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Leaded and Lead-Free Wave Parameters

Views: 4109

#54828

Leaded and Lead-Free Wave Parameters | 21 May, 2008

Good morning gentlemen,

I could use some advise as to the min / max windows for the wave process.

We have had little problems with our leaded wave but when applying the same process to lead-free wave we are having problems. Obvisouly the temps are hotter, but the real issue is the process windows are so much tighter.

SO i believe our leaded wave is riding towards the edges of the wide process window but still OK. However when we applied these same ideas to the leaded wave we are obviously outisde the process window.

Could I have someone help with standard wave process windows.

Leaded: Dwell Time is? Top side board temp max? If some small SMT parts reflow are we too hot?

Lead Free: Dwell time is? Top side board temp peak?

If the perheats are OK, but the topside has any reflow it must mean our dwell times are too long.... correct?

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#54832

Leaded and Lead-Free Wave Parameters | 21 May, 2008

Here's what I've seen for no-clean flux applications:

Leaded:

Dwell Time is? 2 - 3 seconds

Top side board temp max? If some small SMT parts reflow are we too hot? 110 to 120C top side board temp just before hitting the wave(s)

Pot temp. 245C

Lead Free:

Dwell time is? 4 to 6 seconds

Top side board temp peak? 150 to 170C top side board temp just prior to hitting the wave(s)

Water Based No-Clean fluxes have performed better from my experience- they can survive the elevated preheat temps better than IPA based.

Pot temp. 262C

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#54833

Leaded and Lead-Free Wave Parameters | 21 May, 2008

"Good morning gentlemen"

Oh my. I may have to pull up a chair with some popcorn for this one.

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#54834

Leaded and Lead-Free Wave Parameters | 21 May, 2008

I was going to say something - but decided to let it go.

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#54835

Leaded and Lead-Free Wave Parameters | 21 May, 2008

Wow RealChunks!

What happened to that firey b#tchey Asian temper of yours? :-) Speak your mind and forever hold your peace!

Here's what I know about Lead-Free Wave Soldering:

1.) Hotter pot 2.) Longer dwells

Good info. on fluxes, by the way.

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#54845

Leaded and Lead-Free Wave Parameters | 22 May, 2008

buzzkill.

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#54846

Leaded and Lead-Free Wave Parameters | 22 May, 2008

#54847

Leaded and Lead-Free Wave Parameters | 22 May, 2008

So here is my problem with the info you gave.

If my preheat topside max is 150 - 170 C but my flux calls out a topside temp of 93 - 104 C.....

....Im pretty much up a creek becuase of a poor flux choice?

FYI. we are using the Indium 3590-TX for both our leaded and leadfree.

FYI#2 I've called Indium's App Eningeers about 4 times without a reply so you guys are the be all end all atm. Any insight as to anyone using this flux for leadfee wave?

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#54849

Leaded and Lead-Free Wave Parameters | 22 May, 2008

Does your top-side preheat NEED to be that high, and so high that you are exceeding the flux manufacturers' spec? If so, what is the reason? Top-side wetting? Are you measuring this temperature at the substrate or solder joint?

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#54850

Leaded and Lead-Free Wave Parameters | 22 May, 2008

I'm not b*tchy. You "guys" are too sensitive. I took my HR training and now know how fragile you "guys" all are. It's not your fault, it was my fault and I learned to deal with it. Go pop some popcorn.

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#54852

Leaded and Lead-Free Wave Parameters | 22 May, 2008

Indium got back to me with the attached PDF.

I always assumed, that in order to avoid thermal shock, there could not be any more than 80 degrees C difference between the solder pot and the pre-heated board.

However, it would seem that any thing less than 140 degrees C is completely acceptable when considering thermal shock. The 80 degree limit is probably the top side board temp spike limit as it passes over teh wave. So if my Pot is 260 degrees C my preheat can be as low as 120 degrees C as long as the board topside temp doesnt spike higher than 80 degrees C?

Also the Indium 3590-TX spec sheet states a board topside temp of 93 - 104 degrees C. This would apparently be the minimum temps for the flux to activate. Just a very poorly written data sheet in my opinion.

Attachments:

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#54862

Leaded and Lead-Free Wave Parameters | 23 May, 2008

This is one of the biggest mistakes with the Lead Free process. We have all listened to the 'industry experts' and followed their advice and unfortunately got it wrong. Keep the dwell times (dependant on alloy selection) the same as Leaded so you are looking for 0.5 seconds in chip wave and then 2-3 in main wave. Preheat stays the same so 100 - 110C is sufficient. Solder angle is VERY (BRIDGING) important if you have purchased the cheap Asian import machine well check the angle as this will be around 4.5-5 Degrees - which is WRONG Keep the angle as close to 7 as possible. Shorter angle only allows for drainage on the exit end only,increases dwell times which kills flux (even the sustained pedigrees),kills resist and composite solder wave board carriers which increases the occurance of spongy solder dross dramatically and deposits a brown tar like substances in the wave.(check your pot) Flux is another story we have great success with most of our formulations both Alcohol and VOC Free but the later has the edge. For instance our main stay Leaded Alcohol flux is 35-90 No Residue great for Leaded but not the best for Lead Free. Most 'experts' suggest 4-5 seconds for dwell times purely as their alloys they market fiercely dont wet very well and wicking with the metal was very poor hence leave it in longer,effecting everything else. If a solder will not wick to the top of the board that is typically because the alloy chosen is inmobile and sluggish, choose a different one, biggest or most marketted is not always the right choice Best of luck Cheers Greg York Great Britain or should I say EU

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