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JLCPCB is trying to tell me that the RPi Pico W needs to be baked to reduce moisture before putting it through reflow soldering. They're saying that "It is moisture-sensitive according to the datasheet and it is suggested to bake the components before soldering. If not, water evaporation during high-temperature soldering can damage the internal structure of the component, which can affect functionality."

I see no mention of this on the datasheet. Does anyone have experience with this? Are they just trying to get me to pay extra?

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    \$\begingroup\$ Would be interesting to know why someone downvoted this question. It's a very clear and specific question that can be difficult to find answers to if you don't know what to look for or if you don't have experience in the subject. It's an exclusively electrical engineering problem, and a common and important problem. It can be answered by more experienced professionals. Heaps more useful than "my toaster broke what is this component?" that everyone seems to love. \$\endgroup\$ Commented 2 days ago
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    \$\begingroup\$ What pcb quantity? If low, then have them leave that part off, and then solder it on by hand yourself. \$\endgroup\$ Commented 2 days ago
  • \$\begingroup\$ If you like to play the odds you could probably waive the requirement and take responsibility if the packages don't make it through reflow and pop. n.b. Relative humidity in Shenzhen right now is 60-75%. \$\endgroup\$ Commented 2 days ago

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The RPi2040 itself is MSL 1 so no issue there but if we can find another component on the board with a higher MSL then that will be the limiting component. And indeed we can: the RT6154AGQW buck-boost regulator is MSL 3 and requires baking after a week outside of a humidity-controlled environment (the MSL is not noted on its datasheet either, that information came from the distributor); there may be components with higher ratings, possibly including the PCB material itself.

I doubt a high-volume outfit like JLPCB frequently upsells customers on non-essential services, they want to get your stuff out the door as quickly as possible.

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  • \$\begingroup\$ I would have assumed that companies would always put the "moisture sensitive" label on a breakout board with moisture-sensitive components. But I guess you have to check each component individually. Thanks. \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ If I had to guess I'd say it's that they expect hand-soldering of the castellations or PTHs to be far more common than reflow and putting MSL requirements on the board would lead to endless questions from hobbyists (and broken boards from e.g. people trying to bake them in their toaster ovens "just to be safe"). \$\endgroup\$ Commented yesterday
  • \$\begingroup\$ @VitalDuval, moisture sensitive is only related to manufacturing process (during reflow), it is not a concern for daily usage or for finished breakout board. \$\endgroup\$ Commented yesterday
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I think what JLCPCB is referring to is probably the Infineon WiFi module CY43439KUBGT that you see on the PICO W.

enter image description here

For module like that, the components are packed and small, if moisture is trapped inside the metal shield, during reflow process, component(s) can pop and jump off the PCB, causing damage/malfunction that it would be very difficult to find out. For such kind of modules, it usually requires at least 24 hours of baking.

They are not trying to get you to pay extra? They've been professional.

Edit:

If you buy such module directly from vendor, it will shipped in seal anti-moisture package, in addition with the instructions like the one shown in the picture below.

enter image description here

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