Can we convert our existing wave soldering machine to use lead free?
We are an EMS company and we have a wave soldering machine. We are now having stronger demand to produce lead free products with through hole components. The problem is that we still have leaded products with through hole components that also require the wave soldering machine.
Can we convert our wave soldering machine to lead free (change the bath and the alloy) and still solder the leaded products using the same machine?
Arbel Nissan TKS
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Ask the Experts Comments
Have you considered selective soldering vs. updating your wave machine? You could leave your existing wave machine as is and get a dual pot selective soldering machine with a full wave (up to 18") for your Pb free PCB's,and have multiple selective mini-waves for both Pb and Pb free. This solution will give you the flexibility that you are looking for.
Mr. O'Neil has been part of the electronics manufacturing field for 17 years. As Sales Manager for all Soldering products at JUKI, his main objective is to continue to supply equipment providing the "Lowest Cost of Ownership."
Once you have changed the solder bath to leadfree you cannot run products with leaded solder on them or you will contaminate the leadfree solder in your pot. Don't forget if the nozzles, flowducts and pumps are not for leadfree solder they will have to changed as well.
In the Electrovert systems we have an option that is called a quick change solder pot. This allows you to have 2 solder pots on moveable carts. One for leadfree and one for Tin/Lead solder. This option would then give you the capability to process either feadfree products or Tin/Lead products using the same basic machine.
If the solder machine you have is too old you may be faced with replacing it with a new machine to get the dual pot capiability and the wavesoldering equipment technology needed to successfully process leadfree products.
Kenneth Kirby, Applications Engineer Speedline Technologies Mr. Kirby has been in the electronics manufacturing industry for 18 plus years. Over the years Ken has been in roles such as Equipment and Process trainer, Senior Process Engineer, R&D Application Development Engineer and currently Process Application Engineer.
One alternative is Intrusive reflow which eliminated the need for Wave soldering all together. I have attached a technical paper which covers this alternative.
For over 18 years, Dr. Coleman has been the vice president of technology for Photo Stencil, working closely with customers to understand their printing requirements. His efforts have resulted in several new stencil products.
It is definitely possible to solder traditional lead containing finishes using lead free alloys in a wave solder bath. However there are a couple of things to remember, first and this is independent of the alloy, lead will leach into the pot. Over time this can easily build to a point where the lead level is greater than the 0.1% limit in the RoHS legislation. Once this happens the pot can't be used to make "lead free" parts any longer.
The rate of lead build up will depend on the volume of production, but with only 50% lead based product Messrs Forsten, Steen, & Wilding, in there Soldering & Surface Mount Technology 12(3), 2000, pp. 29 - 34 article exceed the lead limit in less than 2 months.
The second point is that with the increased leach rate of lead free alloys (not only lead but also copper, and silver etc.) the frequency of pot analysis will probably need to be increased. The exact frequency will depend on the volume of production and to some extent the product mix (lead to lead free and pad finish).
Dr. Poole is a Senior Applications Chemist in Henkel Technologies, electronics assembly materials application engineering group. He is responsible for all of Henkel's assembly products including soldering products, underfills, PCB protection materials, and thermally conductive adhesives.
