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wave soldering and solder bridge

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#52909

wave soldering and solder bridge | 17 December, 2007

Hi,

I have a lot of solder bridge in our wave soldering process.We use SACX0307 and Surf 11 flux.the SW mashine is Vitronics delta 6622.Itry to change flux and termoprofile but results is not god.Can you halp me - recommend me some flux or other advice what I can do.

Regards,

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#52920

wave soldering and solder bridge | 17 December, 2007

First of all, more info is needed. Solder shorts can be caused by much more than flux. Is the solder short always in the same spot or all over the place? More detail please.

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#52922

wave soldering and solder bridge | 17 December, 2007

I recently had the same problems, solder bridges on every thing I made, different customers boards, etc. I wave with no-clean flux. As I sorted out problems (pin holes, blow holes, splatter, etc.) I found a lot of variable factors.

I changed flux, went more aggresive. It improved solderability significantly.(even improved top solder where all other efforts failed. I found with parts on the shelf too long that oxidation occurred. I found that component tinning (under 50x microscope) was poor.(Supplier problem). I found solder tail lengths on connectors are too long, lead protrusion caused the same defect repeatably. There are generic parts made, one size fits all. That does not always work.

Use SPC defect data collection by assembly, location, defect type. Pareto results. Be sure to differentiate from SMT and through hole. I follow IPC-9261A and also IPC-7921A. They are both for DPMO (defects per million opportunities), you can trend chart PPM, also use collected data for Pareto (top ten defects per assembly).

Contact me for excel spread sheet format. I can help get you started if you do not collect data.

DaveF- chime in if I missed sumtin, I know you have much more. Happy Holidays to you and the wife. Got some Californy spill with your name on it if you ever get to Vegas.

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#52923

wave soldering and solder bridge | 17 December, 2007

5 Steps to Eliminate Bridges:

1. Establish (wave) Parallelism First and foremost, you must establish board-to-wave parallelism. This is the prerequisite to any wave solder process control. For an understanding of the power of this approach go to http://www.WaveSoldering.com/WSO/Parallelism.htm. Remember, you must establish parallelism from -0.2 seconds to +0.2 seconds based on your left and right dwell times. Disparallelism causes bridging!

2. The Secret Technique of Marking Your Fingers All our best customers are using this simple technique. It eliminates your fingers as a variable in your board quality. Parallelism readings that are taken in the context of this technique are meaningful and helpful; parallelism readings taken outside of this framework are not reliable. Affix the special finger marking stickers to your wave machine today. Use them right away and call us if you have any questions. Full implementation of steps one and two can immediately reduce a significant amount of your bridging.

3. Control Immersion Depth For the significant amount of bridging that may remain, the next step is to measure and control immersion depth. Too deep an immersion depth causes bridging; too shallow causes insufficients. In general, for 62 mil thick boards you'll want an immersion depth reading from 36 to 48 mil. Remember, immersion depth is not wave height, lead clearance or pump speed. Also, immersion depth variation directly changes your dwell time. A shallower immersion depth produces a shorter dwell time while a deeper immersion depth produces a longer dwell time. To ensure repeatability, are you verifying your immersion depth by measuring it every shift and with every board changeover?

4. Optimize Dwell Time This is the single most powerful process technique in wave soldering! After steps 1, 2 and 3 you are ready to optimize your dwell times by board type. Too long a dwell time causes bridging. To reduce bridging, shorten your dwell time by increasing your conveyor speed. This is simple, quick and immediately makes your life easier. Go to http://www.WaveSoldering.com/WSO/DwellTime.htm for background and procedures. Dwell time is the time each lead is in your wave, not the amount of time a board is in the wave. And remember, your dwell time is directly determined not only by your conveyor speed, but also by your immersion depth, contact length and wave shape. Have you identified the best dwell time for each board type that you assemble, and do you verify optimal dwell times every shift?

5. Improve Solder Conditions Your solder conditions are a factor in your bridging. One condition is dross, which on its own can cause bridging. Another condition is the viscosity of your solder. Adjusting your solder temperature can reduce bridging. Your solder temperature should be independently measured every shift.

� Technology Information Corporation 2003 (240) 221-0590

Some others are:

1. Component orientation- DIP leads should hit wave parallel, not perpendicular 2. Flux deposit- not enough, not uniform 3. Excessive dross in wave 4. Contaminated of solder, PWBs or components 5. Solder temp too low 6. Preheaters too low or too high 7. Improper board handling 8. Conveyor angle- 5, 6 or 7 degree

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#52929

wave soldering and solder bridge | 17 December, 2007

I made my own wave measuring device using KIC2000 system. KIC2000 has automatic wave detection, so now I have a profiler for both reflow ovens and wave solder. The delmat carrier only cost $500. A guy, Samir, from this forum gave me the idea, actually (thanks dude!)..So, if you have a profiler already in your shop, you too, can do this.

Getting back to your solder shorts, try slowing down the conveyor speed (DON'T SPEED IT UP). It causes your wave to have less contact length per unit time, and better peelback.

I base this theory on my "hands-on" experience with wave process troubleshooting.

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#52930

wave soldering and solder bridge | 17 December, 2007

This is funny. Poeple giving answers to a question that isn't specific. What if the shorts he is having are on the top of his board, caused by flooding or Omega wave too high?

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#52931

wave soldering and solder bridge | 17 December, 2007

Blew chunks - thanx for thinking outside the box. Of course there's two sides to every story. Just last week I had a new operator "splash" a couple of boards. Top solder was great, it was all one big solder bridge. Come to find out, the operator forgot to fine tune the conveyor width (we got old tweaked fingers, new ones are "in the mail", yeah right).

So I hung the "solder bridge" splashed board over the wave - labeled it "Titanic"

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#52932

wave soldering and solder bridge | 17 December, 2007

Ha-ha-ha-ha-ha,me lad. Wave solder is like an onion, it's got many many layers. Kind of like me-self. I'm a big ogre with many complex layers.

At any rate i like the other colleague with his adverstising trigger finger. by golly, me chap, he's almost as bad as that other fella toutin' his stuff on ebay. i bet ya he has that verbiage on some word document somewheres and copies and pastes at will or at least when there is some wave solder jargon on this here net.

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#52936

wave soldering and solder bridge | 17 December, 2007

As someone with a LOT of experience with the "low cost" alternative alloys, primarily SACX, I have one simple question....Are these shorts a new phenomena? WAS your process in control, and all of a sudden it's not? If the answer is YES, take a look at your dross...is it a fine black powder, or is it "chunky" and full of metal? Chunky and full of metal??? Get some SACX additive pellets from your supplier. This replenishes the X factor in the alloy, and brings the process back under control. Before everyone starts in on me...the SN100C has elemental additives also, which need occasional replenishment. There is a REASON the industry looks for an L J-STD classification in fluxes!! More aggressive flux is not the answer if you had a good process...The possible repercussions just make me SHIVER and look for somewhere to hide before the customer returns go off the scale!!

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#52940

wave soldering and solder bridge | 17 December, 2007

Thanks bud. Merry Christmas and happy holidays to all.

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