DESIGN FOR MANUFACTURABILITY
How to Prevent Tombstoning
ROLLING MEADOWS, Ill. – Now you may say that this is an “assembly issue????” But not so fast. Yes it is true that assembly materials including solder paste and stencil design, improper profiling or even inaccuracy of the pick and place machine accuracy may cause tombstoning but the PCB layout may be a cause as well. Possible culprits include the following:
- The lack or imbalance of thermal relief’s
- Incorrect land patterns – when in doubt use the IPC standard guidelines
To control the effect as a designer, you have to look after symmetric soldering process on both sides of the component. Make sure there are symmetric pads in your design. This can easily be checked via automatic scripting.
Finally, look to problems in the manufacturing of your PCB’s for potential causes. The thickness of a soldermask is critical. Make sure the mask is below the level of the lands.