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reflow profile development

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reflow profile development | 2 September, 2008

Good morning everybody!

I'd like to receive from you articles or tutorial links teaching how to develop a reflow profile and its process variants, I'm a new user from SMTnet forum and I can see profesional with grate knowledgment.

thanks in advance for all.

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reflow profile development | 2 September, 2008

Try this. Basic reflow profile build up and explanation of its parts: ramp-up, soak or no soak, peak, cooling. Good starting point.


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reflow profile development | 2 September, 2008


reflow profile development | 9 September, 2008

First and fore most is to find your paste manufacturer spec sheets. Read it over several times and let it all sink in. Then call them with questions as they want to keep your business so their engineers want to help you use their product.

I assume you have a profiler to check the parameters of your oven? Your next step would include running a profiler through your oven to find your base setting.

When applying thermo couples you want to have a minimum of three. Board temp for one directly on the PCB, another for the smallest component on the board, and third on the largest component. The thermal couples would ideally be in the coldest and hottest points of the board. When attaching the thermal couples to the board they should always be in contact with the solder joint not the component body.

There are a few important things you are looking for which will be detailed in your paste spec sheet. One would be your ramp rate. This prevents thermal shock and proper flux activation at the proper times. The next is your soak times. This stage allows for components to rise in temperature before reflow as well as allow the flux to activate properly. The next is liquidous. Right before liquidous, for ideal reflow conditions, you want to bring all the component temperatures together (the hottest and coldest points). This is done several ways but the most common is a spike in zone temps to get the cold parts up to that temp range and then in zone temps so the smaller components loose a little temp and now all component temps (large & small) should be about equal across the board. Ideally you want a leveling out of all component temps right before 183 C. This is important to ensure one of the most important factors. Time above liquidous and peak temps. In this stage your temps begin to rise significantly for a proper liquidous stage.During this time you want your componets to stay above liquidous for a certain amount of time while the board temp doesn't go over peak temps. If done wrong you can have thermal shock, tombstoning, cold solder, etc, etc, etc. Last there is the cool down stage. There is also a maximum limit for cool down rates.

There are also free webinars that explain thing a bit better with visual presnetations that would give you a better idea of what I have explained in a nutshell. Here is one I attended before This is a free webinar provided by heller and it's a great place to start. They even provide you with the PP presentation at the end via e-mail for your reference.

Hope that helps a little but I gotta get back to work .

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Reflow Oven