■Soldering and Mounting
1. PCB Design
1. Notice for Pattern Forms
ꢀ1-1. Unlike leaded components, chip components are susceptible to flexing stresses since they are mounted directly on the substrate.
ꢀThey are also more sensitive to mechanical and thermal stresses than leaded components.
ꢀExcess solder fillet height can multiply these stresses and cause chip cracking. When designing substrates, take land patterns and dimensions into consideration to eliminate the possibility of excess solder fillet height.
ꢀ1-2. There is a possibility of chip cracking caused by PCB expansion/contraction with heat, because stress on a chip is different depending on PCB material and structure.
ꢀWhen the thermal expansion coefficient greatly differs between the board used for mounting and the chip, it will cause cracking of the chip due to the thermal expansion and contraction.
ꢀWhen capacitors are mounted on a fluorine resin printed circuit board or on a single-layered glass epoxy board, it may also cause cracking of the chip for the same reason.
ꢀ1-3. If you are replacing by smaller capacitors, you should not only consider the Land size change but also consider changing the Wiring Width, Wiring direction,
ꢀand copper foil thickness because the risk of chip cracking is increased with just a Land size change.
Pattern Forms
Item
Prohibited
Correct
Placing Close to Chassis
in section
in section
in section
in section
in section
in section
in section
in section
Placing of Chip Components
and Leaded Components
Placing of Leaded Components
after Chip Component
Lateral Mounting
GRM0115C1C1R1CE11-01A
25
MURATA [ muRata ]
