Modify a 754 CPU socket for image sensor
September 20, 2015 3 Comments
Recently I’m working on a camera design using a CMOS image sensor. The problem is the sensor was built into a custom uPGA package (1.27mm pin pitch) with a lot of pins. The actual socket built for this sensor is very expensive. And it requires force to mount and tools to dismount. Luckily, a lot of old CPU sockets use the similar uPGA standard and they are ZIF (Zero Insert Force) sockets. The problem is just too many extra pins you don’t want. A straightforward way is to cut off every unused pin on the package but could risk bending an unintended pin in the process. And most often the cutting process is not clean to the edge, preventing a flat and smooth fit on the surface of PCB.
After a bit investigation, I found the upper movable lid (white color) can be easily disassembled by gently prying the side rail. This will expose the bottom part holding all the ZIF contacts and the pins in each square hole.
The lid holding the CPU
The releas e/lock handle
Bottom part with tons of ZIF contacts
Now with a jumper cable pin (2.54mm pitch male end), you could easily pop out all the unwanted ones, leaving a custom ZIF socket!
And here’s the actual ZIF contact.
The ZIF acceptor assembly is inserted from bottom and locked inside the square hole. The CPU pin comes down from above. Once the locking handle rotates, all the pins are carried and pushed towards the narrower slot between the 2 U-shaped hairpins to establish the electric contact.