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PCB007-Aug2021

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72 PCB007 MAGAZINE I AUGUST 2021 was more or less done, but had the design sent for verification before he closed it and submit- ted it to procurement. What About the Stackup and Changes? e purchaser received the Gerber files and submitted his request for quotation to two or three of his most trusted PCB suppliers. He got the first quotation within eight hours but de- cided to wait another two days to make sure he had the best price. Order placed as usual, but now things started to happen. e PCB factory replied that the materi- al supplier for this brand and type suddenly had eight-week lead time. He sent back an en- gineering query for alternative materials that would keep the stackup and those designed im- pedance lines. Designer rejected; the stackup had been approved by the end customer with no chance to change it now. So, what happens next? e EQ is sent back to the PCB supplier, with the result of a five- to six-week increased lead time compared to the original offer. What Can We Learn? First, in a normal situation this is not neces- sarily an issue, but today with increased and less predictable material lead times, and on top of unpredictable material prices, we need to adapt to the situation and be smart. But How? First, make sure the stackup and material se- lection is as open as possible. 1. Don't lock your stackup to one material brand or type of material. Allow for factory standard materials to be used. 2. Try to use IPC 4101 slash sheet numbers, unless you have special needs. 3. If you have impedance lines designed in, make sure to describe what you need. e factory will in 99% of the cases be able to tune track and gap to meet their standard materials. 4. If you ask for a factory stackup, make sure you allow standard materials to be used. 5. Also consider releasing the stackup for material to be allocated, or even placing a material preorder. By these actions, you can simplify the pro- cess of approving the design, and, as we cur- rently face an unpredictable material situation, avoid sudden increased material lead times from when the stackup is approved, and up to order placement. Remember that the PCB fac- tory doesn't order material before all EQs have been closed, adding on another two to seven days. Is Price the Key to Success? We all know price matters when procur- ing printed circuits. Some buyers only target on price, benchmarking, and swapping sup- pliers more oen than the Kardashians shoot selfies. Long term relationships might sound boring, but also offer predictability, priori- ty, and dual source if needed. Just to specify, I am only talking about relationships with your PCB supplier. In a market like today, a few pennies saved can be at a high cost. My advice aer decades in the industry and facing the current challeng- es daily: 1. Place the material allocation order as early as possible—as soon as the stackup is fixed. 2. Don't start negotiation prices and lead times the day you expect to place the order; it is too late. Not even the same week. 3. Select a trusted supplier that accepts material allocation on orders and stay with them. 4. Work on long time trust and be predictable within the nature of your business. Be Realistic e last thing I want to mention is the need for a PCB supplier that has skills and knowl- edge to guide you in the right direction. As in

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