Mime-Version: |
1.0 |
Sender: |
|
X-To: |
|
Date: |
Mon, 5 Oct 1998 16:32:36 +0100 |
Reply-To: |
|
Subject: |
|
From: |
|
In-Reply-To: |
|
Content-Transfer-Encoding: |
7bit |
Content-Type: |
text/plain; charset="iso-8859-1" |
Parts/Attachments: |
|
|
Hi Rick & all
We as a company have experienced the observation you mentioned along
with I guess a million other users. A while ago we carried a
collaborative assembly exercise along with several other companies for
the National Physical Laboratory looking at the effects of using
Palladium coated components.
The results of this exercise are due out at their SSTC autumn meeting
on the 22nd October. Early indications are that the wetting effect or
lack of as the case may be (that cause of the muddy footprint
phenomena) is down to the dissolution rate of Palladium. As with
conventionally coated SnPb components there is a solderable medium
already on the component which melts & merges with the solderpaste
enabling good wetting, all othet things being right.
With Palladium coated components, melting of the Palladium doesn't
occur (it req's >1000C to melt) soldering relies on dissolution of the
Palladium to enable connection to the underlying material. It's a
trade off between a very thin coating of Pd allowing quicker
dissolution against a thicker coating which provides less porosity but
won't allow a good soldering action, either way their isn't sufficient
energy in the paste to provide a similar wetting effect to SnPb coated
components.
Having said all this the interesting fact must be is it a problem wrt
joint failure, the answer to that is wait and see the outcome of the
report - I don't want to steal their thunder!
There are a lot more interesting points noted & spelled out in more
detail in the NPL report so it's probably worth contacting them for a
copy. Try - [log in to unmask]
Regards Iain.
______________________________ Reply Separator _________________________________
Subject: [TN] Soldering Palladium plated leads
Author: rthompson ([log in to unmask]) at Internet
Date: 10/2/98 3:39 PM
*** WARNING ***
This mail has originated outside your organization,
either from an external partner or the Global Internet.
Keep this in mind if you answer this message.
Hi,
With all the current discussion of solderability issues, I'm hoping some of
you may be able to apply your expertise and give me some insight into a
problem we seem to consistently have. When soldering components with
palladium plated leads, we do not seem to get any wetting on the leads. It
kind of looks like the 'footprint in mud' affect. On pcb's where we have
this condition, all other components have soldered fine with good fillets and
wetting. Checks of the oven profile indicate a good profile for the paste
we're using (Kester R598, water soluble). Currently we've only found this on
components from TI, so I don't know if it's only their components or the
plating in general.
Question: Are there any recommendations for profile, paste, process, etc.
that differ from 'standards' when working with these types of components?
Thanks.
Rick Thompson
Ventura Electronics Assembly
2665A Park Center Dr.
Simi Valley, CA 93065
[log in to unmask]
(805) 584-9858 voice
(805) 584-1529 fax
################################################################
TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for
additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700
ext.312
################################################################
################################################################
TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################
|
|
|