Designing PCBs: Who owns the problems?

Article By : Kella Knack

Ownership is at the heart of the challenge in designing and manufacturing PCBs.

« Previously: Why consistency is needed in PCB manufacturing

One of the factors that come into play is an unrealistic attempt to place burdens upon board fabricators. Rather than specifying certain materials, some product developers call upon board fabricators to achieve a certain performance curve. This is not and never can be the role of board manufacturers. In addition, in the process of specifying certain performance matrices over a particular laminate designation crucial factors such as glass-weave induced skew have, at best, been overlooked and, at worst, totally ignored.

Because PCBs are often viewed as commodity items that don't require careful design and manufacture, the tendency has been for product developers to go the route of what's the fastest and cheapest way to go either in the bare board manufacturing processes or in the board-to-chip connections. Several years back in the global supply chain world of component manufacturing, FPGA suppliers opted to use third-party chip carriers in an attempt to keep costs down. The results were cataclysmic.

Because little attention was paid to the quality of these chip carriers, the board- to-chip connections were unreliable. And, the problems associated with these faulty connections weren't readily traceable. The problems only occurred under certain operating conditions and it took a fair amount of research (high non-recurring engineering costs) to locate the source of the problems. What was even more dire is that there was no fix to the problems because they occurred at the interconnect level and there was no work around. Designs had to be scrapped and started from scratch. Some companies missed critical market windows. A few went out of business altogether. This was one time when, as a consulting company, we found ourselves wishing that the phone wasn't ringing off the hook because the answers to the questions were not going to be good.

Who owns the problems?

Ownership is at the heart of the challenge in designing and manufacturing PCBs. Electronic product companies have huge software development teams and small or non-existent hardware development teams (this is what keeps engineering consultants in business). Little or no emphasis is put upon the laminate and prepreg selection process so product engineers aren't always sure which laminate properties are the most important for their particular designs. Or as noted above, in an even growing number of cases, they are designing products that are really pushing the parameters of laminate properties and what can be achieved within their confines. They don't want the answer to be that their products, as they are designed, are not readily manufacturable using widely available, current technology.

Laminate suppliers also share responsibility. They need to provide all of the relevant information necessary to ensure that product development engineers are making the right selection for their particular product implementation and that there are sufficient quantities of materials available within the global supply chain to meet those requirements. On their websites, laminate suppliers need to provide in very clear, easy-to-access information all of the information a product developer needs to have such as technical data sheets, processing guidelines, laminate and prepreg line-ups with glass weave styles, resin content, dielectric constant and loss tangent to select the best material for his/her design.

And, fabricators need to be able to show that they have the processes in place to manufacture boards using certain laminates. This is no simple task. Laminates and prepregs need to be qualified to a fabricator's processes and capabilities. There are a number of qualification hoops which a PCB fabricator needs to jump through and, in a global supply chain world, the fabricator needs to know that there will be enough product demand to warrant going through these hoops.

So, the end goal for PCB production is fairly straight forward—ensure that the laminates used in U.S. protoptyping efforts will remain the same for off-shore volume production. But there are issues and challenges associated with achieving this goal in the global supply chain and they are similar to what they are for any aspect of product design. There are multiple layers to the problem; there are no easy answers or quick fixes and there are no miracle next-generation materials on the horizon that will satisfactorily address all of the issues. What is a given is the ownership of the issues and challenges stretches across the entire global supply chain world as well as the entire product development process. Communication in all forms—from product development groups to laminate suppliers to fabricators is the first, most critical step in the right direction of a journey that spans thousands of miles.

« Previously: Why consistency is needed in PCB manufacturing

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