ElectroHolography Laboratory

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====== Eagle CAD ======

===For simple RF boards printed at the ECEN shop:===

You have two options: double and single sided copper. Double sided is for more complex boards that need to run signals on both sides. It is common to use the back face as the ground plane. 

If you are using a single-sided board, you can send the shop a .sol file (bottom layer) that contains an outline of your full circuit board and they can cut it out with their machine. 

When drawing your circuit, remember that you are defining objects that the machine will route around. Sometimes it is better to not define an object and use the copper that is already on the board. 

As a general rule, stay away from polygons. They take a really long time to process. Instead, stick with rectangles and wires. You can also use existing components from the menu on the left. 

When you are finished creating your board, save it and click the CAM processor button on the top. Click File -> open -> job. This opens up a list of processing options that will automatically generate the files the ee shop will process. If you have any holes in your board, open the excellon.cam job. This will generate your drill files. For all other needs, use the gerb274x.cam job. This will generate your top (component) .cmp file and your bottom (solder) .sol file. It also throws in files for silk layers and things that are necessary when creating a professional board at a separate company. 

Go to ee.byu.edu and open up a ecen shop project request form and submit all information. Then send an email to ecenshop@gmail.com with a brief description and all relevant (.dri .drd .cmp .sol) files. 

Once you get your boards back, use a soldering iron or other tool to clean the traces and make sure you do not have any electrical shorts. You can also pull off all unwanted copper to keep your board really clean. 


===For more complex boards:===

Tented Vias: Design Rule Check (DRC) -> Masks -> Limit: 28mil

[[https://www.sparkfun.com/tutorials/115|SparkFun PCB tips]]

small text: size 0.04, ratio 10%

dimension check:
  * check that parts aren't intersecting with each other - happened on early revision of Scanner Shield

electrical check:
  * check for accidental cross-over routing - happened on early revision of Synchronization Board
  * check for unrouted signals - happened on early revision of MixAmp Board

silkscreen check:
  * it's preferable that vias aren't underneath silkscreen, but this is fine with tented vias

----
==== Gerber Files ====

Once a board layout has been finished in Eagle, you'll have to generate CAM (computer-aided manufacturing) files, which are typically Gerber files. These files are generated by running a CAM Job using the ''holography gerb274x tbDocu.cam'' file in ''\groups\holography\~Monitor Development\~Eagle Custom Libraries\'' (as of Wed 29 Mar 2017).

The following files are generated from the CAM file: (see [[https://oshpark.com/guidelines]])

<code>
*.GKO   Board Outline
*.XLN   Drills (GERBER_RS274X format)
*.TXT   Drills (EXCELLON_24 format)
*.GTP   Top Cream/Paste (not official)
*.GTO   Top Silkscreen
*.GTS   Top Soldermask
*.GTL   Top Copper Layer
*.GBP   Bottom Cream/Paste (not official)
*.GBO   Bottom Silkscreen
*.GBS   Bottom Soldermask
*.GBL   Bottom Copper Layer
*.G2L   only if you're uploading a four layer board
*.G3L   only if you're uploading a four layer board
</code>

To verify the output of the produced files, use [[http://gerbv.geda-project.org/|GerbV]] to inspect the files. In GerbV, click on ''File''>''Open Layers...'', and select all of the generated CAM files. Ignore the .gpi and .dri files. Arrange the order of the layers using Ctrl & Up/Down arrow-keys until they're in the order listed above and hide/show as desired. If there are changes that need to be made, make those changes in the Eagle schematic / board layout and re-generate the CAM files.

{{gerbv_example.png?500}}

----
==== Hotkeys & Setup Script ====

It's been found to be convenient to use hotkeys with the left hand while moving the mouse with the right hand. Also, a dark background is easier on the eyes than a white background. For these reasons, loading the following script assigns hotkey commands and color palette formatting.

The following is a copy of the "HolographySetup.scr" file in ''\groups\holography\~Monitor Development\~Eagle Custom Libraries\HolographySetup.scr'' (as of Wed 29 Mar 2017). It's been set up so that there's some overlap between actions in the schematic editor, the board layout editor, and the parts library editor.

<code>
# http://www.island.net/~kdbrown/EaglePalettes.php

BRD:
ASSIGN C+E 'MOVE'
ASSIGN CS+E 'SPLIT'
ASSIGN C+R 'ROUTE'
ASSIGN CS+R 'RIPUP'
ASSIGN C+D 'DELETE'
ASSIGN C+G 'GROUP'
ASSIGN C+C 'COPY'
ASSIGN C+A 'RATSNEST'
ASSIGN CS+A 'EDIT .sch'
ASSIGN C+T 'TEXT'
ASSIGN CS+S 'SHOW'
set palette black
GRID INCH 0.05;
GRID ALT INCH 0.01;

SCH:
ASSIGN C+Q 'JUNCTION'
ASSIGN C+W 'NET'
ASSIGN CS+W 'LABEL'
ASSIGN C+E 'MOVE'
ASSIGN CS+E 'SPLIT'
ASSIGN C+D 'DELETE'
ASSIGN C+R 'NAME'
ASSIGN C+G 'GROUP'
ASSIGN C+C 'COPY'
ASSIGN CS+A 'EDIT .brd'
ASSIGN C+T 'TEXT'
ASSIGN CS+S 'SHOW'
set palette black
GRID INCH 0.05;
GRID ALT INCH 0.01;

LBR:
DEV:
SYM:
PAC:
ASSIGN C+Q 'PIN'
ASSIGN C+E 'MOVE'
ASSIGN C+T 'TEXT
ASSIGN C+G 'GROUP'
ASSIGN C+D 'DELETE'
ASSIGN C+C 'COPY'
set palette black
GRID INCH 0.05;
GRID ALT INCH 0.01;
</code>

----
==== Circuit Board Manufacturers ====

Circuit board manufacturers have to spend some time on each design they receive, to format it the way they need, align layers, and to check for / correct any tooling mistakes they find. They don't fix functional or electrical errors. (IE, if you have two traces that pass through (short with) each other, they will make it with that short, and you'll have to fix that later.)

That being said, there's five metrics for a fab house we're concerned with:
  * Incremental Cost
  * Setup Cost (Non-Recurring Expense "NRE")
  * Turnaround Time (time to fab)
  * Capabilities
  * Quality

Practically all fab houses offer regular PCBs (FR-4, 5 mil clearance, 63mil/1.6mm thickness, 1oz copper, 2-sided). Other board types such as Rogers dielectric or +4 layer boards cost more. Some fabs offer different colors for silkscreen and solder mask.

Here is a list of manufacturers / fab houses:

  * [[https://oshpark.com/|OSHPark]] - located in Lake Oswego, Oregon; 2-3 day shipping is $5.00 USPS Prioritiy Mail
    * good for small, low quantity boards
    * Regular Service - $5/in^2 for 3 copies, 12 calendar days fab time
    * Super Swift Service - $10/in^2 for 3 copies, 5 business day fab time
  * [[https://circuitboard.com/|CircuitBoard.com]] - next to I-215, close to the Salt Lake City International Airport; also named Circuit Graphics
    * can do local pickup
    * good for medium or ASAP orders
    * one defect has been found in their boards (a short between a trace and ground)
  * [[http://www.4pcb.com/|Advanced Circuits]]
    * good for large orders
  * [[http://www.qtcircuits.com/|Quick Turn Circuits]]
  * [[http://www.rushpcb.com/|RushPCB]]
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