Design007 Magazine

PCBD-May2014

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May 2014 • The PCB Design Magazine 37 One option is to develop some standard, ba- sic DFM checks which all designers can handle for simple to moderate (Level 1 and 2 produc- ibility) designs. In this case, an industry body could publish a list of DFM checks and their tolerances which could easily be ported into any ECAD design rule check engine, so de- signers could efficiently apply them and have confidence that most fabs would successfully produce the boards. This sounds good, but it's actually quite a difficult thing to achieve—the number of constraints that would have to be thought of ahead of time is staggering. Another option is for the fabricators to be more involved in ECAD tool development. While some have actually used free PCB design tools as a loss leader, it is a very difficult thing to make tools which can handle cutting edge or even some mainstream designs efficiently. I would go as far as to say it could financially de- tract too much from the core business of the fabricator. Personally, I would prefer the fabs to put money into expanding their production lines with newer equipment to tackle the next generation of products. But I do think for DFM, we might actually be onto something here… A better solution space for this problem then, the best in my opinion, is for fabricators to have technical staff actually involved in design plan- ning and in setting up the rules and constraints as early as possible in the design process. The difficulty on the face of this solution is that you may have to know up front who your fab is. Most companies tend to use the same fabs over the long haul so it's not such a big deal. This can be further eased by the fabs. The fabs have a great opportunity to improve business here and I can see at least a few ways of making this easy for designers to really get it right the first time: At the simplest level, the fabs need to get into each ECAD toolset, and produce a pre-packaged set of DFM rules (or constraints) for each pro- duction line or process complexity level they support. Then, those DFM rule sets can be pub- lished or made as a download from the web for the customers who are working with that fab. In turn, the designer can then run a DFM check which gives a high confidence when everything passes, that the fab they are using will be able to get good yields with their design. Going a step further, PCB fabs could offer whole template projects for various toolsets as free downloads for their registered customers, which in a "shrink wrap" include the various DFM checks for their production lines. Take this one step further again: ECAD tool vendors like Altium could make the API for the software available to the fab, who can build their own quoting and DFM check systems into the ECAD tool, so the designer who intends to use that fab can make sure their design is good with the click of a button and even receive a quote from the fab for prototyping. There's a lot that can be done here. The third solution requires the fabricator to have the necessary software infrastructure in place and secure links between ECAD and online DFM servers. However it adds two distinct ad- vantages. The first is that the PCB fabricator can run full DFM without exposure of their process- es, and the other is that the designer can run DFM checks against a real fab's processes with- out other humans interacting with their design source documents. For these problems to be solved in a way that best suits the designer, integration is really needed. Closing the gap between design and fabrication needs reliable and universal data transfer, yes, but above all, it needs good col- laboration between all parties involved. Having good file formats is important, but it is not the complete solution. While work has been done with ODB++ and IPC-2581, the uptake is slow— ODB++ has less than 20% use according to the fabs, and IPC-2581 is in its infancy. But if we at- tack the problem with a one-two punch of good data format combined with early, integrated and direct involvement from fabricators them- selves, then lots of wasted time and materials can be avoided. PCBDESIGN This article originally ran in the February issue of The PCB Magazine. Ben Jordan is a senior manager at Altium. To contact him, click here. feature CLOSING THE GAP BETWEEN DESIGN AND FAB continues

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