Contents
How to prevent solder bridging?
1) Change the circuit board design. Additionally, solder mask dams can be added between fine pitch pads to prevent solder from bridging. Solder mask defined pads can also prevent bridging, especially in tight pitch areas like BGAs and LGAs.
What is a solder land?
Solder Mask Defined (SMD) Solder Lands The solder land size is defined by the solder mask opening. Considering the offset tolerances for the solder masking process, the copper must be larger than the actual solder land by at least 75 μm on each side. This value may vary depending on the class of PCB used.
How to avoid solder bridge in PCB design?
Another way to prevent Solder bridge is to ensure that you have a solder mask dam between each of your SMT pads. A solder mask dam acts as isolation wall between the application of solder on each of your pads.
What kind of solder should I use for LGA Assembly?
In general, the solderable termination area should match the PCB substrate pad 1:1. Users have the option to either use solder mask defined (SMD) pads or non-solder mask defined (NSMD) pads. High temperature FR-4 or BT laminate (glass transition temperature Tg = +170 °C to +185 °C) is generally recommended for lead-free LGA assembly.
How to reduce the amount of solder paste during assembly?
Increasing soak time will equalize temperatures across the assembly and reduce the tendency for solder to flow to the warmer surfaces. 3) Reduce the likelihood of off-contact solder paste printing. Try modifiying the stencil design to reduce the amount of solder paste in trouble areas.
Can a SMT pad be used as a solder bridge?
In case of very tightly spaced pads on a Ball Grid Array (BGA) or Land Grid Array (LGA), there is not enough room to maintain a barrier and mask relief to have a solder mask dam between two SMT pads. If such cases, you can use a solder mask defined pad which provides a solder mask relief that’s the same size as the copper pad it is protecting.