Get Design for Manufacturability (DFM) tips from Jay Colognori, Director of Business Development at Electronic Instrumentation & Technology (EIT). DFM and Design for Assembly (DFA) are important to engineers who know you can’t just design a PCB and throw it over the wall to manufacturing. Early and proactive optimization of all the manufacturing functions from fabrication to assembly of the final system is key. Listen to Jay and Judy discuss high-yield designs, EIT’s value-added engineering services and the latest state-of-the-art inspection technology and test capability.
- Jay was educated at Virginia Tech where he attained an EE Degree, followed by a Master's in Electrical Engineering at the University of Virginia.
- He spent most of his career in the mid-atlantic and his career spans from board level electronic design to applications engineering doing custom microelectronics for a couple of years, eventually ending up in PCB Design first at TTM and now at EIT.
- EIT has been in existence for 42 years, and specialize in electronic manufacturing services, turnkey builds, box builds, and demand fulfillment and consider their Engineering value add as part of their DNA.
- EIT has three facilities on the East Coast, consisting of over 200,000 sq ft. They have a facility in Danville Virginia, headquarters in Leesburg and another in Salem, New Hampshire. Altogether they have eight surface mount lines.
- The Danville facility is designated as the low-cost center of excellence and is also a 100% vertically integrated location - it is built for box builds.
- Leesburg and Salem are high-tech facilities with the latest state-of-the-art universal equipment, as well as the latest and greatest inspection technology and a full suite of test capability - with a lot going on and a story that needs to get out - it’s almost been a secret!
- New EIT website
- DFM: Bare board tips
- 2 objectives - 1) to design so that it can be fabricated reliably and with high yields, and 2) so that it can be assembled
- VM Pad requires a wrap plating process to provide a reliable button around the via.
- This process requires more copper which can wreak havoc with fine line design, so be sure to plan upfront and move those fine line geometries to the inner layers.
- Overlapping via structures can’t be made. They need to be stacked and sequential, not overlapping.
- Sit down with your PCB Fabricator at the time of stackup development, before you even start that router and make sure everyone’s happy with the stackup.
- FR4 has too high a Dk for high speed designs today and new materials such as teflon or ceramic-filled laminates are becoming more common.
- If you work with a new material, consult with your PCB fabricator to see how the rules have changed with that new material for the speed you desire.
- DFA Wisdom:
- Common Pads - so close together that they touch, rather than routing a thin signal from pad to pad is a common problem. We don’t want them to physically share the same space which will cause loss of control over the solder flow.
- Keep the pads apart and just run a small solder trace between them.
- The via in the pad has to be filled, it must be plated over and planarized.
- Sometimes the planarization isn’t done properly and even a little dimple, with a BGA on top, will cause the gas trapped beneath the solder paste, to expand ferociously and blow all the solder out of the pad at reflow.
- Always use non-conductive filler it’s much less expensive.
- The benefit of using conductive fill from a thermal point is negligible and is too expensive for the return.
- Thermal conductivity is defined in Wattmeters - if you use a conductive fill, you only get 6 more wattmeters which is rather pointless because the copper is already doing all the work.
- When a thermal via is located in a big plane, with a copper button around it - the button will be in contact with the plane and this is a big no-no. It compromises the solder flow again.
- Do a sprocket arrangement around that thermal via button. This will create a gap between the button and plane and sprockets simply act as traces surrounding it - very good design practice, frequently missed. Especially on backplanes with active components, this will require retooling to enable manufacturability.
- Why has design migrated as a service inside many EMS companies? What is the value to the customer?
- It’s a benefit to both the customer and the EMS. We want to do more for the customer than just assemble the circuit cards. We want projects going through without a hitch, no delays. What we all want is production of electronics.
- Why did EIT recently choose to onboard Altium Designer internally over other tools?
Firstly it’s an all-inclusive package. It’s schematic and design, we like the ECAD and MCAD interface which makes it easy to do 3D fit models. We love the room creation capability that allows you to reuse previous designs. It has very solid DFM rules capability which are set up in advance - that’s a nice piece of insurance. It’s reasonably priced compared to the other high-end tools as well.
- Engineers After Hours: Big hiker, especially the Rocky Mountains. We’re going to do 3 national parks this summer.
- Unique hobbies? Jay has been a dart player since the age of 19. Played in a couple of US opens. Pro advice: 2-3 beers is the sweet spot for optimal dart throwing performance.
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