Pre-Order Checklist for Prototypes: Eliminating the Fear of a Bad Board

There’s a lot to know when you’re going through your pre-order checklist for prototypes. Here at MacroFab, we want your first prototype for your next product to be assembled correctly the first time. Here is our suggestions of what to consider while preparing to get your next prototype prepared for manufacturing.

Your first item on Pre-Order Checklist for Prototypes is to verify your parts and component selection. This includes:

• Voltage regulator pinouts
  • SMT regulators typically have a thermal pad that is electrically connected
• Discrete mosfet and transistor pinouts
  • Common error is getting SOT-23 transistor and mosfet package pinouts flipped around
  • Verify mosfet gate, source, drain pins and transistor base, collector, and emitter pins
  • N-channel and P-channel mosfets have different pinouts! Same with NPN and PNP transistors!
• Proper pin one markings on ICs
• Diodes and polarized capacitors are marked correctly
• Some manufactures draw the mechanical layout of the part from the bottom: Verify datasheet drawing with footprint
• Double check all unverified footprints to make sure they match the parts package

• Part Substitutions
  • Passive parts like resistors and capacitors are typically easier to find substitute parts
  • Active parts like mosfets and transistors can have part substitutes by finding parts that are similar in specifications
  • The more parts that you as a designer can substitute for other parts, the easier it will be to get your boards made
• Required Components / No Substitute
  • To reduce future stock problems of required components make sure to verify the needed lifespan of the part
  • Check part life cycles: New Product, NRND (Not Recommended for New Designs), EoL (End of Life)
  • Check part lead times, if a required component becomes out of stock will it impact your timeline for production?

Your second step is to go through a PCB layout verification.

• DRC (Design Rule Check)
• Your PCB layout needs to meet the Design Rules for our manufacturing process
• MacroFab DRC rules

• Most EDA tools have a concept of “airwires” or “rat lines” which visually show which part pads are connected to each other on a signal net
• Designs should not have these when the layout is complete, check each airwire/rat line before preparing manufacturing files

Update any silkscreen text for date codes, PCB versioning, or meta data

To build your PCB, MacroFab needs PCB layer information in the form of Gerbers, a Bill of Materials for the components, and a Placement file for where the components go on the PCB. Generating this data depends on which EDA Tool you are using. MacroFab supports some EDA tools natively which means you only need to drop in the design file and the MacroFab platform generates all the data it needs to build your board correctly. Check out the EDA Tool Help Knowledge Base to find the steps needed for your EDA Tool. This is an important step in your Pre-Order checklist for prototype builds.

• If generating an ODB++ package make sure to not include the assembly layer on all layers
• Make sure that your generated gerber files or ODB++ package does not contain a title block or features on the outside of your border area
• If you are using gerber files directly please name them in this standard naming convention to speed up your PCB file uploading process
• Check to ensure your Bill of Materials only contains unique part designators

The MacroFab platform renders your PCB, displays the Bill of Materials, and shows where parts will be placed on the board. This enables you to verify your manufacturing information before ordering to reduce confusion and speed up the process. Simply upload your manufacturing files and let the platform do the rest!

• Missing layers? Check the unassigned layers section.
• If running a 4 or more layer PCB check the internal planes. Some EDA Tools generate inverted internal planes.
• Make sure you assign all layers to a category or remove them. Unassigned layers will prevent the PCB from being ordered.

• Verify layer count is correct
• Select the correct manufacturing type
  • This depends on which DRC rule set your design conforms to
  • Failure to select the correct option could result in delays, cancellation, or a failed PCB

• Check to make sure all your parts are on the list
• Make sure the correct parts are selected and from the correct source

• Parts that need a specific note can be added here
• Make sure all the parts line up

On the quote and order page you can double check the PCB Specifications and Bill of Material list. Here the MacroFab platform will let you know of any errors or problems that where detected in your PCB and how to solve them. Post ordering, if there is any problems with your design files or part selection you will be notified right away to minimize down time and delays. If your order contains consignment parts make sure they are shipped on time with correct packaging and overage.

After you receive your PCBs let us know about your experience on social media! We also like to showcase awesome PCBs and products on our blog with our Red Hot PCB series (PCBs do not have to be red) so let us know if you are interested in doing so!