ask Ablestik about the extrusion rate of the paste...jk
At 10:07 AM 8/18/99 +0200, you wrote:
>Good Day to all,
>and also Paul: don't be sullen, I said 'Honeywell' not 'Honey'. So I
>didn't button up someone, indeed they call themselves Honeywell, small,
>little known company. End of joking.
>
>I thank you Paul for your most superiour aid. Drs Dot will be taken
>seriously. I also got following advice from another senior in the game:
>
>- use a V-grove plate for size distribution test of silver flakes. He
>said that flakes as large as 50-80um is not acceptable if the syringe is
>only 200um on inside. Even as far as 6sigma, no large flakes are
>allowed, they are a risk.
>
>- today's syringe (Camelot) is a medecin needle, cut and pressed into a
>machined steel part, that is mounted on the pump. The interface between
>the cut needle and this steel part creates a mechanical step that can be
>a silver particle trap, says same senior. He said that simple syringes
>for hand dispensing are better, because they are polished on inside.
>Anyone who knows?
>
>- another guru advice was to wash out the silver paste particles in a
>solvent, and take photos on the dry flakes. The dry geometric
>configuration is important: too flat flakes will clogg easier between
>the auger and the pumphouse wall, especially sensitive are silver flakes
>because they are so soft. Such a work will get the paste maker to the
>door in two minutes, he said.
>
>- I also have a thought about the auger: what's the meaning with that
>part? To make wanted portions (dots) of paste or to just keep the paste
>in good condition? For making extremly small dots, diameter 300um, it
>seems to me that the screw rotation is not in proportion to the
>dispensed amount of paste. Isn't it in fact the air pulse that decides
>the dot?
>
>- Camelot are not very alert to assist and explain, says the machine
>responsible at our plant, but Ablestik are rapid and helpful, blessed
>they are.
>
>We are now gathering these facts of process importance:
>
>- flake size
>- flake geometry
>- viscosity
>- friction caused temperature rise on tip
>- friction caused wear of pumpwalls and screw
>- paste humidity (humidity accelerated local curing)
>- paste temperature
>- screw material
>- depth of threads
>- pumphouse material
>- pressure
>- space between screw and house
>- screw and house polishing conditions
>- screw rotation speed
>- tip contact with board (building up local heat)
>- syringe inside surface
>- syringe-to-interface mechanical steps (flake traps)
>- paste sedimentation
>- paste mixing conditions
>- using of day-and-night paste syringe rollers?
>- fluid separation due to locally clogged-together flakes
>- dwell time (wetting)contact with the chip mounting pad
>- shape of paste drop hanging on tip when lifted up.
>- comppressed air content of oil and humidity.
>- adiabatic compression of flakes
>- search for best paste for this application (dot dia = 300um!)
>  Ablestik is said to be one of the best in the game. I myself am
>curious about the japanese pastes.
>- try the needle-dip-into-paste method instead of using a dispenser.
>
>There are possibly a few more, but in the end I think all will be
>reduced to, say 5,  parameters of most importance.
>
>Thanks all netters, especial attention to Paul Aussimeyer (did that
>help?)He-he./
>
>Ingemar Hernefjord
>Ericsson Microwave Systems
>
>##############################################################
>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 Gayatri Sardeshpande at [log in to unmask] or
>847-509-9700 ext.5365
>##############################################################
>

##############################################################
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 Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################