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Green inductors

Views: 1351

#39752

Green inductors | 16 February, 2006

We have been using Coilcraft 1008CS inductors for several years. We have had problems with them turning green when we use lead-free solder paste. We have tried several solder pastes (water soluble and no-clean)from different manufacturers, but the inductors still turn green. Has anyone run into this problem before? Was a solution found ? Right now we solder the inductors on by hand after the machine build, but when we go mostly lead-free, we will have to hand solder tens of thousands of inductors and we won't be able to do that.

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#39761

Green inductors | 16 February, 2006

We saw something like this in the machine shop years ago. Fumes from a soldering operation in the shop turned exposed iron and steel tools and the spindle on my Bridgport mill green. Can your supplier apply plating or a coating to the exposed parts of the inductor, this will be a problem they will be seeing more of as lead free soldering takes over. Maybe green paint?

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Rob

#39765

Green inductors | 17 February, 2006

Ask the distributor (or coilcraft) what the termination material is & if they do alternative ones. These maybe from old stock.

If you get no joy have a look at Epcos & Murata who both have wide ranges of surface mount inductors.

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#39807

Green inductors | 20 February, 2006

Thanks Rob. We've been in contact with Coilcraft, but haven't gotten anywhere, yet. We'll check out the other coils. We started using Coilcraft because of their high Q.

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#39808

Green inductors | 20 February, 2006

> We saw something like this in the machine shop
> years ago. Fumes from a soldering operation in
> the shop turned exposed iron and steel tools and
> the spindle on my Bridgport mill green. Can your
> supplier apply plating or a coating to the
> exposed parts of the inductor, this will be a
> problem they will be seeing more of as lead free
> soldering takes over. Maybe green paint?

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Rob

#39809

Green inductors | 20 February, 2006

No problem. If you get no joy you're going to have to change the footprint to a 1206 or 1210.

Murata have a range of high Q value inductors (50-60) & from memory Toko used to be pretty hot too.

The terminations on the coilcraft part are listed as Platinum/Silver/Palladium, & I'm guessing it's the Platinum as I've never seen any Silver Palladium issues.

Anyone seen any issues with Platinum plating oxidisation/contamination?

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#39812

Green inductors | 20 February, 2006

It appears to us that the problem lies in the lead-free solder paste rather than the inductors. We have not found a lead-free solder that does not do this. The green is on the copper wire. We believe it gets there during the reflow. The gasses from the flux are released and the coil wire has minute holes in its insulation. We have tried several paste manufacturers and we have tried both water soluble and no-clean paste. We are going to retest the no-clean because there is some question as to reaching the wrong conclusion. Hopefully, the no-clean will be the solution to that problem. If that's the case, the next problem would be cleaning the "no-clean" from the pcb. We have always used water soluble solder paste and water wash.

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