| | | Has anyone had trouble waving and gluing 0603 R's and C's? At my company, our designers have "opened the floodgates" on bottom-side 0603's. | | | | | | We've got an EPK+ with rotary chip and omega wave but can't seem to get skip-free soldering on these guys. Often times, we find glue that's migrated to the pads, as well, and these parts aren't friendly with our glue process either. | | | | | CK | | | | Glueing 0603's, eh? Major pain in the butt. The rotary chip wave is capable of slapping solder on them. It may help if you turn up the RPM's on the rotary shaft to attenuate the activity a little bit. | | | | My guess is that the problem lies more with the glue process than the wave. It's hard to get good dots large enough to provide adhesion but small enough to stay off the pads. What type of adhesive dispensing are you using? Positive displacement pump, time/pressure syringes, or stenciling? Stenciling "dogbones" for these will be your best bet, followed by a diplacement pump, and heaven help you if you are using time/pressure. | | | | If you are unlucky enough to be using time/pressure, let me know and I'll email you an article on how to get the best possible performance out of this all-too-common dinosaur. | | | | Chrys | | | | | Chrys: | | We've got the rotary chip at full blast (300 RPM's)!! I've studied the parts under a high powered camera and found some of the skipped parts with glue on the pads, and some skipped parts with NO GLUE on the pads.....so, we can't say that it's the glue 100% of the time...we've also got an omega wave running at full blast as well!!! | | One of our self-proclaimed "gurus" here thought that we had a weak flux...currently we are using alpha 351 alcohol based no-clean, but as i mentioned to you before we're looking into voc-free, with alpha nr310b as one of the top candidates. | | Surprisingly enough, ever since the addition of an omega wave, we solder those often-troublesome SOT23's just fine and dandy.. anyways, long-term, well be getting a universal GDM which uses positive displacement pumps..currently we're using fuji gl's time/pressure pumps... hopefully gdm will cure some of our problems with these little fellas.. | | | Hey CK,
(Not trying to oversimplify or anything, but) It takes three things to make a solder joint: Flux, Heat, and Solder. If you're missing any one of those three, you don't get a solder joint.
When there's glue on the pad, it's easy to determine that the missing component is solder. When there's not glue on the pad, it's time to look elsewhere. Given that the rotary chip is at 300 RPM, let's assume there's plenty of solder available for anything that's fluxed and hot. If it's an EPK +, there's convection preheat, so I'll assume that heat ain't the missing element, either.
So that brings us to flux. The alpha 351 is a good product, but the 310B is AMAZING. It's the only thing that I can get to solder my dog-boards. These puppies have bare copper pads with a cheap Entek knockoff on them and have been sitting on the shelf for well over a year in open packages.
So what makes the 310B so great? Well, it's got a couple of good things going for it: - Water based. Water ionizes better than alcohol, so it is by nature more active. The water carrier doesn't evaporate as quickly as alcohol, so the carrier can get spread into the nooks and crannies and up into holes to get the activators where they need to be before it dries up. - Thermal stability. This "new generation" of wave fluxes has a longer thermal stability than its predecessors, so it doesn't get exhuasted by the chip wave or too much preheat. - Stonger activators. I forget, off the top of my head, which acid this contains and why it is stronger than the alcohol-based fluxes, and since I'm at home right now I can't just whip out the data sheet and look it up, so you'll have to take my word for it.
So, in a nutshell, the stronger flux should definitely help you. In no case can it hurt you, except that you may have to verify your profile to avoid the snap, crackle, and pop when you make wave contact.
The other area to investigate is the fluxer. Have you verified good distribution from your fluxer? A quick & dirty test is to sandwich some thermal fax paper between two boards. Flux them, pull them out, and look at the paper. Alcohol turns the paper varying shades of gray, depending on how much alcohol is on the paper. You can do this to verify that there are no skips or light area in your flux pattern.
Good luck!
Chrys
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