Can a Vertically-Mounted Component Carrier Replace Flexible PCBs?May 01, 2020 by Robin Mitchell
This week, HARTING announced their latest product innovation that they say redefines the word "carrier."
Component carriers and sockets come in all shapes and sizes to give designers a number of options when replacing a part. This is particularly useful when prototyping. In other cases, sockets are helpful for those who hand solder circuits and want to prevent heat damage to sensitive parts.
This week, HARTING announced their latest product innovation that they say redefines the word carrier. According to the company, this device may change how design engineers create PCBs of the future.
The component carrier, which can be vertically mounted, aims to replace flexible PCBs and reduce production costs by as much as two thirds. What are these carriers? How are they made? And how will they replace flexible PCBs?
A Replacement for Flexible PCBs?
Flexible PCBs are often required for applications in which sensors need to be mounted away from a PCB at odd angles. For instance, they can be a good option in antenna applications for clearance issues. But while flexible PCBs can solve these problems, they are often expensive to manufacture and require complex production steps, including mounting and gluing.
Olympus Stylus camera that shows flexible PCB assembly. Image used courtesy of Steve Jurvetson [CC BY 2.0]
The use of chip carriers can solve many of these issues by allowing sensors to be mounted away from a PCB. The antenna can be positioned away from the main PCB for maximum efficiency and for heat dissipation so the components' heat isn't concentrated on the main PCB. These chip carriers help to eliminate cabling that connects to components mounted away from the main PCB.
HARTING also describes the component carrier as flexible. They claim any electronic components—be it a sensor, LED, IC, or photodiode—can be placed on its surface "in any position, orientation, and quantity," within the available amount of space. Components in packages SOIC-8 and smaller will fit on the component carrier.
So far, the carrier has found its way into medical, industrial, and consumer technology.
Vertical Mounting on PCBs
The new component carriers are designed to mount to SMD components and route their connections 90 degrees to the board, allowing components to be mounted vertically on a PCB instead of horizontally.
The component carrier. Image used courtesy of HARTING
The carriers are manufactured using a thermoplastic. Using injection molding and an additive in the plastic allows a laser to create areas that have a micro-rough structure. From there, metal particles are applied to the component carrier. These particles stick to the activated areas thereby producing electrical connections.
While generic carriers are available for housing commonly-used ICs, HARTING also offers a custom design service for its customers, so more designs can be realized using this technology.
The Advantages of Vertical Mounting
The ability to mount components 90 degrees to a PCB opens up a lot of possibilities.
For one, the ability to orient components perpendicular to the PCB can increase component density. But this possibility depends on the chip carrier pinout being smaller than the components it houses.
The second advantage: small circuit units could be manufactured onto chip carriers (including passives and other supporting hardware) and this may help to reduce interference from signal traces, thereby improving analog and digital performances. However, the increased trace length and contact resistance might hinder this option.
Infographic for the benefits of components at a 90-degree angle. Image used courtesy of HARTING
One of the most compelling advantages of this technology involves heat dissipation and sensor connections. ICs that are not attached to the main PCB will be able to diffuse heat in ways that don't affect nearby components. If designers choose to keep the PCB horizontal, they can also enhance heat removal due to convection currents—a big plus for power circuitry.
While 3D component technology is something that is still in its infancy, there is an alternative to the chip carriers produced by HARTING: board-to-board pin headers. Small ICs can be mounted parallel to the plane of the PCB. A PCB that uses secondary PCBs with pin connectors (such as those found in PCIe) can easily achieve higher component density.
The cost of an additional PCB for every module or subcircuit may be justified by the huge increase in component density as well as simpler manufacturing techniques. The use of board-to-board connectors is well established and many connectors are suitable for reflow soldering. This means the manufacturing of such boards can be automated.
A Useful Option for Power and Sensor Circuits
The HARTING 3D component carriers provide engineers a new range of possibilities and design concepts. Power circuitry can take advantage of better cooling while sensor circuits can remove the need for any wires or connectors.
Some designs may be able to increase their component density while others can take advantage of better radio signals thanks to the antenna being mounted away from power planes.
It's important to note that this technology cannot replace flexible PCBs in applications where the board needs to flex.
Do you know of any useful (but perhaps unconventional) design techniques to mitigate issues with heat in circuit board design? Share your thoughts in the comments below.