Contract Manufacturing

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The manufacturing process presents some challenges that are quite different than product design challenges.

Product designers are good at creating new products but trying to get those products manufactured at higher volume takes a different set of skills.

If you desgined a product and were able to assemble some working prototypes, you may think the design process is finished. But when moving into production some design changes may be required for different reasons: relocating components to allow the Pick and Place machine operation replacing components that are too hard to find optimizing BOM cost substituting expensive components

Before submitting a product for manufacturing, all the details about the product need to be documented (in writting). Any detail not defined will imply that the manufacturer can freely decide for himself at manufacturing time. For example, if you don't specify PCB color, the manufacturer can decide to make the board green, or black or whatever color they're using at the time.

Quality control is part of the manufacturing process and the designer is responsible for providing a test procedure. Different products require different test conditions. Some can be tested in just seconds and others require complex (expensive) test jigs and long testing times. This affects pricing so for SimplyTronics to process a quote, we will need to receive full product documentation, including testing.

What do you need to get a quote? You need a Specification Package that includes the following:


Gerber Files

Your layout program usually can output these files and we need the complete set. The gerber files should include the board edge and some programs do not include this basic information.

In some cases customers send their original design files but this is not required. Having the original design file allows the PCB manufacturer to generate a different Gerber export that fits their equipment. Most Open Source Hardware designers send the original files, since they ususally post them online anyway, but conventional product designers would rather send just the Gerber and resubmit in a different output format if needed.

Bill of Materials

This is one of the most important files and it's sometimes overlooked, leading to problems down the road.

The BOM is the document that specifies the parts intended to be used in the board. Use as much detail as possible but take into account that for manufacturing we may be buying components from a different source. If you list Mouser or DigiKey as a refference, we will take the information from the part listed and find a component that meets those requirements. In comse cases you may list some specific sources, mostly with Integrated Circuits, but standard components will be sourced from different vendors.

BOM should include:

  • Component Desinator (name used in the PCB files)
  • quantity used per board
  • Description (as much detail as possible will reduce chances for misunderstandings)
  • Supplier you used to source the part for your prototype (i.e. DigiKey, Mouser, Jameco, etc)
  • Supplier part number or stock code


Most PCB design software tools will generate a schematic that matches your PCB layout design. It's very important that both are linked and that any changes you introduce in layout are updated in the schematic and vice versa.

File format can be pdf.

Assembly drawing

Some software tools can also generate this file.

Usually the file is a pdf with some graphic showing the component location in the PCB and you can also add in this file any notes for the manufacturing process, as if a component needs to be soldered to the board after being washed or any out of the ordinary detail the manufacturer should be looking at.

Test Procedure

This is one of the most overlooked details when thinking about manufacturing a product. The product designer should be always thinking about how to test the product on each manfuacturing stage. Sometimes the designer will have to add pads to the board where the manufacturer can connect some spring loaded gold connectors for testing the boards before going into the next step or at the end of the manufacturing process or to load testing or final firmware to the product. Most designers make a prototype and think that manufacturing can just make 500 exactly like that, but it doesn't work this way.

The test procedure is an integral part of the product design to the point that SimplyTronics requires the test procedure to be included in the Specification Package even to produce a quote.

The information we need includes:

  • Document that explains all material needed for the test (test jig, PC, software, firmware, IC programmer, etc)
  • Document detailing the testing steps in the same sequence the QC operator should follow while testing production units
  • Testing software, sample code and any firmware needed for testing (and final firmware for the product if to be loaded during production).

Detailed description of the board

This text document will be used to transfer all the details about the product from the designer to the manufacturer. If you have a hard time figuring out what to write here, just think that you are walking into the manufacturing floor and talking to the manufacturer. What do you want to tell him about this product? Which detail is important and what you don't care about? Information to be included here is:

  • PCB color (soldermask)
  • Silkscreen (text and fraphics printed in the PCB) color
  • PCB thickness
  • Any particular detail to be considered, as whashing the PCB before mounting a microphone for example, can go here too.
  • Packaging information. Which kind of bag should be used (with any relevant specs) and product sticker information (and file) if any.

Product sample

If you are ready to move into production, you certainly have more than one prototype that was assembled and works succesfully. Nobody makes 1,000 units from an untested design (hopefully). The sample you send not only should be fully functional but also be as close as possible to the expected look and feel of the production units. Even though we include so much information with the documentation, there will be always some gaps and the manufacturer will obtain any missing information from that sample. In some cases the prototype was made in green PCB and production units should be of a different color and if this is the case, it's still useful to have the green prototype on-hand while we make very clear in the documentation that the production units should be of a different color. Ideally you will pack the sample in the same way production units should be packed (including the style of bag and sticker, if any).