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94 The PCB Magazine • October 2015 2. Involve the fabricator early in the design process. Ask questions. Talk to your supplier frequently during the design of the PCB. They should encourage questions and be happy to make recommendations. Once the fabricator understands what you are trying to accomplish, they can make recommendations that will ensure that the design is manufactur- able. As a final step, or even an intermediate step during the design process, ask your fabricator to run a design rule check based on your files. This may not catch every issue and eliminate all en- gineering questions at the CAD/CAM stage, but it will catch the major issues that would require lengthy redesign once a project is released. 3. Verify that material is available and will be in stock when the design is complete. Fabricators try to stock the com- mon materials and even small quantities of the less common materials to avoid delays. Unfor- tunately, they cannot stock all materials. Once the stack-up is finalized, ask the fabricator if this is material that will be in stock. If not, work with your supplier to pre-order the material to have in-house when you are ready to release the design. Some fabricators will secure material based on a simple email authorization; others will require a purchase order. Either way, plan- ning for material to be in stock when the design is complete can save anywhere from five days to six weeks. After a Purchase Order is Placed 1. Send complete files. Review the files being submitted with the purchase order to en- sure they are complete. Is the net list included? Are the fab notes complete, confirming any quality requirements, material specifications, and surface finish requirements? Do the fab notes match the Gerber data? These are all very common reasons that files are placed on engi- neering hold. 2. When you receive questions from the CAD/CAM tooling group, ask if this includes all questions associated with the design. Sometimes two different engi- neers may be working on the same design to meet an expedited delivery and both may have questions in their portion of the process. Other times, when the initial issues are encountered, the job is set aside only to find additional is- sues when work is resumed. The process can be streamlined by taking all questions to your de- signer or your end customer at one time. 3. If necessary, schedule a conference call between your fabricator, your de- signer or end customer and yourself to resolve the issue as quickly as possible. E- mail offers a great documentation trail for any changes, but can drag the process out longer than necessary. If communicating via confer- ence call, ensure that someone is responsible for documenting the discussion and sending that to all parties involved. 4. Follow up with your supplier to confirm that the questions involved in the tooling process have not impacted your delivery schedule. Delays of a few hours are usually absorbed into the initial lead- time. Longer delays can impact delivery. PCB fabricators are typically very good about notify- ing customers of any changes in delivery date due to engineering questions, but it is always a good practice to ask. You don't want to be sur- prised on the day you are expecting your print- ed circuit boards. In summary, communication with your sup- plier is the best way to reduce the cycle time needed for fabrication of time-critical, new PCB designs. Ask for recommendations during the design phase to ensure the design is manufac- turable, verify that material will be available when the design is released, and if there are en- gineering questions, communicate quickly to have those resolved. Take advantage of the fab- ricator's expertise and ask questions! PCB TIPS FOR TIME-CRITICAL PCBS Flex TAlK Tara Dunn is the president of omni PcB. To contact the author, click here.