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I am designing a PCB that has will hold an Arduino Micro, as well as other components. One of the electrical engineer mentors that are overseeing the board development has told me to increase the copper pad size/decrease the hole size for the pin headers in order to have an overall larger pad surface area. He told me to do this because it lowers the risk of the pads coming off in the event that we have to desolder the Arduino from the PCB (dead board, etc.).

Currently, the holes and pads are circular, with the total edge-to-edge exposed copper diameter at 2mm, and the hole size diameter at 1mm (picture below).

We are planning on ordering our board from OSH Park with their 2 Layer 2oz 0.8mm Service instead of the standard copper.

Is there a need to make the copper pads larger in the case of a desolder, or will keeping the pads their current size be fine after a desoldering?

NOTE: I cannot make the pin header hole much smaller, as they are square headers with a 0.65mm side length (corner to corner length is just under .92mm), but I can make the pads slightly larger if absolutely needed.

-Ben

Pin header hole and pad with measurement: Pin header hole and pad with measurement

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    \$\begingroup\$ Ugh... are you really doing this instead of leaving the 80 cent microprocessor on the dead board? \$\endgroup\$ – Bryan Boettcher Feb 15 '17 at 22:39
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    \$\begingroup\$ The reason we want to know is because these boards will cost $55 for 3, and if the Arduino dies, we would like to be able to desolder it and replace it with another one while leaving all of the other components on the still-working PCB. \$\endgroup\$ – AngryCupcake274 Feb 15 '17 at 22:44
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    \$\begingroup\$ Socketing the arduino is unpalatable? \$\endgroup\$ – vicatcu Feb 15 '17 at 22:49
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    \$\begingroup\$ Desoldering 28 through hole pins from a PCB is no small effort, and wrought with peril regardless no matter your pad landing ratio. \$\endgroup\$ – vicatcu Feb 15 '17 at 23:08
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    \$\begingroup\$ If the 28pin part is dead, take a pair of side cutters to it. Clip each pin and remove the chip, then desolder each pin individually. \$\endgroup\$ – JRE Feb 16 '17 at 5:53
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I fail to see in which way having narrower holes may help with desoldering. Less solder to remove? Well, maybe. But it will also make the removal of the part harder as you will have less room for waggling the Arduino pins to break any tiny residual joints in the hole. Thus, slightly wider holes could actually be more useful for the purpose of easy desoldering.

OTOH, bigger pads may help, but only if you use certain desoldering procedures. They can be helpful if you use solder wick, serving as a comfortable landing and working zone for it. In fact, if you're going to use solder wick, leaving some room around the Arduino Micro footprint for the desoldering operation helps too.

Of course, using a socket would be the best way to go. But if you can't due to design constraints, don't be afraid about having to desolder the Arduino. It's all down to using adequate desoldering techniques, it doesn't even require exotic expensive tools. Take a look at this video and see if for yourself.

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If the person performing the de-soldering is competent, it shouldn't make much difference. Honestly, if the boss says do it, do it. Alternatively, if these are protoboards you could suggest adding a socket designed to hold the arduino. These can be expensive depending on the package, but well worth the added expense if you'll be testing etc.

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