Uses for Fixtures and Pallets During SMT Soldering

Fixtures are primarily used to assist in the production during solder paste printing and pick-and-place. They are necessary for PCBs thicker than 0.8 mm, as well as such as panels with narrow areas which are prone to breaking if not supported properly.

Usage Scenarios for Fixtures:

1. Thin PCBs:

For PCBs with thicknesses of 0.4 mm, 0.6 mm, and 0.8 mm, fixtures are required to support the PCB during solder paste printing and component placement. For solder paste printing, this support is necessary for the PCB to maintain tight contact with the stencil. During pick-and-place, the support maintains placement accuracy by keeping the PCB flat during component placement. During reflow soldering, a fixture helps keep thin boards flat, preventing them from warping and falling out of the conveyor due to the high temperatures encountered.

2. Double-Sided SMT Placement:

When both sides of the PCB have heavy or densely arranged components, fixtures are used to ensure the yield of production processes.

3. Components Extending Beyond the PCB Edges:

If components extend beyond the edge of the PCB, causing the center of gravity to be off the board surface, or if it's impossible to ensure stable transportation on the conveyor, fixtures are used to prevent the board from shifting and falling off during movement.

Pallets are mainly used during through-hole wave soldering to assist in the soldering process.

Usage Scenarios for pallets:

1. Thin PCBs:

For PCBs with thicknesses of 0.4 mm and 0.6 mm, pallets are needed to support the PCB during wave soldering. The wave soldering machine's conveyor cannot properly secure thinner boards, leading to potential deformation and soldering defects. Additionally, the boards can warp and fall into the solder pot due to the high temperatures.

2. Double-Sided Soldering:

When the PCB has SMT components already soldered when going through wave soldering, pallets are used to protect these components from falling into the solder pot during the wave soldering of through-hole components.

3. Components Extending Beyond the PCB:

If through-hole components extend beyond the edge of the PCB, causing the center of gravity to be off the board surface, or if it's impossible to ensure stable transportation on the conveyor, pallets are used to prevent the components from shifting or falling off during wave soldering.