PCB Assembly

Common Mistakes to Avoid in Consignment PCB Assembly

Consignment PCB assembly means the customer sent all parts and boards in a single consignment. So assembly vendors have performed the assembly process after receiving that consignment. Consignment PCB  assembly is the easier solution between customers and manufacturers because it provides freedom, and reliability to customers for consignment PCB assembly. It’s a cost-effective solution for customers.

Benefits of consignment PCB assembly

  • Quality control and assurance are the best in consignment PCB assembly. They make sure the whole thing like procuring the parts follows the quality requirements which provide the best quality of consignment PCB assembly and many benefits. There are many techniques for quality checks for assembly like AOI, x-ray, ICT, manual inspection, SPI, etc. They give the best resolution for each assembly.
  • Time saver: the whole manufacturing process is automatically in the assembly house. So it’s a big advantage for customers to reduce lead times and provide consignment PCB assembly easily and faster.
  • Reduce the cost: now, many technologies are developed in PCB assemblies like SMT, THT, and mixed technology, which provide low labor costs for customers if customers allow outsourcing.
  • Consignment PCB assembly gives one-time shipping for each customer to make it easier to deliver to the customer without any stops.

Common mistakes to avoid in consignment PCB assembly

1. Less inventory

The customer provides the parts in consignment which is required for PCB assembly. They are the customer’s own required parts. So, sometimes they would be less or higher. Production houses do not carry more parts in inventory. If any parts are having issues at the production house, then parts are not available in inventory.  So it was a huge mistake in the assembly process due to less inventory.

2. Alternate parts

Generally, the customer prefers alternate parts to replace the original parts. But, sometimes customers are not provided alternate parts and do not change the original parts. The customer doesn’t want to change original parts to alternate parts if any special requirements are going on for that particular project. To avoid this issue in consignment PCB assembly, please communicate with the customer first for substitution requirements.

3. Moisture parts

When the customer buys parts, it does not show some parts have moisture like sensors, actuators, Relays, etc. So these parts needed some extra handling processes when they shipped the parts. So these types of parts are opened in consignment. This will be a major issue for consignment PCB assembly if parts are installed at the assembly stage without any baking and handling process. No one can define the life cycle of those parts.

Common mistakes of consignment PCB assembly

4. Split consignment

Customers have many projects assigned to one assembly vendor. Sometimes consignments are interchanged due to many projects being assigned at the same time. So parts and boards were interchanged at the assembly house. That time communication is increased with the customer due to the split consignment and lead time being expired. Assembly vendors need to create a new consignment at that time or divide the parts as per the bill of materials.

5. Missing files

The consignment PCB assembly process needs BOM (bill of materials), pick and place files, Gerber files, assembly drawings, etc. Sometimes some files are missing in customer customer-supplied data packages. To avoid this error, we can make sure all files are received properly at the order-receiving time.

6. Production capabilities

When the customer sends files for the first time to consignment PCB assembly manufacturers, the manufacturers confirm their production capabilities after setting the final quotation to the customer. Because if we do not confirm the production capabilities then, we need to outsource vendors for assembly. It’s very costly for assembly.

7. Improper labels

There are many ways to label the PCB using reference designators. These reference designators are provided by the customer. Now all designers are provided reference designators in the Bill of Materials and silk also. This is a unique technique to identify parts. But sometimes reference designators are not provided accurately. So this time more attention is needed for the consignment of parts kits and installing them on the PCB.

8. Inaccurate placement

Inaccurate placement will occur due to spacing between part leads. Solder floating on pads due to inaccurate placement. To avoid this make in consignment PCB assembly, you need to make sure the spacing between leads of the part is accurate at the DFA stage. So this will not happen on the production floor.

9. Old techniques for solder

Sometimes weak connections, solder joints, and solder bridges come at the Soldering stage. This error comes due to old technology used in production houses for soldering. The proper soldering materials and tools are used in the assembly house. So this type of error does not come in the production house.

10. Don’t skip the DFA

DFA is design verification for consignment PCB assembly. In DFA, the whole assembly work is verified including parts placement, solder joints on stencil, improper silkscreen, layout issues, polarity placement, assembly requirements from drawings, and all. So, the DFA report gives one type of assurance that all assemblies are verified and there are no worries for the production house.

11. Communication loss

Sometimes, special requirements slow down the whole consignment PCB assembly process. So that time assembly teams communicate with each other. And then there’s a communication gap if anyone does not reply to each other. To avoid this error the whole team makes sure all assembly questions are solved promptly to avoid any delays.

Conclusion

After reading the above mistakes and COS, I concluded that we have to make sure the whole capabilities and files of assembly are fulfilled or not. Then place a consignment PCB assembly order in the assembly house. It’s beneficial for the customer and assembly house also.

After that make a DFA report and see what type of error comes in the assembly file and suggest to the customer how to solve this error Or if new data is needed then ask for new files.

If our capabilities are not fulfilled and outsourcing vendors are doing the same requirements, then ask the customer for that. If the customer wants outsourcing with the help of our assembly vendors, then it’s also working for us for future orders.

Also, technology is a big advantage of the assembly house because it’s working on various types of assemblies and their capabilities.

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