What should I check if my boards are not reflowing?

Bad component joints coming out of the oven are common issues many operators experience at some point, but understanding the cause can help resolve the problem. Work through these in order.

1. Solder paste. Expired paste, paste stored warm, or paste that sat out too long will usually produce bad joints no matter how good your profile is, so checking the quality of your solder paste is a good place to start.

2. Reflow Profile. If the solder paste is good, measure what your board actually experiences inside the oven. Every oven ships with a temperature probe designed for real-time thermal profile testing; attach a probe to a board and compare the measured curve against your paste's data sheet. A large or copper-heavy board may need more time or heat than the starting profile provides. Also make sure the oven is fully heat-soaked before the board goes in: the green indicator light means all zones have reached their set temperature, and a cold oven takes 25 to 30 minutes to heat up to the desired temperature.

3. Conveyor Belt Speed. If a profile that used to work has stopped working, check that the conveyor is actually moving at the set speed. You can simply use a ruler and a stopwatch to measure this. Any time you change the speed on purpose, re-measure your curve.

4. Heating Plates. If a zone is slow to reach its set-point or never properly reaches it, this could be due to one or more heater elements not functioning properly. If you believe the heating elements may be the issue, they can be replaced. Contact support and we will help you confirm whether you need a replacement and will help get you the ones you need.

If you are still having issues with improper reflow, email support@neodenusa.com with your specific known issue, paste type, your profile settings, and a photo of the problem, and we will help determine the cause of the issue and provide the best solution for your situation.