TECHNET Archives

March 2011

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:
Mike Fenner <[log in to unmask]>
Reply To:
Date:
Mon, 28 Mar 2011 14:50:58 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (139 lines)
I am not a process engineer so I give you the below pending their responses.

Placing the component at different heights won't do anything as that will
not change the component and pad wetting when the solder joined is formed
and that is what primarily determines overall joint volume and shape. You
could try reducing pad size so that the overall height of solder is greater
by having a smaller footprint, but this runs risk of solder balling/beading
off the pad. (Or printing extra solder to existing pad to give same effect).
An alternate might be to use a blob of SMT adhesive (of the type used for
bonding components prior to wave soldering to give a stand off. 
What is the height you are achieving now and why do you think extra height
is necessary might be better questions to address before doing any of this
though. Also I am sure other Technetters will want to know about actual pad
sizes, aperture reduction and stuff like that, so you might want to start
doing a little researching.

Regards
 
 
Mike-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Thayer, Wayne - IIW
Sent: Monday, March 28, 2011 1:53 PM
To: [log in to unmask]
Subject: Re: [TN] Solder Joint Height Control

Hi Dale-

I've responded with a different subject name because that is how TechNet
keeps track of the threads.

I think you're doomed without a process engineer, because I don't believe
there is a fixed answer to your query.  The simple approach is to "try" a
thicker stencil, but frequently that makes no difference with a big heavy
part having only 2 leads.  So you may have to put something underneath to
get a required joint height.  That's really complex because it would be
simple to put something beneath there that destroys reliability.  Someone
used to make a spacer for apps like that which dissolved in the
post-soldering cleaning process, but I haven't used them in the last 20
years, so I can't tell you where to find them.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dale Hart
Sent: Monday, March 28, 2011 8:36 AM
To: [log in to unmask]
Subject: [TN]

Technet Folks

 I'm not a process engineer, sooo how would one go about increasing the
solder
joint height (G dimension) under a component.  The company's components
generally have a height of 10 -20 um.  The screen thickness is 6 mils.  The
solder is 62Sn 36Pb 2Ag not sure about the flux, particle size, storage time
between printing, pick and place, and convection reflow, if that is
important.
The chip resistors are about 2012, caps 3225, with SOP16 (copper lead
frames).
Didn't actually measure the pad size but visually they appear properly sized
for
the various components.  The pick n place machine is an older type that uses
a
spring loaded head and they program each component height into the machine.

Dale Hart
Universal Technology Corporation

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------

This e-mail and any files transmitted with it may be proprietary and are
intended solely for the use of the individual or entity to whom they are
addressed. If you have received this e-mail in error please notify the
sender.
Please note that any views or opinions presented in this e-mail are solely
those of the author and do not necessarily represent those of ITT
Corporation. The recipient should check this e-mail and any attachments for
the presence of viruses. ITT accepts no liability for any damage caused by
any virus transmitted by this e-mail.

______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site
http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100
ext.2815
-----------------------------------------------------


***This email, its content, and any files transmitted with it, are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient, please contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination, or other use of, or taking of any action in reliance upon this information by persons or entities other than the intended recipient is prohibited.

Messages sent via this medium may be subjected to delays, non-delivery, and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. Indium Corporation does not accept responsibility for changes made to this email after it was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.***


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/ContentPage.aspx?Pageid=E-mail-Forums for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2