How to control the mechanical stress of PCBA assembly production?
Oct 16, 2019
Mechanical stress refers to the internal force that interacts between various parts of an object when the object is deformed due to external factors (force, humidity change, etc.) to resist this external factor and try to restore the object from its deformed position To the position before deformation.
The mechanical stress in the PCBA assembly manufacturing process has the following aspects:
Component molding
Controlling factor: PCB support smoothness
Standardization of part library parameter settings
Reflow soldering
Controlling factors: The slope of temperature rise / fall during reflow soldering is an important control parameter. According to the recommendations of IPC / JEDEC, the slope of temperature rise / fall is 6 ℃ / Second max
3. ICT test
Controlling factors: Fixture design prevents interference with parts
PCB board bending (PCB deformation limit board bending is less than or equal to 7/1000)
Sliver
Controlling factor:
Part layout method
l V-CUT is at least 0.5mm away from the edge of the part or PAD
0603-2210 capacitors, inductors and other easily cracked parts within 5mm of V-CUT should be vertical V-CUT
Sliver Knife Management
Strain gage verification
Low risk specification: the strain is less than 599μ ∈