SMD assembly

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You have to start by the SMDs since they are the smaller and trickiest parts and might not be accessible once the through-holes components are soldered. Your best friend is the interactive BOM, followed by the SMD assembly page (tips, details on marking, ...). We might be able to send you a board with the smallest and trickiest SMDs already soldered if you contact us :-)

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

Keypad board

The keypad is a good start if you doubt your soldering skills: it's easy to solder and hard to mess up.

Suggested color-coding for the keypad
  • Delta keypad down.jpg
  • Delta keypad up.jpg
  • Soldered delta keypad up.jpg
  • Soldered keypad back delta.JPG


Soldering order:

  • Side buttons
  • Front buttons
  • Headers

Tip: In case you purchased side buttons without plastic pins that go into the PCB holes, you might want to superglue the buttons to the board before soldering them so they don't slip while soldering, as well as don't tear off as easily. You should then be careful while soldering, though, make sure to not let the superglue fumes near your face.

Front board

-You might want to start soldering with the front board, it has TPA2005 (0.65mm pitch) and AtMega (0.8mm pitch) chips, it will give you the most challenge during soldering. Using solder wick will be helpful here.

Back board

This is the most component-heavy board of the ZeroPhone. Check that everything is in order before you solder the Raspberry Pi Zero, since some components won't be reachable after that.

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