Shop OBEX P1 Docs P2 Docs Learn Events
Does anyone have a gerber file with qfn44 lands? — Parallax Forums

Does anyone have a gerber file with qfn44 lands?

ElectronegativityElectronegativity Posts: 311
edited 2010-12-10 03:30 in Propeller 1
Hi everybody, I just bought some CAD software from a company called Pentalogic, and would like to design a circuit board for the QFN44 Propeller chip.

Designing the land pattern by hand with the software would be super tedious, and I was wondering if anyone could give me a gerber file of the land pattern.

Comments

  • LeonLeon Posts: 7,620
    edited 2010-12-07 21:17
    It should only take a few minutes to create that footprint. If you are really stuck I could let you have it as a Gerber, but I'm not sure if it will help.
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2010-12-07 21:27
    I assume you are looking for gerber data because your CAD software can import that to be converted to raw CAD data? I can post/send gerber tomorrow that contains the QFN44 from my M44D40+ module. I have built 2 units so I know the layout is good. (I have 550 fabs, just no time to move that project forward) Also, the Propstick USB is setup as Open Source so the DipTrace file is on the product page. I use DipTrace, so I can export whatever you may need from that.
  • ElectronegativityElectronegativity Posts: 311
    edited 2010-12-08 04:56
    Hello Andrew.

    I just purchased a program called Viewmate Deluxe and I am standing at the bottom of the learning curve.

    I don't doubt Leon's assertion that this could be done quickly by someone who is familiar with the software, but I am currently trying to figure out how to generate a blank circuit board with it and have projects in mind that would ideally be done by Christmas.

    The software seems incapable of handling the .dip file in the propstick documentation, but claims it can import gerber files.

    The reason I want to use a QFN44 is that the project is a piece of electronic jewelery with the propeller controlling some LEDs. Size is an issue with this kind of thing because gaudiness scales directly with size.

    Any help you can offer will be greatly appreciated.
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2010-12-08 12:43
    The zipfile attached contains the QFN44 from my module (files with QFN prefix) and also the QFN44 from the Propstick USB layout (files with PSQFN prefix). Both include top trace layer, paste, mask, and silk. They are different slightly, but both are proven to work. Hope that helps!
    zip
    zip
    QFN44.zip
    8K
    QFN44_WBA_and_Parallax.jpg
    1024 x 549 - 62K
  • Nick McClickNick McClick Posts: 1,003
    edited 2010-12-08 13:10
    Hey Electro,

    I use Viewmate all the time to inspect Gerbers before sending to the board house, but it's not meant for PCB design - it's really for DFM / DRC checking & light editing. Theoretically, you could design a board with it, but it would be very, very painful. I suggest you try something like diptrace, it has a library of footprints including the propeller.

    Also, a gerber file only contains info on a single layer - for a prop QFN, you'll likely need several gerbers, copper, mask, and paste. Design software handles this automatically, but Viewmate won't.
  • ElectronegativityElectronegativity Posts: 311
    edited 2010-12-09 13:55
    Thanks Andrew and Nick.

    Agh, I just paid $95 for this program hoping to use it to design circuit boards.

    The good news is that it came with a coupon for $95 off my first order of boards, so it isn't really a loss as long as I can get something done before the 45 day expiration date.

    I will check out the freeware version of Diptrace when I get home.
  • Cluso99Cluso99 Posts: 18,069
    edited 2010-12-09 15:36
    Electronegativity: How do you plan to assemble the pcbs? If you intend to do it by hand or a toaster oven then it may be a good idea to extend the pad size outwards by 0.5mm to allow for touchup by hand as QFNs are much harder than QFPs. I do this for QFPs. Be careful, you cannot just change the pad size as you need to change the centres of the pads as well or else you will get the pad extending inwards as well.

    I use an old professional layout program "Protel 3.0" which is around 1995. It was expensive at the time and has become much moreso with time and revisions. However, it suits my needs as I no longer layout pcbs professionally. I have never tried DipTrace but I did try another free layout program which has a schematic program as well (cannot recall it's name -senior moment! - camr from a pcb supplier). It was just OK for small jobs - a bit wierd to use but certainly ok for hobbyists. If you want, I can look on my other laptop for its name - it's quite common.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-09 15:37
    The Pentalogic software is the one recommended by FreePCB to be the independant checker of their output. I have used it for that for years now.

    The free version of Diptrace is very restrictive, on pin count.
  • ElectronegativityElectronegativity Posts: 311
    edited 2010-12-09 16:50
    I plan to buy these particular boards since size is a major issue and I am not set up to manufacture double sided boards with vias. Otherwise I use the Toner Transfer System.

    How critical is it to ground the center plane on the QFN Propeller?

    The pin count is only about 150 on this one, so the freeware Diptrace should work.
    If I like the software and want to build more complicated things then I will pony up the cash.
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-12-10 00:54
    I have heard (Leon, I think) saying that if you drill a "large" hole in the central area PCB pad then you can get a fine tip into the bottom of the QFN and solder it from the reverse side.
  • LeonLeon Posts: 7,620
    edited 2010-12-10 03:30
    That's what I do on prototypes. A fine tip isn't any use, a lot of heat needs to be transferred.
Sign In or Register to comment.