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No solder and solder bridge after Wave solder machine

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#37925

No solder and solder bridge after Wave solder machine | 17 November, 2005

Hi, We have a board with over 100 chips (mixed size) and some long Connector DIP through out Wave solder with many issues of no solder and solder bridge, (using clean flux with bubble fluxer and Kester solder bar). Currently we tried to reduce the defects but can not kill them..Need your helpful advices..

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RDR

#37928

No solder and solder bridge after Wave solder machine | 17 November, 2005

No clean and foam fluxing is not a very good process from my experience. I know that the flux manufacturers claim that they are suitable but I am not sure what "suitable" means. I would bet that you have very inconsistant flux coverage. How often do you check and adjust the solids level in your flux tank during operation?

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Mike

#37933

No solder and solder bridge after Wave solder machine | 17 November, 2005

Hello, Some questions.... Are you running lead free? What alloy? What�s your pot temp at? Temp of the board after preheat? Are you getting any solder in the barrels (<50%)? Do you have Topside preheaters? Conveyor speed? Dwell times for preheat and over the wave? Type of wave? Running a Chip as well? Pallets or bare boards? Lots of copper in this board? Is it over .090" thick?

Answers to these will help narrow down the issue.

Mike

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#37951

No solder and solder bridge after Wave solder machine | 17 November, 2005

Hi Russ, We control the gravity of flux each 8 hours and will mix thinner to balance it if any.. Do we need more any action for this.. Thanks for your advices.

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#37953

No solder and solder bridge after Wave solder machine | 17 November, 2005

Morning Mike, We use Pb63/Sn37, Alpha Metal alloy. Solder pot is at 250 C. The profile of board after Preheat about 100 C, Lambda Wave about 220C (use both Lambda and Chip wave), DWell time 2.1s ~ 3s. Conveyor speed 1.5 in/min. We run by bare board and not use topside preheater. Board thickness is .062" and have a little of copper in board.. Pls. give me your advices.. Thanks.. Cang

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C. Kolokoy

#37954

No solder and solder bridge after Wave solder machine | 17 November, 2005

With DIP type components, a sub-par fluxing method (foaming a no-clean), and a chip wave where one is not needed are formulas for bridging and insufficient wetting. If you have SMD's on the wave solder side of the board greater than 0603, and no SOT23's, and all SMD's in the "correct" orientation whereby both pads and terminations are hitting the wave at the same time, hence no shadowing of your SMT devices, you may be able to do without a chip wave. Sometimes the chipwave CREATES shorts because your flux activator has already been burned off at the chip wave and there is a minimal amount left to obtain ideal wetting conditions, as well as "cleanup" and peelback from the main wave. Personally, I've had poor results at the wave, with a similar situation like yours with the older Kester (circa 1990) formulations. Hence, another solution, if you absolutely must use a chip wave, would be a flux change - try to use a newer chemistry with better activators, like Carboxylic acid, and fluxes with more surfactants content. If your budget permits, switch to spray fluxing as well to get a better and more controlled flux deposition and eliminate the need for titration and specific gravity checks.

Other things worth trying to mitigate solder bridging - slow down the conveyor speed a bit to reduce contact length. These variables are directly proportional, but at the same time, reduce your pump speed to get the same dwell time. If possible, measure the dwell at both Chip and Lambda waves if you have a profiling device. General paramaters which yield good results - about 0.5 s at the Chip wave and 1.5 - 2 seconds at the main wave. Wave Soldering is an artform, my friend, and knowledge of the Physics and Chemistry behind the process and all the variable interactions will help you a long way. Best of luck....

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#37978

No solder and solder bridge after Wave solder machine | 18 November, 2005

This is way too long of a time. The SG probably changes significantly over this time. This could be a major contributor to your problems.

Jerry

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#38009

No solder and solder bridge after Wave solder machine | 21 November, 2005

Go to this link for a nice tool for wave solder process troubleshooting:

http://www.speedlinetech.com/news_publications/application-notes.aspx?OnId=5

Look for "Wave Solder Troubleshooting Wizard"

If you have an Electrovert machine, contact applications support out of the factory +1-573-346-3341.

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