One of my favorite pastimes is playing board games with family and/or friends. Some of my favorites include Monopoly, The Game of Life, and Scrabble. All of these games involve weighing options to arrive at the best decision; however, they also include a random variable, such as a dice roll or spinner. I suppose that is why I prefer Chess, an ancient game of strategy that is not based on luck or chance. Instead, there are boundaries on the movement of the game pieces that must be factored into your decisions.
Similarly, when determining how your circuit board design will be assembled, you should weigh the options before making a final decision. This is not a trivial decision, as the best design is highly dependent on the quality of your board’s manufacture in order to fulfill its operational objective(s). Furthermore, quality rests with your choice of contract manufacturer (CM) and PCB manufacturing services. Thus, to ensure the quality of your board build, let’s take a look at the PCB assembly quote options available, which can be best appreciated within the context of PCB manufacturing options.
PCB Manufacturing Options
As PCB assembly or PCBA is a part of the PCB manufacturing process, the quote options for it should be evaluated with respect to their relationship to the overall process. The options available to you that influence the quote you will get back from your CM are summarized and compared in the table below depending upon the manufacturing services that will be provided.
|PCB MANUFACTURING OPTIONS|
|Fabrication Only||Assembly Only|
Bare board construction quality
Component connections quality
a Although the CM may be responsible for procuring the components, this may be limited to supplier partners of the CM and you may be required to supply exotic or “special components.” In any case, component selection is the responsibility of the designer; however, your CM may make suggestions based upon availability or other considerations.
b If your boards are furnished to your CM as individual units, this will not apply.
As shown in the table, your choice of manufacturing service determines the attributes for which your CM has responsibility. Now, let’s see how this choice impacts the PCB assembly quote that you receive from your prospective CM.
PCB Assembly Quote Options
As shown in the last two columns of the table above, there are many aspects of your board’s manufacture that are assembly specific. And ultimately, the final PCB product depends upon your choice of the best PCB assembly manufacturer for your design. In order to make this determination, you first must decide whether to use assembly only or turnkey manufacturing as there are varying PCB assembly options available to you for each and these will be reflected in your quote from the CM.
Assembly Only: PCB Assembly Quote Options
For assembly only, the following options should be defined as part of the quote from your CM.
- DFA review
The dimensions of your board must fall within your CM’s limits; therefore, an internal review on their part has to be done. Additionally, you may be able to acquire files or information prior to submitting your design. If available, these will most likely be included as part of a DFM file. However, in many cases, this information will need to be incorporated manually to utilize for DFM checks during design.
- Component sources and availability
If your CM is procuring the components, it is important that you know where they are sourced from and whether you must furnish any of them that are unavailable due to shortages or other reasons.
- Component testing
If component testing is requested then your quote should reflect what, if any, inspections and testing of components your CM will or does perform.
- Individual board assembly
It is common for boards, whether fabricated or completely assembled, to be delivered as individual units or pieces. If this is the case, your CM may need to assemble each board separately, instead of the typical batch or panel method. As this will require labor and extended processing time it will likely increase assembly costs and will be noted in the quote.
- Conformal coating choices
Your quote should also include a conformal coating type. However, this must be requested or it is typically omitted.
Turnkey: PCB Assembly Quote Options
Your quote from the CM for turnkey services should include the following.
- Bare board construction specifications
Although board construction is performed during fabrication, all selections for your bare board’s construction will be included as part of your CM’s quote.
- DFM and/or DFA review
As stated for assembly only, these will be performed by your CM. These may or may not be furnished to you by the CM by default. If not, you must request these and there may be additional costs that will be detailed in the quote.
- Type of finishing
Finishing is performed during fabrication to protect the board for assembly. As this is often foregone by fabricators, especially for fabrication only manufacturing, you must ensure that it is requested; otherwise, it may not be included as part of your quote.
- Component sources, component testing, and conformal coating
Same as for assembly only, above.
Depanelization depends upon the panelization design and your CM’s capabilities. However, if you have special requirements for installation you will want to ensure that your CM can meet these and include any design requirements and/or additional costs.
|Tempo‘s Custom PCB Manufacturing Service|
In addition to the above options, you should inform your CM of any special considerations that will impact the PCB assembly process. If you opt for turnkey manufacturing you should also consider whether assembly or fabrication is outsourced as your board quality can be significantly affected. At Tempo Automation, the industry leader in turnkey PCB prototyping and low-volume production, the final product rests with us and we are committed to providing you with the highest quality boards and fastest service.
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.