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Design for manufacturing (DFM) is an important component of the design process. Although not as popular as DFM, design for assembly (DFA) is just as important. If you optimize your printed circuit board (PCB) so that it would be created perfectly, yet make it so the PCB would only be assembled through laborious hand soldering, then you would save cents for each board when it comes to PCB fabrication. To prevent this, both the assembly and manufacturing have to be considered during the design stage. Fortunately, you do not have to compromise between assembly and manufacturing, and in most cases, you can come up with a design that is both easy to assemble and fabricate. The first step for DFA is to get to know the assembly process.
Have a Smooth Relationship with the PCB Manufacturer
You need to contact the PCB assembly house and discuss the project with them. There should be constant communication all through the life of the product as well as regular discussions and feedbacks between the two parties. Every manufacturer would have its own procedures, requirements, and strengths that you need to know. The manufacturer would likely assign an account manager to help you coordinate with every team member as necessary. Personally visit the PCB fabrication site, if possible, to meet the team and be familiar with the process.
This would be a great opportunity to get an impression of the company and to know how professional and responsive their employees are. Observe the production floor and make sure that they follow safety precautions on electrostatic discharge (ESD), that ongoing projects are well-planned, and that the facility in general is free of chemicals, dust, and debris. Still, some of the things you might have difficulty with later on include lengthy communication delays, inconsistent views from different team members, and disorganized facilities.
Importance of Providing the Right Information
In preparation to submit the PCBs for assembly, there are some things you have to provide the manufacturer. This includes the bill of materials (BOM), which includes the description, part number, reference number, package type, and value. The information has to be correct and complete, so the manufacturer would put components on the right places. A good PCB fabrication house would ask for clarification if there is something that seems strange to them.
When the PCB assembly house has obtained all the necessary information, they would start by evaluating what they’ve received. They would find faults and work with you to resolve them. A few PCB manufacturers run designs using their own verification software to create digital design images and help detect errors from part to footprint.
Afterwards, depending if it uses a turn-key procedure, they could order components on your behalf. If it is only for PCB assembly, you have to ship them the parts and boards, ensuring you provide them with the proper supplies. Again, appropriate labelling and paperwork is crucial. If the board and BOM match with the right reference designators, but parts were mislabelled, there would be delays. The worst thing that could happen is requiring a rework for the entire run, which significantly increases PCB fabrication costs. Discuss with the manufacturer for equipment checklists.
Some assembly houses would even provide you custom equipment labels for free to help you with supply preparation. When the first step is done, the next is to start the physical assembly process using pick-and-place machines. Then the PCBs will go through soldering and testing. Dedicated PCB manufacturers have the experience, expertise, and proper equipment to do all these. By knowing the PCB fabrication process, you could improve quality and increase quantity while reducing costs.