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X****Liu
Weird unconnected ?0 Ohm SMD resistors
1194 1 Mar 28.2019, 10:59:14

Hello,
I have the habit of disassembling anything that I get my hands on just to look at what is beneath the hood. I recently got a generic LED driver module form one of the local bricolage DIY retailers. 
When looking at it I found some interesting/weird thing that I had no idea how to explain. Close to each of the corners of the board there is an 0 ohm SMD resistor that is not connected to anything. It's just the footprint and the resistor soldered to it. (Photos attached)
I believe that this should be related to the assembly process, but I have no idea why they would need such a thing. The board is two layers, with SMD components glued to the bottom and both SMD and TH components on the top. You are seeing the top.
Anyone know what these are for?

Regards. 

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A****min

Mar 30.2019, 11:16:18

Yes this is assembly process aid, 0R resistor is least expensive component. This is for checking/tuning reflow temperature profile in case there's big thermal mass components on the PCB. It also will be aid for AOI that cannot look under big component in critical area of the PCB.

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