Script – Selective Soldering
Through hole components can be soldered manually, over a solder wave, or with a selective soldering machine or soldering robot.
Selective soldering is a process to solder individual through-hole components on a PCB .
The machine includes a flux spray, preheater and a soldering pot that feeds a solder fountain.
The solder fountain or head moves to the position to solder from underneath. Compared to manual soldering, this process is faster, repeatable and leads to a better result.
As always this technology has limitations.
We don’t use the selective soldering equipment when component leads are too long ( 2 mm or more), because the solder head stays too far from the pads, and a good solder joint is not guaranteed.
When there are components close to the point to be soldered, we risk damaging the component, or wash it off the board.
Compared to a solder wave selective soldering has some clear advantages.
Many components cannot be processed on wave soldering.
A selective soldering machine uses a single head that moves to the point where solder needs to be applied, and leaves the rest of the board untouched.
Wave soldering works much faster, but the whole board is touched by high temperature molten solder.
For selective soldering, components do not need to be glued to the board when soldering, we use less flux and solder, and there is no need to cover parts of the board with a mask to prevent solder deposition or heat damage.
The equipment we use is an Ersa Ecoselect 2 selective soldering system, perfectly suited for prototype and small batch production.
We program the machine with simple point and click programming.
A canvas with the image of the bottom side of the board is loaded, and we indicate the points and route the flux sprayer and solder head need to follow. We can adjust the distance of the head to the board and the soldering speed to get a good solder quality.
When the program is loaded and the solder pot is heated, the boards enter the machine from a conveyor, and the soldering process starts once the board reaches its destination.
First the machine sprays flux on the selected area. Next the board is preheated, and finally the solder head follows the programmed route to solder the connections.
At the end of the process , the boards exits, and the process starts over again with the next board coming through the conveyor