Multinivel
The Multilevel Stencils are designed to print more than one height in a single pass and to deposit the necessary paste for the different components of a single circuit.
This is achieved by making the recess on the squeegee side of the Stencil. It is also increasingly used to bridge areas of the PCB such as graphite, silver bridges or via true hole and to ensure that the Stencil has good contact with the PCB. In this case, the recess is made on the PCB side of the Stencil.
There are different manufacturing processes to achieve the different heights in the Stencils for SMD:
Chemical photoetching
- It is carried out through a chemical photoetching process to lower the material in certain areas and achieve different levels on both sides of the Stencil.
- To achieve good roughness and thickness tolerance, making jumps or recesses of more than 100 microns is not recommended.
- Tolerance in thickness of +/- 10 microns.
- Dimensional tolerance of the recess of +/- 150 microns.
Mechanised - CNC
- Carried out through a high-precision mechanised process to lower the material in certain areas and achieve different levels on both sides of the Stencil.
- This process allows a ramp to be obtained between the different levels to facilitate the adaptation of the spatula.
- The recesses can be greater than 100 microns without compromising the material’s roughness or the thickness tolerance.
- Tolerance in thickness of +/- 5 microns.
- Dimensional tolerance of the recess of +/- 100 microns.
Spot laser welding
- Carried out by welding two sheets of welded material on top of each other using the laser to achieve the desired heights on both sides of the Stencil.
- The added material must be thinner than the base material to achieve a good welding result and the final flatness of the Stencil.
- Tolerance in thickness of +/- 5 microns.
- Dimensional tolerance of the recess of +/- 50 microns.
Benefits
- Multiple solder paste heights in a single print cycle.
- Solution for silver, graphite and “ via true holes” bridges.
- Ideal solution for carrying out Pin-in-Paste.
