At a previous employer, we solved our fiducial recognition problems by glassing over the fiducials. This cut down the glare and increased contrast. Worked better with blue than green for us. I was using a Contact 3S at the time.

All ceramic boards were fixtured on simple "in-house" made quick adjustable [magnetic] pallets.

Also there is difficulty in rework, it is necessary to use a hotplate to pre-heat the substrate prior to rework. We preheated substrates to about 100 - 105 C before reworking.

Don't expect nice and shiny solder joints if you are using a convection reflow oven (we used a heller 1088). They always came out a little dull. What did make really nice solder joints though was using a conduction oven (Sikama Falcon 5C). [Note: I was severely disappointed with the poor manufacturing of the Sikama but it worked great. Maybe by now they've got their act together.]

Also, I found through experimentation with the 5c oven that very short reflow times (9-16 sec as I recall) produced the best solder joints. As I recall this was true regardless of the curve of the reflow profile. The joints would look great on the outside, but if you cut them open they would be hollow or full of pinholes.

Feel free to email direct for more info.

Best of luck, keep us up to date on your progress.

-Dave Ratte


David Ratte
Mfg/Process Engineer
Superior Circuit Technologies, Inc.
Tel  (407) 733-7021
Fax (407) 733-7118
[log in to unmask]
http://www.superiorcircuits.com



Hi Rick!

Just some thoughts from the equipment aspect...

- Fiducial recognition on some machines may be a problem because there
is not high contrast between the white ceramic and the metal fiducial.
- Depending on the quantities you need to run, if the substrates are run
directly on machine rails, you might see some premature wear on aluminum
rails.  Boards can be fixtured.
- Regarding rail conveyance...what is paste and part clearance on the
edge of the boards?  Will the way your machines convey and secure
substrates interfere with edge clearance?  (Might they chip, snap, or
crack the substrate?)  Again, boards can be fixtured to overcome this
problem.

Good luck!
Enza Hill

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