Soldering assembly recommendations

TN0991

14/21

DocID024463 Rev 2

WLCSP can withstand three times the previous recommended reflow profile to be

compatible with a double reflow when SMDs are mounted on both sides of the PCB plus

one additional repair.

A maximum of three soldering reflows are allowed for these Lead-free packages (with repair

step included).

The use of a no-clean flux is highly recommended to avoid any cleaning operation. To

prevent any bump cracks, ultrasonic cleaning methods are not recommended.

Figure 8. JEDEC STD-020D soldering reflow profile

3.2.1

Protection against light exposure

WLCSP, when placed in a non-opaque housing for specific customer application, may be

exposed to various light sources such as incandescent light or sun light.

Since WLCSPs are light sensitive, it is recommended to protect them with an opaque layer

to prevent light from entering the semiconductor substrate through the top side or through

the lateral edges of the device.