Low Volume PCB Assembly: The Proving Ground for Your Design

February 7, 2020 , in Blog

Over the course of our lives, there are many times when we are called upon to demonstrate that we are able or capable to perform some feat. For many of these examinations, we may be the only one participating. For example, when taking a driving test for qualification to operate a car or motorcycle. In many cases, however, we will be a part of a team that collectively must prove mastery of an activity or the completion of an achievement.

Circuit board assembly

Low volume PCB assembly

The development of a circuit board is an example where a team is typically required to prove the veracity of a design. This is due to the fact that the process of demonstrating a successful PCB design consists of three stages: design, manufacturing, and testing. For boards of any degree of complexity, development is a cyclic process consisting of several PCB prototype iterations. And to a great degree, the efficiency of this process depends upon how well you take advantage of the flexibility of your board’s assembly. Before expounding on the options available to you during prototyping, let’s first define low volume PCB assembly.

Low Volume PCB Assembly Defined

The manufacturing process for printed circuit boards consists of three parts. These are board fabrication, component procurement, and PCB assembly. The optimization of these three manufacturing activities depends upon the synchronization between the equipment and processes used by your contract manufacturer (CM) and your design. In fact, there is a direct proportionality between the quality of your boards and the incorporation of your CM’s DFM rules and guidelines. For production, low-volume or high-volume, strict adherence to DFM and DFA is necessary to achieve the highest yield rate and lowest production costs.

Irrespective of the level of development or production, the fabrication of your board is likely to remain the same unless design changes dictate otherwise. Assembly, on the other hand, may vary based on whether you are working on the prototype (or refining your design) or producing boards for delivery. There are cases when production levels may be low-volume. For example, when manufacturing critical or special purpose PCBAs for aerospace, medical devices, industrial, automotive, or military PCBAs. However, low volume PCB assembly, as defined below, is an essential part of all board development.

Low volume PCB assembly is the mounting of components on a relatively small number of bare boards, which may range from a handful to 250 or less.

Assembly, although fundamentally well-defined in terms of the steps, provides a great deal of flexibility, as described in the next section. If leveraged properly, it can truly improve the efficiency of your board development.

Using Low Volume PCBA to Prove Your Design

For all circuit board development, there are essentials of good PCB design which should be instituted. For assembly, in addition to smart component placement decisions, you should be aware of the various options available to help expedite the proving of your design that is commonly referred to as prototyping or the design⇒build⇒test iteration process. These options can be classified as part of a sequential or parallel prototyping strategy.

Prototyping Options for Low Volume PCB Assembly

  • Sequential 

A sequential prototyping strategy where a single or a small number of design changes are incorporated and tested each cycle is the most common approach to design verification.

  • Parallel 

Parallel prototyping can be used to reduce or minimize the number of manufacturing runs required. This is done by applying multiple design changes to a small number of boards and then testing all of the variants prior to the next manufacturing run. These variants are applied to assembly only and all of the bare boards are similarly fabricated.

For both of these strategies, the following assembly options may be done:

  • Do not place (DNP)

In order to test a particular component or sub-circuit, it may be advantageous to not place other components that may make testing and troubleshooting more complicated and difficult.

  • Using different variants

An extension of DNP is to place different sets of components on different boards to simplify testing.

  • Using leaded solder instead of lead-free

During prototyping, it is common for re-work to be necessary, which is much easier with leaded solder than with lead-free.

  • Using a reworkable surface finish 

As rework may be necessary, it may is better to use a surface finish that is easy to rework or none at all during prototyping.

Tempo‘s Custom PCB Manufacturing Service
  • ISO-9001, IPC-600 and IPC-610 commitment to quality certifications.
  • Accurate quote in less than 1 day.
  • Performs entire turnkey process in as fast as 3 days.
  • Emphasizes DFM to eliminate time-consuming back-and-forth design corrections.
  • Sources components from the most reputable suppliers in the industry to reduce procurement time.
  • Performs multiple automated inspections during assembly to ensure PCB quality for prototyping.
  • Provides support throughout the PCB manufacturing process, beginning with design.
  • Smooth transition from prototyping to production.

In addition to being critical for PCB development to ensure that your boards will perform as designed, low volume PCB assembly is the most flexible aspect of the board manufacturing. However, making the best use of this activity requires that you apply the keys to good prototype circuit board assembly design. At Tempo Automation, the industry’s fastest turnkey manufacturer for low-volume production and prototyping, we will work with you to expedite your board bring-up.

And to help you get started on the best path, we furnish information for your DFM checks and enable you to easily view and download DRC files. If you’re an Altium Designer or Cadence Allegro user, you can simply add these files to your PCB design software. For Mentor Pads or other design packages, we furnish DRC information in other CAD formats and Excel.

If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on low volume PCB assembly, contact us.

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