June 3, 2015
Flex circuits are designed to solve electronic packaging and assembly problems solve interconnection issues, assist in miniaturization, provide a dynamic electro-mechanical solution, and are configured with repeatable conductors that fool proof assembly errors. Flex is used in designs where standard printed circuit boards, connectors, and cable assemblies just don’t provide the right electrical or mechanical solution.
For solving standard type of solutions, PFC uses “off the shelf” materials such as rolled annealed copper, Kapton/polyimide and various adhesives. In some other applications, we build rigid flex where we would add FR4, Pre-Preg and solder-mask to get to the right mechanical construction. From a flex assembly perspective, we are placing thousands of .0201s (0.02”X 0.01”) and .0402’s components every day. These types of material constructions and component assembly can be found in many flex circuits shops today.
But today, PFC is seeing a new wave of flex circuit challenges to solve. These challenges are arising out of the need for wearable electronics, higher speeds, mobility, component miniaturization, and overall electronic packaging density. Let’s take a look at some of these.
Density and miniaturization
Two examples of new applications in the medical market that are driving flex technology are: 1) Remote Patient Monitoring which is forecasted to grow at a 77% CAGR and 2) Wireless Healthcare which is forecasted to grow to $9.6 billion by 2018.
Imagine wearing a device on your body that would connect wirelessly to the internet and feed your doctor various bits of information about your body from your home? Or in this case, from your body?
Medical devices and sensors are now “wearable”. We have multiple applications at PFC today that are wearable solutions. “Wearable” applications require thinner materials, new circuit geometries, and miniature components. The wearable market is forcing components to be smaller, smarter, faster, and the packaging and assembly to become complex.
To meet the needs of the medical market requirements standard, “off the shelf “1 oz copper just won’t work. Flex materials are getting thinner, providing densities and flexibility increase. For example, PFC has qualified a 12 micron (.00047 inches) adhesiveless material and there are discussions around 9 micron (.00035 inches) adhesiveless materials. These types of densities are required to meet flexibility, geometric and component requirements of the “wearable” market.
For example, PFC is evaluating opportunities that, in the past, would have been designed as a standard PCB. But, because of the dense requirements- lines, space, and assembly/component placement, standard PCB suppliers and contract manufacturers cannot support the density of the components.
PFC received an email from a Product Designer that is developing a wearable solution requiring a specific .4mm pitch BGA Bluetooth component. His “go-to” PCB vendor had to add lots of layers to support the component, making the PCB too thick for the solution. Remember, flex circuits have the ability of being almost any thickness – depending on chosen materials and electrical requirements. Flex is not bound by .031 or .062 standard thicknesses like PCB’s. In addition, his go-to contract manufacturers could not place the .4mm pitch BGA Bluetooth component.
The Bluetooth component manufacturer suggested they work with PFC, since we have placed the component for other projects. PFC could support the trace layout required, the thickness requirements and is now regularly placing .4mm pitch components.
The important fact here is that the Design engineering firm is using flex circuits instead of a PCB – not because of the electro-mechnical characteristics of flex, but rather because flex can provide the thickness and package density required.