Alejandro,
I'm with Russell on this one, about two years ago I also had similar
problems with the plastic film caps from Panasonic, ECHU family. I was able
to contact Panasonic Japan and get samples of the improved "X" version, it
actually help diminish the problem, but it did not go away completely. Two
things causing this as I understand are: one, the component does not heat
evenly because of the polymer, and second the component layers tend to
flake off letting the dielectric out contaminating the terminations. I would
work with the supplier to determine the root cause, but knowing this issue I
bet is a component related problem. We recently had a similar issues with
plastics caps from a particular manufacturer, we took them off the AVL list,
and the problems went away. You said you're having tombstoning on 1206,
that's is not very likely to happen because of the pad design; the two times
that I've been involved with this issue it was across different part numbers
and different component sizes.
Good Luck
Jorge Rodriguez
Process Engineer
Varian, Inc
-----Original Message-----
From: Becerra Alejandro [mailto:[log in to unmask]]
Sent: Tuesday, December 03, 2002 7:10 AM
To: [log in to unmask]
Subject: Re: [TN] Tombstoning Film Chip Capacitor
Russell,
We're using the (B) version, reviewing this information in the web I found
that the (X) version is recommended for reflow only and (B) for Wave and
Reflow.
Do you know what is the difference in construction between (B) and (X)
versions?
I would suggest change the version and footprint.
Regards
Alejandro Becerra
-----Original Message-----
From: Nowland, Russell Howard (Russell) [mailto:[log in to unmask]]
Sent: Tuesday, December 03, 2002 7:04 AM
To: 'TechNet E-Mail Forum.'; Becerra Alejandro
Subject: RE: [TN] Tombstoning Film Chip Capacitor
Alejando,
I had the same problem with the Panasonic ECHU family of thin film
capacitors. I had 142 on my board so you can imagine my frustration. The
problem is the polymer doesn't conduct heat therefore the part doesn't heat
evenly. The part body also does not stand up to heat very well. During
hand soldering you cannot apply much heat to the endcap or the body will
melt. Also, if you are repairing an adjacent component you must be very
careful because the body will easily melt. I don't like the parts but the
circuit designers praise their functionality. I worked with Panasonic and
found that a standard discrete footprint did not work with the part. I
even ran a test vehicle that Panasonic provided to prove that the footprint
is the biggest contributor to the phenomena. They also came out with an
improved endcap on the part but they gave it a new suffix. The original
version was the (C) and the new version has a (X) i.e. ECHU1H152JX5. Using
the (X) version improved the solderability marginally. We then changed to
their recommended footprint, which is in there datasheet, and the problem
went away. There footprint is not much bigger than the endcap on the part.
It is not what I would design but it works. We did not play with the
solderpaste composition by adding 2% silver so, I do not know how much that
will help. Here is the link to the Panasonic (X) version part.
http://www.panasonic.com/industrial/components/pdf/ef029_echu_x_dne.pdf
<http://www.panasonic.com/industrial/components/pdf/ef029_echu_x_dne.pdf>
Good luck,
Russell Nowland
Lucent Technologies
Oklahoma City Works
Phone: (405) 782-7765
Fax: (405) 782-7905
email: [log in to unmask]
-----Original Message-----
From: Becerra Alejandro [mailto:[log in to unmask]]
Sent: Monday, December 02, 2002 7:24 PM
To: [log in to unmask]
Subject: [TN] Tombstoning Film Chip Capacitor
Hello to All,
We have had tombstoning in a Film Chip Capacitor (Size 1206).
It is being soldered in a normal reflow process, and this is the only
component that it is showing tombstoning.
Reviewing the specs. of the component in the web I found that this capacitor
is recommended for Wave Soldering.
Does anyone know the difference in construction between the Capacitors for
Reflow and Wave Soldering?
Is it possible that this be cause for the tombstoning?
I am also sending pictures for cross section for the capacitors that we are
using (Recommended for Wave Soldering).
They could be seen at Steve's site.
Regards
Alejandro Becerra
--------------------------------------------------- Technet Mail List
provided as a free service by IPC using LISTSERV 1.8e 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/html/forum.htm for additional information, or 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 1.8e 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/html/forum.htm for additional information, or 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 1.8e
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
