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Which type of lead-free solder is the best?
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Simon:
Lead free is no longer an issue although the old folk like to rat on it. The early days were bad i hear but that's over, we have had years of lead free.
eti:

--- Quote from: newbrain on August 17, 2020, 09:04:51 am ---
--- Quote from: eti on August 16, 2020, 05:40:10 am ---Lead-free solder = unreliable joints = shorter product lifespan = unjustifiable repeat sales = more revenue for the product manufacturer = more tax for the country.

--- End quote ---
Bollocks. :bullshit:

I work in a place that designs and produces electronic equipment which is sold by the million units and used all over the world, in all kind of internal and external environments.
Replacement cycles can be long or short, but we have a lot of very old stuff around.

When we made the move to lead free (and all the rest of Rohs), there were some teething problems - as with any process change: I still remember some early BGA based boards...

To my knowledge, we have not experienced any increased field failure rates or returns due to lead free solder, and I've never seen a recall issued specifically for Rohs related problems on the stuff I worked on.

--- End quote ---

Okay then  ;)
peter-h:
The issue of whiskers never actually went away.

I think the reason why it is not a problem today is that packages with pins on the periphery (QFP etc) never went below about 0.5mm pitch. I had seen some 0.35mm but that was in the leaded solder days and it was OK then. The high pin count stuff went to BGA where the balls are not that close so the problem was avoided.

Whiskers could also be avoided with special conformal coatings but they are expensive.

Military and medical still have exemptions. In fact I think the whole "control and monitoring equipment" exemption may still be there; if not then it ended quite recently. A huge raft of small manufacturers were operating under that. And if you are using up old component stock then you have to because the pins can be tin/lead plated.

For hand soldering, leaded solder works much better. However a lot of the challenge is the flux composition and this is where the super pricey Almit solder works quite well. But it works only as well as the cheapest dirtiest no-brand-name leaded solder which is 1/10 of the cost.

The whole ROHS thing is pointless because lead from other sources (e.g. car batteries) is vastly bigger than lead getting into the environment from electronics.
perieanuo:
hi,
my 2 cents: if the law says you have to work with lead-free, ok.if not, take a good 60/40 Sn-Pb alloy.
I haven't see any lead-free that beats 60/40.
regards
ebastler:

--- Quote from: peter-h on August 18, 2020, 09:10:58 am ---Military and medical still have exemptions. In fact I think the whole "control and monitoring equipment" exemption may still be there; if not then it ended quite recently. A huge raft of small manufacturers were operating under that. And if you are using up old component stock then you have to because the pins can be tin/lead plated.

--- End quote ---

RoHS exemptions for medical equipment ended in 2016, and for monitoring/control equipment in 2014 (except industrial instruments) and 2017 respectively (industrial).

You can't legally use up old component stock any longer. The only exception applies to their use as spare parts for units which were placed on the market before the relevant RoHS effective date.
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