also, the fix of changing the wave solder parameters is good too.
Another idea for corrective action, if changing the wave parameters is not
a good choice is to add a thermal barrier to the area under the QFP on the
bottom side of the PCB. Polyimide tape (Kapton) works good for this. A
longer term fix may also be to mask over the vias in that area under the
QFP. The mask can provide enough of a thermal barrier to prevent 2ndary
reflow.
Kelly
On Thu, 6 Jan 2005 12:27:31 -0600, Cheryl Tulkoff <[log in to unmask]>
wrote:
>Roger -
>
>Does this board go through the wave solder process after SMT? You could be
>seeing secondary reflow of the SMT joint at the wave. This happens when the
>temperature of the wave process is sufficient to remelt topside joints. It
>usually happens only on fine pitch QFPs(smaller joints with less solder
>volume). To avoid this, most people will run the wave solder temperature
>lower (240-250 C rather than 260C) and the conveyor faster (5.5 ft/min or
>higher).
>
>I can send more info if you're interested in checking it out.
>
>Thanks,
>
>Cheryl Tulkoff
>Phone:(512) 683-8586
>Fax: (512) 683-8847
>National Instruments
>11500 N. Mopac Expressway
>Building A
>Austin, TX 78759-3504
>
>
>
>
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From: [log in to unmask]
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
X-To: [log in to unmask], [log in to unmask]
To: [log in to unmask]
Precedence: list
Roger,
If this part isn't having problems elsewhere, have you verified the same
pad pattern exists on all PWBs? I am assuming the same automated
soldering process is used on all these other assemblies. Do the other
assemblies see the same levels of vibration? Have you visually verified
the solder joints prior to vibration? Do all of the leads appear to have
this dewetting, or are there specific locations with the issue. If none
of these issues lead you anywhere, it would seem to point back to a
mechanical issue (resonance?) on this particular assembly.
Good luck!
Jim Carlson
Reliability/Quality Engineer
Rockwell Collins
Roger Stoops <[log in to unmask]>
Sent by: TechNet <[log in to unmask]>
01/06/2005 01:19 PM
Please respond to TechNet E-Mail Forum; Please respond to Roger Stoops
To: [log in to unmask]
cc:
Subject: [TN] Solder Joint Failures after Short-term Vibration
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and
mechanical mounting apparatus were designed with vibration in mind, and
have passed vibration testing in the past. The same processor is used on a
dozen other assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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From [log in to unmask] Thu Jan 6 10:58:09 2005
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Thread-Topic: [TN] Solder Joint Failures after Short-term Vibration
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Message-ID: <[log in to unmask]>
Date: Thu, 6 Jan 2005 13:56:34 -0500
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
Roger Stoops <[log in to unmask]>
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From: Roger Stoops <[log in to unmask]>
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
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Sorry I did not provide more parameters...
No wave solder. Process is: 1) Screen paste bottom side. 2) place comps. 3) reflow. 4) screen paste top side. 5) place comps. 6) reflow. 7) clean. (etc, etc.). And the bottom side joints look pretty good.
I do not have more process info such as reflow profile.
And thanks Dave, we will need to have a cross-section FA done to really get at the bottom of this, but I will now be able to put together some specific questions that need to be asked of the EMS.
Have a conference call tonight, means I'll have to tape CSI...
Rgds,
Roger
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Cheryl Tulkoff
Sent: Thursday, January 06, 2005 1:28 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Joint Failures after Short-term Vibration
Roger -
Does this board go through the wave solder process after SMT? You could be
seeing secondary reflow of the SMT joint at the wave. This happens when the
temperature of the wave process is sufficient to remelt topside joints. It
usually happens only on fine pitch QFPs(smaller joints with less solder
volume). To avoid this, most people will run the wave solder temperature
lower (240-250 C rather than 260C) and the conveyor faster (5.5 ft/min or
higher).
I can send more info if you're interested in checking it out.
Thanks,
Cheryl Tulkoff
Phone:(512) 683-8586
Fax: (512) 683-8847
National Instruments
11500 N. Mopac Expressway
Building A
Austin, TX 78759-3504
Hello all,
We are having an ongoing problem with solder joint failures on a 144-pin
PQFP processor, after short-term vibration. The board layout and mechanical
mounting apparatus were designed with vibration in mind, and have passed
vibration testing in the past. The same processor is used on a dozen other
assemblies, none of which have this problem.
The solder joints appear to exhibit dewetting, although there is a toe and
heel fillet. The heel fillet is unusually large, and the top of the PQFP
lead has a grainy appearance instead of a matte or shiny appearance. Some
leads can be pushed off the solder joint with very little pressure.
Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim
that boards meet IPC-A-610 class 2 requirements.
Any ideas as to what may be causing solder joint failures?
Also, any suggestions or recommendations (preferred) for a test house to
provide x-ray, microsection and composition analysis?
TIA & Best Regards,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
Oh, and BTW, changing EMS providers is not an option...
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