Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Lead Free Wave Soldering

#29600

Lead Free Wave Soldering | 22 July, 2004

Hi,

Does anyone have experience Or any information regarding Wave Soldering with Lead free alloys ??? - Solderability of SMT glued components & TH solderability and capillarity ? - Bridgind and skiping/opens ? - Solder sorface apearence ? - reaction with PCB SolderMask ?

Roni

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#29603

Lead Free Wave Soldering | 22 July, 2004

Do a search on it there are some old listings of it im sure.

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KEN

#29612

Lead Free Wave Soldering | 22 July, 2004

I have been LF wave soldering for well over a year now.

Yes, yes, no, maybe....What exactly are you looking for?

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#29613

Lead Free Wave Soldering | 22 July, 2004

Notes from an AIM No-Lead Presentation ...

Wave Soldering * May require a higher pot temperature than tin/lead: 255-265*C * May require a change in liquid fluxes to compensate for the poor wetting of some alloys and high thermal stresses of the wave process. * Makes OSP a bad choice for wave soldered boards.

Solder Maintenance * Certain lead-free alloys, such as Sn/Cu, suffer from high copper dissolution rates. * Unfortunately, whether Sn/Cu or Sn/Ag/Cu is implemented for wave soldering, the density of both alloys is less than Sn63/Pb37. Therefore, instead of the intermetallic floating off and easily being removed as when in Sn63/Pb37, the intermetallics sink and are dispersed through the lead-free alloy in the pot. This could result in additional solder maintenance and pot dumps. * The good part of this density issue is: it takes less more expensive solder to fill your pot. [Maybe that's not so good after all, erzit?] * Probably have to watch copper concentration more closely than with SnPb.

Wave Soldering Equipment * Most modern wave solder machines can provide the necessary heat (preheat and wave) for lead-free soldering. * Nitrogen blanket may be required, depending upon the alloy selected. * High-tin alloys rapidly dissolve the materials often used in wave solder equipment. SS pots, nozzles, impellers, etc will need to be replaced with cast iron, titanium, or a special coating. * Wave soldering equipment manufacturers have had success using a Melonite coating over SS. ["Equipment Impacts of Lead Free Wave Soldering" Morris and O�Keefe. APEX 2003] * Converting a SnPb filed cast iron pot to lead-free requires removing the SnPb, then two cycles of filling, running, and removing pure Sn. [Recyclers dream.]

We have no relationship, nor receive benefit from the company referenced above.

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greg york

#29615

Lead Free Wave Soldering | 23 July, 2004

Many trials conducted so far from single sided to Mixed technology dual wave with our LFB227/S 0.3Ag silver Lead free. Results are excellent, some say better than 63/37. One continueing problem though is the age old area of undercured resist and running at 260C pot temp is causing some major concerns. A problem only ever rectified when flux change to low solids rosin then problem is sorted immediately. About time the PWB vendors sorted this issue out. Best regards Greg York Technical Sales Manager BLT Circuit Services Ltd England

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Loz

#29616

Lead Free Wave Soldering | 23 July, 2004

I'd be interested to hear what the PWB vendors have to say about your comments. This is something I have questioned before, but I fail to see how this problem can be proved. Because of all the technicalites of the wave soldering process, it is sometimes easier to attribute blame to the PWB vendors. Their are too many other issues, such as pcb design, solder and flux selection, machine variables, etc that can obviously impact the quality. Blaming the PWB vendors to deflect the issues is an easy way out.

Loz

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teilo

#29654

Lead Free Wave Soldering | 26 July, 2004

We manufacture conversion kits for lead free wave solder machines. We recommend that all component parts be manufactured from grade 1 / 2 Titanium which is far superior to any coatings applied to stainless steel and not as expensive as people think. There are currently seven machines sucessfully in production at Sony Pencoed.

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KEN

#29672

Lead Free Wave Soldering | 26 July, 2004

May I ask why silver in your wave solder bath? This is an interesting debate of "silver or no-silver" at wave solder.

Many thanks for your input.

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#29725

Lead Free Wave Soldering | 28 July, 2004

Found problem many years ago by chemical extraction and IR analysis, produces alarming amounts of plasticizer from under cured or incorrect mix of hardener to liquid photoimageable solder resist. Problems this causes are endless and many things blamed on process or flux is more than often due to this. Just need to speak with good supplier who is capable of testing in this method. One crude but quick test is to wipe PWB with solvent wipe impregnated with Propylene glycol ether this is not a be all end all test but good for indication. Make sure you wipe before and after wave as can sometimes only occur after heat cycle of the solder wave only. We add silver to the Lead free at 0.3% as this increases the flow characteristics considerably compared to 99.3Sn /0.7Cu. Results are excellent you should try it considerably cheaper than 3% Silver. We ran a solder wave continuous 24 hours per day five days per week for seven weeks and got 4.4grams of dross production per hour hope this helps

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