Electronics Forum: stencil (Page 405 of 540)

Re: Tombstoning

Electronics Forum | Tue Dec 21 19:57:45 EST 1999 | Russ

All of the information so far has been great, I would like to add one more thing to the puzzle. We have utilized a "homeplate" aperture on the stencil when the pad geometry or PCB design prohibits all of the above mentioned remedies. The hompeplat

Solder Wetting

Electronics Forum | Tue Dec 14 12:00:34 EST 1999 | Kris Wiederhold

We recently reduced our standard aperture reduction to aid in the reduction of solder on gold defects. Since this reduction in aperture size, we have been experiencing exposed copper at the end of the component pads. The heel and toe joints are per

D-Pak misalignment Problem

Electronics Forum | Thu Dec 02 23:43:23 EST 1999 | Kantesh Doss

We have a serious misalignment problem of D-Pak components (Specifically Motorola's part number MJD-3055/MJD-2955)following reflow soldering process. We are using Alpha Metals UP78 solder paste. Our reflow oven is Nitrogen inerted and our oxygen leve

Re: PCB Support

Electronics Forum | Tue Dec 07 22:13:43 EST 1999 | sin

Like Wolfgang said, the breakaway tab is just another bar added to the edge of the pcb. This breakaway tab can be added by the FAB house in addition of extra cost...You can write DFM for your customer to see if they will pay for the cost or not...if

Re: Info. on Stencil cleaners

Electronics Forum | Mon Nov 29 11:37:51 EST 1999 | cpitarys

Hello Jason, I will look for the best price and service support to start. Also request an in house trial at the vendor. Jason, are you looking to remove a no clean paste or water soluble paste? Single Chamber Equipment: Most stencil cleaners opera

Re: Gold embrittlement

Electronics Forum | Fri Nov 12 16:27:43 EST 1999 | Michael Allen

The papers I've read suggest that we need to be concerned if the weight percent of gold in the finished joint exceeds 3%. You might want to do the calculations to see where you stand, before you set up a process to "tin" the leads. If you find that

Re: Solder Balls

Electronics Forum | Thu Nov 11 14:55:23 EST 1999 | Dave F

Dave: I think you�re correct. The solder balls are probably from either: � Excessive paste � OR � Paste "exploding/popping" during reflow � OR � Some other variable. Two things: 1 It�s virtually impossible to determine the cause of your ball gen

Re: paste release from stencil, and volume calculation

Electronics Forum | Mon Nov 15 12:13:41 EST 1999 | Dave F

Steve: There are guidelines for determining if your aperture has the correct proportions to the foil thickness. Maybe that�s what you�re looking for: 1 Aspect ratio = aperture width/foil thickness Chemically etched SB GT 1.5 Laser cut SB GT 1.2

Re: Solder on gold fingers

Electronics Forum | Thu Oct 28 18:14:51 EDT 1999 | John Thorup

Try looking for paste contamination somewhere. Dirty stencil, printer table or fixtures. Placement table/fixtures. Reflow belt/conveyer. Reuseable finger covers, if used. Try covering the fingers with Kapton tape during different stages of the proc

Re: PCBA First Article in production

Electronics Forum | Thu Oct 28 12:02:13 EDT 1999 | John Thorup

Automation and low cost is an oxymoron sort of like jumbo shrimp. Automation will set you back $20,000-100,000. Optical comparitors aren't cheap either. Low cost means good eyeballs, a "golden" sample board and up-to-date documentation. Also low c


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