Mini LED lighting board part 3
Continuation of the last time.
The following photo shows the completed "Replacement board for the LED matrix board used in the evaluation board for LED driver ICs of Lumissil" (long).
Since it is a part related to know-how, we can not introduce it in detail, but the photo shows the board on which the LED is already bonded.
Since this board and LEDs are lined up with a 0.1 mm width and a 0.1 mm gap, it was very difficult to make the board. Since it was made with a normal FR-4 printed circuit board, the pattern shape that was too thin did not resolve well, and we had to redo it many times. In addition, in the end, the board maker said, "I was originally at the level of refusing, but I received an order by mistake. I made it intentionally, but I want you to forgive me for repeats."
Thanks to this, it was a challenge that the technical team could not afford to fail.
(The second half of this series of posts is an example of a mini LED bonding on an FPC. The FPC tried to form a pattern similar to a PCB, but there were no manufacturing issues.)
Although failure is unacceptable, it is a challenge from setting conditions. The introduced bonder can place the mini LED chip in a fixed place. There are various ways to mechanically fix the LED while making it conductive. In early 2019, we worked on LEDs with a chip size of 0.2x0.38mm. From there, the chip became about half the length and width, and the same conduction method and fixing method could not be used.
After trying various methods, we used the completed 10 PCB boards, and finally all the LEDs turned on in the last 2 boards.
(Continued to Part 4)