Removal of the cover glass:
- Use a sharp blade and scrape off all the resin around the sensor. Scrape both ways, using sharp and blunt edge of the blade. You will need to get every little bit off. It comes off as yellowish powder (see photo 1). If you have any left you will run into problems later. Even when you think it is off scrape some more. Change angles of the blade and scrape more.
- When you are 100% sure that the resin is gone, you can use the heat gun to heat up the glass and get it separated from the resin under it. Glass will expand when heated and break the bond.
- Start heating in one corner and wait until the colour changes. See photo 2. Keep pushing the "discolouration" until it is all around the sensor and the glass is separated.
Make sure you let the sensor cool down. I held the metal frame by my hands and when that got too hot to hold I stopped for 5min and let the sensor cool down. Filip used a wet cloth to keep the sensor cool.
I did this over the course of several hours and it took me about 10 heating sessions.
DO NOT OVERCOOK THE SENSOR.
For my broken test sensor I used max temperature of the heat gun (450 degrees C from memory). The glass got cloudy but could be wiped clean. I managed to get the glass without cracking.
For my other sensor I used 340 degrees C and the glass cracked at the very end.
I am not sure which temperature would work the best but I would go with the max if I do it again. Higher temperature will heat the glass faster and hence create a larger temperature differential which will break the bond to the resin faster. However, the sensor will heat up faster as well and faster breaking of the bond may lead to cracking of the sensor. Not sure
Once the glass is off you have to be
extremely careful not to damage the gold wires.
To be continued...