One thing for sure, no matter the recipe you end up with, a thermal profile of the assembly will be needed to determine if you are reaching the required temperatures and times. Six sigma and statistical process control generalist.Ī thermal profile will be the best tool to help you find the right oven recipe. Intimate knowledge of soldering processes and measurement systems. Mark Waterman is a trainer and field engineer with 17 years experience in service and applications specialties. This won't be exact, but at least this will be a better representative than a bare board. If you don't have a sacrificial assembly to use (ie: the customer won't allow or too costly), then you should attempt to replicate the assembly with like type board and components. The only way to KNOW your thermal profile is correct is to measure it on an actual assembly. Other variables to take into consideration are component densities and types, potentially thermally sensitive components, solder paste recommendations, your specific oven's ability to heat (regardless of zone counts), etc. Knowing the copper weight of the PCB material is only a small part of the equation though, as the layers between the copper are insulators. MAP software), and these would be a good place to start. There are several thermal profiling packages that include software prediction features that can help you with developing a robust reflow recipe (like ECD's M.O.L.E. The short answer is you will need to increase your zone temperatures and/or lengthen the heating time (slowing the conveyor speed). He has software and electronic design experience specifically in the development of thermal profiling solutions for the electronics industry. We also have the ability to define individual process specifications for each measurement channel/components – so if you have a special/sensitive component we can define special limits for those areas.Ĭo-founder and M.D of UK based thermal profiling equipment manufacturer SolderStar Ltd. In Solderstar profiling tools we have automatic prediction tools to help establish the best profile settings, once we have captured a profile from a test PCB and the oven – our software creates a mathematical model which can simulate oven and speed changes and drive towards more optimal solutions. Your oven manufacturer/supplier is best person to suggest a starting point zone for temperature/speed – as they are most likely to have seen similar boards and all ovens perform differently - but it will only be a starting point. It is likely you are going to have to slow the conveyor speed from what you normally use – this will allow temperature settings for the zone to be more achievable.Īdjacent zone in a reflow oven should not exceed typically < 40C, as the two zones will struggle to maintain differentials, this maximum zone delta value may vary oven to oven. Ultimately you will need to perform some thermal profiling, if you are currently using linear ramp profiles you are going to have to make a best guess – otherwise start with a ramp soak spike shaped profile and go from there. Selecting a paste with a generous working window would also help, if you have wildly differing thermal mass components or any temperature sensitive components it will be a challenge. This allows you to drive a good amount of heat into the board in the Ramp, then time to Soak/equalize as best as possible minimizing any temperature differences across the assembly before reflowing. You will most likely need to set up a Ramp-Soak-Spike profile, committing typically Zone 1/2 for Ramp section, Z3,4,5 for soak and Z6/7 for reflow. You are right, given you have 7 zones, you have a fighting chance. My reflow oven has 7 zones though so I think it is possible, any advice would be great. copper on the bottom layer, sounds like a tough challenge. I have a new product coming in and need some ideas on reflow recipe creation. Seeking Advise for a Solder Reflow Recipe
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