Flex Circuit Assembly: Challenges and Strategies for Success

Estimated reading time: 7 minutes

Moody says it's very important to have upfront engagements before the design gets set so that potential assembly issues can be addressed. "Often times, we found this to be very true before we brought assembly in-house. As Bob said earlier, it’s that throw it over the wall mentality, let them figure it out—and that can add costs to the program, not only in dollars but in the delay of getting the product out the door," says Moody. "The time that’s spent upfront to help design everything, including the assembly efficiently, in the end, gets you a better product and more efficient and all of those things. It’s really important to do it all upfront."

Material Considerations

Most of the time, there are still misconceptions when it comes to flex materials to use to ensure better assembly.

Wettermann says some of their customers misunderstood the fallacies of some of the materials that flex circuits are made of, such as Kapton™. "If you talk to people who are our customers, generally they’re the product managers or the project managers, and you tell them that Kapton can actually rip—even though it has this great temperature withstand spectrum and it’s got great mechanical stability, good thermal withstand properties, good dielectric properties, all the reasons they’re using it—it still can actually shear and rip. They respond with 'No way, it can't happen.' Well, yes, it can happen," he adds.

And Moody notes that there is not a real good understanding of the limitations of the material. "The other thing that I would point out is, and it's not strictly part of a component attachment aspect of the assembly, but when you're taking the flex circuit and you’re going to then put it into a box, and that flex circuit has its components on it, ready to go, there’s still somewhat of a misunderstanding about how flex circuits can bend and what degree of bend they can have. You could make it too inflexible, to the point that it really won’t bend, and therefore you have a very difficult time reaching that curve aspect that you are looking for, or the function of the circuit to get from one level to another," he explains. "We have a lot of cases where we have to counsel people in regard to the materials stack-up in order to fit the functionality or the form function of the circuit in the assembly. And again, that has nothing to do with these difficulties or peculiarities of getting the components on the circuit itself. It's just trying to get that circuit to conform within the box, once it is assembled. So that’s another aspect of flex assembly that goes beyond just simply the component placement aspect."

To read the full version of this article which appeared in the June 2018 issue of SMT007 Magazine, click here.

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