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. The problem is that we still have leaded products with through hole components that also require the wave soldering machine.produce lead free products with through hole components.

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?

A.N.

Expert Panel Responses

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 more information see: Stencil Design Through Hole SMT Mixed Technology.pdf

Bill Coleman
Vice President Technology
Photo Stencil

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).

Neil Poole
Senior Applications Chemist
Henkel Electronics

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.

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.

Todd O'Neil
National Sales and Marketing Manager, North America
Business Development Manager, DAGE | X-Ray component counting

Mr. O'Neil has been in the electronics manufacturing industry for over 20 years.

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 movable 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 wave soldering equipment technology needed to successfully process leadfree products.

Greg Hueste
Senior Applications Engineer
Speedline Technologies

Greg joined Electrovert in February 1984. Based out of the Electrovert applications laboratory in Camdenton Missouri, Greg has been in the process applications support role since 2000. His primary responsibilities include providing process and machine applications support for the wave soldering lines as well as process, machine and operations training. He also provides applications support for the reflow and cleaner lines. Greg is a PBET certified trainer and holds two patents on wave solder nozzle design.

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