Solder Me (Seed Mix) - Woven - Solder Me
Can you mix a leaded component and a lead-free component in the same circuit board and still say the product is lead-free even when you are using lead-free? Jim If we're talking about the legal definitions defined by RoHS, the question is maybe. There are some kinds of lead that are exempted under the RoHS law. However, for most parts, chip capacitors, BGAs, and so forth, if you have any lead on one part on an assembly, that whole assembly violates lead-free as defined by RoHS.
So I hope that answers your question. The bottom line is don't mix your parts. Phil So beware of the caveats and know the rules and regulations. That should be it for Board Talk today and whatever you do and wherever you're doing it, don't solder like my brother.
Submit A Comment Comments are reviewed prior to posting. You must include your full name to have your comments posted. Solder Me (Seed Mix) - Woven - Solder Me will not post your email address. Comments Except for the cases where forward and backward compatibility of lead-free LF components is critical, the answer is YES, you can mix.
During that time, most process engineers mixed and soldered these components together on a same PCB and got very good results. Of course, if you intend to mix LF BGA with tin-lead components in SnPB reflow tin-lead solder pasteyou should think twice and avoid this, once several reliability studies are showing this is not a good idea. Leaded components with LF plating in SnPB reflow need to be checked for wettability of the terminals, mainly looking for bubbled solder surfaces and excess solder voids in solder joints.
In this case, a low thermal profile normally is the major contributor for these "defects". You can always mix some lead-free components in leaded solder. With current industry trends towards lead-free, you face this situations with components you may not know. Problem is not all lead-free components are easy to solder with tin-lead.
Not all solder fluxes for tin-lead create a good joint for lead-free components. Contact your solder provider and let them know the situation. Might help to see what finishes you are using and change flux. Try to avoid bright tin, palladium, silver, lead-free components. Mate tin, gold or pure tin dip are easy lead-free options for tin solder. Pedro I. Zaragoza, Rockwell Collins Inc.
Since we are a defense industry company, we are exempt from the RoHS requirement, but as many others Solder Me (Seed Mix) - Woven - Solder Me have discovered: you cannot get the new cool IC's with lead, and the old cool IC's with lead are going obsolete and replacement are RoHS compatible. Therefore we see Solder Me (Seed Mix) - Woven - Solder Me Till The End Of Time - Various - Волшебные Мелодии - 4 - Лунная Соната lead and RoHS components is an interesting issue.
We have conducted some initial testing on mixing RoHS compatible components and lead Nostalgia - Orchestra Tipica De Ramon Littee - Nostalgia / Reflejos (Shellac) on the same PCB, but only with manual soldering using lead solder.
No report or final conclusions have been Solder Me (Seed Mix) - Woven - Solder Mebut our initial findings is that this causes a lot of poor solder joints cold solder that looks like proper solder joints proper wetted. There is a clear difference between large and small components. Small components, up to capacitors, achieves a correct soldering with proper mechanical strength.
Larger components get solder joints which seem to be correctly wetted, but have a very low mechanical strength, and behave like a cold solder oint. SO-8 packages seem to be the limit between good and poor solder joints.
Our initial guess is that the lead solder melts at C, and as the temperature increases towards the melting temperature of the solder pre-applied on the RoHS components, the surface of the pre-applied solder begins to melt, but not all the way through. To the operator soldering this looks like proper wetting, and the soldering iron is removed. This causes an incomplete mixing of the two solder types, and gives a weak joint that looks strong visually.
The reason why we see a difference between large and small packages, we believe is caused by the thermal mass of the components. Smaller components have small mass, and the solder iron has a large thermal reservoir compared to a capacitor. The solder iron has a temperature of at least C. The operator soldering removes the soldering iron as they should, but since the time required to heat the small components to temperatures above the melting temperature of RoHS lead is so short, all the solder around small packages melts and mixes properly.
Larger packages will take a longer time to reach the same temperatures, so when the solder joint looks properly wetted abovebut below the operator remove the soldering iron. This causes the RoHS solder to not melt completely, only on surface, and gives the weak joint. The mini-experiment was conducted two different qualified soldering operators in a controlled environment.
Are there any others out there with similar experiences? Have you come to the same conclusion? We plan to conduct a similar experiment using automated reflow process. Do any of you have any good ideas or recommendations on how to conduct these tests? Was the question about Rohs compliance or was it about the metallurgical or processing pitfalls of mixing lead with lead-free components? I think you answered the easiest question!
What are some of the common pitfalls that one should be aware of? Ashwin Kasi, Tellumat, South Africa. Hello R. It is my observation that most suppliers plate all their leads with Matte Tin regardless of the pitch. You should read the RoHS document, it isn't that long. Recently you commented on using leaded and lead-free components on the same assembly. You said that fine pitch parts, those whose pitch is. Please tell me where I can find this exemption written.
Ralph Longton, LoJack Corp. Do you have results of mixing lead and lead-free components, so that I can keep the company I work for from doing this. Asalene Coffey. Free Newsletter Subscription Every issue of the Circuit Suoni Nella Notte - Various - Fabio B.
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