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 ##############################################################