SMD assembly

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Use as the SMD assembly guide. If at any stage you have photos and you'd like to verify you're soldering everything the right way (at any stage), message the photos to us on IRC/Matrix, or email them to me (contact details available on the main page).

SMD markings on PCB

To make from-scratch assembly easier, there are silkscreen markings on the PCB for various components, usually inside the components' outline or near the component. Some of these markings are written fully, so you can look at the BOM item nd find the needed component (like "MCP23017", "270R" or "33pF"), however, some markings are shortened - for those, the disambiguation is as follows:

Marking Component
R (2-pin) 10K 0805 resistor
C (2-pin) 100nF 0805 capacitor
0 (2-pin) 0 ohm 0805 resistor
4 (2-pin) 47R 0805 resistor
Z (2-pin) 5V1 Zener diode
SS (2-pin) SS14 (1N5819) SMA Schottky diode
1N (2-pin) 1N4148 MiniMELF diode
B (3-pin) BC847 SOT-23 NPN transistor
F (3-pin) IRLML6401 SOT-23 P-FET
9 (3-pin) BAW99/BAT54S SOT-23 ESD diode

ATMega soldering from the Arduino Pro Mini - flashing

TODO: rewrite

[21:33] <Ser134> Q: do i need to flash sw to atmega, then take it off with a heat gun, or i can take it and flash after soldering to zero board? How to flash on board then? 
[21:34] <CRImier> you're using the Arduino Pro Mini, right? 
[21:35] <Ser134> Most probably, whatever was on wiki 
[21:35] <CRImier> If so, the front board has the same 6-pin connection that the Pro Mini has 
[21:35] <CRImier> but 
[21:35] <CRImier> you're taking the ATMega328P off an existing board? 
[21:35] <CRImier> if so, that's what is suggested on the Wiki, indeed 
[21:35] <Ser134> As far as i understood from wiki 
[21:36] <CRImier> what I suggest is flashing the ATMega on the first board, making sure it works 
[21:36] <CRImier> then, moving it to the front board 
[21:36] <CRImier> and if you can flash it again, that means the test was successful 
[21:37] <CRImier> oh no not the test 
[21:37] <CRImier> the soldering was successful, I mean 
[21:37] <Ser134> How to test after flashing at pro? 
[21:37] <CRImier> the flashing process is the test 
[21:38] <CRImier> if you can flash it, that's good enough of a test 
[21:38] <Ser134> Ok, thnx, so the sequence is: flash atmega pro, take off, solder, flash on front.. 
[21:39] <CRImier> yep 
[21:39] <CRImier> the second flash is for testing the soldering 
[21:39] <Ser134> Ok, thanx, iam waiting some smds, so may test it that way in jan i think 
[21:39] <CRImier> which SMDs? 
[21:40] <Ser134> Didn't order all of them 
[21:40] <CRImier> the front board part with the ATMega is pretty well-isolated 
[21:40] <CRImier> so you should be able to assemble it separately and test 
[21:40] <CRImier> I've done it once 
[21:40] <Ser134> Miss mosfet transistors :-( 
[21:40] <CRImier> neither are necessary for the ATMega-on-front-board test 
[21:40] <CRImier> so don't worry =) 
[21:40] <Ser134> Ok, got it... thanks a lot
[21:41] <Ser134> I want to solder all smds first, and 2 capasitors are to close to atmega, want to solder them after i solder atmega 
[21:42] <CRImier> that makes sense, yeah