The dipping, or flux-dipping, technique is a procedure used in the assembly of electronic circuit boards. It is a particular process for particular boards, and at EMSPROPTO we are masters of this technique and we have the equipment to perform it.

Jeremy, Quality Technician at EMSPROTO, tells us everything there is to know about this assembly technique.

What is dipping ?

It’s an assembly technique which consists of adding a quantity of gel flux for soldering of a BGA component, without using soldering paste. The principle is to dip the solder balls, which are on the BGA, in a bath of gel flux.  Depositing flux on the solder balls facilitates the reflow process for these components.

This technique is possible with BGA components because the solder is already present on the component.  For information, soldering paste is a mixture of solder powder and gel flux.

In which cases is this procedure used ?

This procedure is used in 2 cases:

• During a rework: it is often impossible to deposit new solder paste on the receiving pads, either due to lack of space on the board, or because the adjoining components do not permit it.
• During the assembly of an electronic board: for some BGAs which have a very fine pitch (less than 0.4 mm) depositing solder paste is difficult. Using the dipping process avoids an excess of solder – solder paste contains solder which would be added to the balls of the BGA.

What are the tools needed for this procedure ?

Performing this technique requires a rework or SMD placement machine equipped with a dipping station, so the deposit of flux is well controlled.  Thanks to the different heights offered by the station, the flux is deposited uniformly on all the balls without touching the BGA package.

It’s preferable to use a gel flux rather than a liquid flux, as it adheres better to the balls of the BGA, and the flux transfer is much better on the board.

Thanks to Jeremy for his explanation of this procedure.  You will have gathered that the main advantage of this technique it that is not necessary to use solder on the component because it is already present on the component.

If you would like to know more about our Rework machine, go to our Youtube channel to find out all there is to know about our circuit board assembly lines !

https://www.youtube.com/watch?v=ZQ2QSFVxXhs