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manufacturer, which can be overcome by estab- lishing close communications between a design firm and its manufacturer. A manufacturing com - pany should be treated as a partner, capable of providing invaluable insight into how design and manufacturing decisions can impact cost, manu- facturability, yield, and final product quality.
Mismatched Rule Sets Another process problem is a mismatch be-
tween DFM rule sets at a design firm and its man- ufacturer. From the beginning, it should be con- firmed that a design company and its manufactur- er are using consistent DFM rule sets and compo- nent footprint files. The same should be done be- tween a design company and its suppliers, since the accuracy of the footprint files on a circuit board
www.us-tech.com Guidelines for Ensuring PCB Manufacturability
can also affect a design’s success. Close communi- cation with suppliers helps ensure that a design incorporates up-to-date footprint files. Yet another potential process problem in-
volves electrical performance problems in complet- ed boards. To avoid costly circuit redesigns, com- puter simulation tools should be used to check the electrical performance of a design against other target requirements, such as size and yield. Another potential process problem is when a
design that has been successfully implemented with one manufacturer fails when produced by an- other manufacturer. When using a rapid prototyp- ing service for PCB manufacturing, for example, that service might have specific process require- ments. Good manufacturers can help make sure that circuit-board parameters will fit with specifi- cations unique to a particular rapid prototyping
Finally, a Pb-free solder paste that takes a shine to ENIG/gold PC boards.
Introducing NC-560-LF, the Pb-free no-clean solder paste designed for hard-to-solder metallization surfaces
Nothing increases production yields like AMTECH’s NC-560-LF, the lead-free, no-clean solder paste for hard-to-solder metallization surfaces, including ENIG (Gold),OSP, HASL and immersion silver
boards.This fully RoHS-compliant solder paste delivers unparalleled lot-to-lot and stencil printing consistency, and enhanced solderability due to superior print performance characteristics, including excellent wetting and activity, ideal viscosity, long stencil life, thermal stability up to 300
o C, and minimal residue. NC-560-LF
solder paste is also low beading, low voiding, and anti-tombstoning to reduce scrap and rework. Looking to strike it rich with greater hourly throughput? CallAMTECH today, and you’ll be golden.
AMTECH
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FI LLI NG TH E VO ID See at APEX, Booth 549
service. Another process problem can be with toler- ance violations, which can be avoided by checking tolerances at every level, both with parts and with manufacturing processes.
Gauging Manufacturer Capabilities
Not all manufacturers have the same capabili-
ties. The largest number of manufacturers will have the capabilities to handle a relatively simple, conser- vative circuit design, whereas a more limited num- ber of manufacturers will successfully produce a more challenging, complex circuit design. Knowing the capabilities of different manufacturers can help avoid expensive rework for a project that might be a bad match for a particular manufacturer. When evaluating different manufacturers, it
can help to consider DFM rule set offerings, front- end expertise, and support capabili- ties at each manufacturer. When evaluating DFM rule sets, for exam- ple, a manufacturer should be con- tacted early in a manufacturing process to confirm that a design firm is using DFM rules matching a man- ufacturer’s specifications. When checking front-end expertise, it can help to learn about a manufacturer’s internal process for moving a CAD file to production. Such issues to con- sider include what kind of DFM checks they perform upon receiving a CAD file, how robust is their quality- assurance (QA) process, how do they resolve design challenges, and what is their scrap rate. Manufacturers that offer a robust DFM process can compensate for gaps in a customer’s DFM expertise. Finally, when evalu- ating support capabilities at a manu- facturer, a responsive support staff at a manufacturer can help solve manufacturing issues during the de- sign process rather than after it. A potential manufacturer’s support ca- pabilities should be fully assessed be- fore they are selected for a project. The key to optimizing the manu-
facturability of a PCB design is to choose tools, processes, and a manu- facturing partner with capabilities that meet the specific needs for manu- facturing that PCB. Implementing DFM practices earlier in the manufac- turing process rather than later can aid the success of a manufacturing process.
Where possible, a PCB design
tool with interactive DFM rule-check- ing capability should be used. If that is not an option, a design process should be defined for multiple partial- functionality checks rather than a sin- gle full-functionality check at the end of the design cycle. In addition, parts suppliers and the PCB manufacturer should be treated as members of the design team, with constant communi- cations maintained with these part- ners throughout the design cycle. The use of computer simulations can help avoid expensive product rework at the production stage. The right manufacturing part-
ner can make it easier and less ex- pensive to produce a working proto- type. Look for a manufacturer that provides free, up-to-date DFM rule sets and product support that meet specific needs for accessibility and expertise. By finding out more about a manufacturer’s DFM and QA processes, greater confidence can be placed in that manufacturer’s capa- bilities to produce a PCB with high quality and controlled cost. Contact: Sunstone Circuits,
13626 S. Freeman Road, Mulino, OR 97042 % 503-829-9108 E-mail:
njohnson@sunstone.com Web:
www.sunstone.com r
March, 2014
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