u/Boxter_7

Hi everyone! I need some advice from someone experienced in ECU reballing. I’m currently facing a frustrating issue where the ECU works fine for about 10 to 20 days after a repair, but then the exact same fault returns. ECU type: DAF 106, Delphi Paccar ETC-3 PCI

I’ll try to describe my process and workstation setup in as much detail as possible:

1. Equipment & Setup: Attached is a photo of the parameters for my WDS-S7 workstation. Both the top and bottom nozzles are positioned 1.5 cm away from the PCB and the processor.
2. Thermal Profile: Using the settings shown in the image, I get the following readings via a thermocouple placed on the board right next to the processor:
   • Preheat: 100°C for 60s
   • Soak: 160°C for 60s
   • Reflow Start: 165°C for 60s
   • Peak Temp: 210°C
   • Cool down: Ramp down to 100°C over 90s, then natural cooling.
3. Materials: I am using Sn63/Pb37 leaded solder balls. For flux, I use Amtech NC-559-ASM-UV for both cleaning the pads and attaching the new spheres.
4. Cleaning: My soldering iron temperature is set to 370°C when cleaning the residual solder from the pads.
5. Reballing Process: When attaching the balls, I set my hot air station to 360°C. I start with minimum airflow until the balls adhere, then I increase the airflow to maximum, add more flux, and gently go over the chip until every ball settles into place with a bright, shiny finish.
6. Cleaning: I clean the chip manually using a brush and Isopropyl Alcohol (IPA), followed by 3 minutes in an ultrasonic cleaner. The cleaning solution is a mix of 70% distilled water and 30% IPA.
7. Inspection: Final check is done under a microscope.

I’m hoping someone who has dealt with these specific units can point out any flaws in my process or suggest what I might be missing.

Thanks in advance!