Thermal monitoring systems can often help you troubleshoot your oven by getting to the root causes of many process-related problems. Information on oven and process changes can be investigated. There is a very important distinction to be made between oven monitoring and process monitoring. Changes or no noticeable changes to your “oven” may or may not impact your process. At best, you can only infer if changes to the “oven” are impacting your process. Changes that occur to your “process” can be tied directly to the inputs that are causing the change.
We see changes to the oven, which is only half of the picture. A sudden spike in oven temperatures strongly suggests problems, but what happens if it is only momentary? Can you say then that your product is out of spec? If so, for how long, how many PCBs do you need to chase down the line for rework?
This is where Process Monitoring comes into play. If I look at each and every PCB profile, then I know whether or not a given product is within spec. Typically, engineers will run their process from SPC Charts tied to Cpk. Only when the system alarms on Cpk or there is an out-of-spec profile will they look at the data presented above to try to troubleshoot the root cause of the problem.
