TECHNET Archives

July 2009

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:
James Mahoney <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, James Mahoney <[log in to unmask]>
Date:
Mon, 27 Jul 2009 09:31:48 -0400
Content-Type:
text/plain
Parts/Attachments:
text/plain (117 lines)
Not a wire bonding person but I would think many things could contribute to
your problem, copper grain direction, poor tear drops to much acrylic
adhesive under the wire bonding area creating a soft point and pressure from
the bonding unit and you need to be careful where the soldermask ends. Any
edge can create problems with flex and thin conductors.
 

www.quickturnflex.com
Thank you, 
Jim Mahoney 
Quick Turn Flex Circuits, LLC 
Applications Project Manager 
P# 603-821-7071
M# 603-305-6250 
** This email and all attachments have been scanned prior to being sent** 
Confidentiality Notice: This page and any accompanying documents contain
information that is confidential, privileged or exempt from disclosure and
is intended for the exclusive use of the addressee. If you are not the
intended recipient, you are hereby notified that any disclosure, copying,
distribution or use of the contents of this information in any manner is
strictly prohibited.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: Monday, July 27, 2009 9:16 AM
To: [log in to unmask]
Subject: Re: [TN] Copper trace shear strength

Are you sure is enig? Not electroless gold for wirebond pad?
--------------------------
Sent using BlackBerry


----- Original Message -----
From: TechNet <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Sent: Mon Jul 27 04:07:37 2009
Subject: [TN] Copper trace shear strength

Dear all,
 
I have a technical question for the "copperheads" out there:
 
I have a Flex-rigid product which has wire bond device attached to the
substrate and subsequently wire bonded to ENIG pads which are 100uM across
connected to an 80uM trace under sodler resist. The solder resist is SMOBC.
This product is experiencing cracking of the pattern to the extent of
creating an open circuit between the trace and bonded pad.
 
The FPCB is BBT'd and passed before final inspection, and delivery to the
assembler, which then fails function test after wire bond and SMT. The
defect can be random pads on the FPCBA, but always a wire bonded pad.
 
Foil used is RA copper foil, panel plated as it's a 3 layer MLB FPCB. I have
suggested that due to lack of ENIG under the resist, we have a "weak"
junction between the pad and solder resist where the copper is less
supported - this is subject to wire bonding pressure, frequency, time and
accompanying temperatures.
 
How do I calculate the shear strength of the pattern junction and work out
the pressure required to create the crack, given the rigid substrate is FR4
(I should also point out that there appears to be a stress fracture going
slightly into the FR4 resin at the crack point seen by microsection.
 
Anyone seen this effect anywhere?


      

---------------------------------------------------
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.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------------------------
This transmission (including any attachments) may contain confidential
information, privileged material (including material protected by the
solicitor-client or other applicable privileges), or constitute non-public
information. Any use of this information by anyone other than the intended
recipient is prohibited. If you have received this transmission in error,
please immediately reply to the sender and delete this information from your
system. Use, dissemination, distribution, or reproduction of this
transmission by unintended recipients is not authorized and may be unlawful.

---------------------------------------------------
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.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------

---------------------------------------------------
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.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------

ATOM RSS1 RSS2