Condensation Soldering

Hi,

Encountered this deference to the vapour phase process that was supposedly "phased" out years ago? *pardon the pun*

Any comments from folks who have used this proces before? how about folks who are currently using this process?

even better, any technical details from folks who have working knowledge, of the pros-cons of this process?

Your advise, assistance and sharing is appreciated :)

Thanks in advance.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ the process : condensation soldering (as follows:) ( an extract summary of the process flow )

1) ...Vapour phase is still around, but has undergone something of a renaissance in recent times. To address environmental concerns and issues such as tombstone/popcorn defects, an alternative process was devised, and is known as "condensation soldering"...

2) Esstenially, condensation soldering is performed in a sealed chamber. The (pcb) units to be soldered enter the chamber. A pertial vaccuum is drawn through the chamber to ensure the units are sealed effectively, and to remove any potential contaminents. The heat transfer fluid is then pumped onto the hot-plate in the chamber.

3) The fluid then enters the vapour phase and condenses onto the units thus effecting heating stage. The amount of material pumped onto the hotplate controls the rate of heating, and by using discrete HTF (whaT de hella is that?) pumping stages, just about any profile can be created and controlled very tightly.

4) When the alloy has reached liquidus, the chamber is then evacuated, again under partial vacuum to remove all the valuable heat transfer fluid from the chamber. This also has the effect of solidfying the alloy. When the chamber is emptied of HTF, the chamber door can be opened and the unit exits via a colling fan to enable handling.

5) Condensation soldering is very efficient and tombstone/popcorn are things of the past (popcorn isn't solely contributed by component-moisture root causes?) Issues such as large losses of HTF and "health and safety" issues associated with vapour phase soldering have been eleimated. In additiona, with lead-free processes in particular, the temperature delta across the board is generally less than 5 deg-C.

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