Why SMT stencils are important for PCB assembly？

Before you can go into production, solder paste is printed onto the component pads of the PCB.

How can you make sure you apply the solder paste with precision exactly where it needs to go?
Stencils, or formally surface mount technology stencils, are the answer.Stencils are the medium used to transfer that solder paste onto the PCB.Can you apply soldering paste without a stencil? Yes, but because of the precision required, trying to apply soldering paste everywhere it needs to go on the board by hand can be an extremely time-consuming, painstaking process. Furthermore, you cannot get the consistency when applying soldering paste by hand that you will get using a single stencil. It’s important to consider that the chances of error are much greater when applying soldering paste by hand.

When applying soldering paste by hand, or trying to apply it without a perfect stencil you could face some very serious problems, like:

1.Short circuits

2.Voids in the soldering process

3.The desired printed result requires:

--Smooth and burr-free sidewalls of the apertures

--Flat, unstressed material

--Uniform tension distribution over the entire surface

--Precision in position and size of the apertures

 

Click here to know more:Introduction for SMT stencil types