help in understanding gerber data for PCb design

Discussion in 'General Electronics Chat' started by payal.kellyyy, Jun 23, 2011.

  1. payal.kellyyy

    Thread Starter New Member

    Mar 28, 2011
    28
    0
    hiii,
    actually I am new to this electronics forum I dont know how to create a new post ...so i feel this is the right thread where I can post my query

    Guys please be simple in ur explaining since I am really new to PCB designing

    I have this query:


    enclosed you find the data format which we need for PCB assembling.

    PCB data:
    Extended Gerber, 274 X
    Absolute position, Unit mm; numeric format xxxx.xxxx
    For solder paste and outline


    Assembling Data:
    component description Housing Value X-Position Y-Position Rotation (separated with Tab)
    for example: C1 0603 10nF 10.35 -12.35 135


    In this PCB data what does this Extended Gerber 274X means....also for assembly data my manufacturer requires in following format how to make this data since this data cannot be generated in Gerber...do I need to ask reference point ?i am using Orcad 9 for PCb designing I need urgent help on this ...kindly help me out.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,429
    3,360
    You can try googling Gerber 274x
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Gerber 274X means the "aperture" data is also stored in the data file.

    Apertures? Gerber files consist of commands to take a shape (aperture) and move it. If you take a circle and sweep it you get a trace land, with nice rounded corners. Those shapes are the apertures and the "X" saves them where they are needed.

    To make these files you have to adjust your PCB program to give them to you. If you are not using a PCB program then you have to convert to gerber format; we used to convert autocad files to gerbers.

    Gerber files are actually just text files, you can open them up in notepad and see what's there.
     
  4. debjit625

    Well-Known Member

    Apr 17, 2010
    790
    186
    All about gerber : http://en.wikipedia.org/wiki/Gerber_format


    Its a file format that is used by PCB manufacturer to make your PCB.

    Gerber files can be generated by most PCB designing softwares,I personally don’t use Orcad but the process of creating gerber files is almost the same in PCB designing softwares,here is how….

    The first step is to create the schematics, then annotation i.e... name the unreferenced components which where not named while the process of schematic creation, like naming the components R1,C1....etc.After annotation a netlist and components list are created, now if you don’t know here netlist is another type of format which describes the connectivity of an electronic design. After netlist is created you can proceed to layout i.e.. input the different parameters like size of the PCB, width,height,trace width,silkscreen,pad size, solder mask and etc.At last after layout is done you are ready to create the gerber, normally in most PCB designing software we have some kind of Gerber Editor to make gerber files drill data and etc after that these gerber files are used by PCB manufacturers to create your PCB.

    Normally I dont make gerber files as I create my PCB at home ,so I just print them...

    Good Luck
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Agreed. Gerber is the industry standard. It is how a designer would send files to a PCB house. It isn't the only way to do this, but it is the industry standard.

    There are several free software packages to draw PCB layouts with. Not all use Gerber, and the one I use I get away from there standard an clean it up using both Gimp and M/S Paint to my personal preferences.
     
  6. payal.kellyyy

    Thread Starter New Member

    Mar 28, 2011
    28
    0
    thanks guys for your replies :)
     
  7. payal.kellyyy

    Thread Starter New Member

    Mar 28, 2011
    28
    0
    HII

    i have one more query in LM111 IC i know it is a wrong place to post but need your help..PLease find enclosed the schematic for the same as taken from national semiconductor datasheet..can u help me in understanding this circuit I am not able to understand the logic of connecting 5 n 6 pin to power supply..What is the main logic of connecting pin 5 and 6 to supply for increasing input current .Also I am not very clear about function of 5 and 6 pin can u help me know it better?
    and how is the slew rate affected because of this ..waiting for some good replies:)
     
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  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It may help you to look at the internal schematic.
    Datasheet: http://www.national.com/ds/LM/LM111.pdf
    Look on page 18. Pins 5 (balance) and 6 (balance/strobe) are shown on the left-hand side. If both pins are connected to +V, then both of Q5's emitters have much more current available; instead of being limited by the 1.3k resistors, they would have roughly 243 Ohms (1.3k||300) in each emitters' current path. This allows the inputs to drive the subsequent stages harder, so they will turn on more quickly.

    If you don't need to trim the offset balance, tying them to +V is a good way to get more performance out of the comparator.
     
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