Thanks a lot John , much obliged for the X rated note,
Gaby almost damped me as an white knight, owe you one.
Never believed you'd suggest water jet,
and while i don't rave about likes cab rollers,
i'd say they're lesser of evils out there, being jets or routers.
Custom hydraulic kiss blades are likely best, i'd say,
as they 'stress' most evenly.
Just between us folks,
you can adapt hydraulic clicker press tables used in shoe industry,
for safe and excellent blade drivers .
Paul Klasek
-----Original Message-----
From: John Maxwell [mailto:[log in to unmask]]
Sent: Friday, 2 June 2000 3:14
To: [log in to unmask]
Subject: Re: [TN] V-Score--stress
Hi TechNet,
To be precise I never recommended water jet cutting due to poor through put
and high capitol expense. I have never been an admirer of roller blade
cutting except when I was a consultant and it put my wife and oldest son
most of the way through university. Ceramic capacitors are sensitive to
cracking and becoming more so due to technology trends reducing dielectric
thickness. Isolating parts from PWB edges is still a good idea and
orienting MLCC parts parallel to a PWB edge helps.
As a second note, in a former life I designed transistor structures for
integrated circuits and I have a comment on X-ray. X-rays are ionizing
radiation and can change transistor gate threshold voltages in your
integrated circuits by damaging the gate oxide. As gate oxides get thinner
the problem appears to get worse. I suggest that a call to your silicon
vendors might be in order and ask them to check with their device
designers. Some that I have talked to have expressed real concern if we get
carried away with our X-ray machines. I have one and it is one of many
process development and failure analysis tools.
John Maxwell
At 10:11 AM 6/1/00 -0700, you wrote:
>John Maxwell discouraged using rolling blade shear but recommended water
jet
>cutting for depaneling. Does any body know who makes such water jet
>cutter? Any
>users out there who can share some experience?
>
>Thanks,
>KK Chin
>Artesyn Technologies
>Fremont, CA
>
>
>
>
>Gabriela Bogdan <[log in to unmask]> on 06/01/2000 09:25:55 AM
>
>Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
to
> Gabriela Bogdan <[log in to unmask]>
>
>To: [log in to unmask]
>cc: (bcc: KK Chin)
>
>Subject: Re: [TN] V-Score--stress
>
>
>
>Being one of John Maxwell's "fans" I recommend his articles about design
for
>manufacturability . Concerning chip capacitors, we follow as much as
possible
>the rules
>, and Dwight's comments are in this spirit. Most of the failures we also
>encountered
>were with chip capacitors, and the separation method , the distance from
the
>edge, and
>the orientation of the chip were the culprits, alone or in combination. We
had
>for
>instance one panel with circuits which were manufactured first as single,
then
>as 4 in
>panel. Due to the proximity of the chip cap to the edge, we had failures
after
>separation, and had to change the artwork accordingly.
>Gaby
>
>Dwight Mattix wrote:
>
> > We score many designs. It's a really useful process to optimize panel
> > utilization and sometimes assy tooling/depaneling tradeoffs. However,
our
> > experience here shows your concerns are valid. I suggest the even
bigger
> > concern should be the risk of latent defects that will pass through all
> > your tests and into the field.
> >
> > We've seen the risk to be with ceramic chip components (chip caps et al)
> > within .1 - .2" of the score. The mode is latent ceramic cracking
leading
> > to leakages or outright device failure. Either way the end result is
the
> > same -- field infant mortality.
> >
> > As a result of our experience (read scar tissue -- and some crude long
> > forgotten rel experiments way back in the early 90's dark ages -- Phil
> > Bavaro may have better memory of that) our design rules don't allow
scoring
> > if chip components are within 0.200" of the score. The exception to the
> > rule we sometimes make is when the assembly has shields soldered out to
> > board edge effectively making a box beam that stops/reduces flex of the
> pwb.
> >
> > I'd be real interested to hear what others have learned and design rules
> > they maintain -- esp if there's been some science applied to their
> > establishing their rules.
> >
> > Dwight
> >
> > At 11:01 AM 6/1/00 -0400, Ed Holton wrote:
> > >We have recently started using boards with V-score for the
> panelization and
> > >we have a debate raging here. There is a concern about separating the
> > >boards before versus after the incircuit test and whether there is the
> > >possibility that there is imparted stress to the board that could
create a
> > >failure mechanism that might have been caught at the ICT and not at the
> > >functional test, thus the requirement to singulate before versus after
> ICT.
> > >I have read various articles, but am wondering what people have found
in
> > >the real world.
> > >
> > >Thanks
> > >
> > >Ed Holton
> > >Manufacturing Engineer and Group Leader
> > >Hella Electronics
> > >Telephone (734) 414-0944
> > >Fax (734) 414-0941
> > >
> > >##############################################################
> > >TechNet Mail List 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 web site (http://www.ipc.org/html/forum.htm) for
> additional
> > >information.
> > >If you need assistance - 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 1.8c
> > ##############################################################
> > 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 web site (http://www.ipc.org/html/forum.htm) for
> additional
> > information.
> > If you need assistance - 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 1.8c
>##############################################################
>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 web site (http://www.ipc.org/html/forum.htm) for
additional
>information.
>If you need assistance - 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 1.8c
>##############################################################
>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 web site (http://www.ipc.org/html/forum.htm) for
additional
>information.
>If you need assistance - 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 1.8c
##############################################################
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 web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - 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 1.8c
##############################################################
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 web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
##############################################################
|
