When Should You Bake PCBs?

by Andy on April 30, 2012

Reflow Oven for Baking PCB's Baking PCBs is a common process that is done more often than it is really needed. You have to be careful when baking boards; if they are baked multiple times it can lower their solderability. This can be especially problematic if you are using lead-free solders as they can be difficult to solder to begin with if you do not know how to use them properly.

In general, it is best to only bake boards when you have a specific reason to do so. Some manufacturing and soldering processes bake boards out of habit or to “be on the safe side”. By looking at your process and deciding if baking your boards is a necessary step, you can not only keep your boards in their best shape, but also save time.

Removing Moisture

One of the main reasons to bake PCBs is to remove moisture from the board. This is one of the easier processes as you only need to heat your board up to the boiling temperature of water. After baking boards to remove their moisture, you should store the PCBs in dry bags with desiccant. By properly storing your PCBs, you can reduce the amount of moisture that they reabsorb after baking, ensuring that you will not have to bake the board again.

Prevent Delamination/Measeling

Delamination or measeling are problems that arise when there is an accumulation of moisture on multi-layer boards. This moisture can cause the board to break during soldering or mechanical processes. If you have sensitive PCBs, then you may need to bake your board even if it does not currently have too much moisture. Baking your board and properly storing it can help stop delamination and measeling before they start.

Reflow Soldering

Reflow soldering is when you place solder paste on a board with components and then heat the entire product to solder all of the pieces at the same time. This can help save time as well as solder joints that may be too small or difficult to do by hand with an iron. It is even more important to only bake your board once during reflow soldering since high temperatures are used, up to 400°F at times.

Baking PCBs is an important process, but should only be done when necessary. All-Spec Industries carries a number of fiberglass trays and fiberglass totes, which can be used to hold PCBs in ovens while you bake them. We also have precision reflow ovens, perfect for low volume production and lab environments. Do you have any other reasons to bake PCBs? Let us know in the comments!

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