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In the final installment of this series on how PCB fabricators and designers can better communicate, Bob Chandler from CA Design and Mark Thompson from Prototron Circuits discuss the importance of “technology fit” and how this concept impacts the synergy of the two parties involved.
Steve Williams: Today’s topic is the importance of getting a “technology fit” between the board house and the designer. Let’s start by hearing your perspective, Bob.
Bob Chandler: When you look at a board house from a designer's perspective, the first thing you need to understand is what technology you're trying to design. If you're working with an eight-mill trace with an eight-mil space and a 15-mil drill, very few fab houses in the world are unable to manufacture that, so the technology fit is a little easier to find. If you're dealing with 3/3-mil trace and space, blind and buried vias, special materials, high-speed circuitry, and all kinds of different technologies, then you need to be a lot more careful. Do a thorough investigation to find out if the fab house that you're talking to understands the questions you're asking and has the technology and experience to do that. You don't want this to be the first board at 3/3 when you need your board to go into production.
Williams: Absolutely. Many board shops will tell you they can build a given technology if you ask, but maybe they have built it only once and are now claiming that it’s one of their core competencies. Mark, what questions should they ask the board shop to make sure that qualified to build that technology?
Mark Thompson: A salesperson usually has that discussion.
Williams: The "we can do it” conversation.
Thompson: Right. Ultimately, when the salesperson says “Yes,” to everything, then I say, “I know I say no to a certain amount of things.” Once the conversation between the designer and fab engineer has started about their raw capabilities, then you can ask some of the following questions, for instance:
- Do you do blinds and buried vias?
- What is the smallest line and space you could do with a blind via?
- What is the smallest line and space you can do on "X" material?
As Bob said, it's all based on what application the designer is doing for their end-user; is it medical, aerospace, or automotive technology? All of those categories different constraints, and you want to know that the fabricator could deal with all of those specifications and technologies. It starts with a conversation.
Williams: In Part 1, we talked about qualifying board shops. Is this a matter of needing to visit the board shop and walk through their process? There are probably certain things that you cannot tell from a paper survey.
Chandler: A little bit. But you can still get a lot of information by talking to the sales and engineering rep, especially if the fab house is not located down the street. If, if they're stuttering or don't know what they're talking about, that's not a good sign; it’s better if they answer quickly and come up with more information about what you asked.
Williams: Mark, do you have anything else to add about making sure there’s a good technology fit and that you’re not faced with trying to build something that a salesperson said you could but actually can't?
Thompson: Again, it all starts with a conversation, but it also has to do with basic fabrication machinery. If you are still imaging with photo tools, you're probably not going to be able to get to 3/3, and the line edge acuity will suffer. You should ask them what machines they have. For example, do they have a direct image device to be able to process 3/3? Do they have agitation on their cuposit lines to be able to agitate the panels going through the electroless line to make sure that they get the sauce, if you will, through those very fine holes? Additionally, do they have air hammers associated with those to make sure that they can dislodge any air bubbles that may be lodged inside those very small holes and disperse it into the solution? All of these items are very important to be able to maintain a decent product and deal with very small geometries like small holes, lines, and spaces.
Williams: And you can ask if they do it in-house or outsource it. For example, many companies say that they build a lot of advanced technology, but when you dig into it, they outsource half of the processes, and they’re not doing it well. Overall, the continuing theme is communication, which has been a major component of every topic we’ve discussed. PCB designers and fabricators need to talk to each other.
Thompson: Don't be afraid to pick up the phone.
Chandler: Or send an email.
Williams: Exactly. And with that, we conclude this six-part series. Thank you both for your time and expertise.
Steve Williams is the president of The Right Approach Consulting and an I-Connect007 columnist.
Bob Chandler is CTO of CA Design (cadesign.net) and a senior Allegro/OrCAD trainer and consultant.
Mark Thompson, CID+, is in engineering support at Prototron Circuits and an I-Connect007 columnist. Thompson is also the author of The Printed Circuit Designer's Guide to… Producing the Perfect Data Package. Visit I-007eBooks.com to download this book and other free, educational titles.