What Every PCB Buyer Should Know About Buying Assemblies
PCBA buyers looking to purchase assemblies should know the potential risks they face with different service levels from an assembly house. A buyer's job is to take the engineering specification and keep it inside, as well as the completed printed circuit boards, and consign these items to a PCB assembly house. Once the assembly process begins, buyers should be aware of all the factors that could increase cost or lead time, as well as watch for these items in a quote from the assembly house.
If these factors aren't understood, buyers may have sticker shock at the price of the assemblies, lead times might be unexpectedly long, or warranties may not be given for certain defects. In the worst case, assemblies need to be heavily reworked or even scrapped simply because a buyer did not understand what they saw in a quote form. Buyers should understand these points as they may need to be specified in a PO or verified in a board house's terms and conditions, and it is the buyer's responsibility to understand what they are purchasing from a PCB assembly company.
Top 5 Surprises When Buying PCB Assemblies
PCB assembly surprises can happen at any point during the assembly process: at the beginning when working up a quote, during assembly, and after boards are received and inspected. Wrong means quotes are too high, lead times are not as expected, or there are multiple pauses throughout the process which delay your delivery date. This includes cases of turnkey assembly, where the only role of the PCB assembler is to source and kit your components.
We have found several common surprises that quickly turn into major headaches:
- Unexpected costs in a quote
- Failing to account for parts attrition
- Inflated parts cost in turnkey builds
- Part-footprint mismatch
- Bare PCB defects that become assembly defects
If you want to avoid these problems, here is some critical information to know.
Turnkey Builds Add a Component Cost Markup
Assemblers essentially offer two service levels for PCB assembly: full turnkey and consigned assembly. In a full turnkey build, the assembler procures the components on your behalf and ensures the delivered parts kits are complete and accurate. In consigned assembly, the customer must order the components from a distributor or kit their own components. The ordered components are then shipped to the PCB assembler.
The most common source of sticker shock in full turnkey builds is due to the markup the PCB assembler applies to the components. The markup can be substantial, and even ordering parts at volume does not do much to offset the markup applied by the assembler. Markups can be as low as 25%, but we have also seen markups exceeding 100%.
Instead, order or kit your own components. The small investment in packaging material and inventory holding will pay off, even on small prototype runs. The franchise component distributor websites make it very easy to upload your BOM and create an order for your build. You can also use free services like the Octopart BOM Tool to scan across distributor inventories and create orders for your components on participating franchise distributor websites.