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Outsourcing a Box Build Assembly. Basic information

Very often, you can hear the opinion that outsourcing of electronic printed circuit board assembly (PCBA) is a simple process, which in each case is similar and schematic. And it is enough to provide the subcontractor with the necessary documentation, files and a bill of materials (BOM). In fact, this is not always the case.

It all depends on the company that will handle the assembly, especially when it comes to something as important as assembling the boxes. That’s why it’s time to explain how to identify a perfect Electronic Manufacturing Service (EMS) partner and get an accurate quote.

The perfect partner for box build assembly. What company exactly?

In an ideal world, your box assembly partners become an extension of your business. They should have the appropriate level of knowledge, experience and skills. Outsourcing assembly services to such a company should be a source of savings for your company in the long run, both in terms of finances and time. Your employees will be able to focus on what they are best at and what absolutely requires their involvement. On the other hand, you can be sure that the installation is entrusted to a real professional.

However, before you start working with an EMS provider, check what you should take into account in order to receive an accurate quote and offer and be assured that the cooperation with the external partner will go smoothly.

Bill of Materials

The BOM is the first thing an EMS provider should ask about. The list of materials should contain in particular such information as:

  • Description and parameters of all major components
  • Determining what materials are to be procured by the EMS provider
  • The type designation from the supplier’s or manufacturer’s catalog for specific items
  • Indication of elements requiring special preparation before assembly.

At this stage, it is also worth considering defining smaller items, such as washers, screws, or adhesives. It would help if you told your EMS provider whether you will provide them with guidelines or whether it will be the outsourcer’s responsibility to get these elements. The same goes for any consumables such as wires and identifiers. Defining these questions at the beginning of cooperation will allow you to avoid cost increases or possible production delays. BOM is not everything, though. Your EMS partner should also ask for a complete set of assembly drawings for all production steps.

At this stage, it is worth making sure that your EMS supplier has an experienced Inbound Material Inspection team to ensure that all materials needed for the box build assembly are within specification. EMS providers often provide this information on their website, as it happens in the case of Assel.

Box Build Assembly

Not every EMS provider has their own CAD packages. However, it would be ideal to start cooperation with a company that has them. This allows the subcontractor to convert the drawings into building instructions. Moreover, if it becomes necessary to update the drawings during the cooperation, after consulting you, the EMS provider will be able to do it without your involvement. Some EMS companies will do nothing but download the CAD file and go to work. Others, however, will analyze the CAD file and make sure that it can be produced successfully.

This approach shows the professionalism and experience of the EMS partner. Regarding the box’s assembly, the subcontractor should also propose the best construction method and indicate all its advantages and possible risks. You can also arrange shipping and storage of the box with the EMS supplier. Consider whether, for example, a special pallet or packaging with non-standard dimensions will be needed for transport.

It is worth choosing a supplier who has design experience and will advise you at every stage, from selecting and delivering components, through the refinement of CAD drawings, to the transport of finished boxes. Not all EMS companies provide this level of assistance. Your subcontractor’s experience can help you optimize assembly costs and unnecessary delays in production.


Before you decide to choose an EMS provider, decide on one more issue – tests. In the case of the Box Build Assembly, it is worth at least indicating the basic electrical safety tests that should be performed. However, it is also worth consulting with EMS in this matter, which may offer factory tests or functional tests. The subcontractor will know what works best for your order.

Client service

Last but not least, pay extra attention to client service. Before signing a contract with an EMS partner, find out whether:

  • Will the company assign a direct-contact person?
  • What will be the waiting time for a reply to your e-mails, and does the company answer calls from clients quickly?
  • How does an EMS provider work when problems arise during implementation?

These are the most critical issues that you should verify before selecting the EMS box build assembly supplier. Don’t be afraid to ask about these and other issues that are causing doubts. When outsourcing a box design, finding an EMS partner can be either a huge benefit or a headache. Make sure you do everything to make it the first.

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Written by Marcus Richards

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