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My first Prop SMT board — Parallax Forums

My first Prop SMT board

RaymanRayman Posts: 14,598
edited 2009-01-28 17:13 in Propeller 1
I just got my first SMP Propeller board working!· Soldered everything by hand.· I wasn't completely sure I could, but it was actually pretty easy...

One big mistake was with the status LEDs for the FTDI chip.· I thought I could connect them through resistors to ground, but this doesn't work.· Seems the outputs are actually open collector, even though the datasheet says they can source as well as they sink...· So, I had to modify the board and run a jumper to VCC.

Other small problem was that the pads for the 28-PIN SSOP (FTDI chip) in ExpressPCB are only 7mm wide, when they really should be 9mm wide and so the pads don't stick out any from the chip.· This made soldering especially difficult...

One thing I'm doing differently is that I'm running the FTDI with 5V I/O...· That's why I have resistors in the RX/TX lines to the Prop.· I'm doing this because I have a project in mind that would need 5V to run, but want to turn it off with the sleep signal...

The miniUSB was easy to solder.

This uSD card socket was easy to hand solder.· Works without pullup resistors.

This board was mostly a test for my soldering skills.· That's why I left so much room around everything.· But, I do have a 2.5" TFT LCD to mount on the other side...· That's the next challenge...
PcbBoard1a.JPG
1424 x 1068 - 655K

Comments

  • AleAle Posts: 2,363
    edited 2009-01-26 20:32
    The board looks quite nice. I use a small "Pinzette" (whatever is called in english) to pick the components and place them to solder: I put some tin in one pad, solder one end and then the other end. I never succedded to solder both ends well when tin was applied to both pads. It looks good. (I also solder my own boards). I found that 1206 componets are small enough to take little space but not that small to give me problems to solder them. My eyes are not exactly perfect due to Keratoconus :-(. It is annoying at times. I think you have to have it to know how we see, nobody deserves it.
  • BTXBTX Posts: 674
    edited 2009-01-26 20:47
    Hi
    It looks good !! but looks like you didn't use flux to sold the chips.
    Try using gel flux, you'll found that is more more easy to sold any chip, and will look more professional.

    Also to sold 0805 or 0603 smd's I prefeer almost not touch them while soldering, just use the flux and leave the component to get auto align in PCB, it's quiet difficult to learn but one you get it ..live is more easy.

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    Regards.

    Alberto.
  • RaymanRayman Posts: 14,598
    edited 2009-01-27 00:31
    I've seen video on the web about how to use flux to do it and that was my fall back plan... But, my tip was small enough to actually do each pin one by one, so I did it that way...

    I did use sticky flux to hold the parts in place while I soldered...
  • BTXBTX Posts: 674
    edited 2009-01-27 01:36
    Hi Ray.
    With the flux pencils that sell DigiKey, you can get similar results as using the gel, you get solder all in one solder pass.
    The difference between solder one by one and the another method is bigger.
    To hold the IC parts you can only sold some opossite pins without any care, then the flux will repair all short circuits.
    Sorry is very difficult for me to explain this process in English.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Regards.

    Alberto.
  • Cluso99Cluso99 Posts: 18,069
    edited 2009-01-27 03:05
    Nice job for your first exercise - congratulations smile.gif

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    Links to other interesting threads:

    · Prop Tools under Development or Completed (Index)
    · Emulators (Micros eg Altair, and Terminals eg VT100) - index
    · Search the Propeller forums (via Google)

    My cruising website is: ·www.bluemagic.biz
  • BaggersBaggers Posts: 3,019
    edited 2009-01-27 11:09
    Nicely done Rayman, I've been tempted too by wanting to do some Surface Mount stuff [noparse]:D[/noparse]
    there's just not enough hours in the day though, to do everything I want to do lol [noparse]:D[/noparse]

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    http://www.propgfx.co.uk/forum/·home of the PropGFX Lite

    ·
  • Project5kProject5k Posts: 58
    edited 2009-01-27 11:55
    thats a good look'n board, i was wondering, how did you etch it? did you do photo masking? iron on toner transfer? or what?
  • RaymanRayman Posts: 14,598
    edited 2009-01-27 13:38
    I used ExpressPCB's prototype service... (I'm too lazy to etch myself...).

    Another interesting thing is that I mixed up the base and emitter connections on the NPN transistor that drives the RESet line...
    But, it works anyway!
  • AnubisbotAnubisbot Posts: 112
    edited 2009-01-27 14:47
    One question how much did you paid for the board ??
    Since it looks like home made : ) sorry no criticisms, but i pay for 10 boards 2 sided with solderstop mask and print for parts with shipping 80-90 $.
    And they are always perfect. And making soldering so much easier.

    Best regards
    Anubisbot
  • Fred HawkinsFred Hawkins Posts: 997
    edited 2009-01-27 16:12
    Whose µSD socket is that? And did you connect the card present switch?
  • RaymanRayman Posts: 14,598
    edited 2009-01-27 17:15
    I've extolled the virtues of ExpressPCB often enough in other threads...

    The uSD socket is Digikey# 670-1355-1-ND. I didn't hook up the detect switch...
  • Fred HawkinsFred Hawkins Posts: 997
    edited 2009-01-28 17:13
    nice datasheet, lots of dimensions. Thanks Ray
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