What is HDI Rigid Flex PCB?

HDI Rigid-Flex PCB

Before we take a look into what an HDI Rigid Flex PCB is, it is important to understand the elements that make it up.

Rigid-Flex PCB

With electronic devices shrinking day by day, and the rising need to produce more and more compact circuits, PCBs have come a long way. Conventional rigid PCBs cannot fulfill the market demand of tiny circuits. A normal flex circuit has its own limitations when it comes to design flexibility. The reliability of a Flex PCB depends upon various factors like bend radius, whether the circuit is designed to be bent-to-install or is dynamic in nature (needs to bend frequently), foil weight, copper plating, etc.

A flex PCB revolutionized the design of equipment. It allowed wearable electronics to become smaller and more compact. But the difficulty in designing, high initial manufacturing cost, and lack of robustness prevent it from being used in sensitive, complex, and large circuits.

The natural solution to this came out as a Rigid-Flex PCB. It combines the best of both circuits. Circuits can be freely and efficiently designed on the rigid part of the PCB, without worrying about the neutral bend axis and where through-holes, while using the flex part of the circuit to bend and mold the circuit to your required shape.

A Rigid-Flex circuit eases the designing process and enhances the design possibilities beyond neither circuit types alone could provide. Thanks to the rigid PCB parts, component mounting becomes easier than in flex circuits and with flex connections, a Rigid-Flex PCB will be much smaller than the same sized rigid PCB.

But that’s nothing compared to what an HDI Rigid Flex can offer.

HDI PCB

High Density Interconnect PCBs are much more efficient, denser, and more compact than normal PCBs. HDI PCBs are designed as an improvement upon conventional PCBs that employed holes and vias. An HDI employs microvias that can be blind as well as buried. These microvias can help connect any two layers of PCBs without interfering with other layers.

While the vias for a traditional multilayered PCB could be drilled as small as 150 nm in diameter, the process is costly and has mechanical limitations. The mechanical drilling, though highly efficient, does have its limitations. The microvias in an HDI PCB, have a diameter of 0.075mm or less. Since the holes are drilled using a laser, the finish is perfect.

The trade-off is the aspect ratio. While a mechanical drill cannot drill a hole after a certain diameter, but they can have a large aspect ratio. Most microvias do not go beyond the aspect ratio of 1:1, which means you can only drill a single microvia in a single layer of PCB. So if you have to connect surface to surface, using microvias, they either have to be staggered or stacked. Stacked microvias allow for a more efficient design.

For an HDI PCB, the individual layers are etched, drilled, plated, and then stacked together. Unlike the through-hole PCBs where the layers were etched, plated, stacked together, and then drilled.

Though the overall setup of designing an HDI seems like a costly endeavor, HDIs can be pretty cost-friendly if efficiently designed. They reduce the number of layers a traditional multilayer PCB would have used. In some cases, a traditional 8 layer PCB can be shrunk down to a 4 layer HDI PCB.

HDIs allow for a higher pin density on the PCB. They also allow finer lines and spaces and capture pads that are smaller than in a traditional PCB. All these factors combine to make HDI PCBs more compact, efficient, lighter, and smaller in size.

Along with the mechanical advantages of an HDI PCB, the electrical advantages are also significant. Since, thanks to a high density, components are closer together. That, combined with better connectivity of layers through microvais, makes HDI PCBs efficient and faster.

HDI circuits also have better electromagnetic compatibility than conventional PCBs.

HDI Rigid-Flex PCBs by Hemeixin

Owing to the increasing consumer demands of more compact circuits and efficient designs, we at Hemeixin have started manufacturing HDI Rigid-Flex PCBs. Which means you can have the density of an HDI and flexible design of a Rigid-Flex in your finished PCB. This combination opens the door to a lot of powerful opportunities.

To put things into perspective, we provide HDI PCBs with up to 68 layers. Imagine the possibilities for your circuit when it can be compacted and miniaturized to such an extent. Employing the power of HDI Rigid-Flex PCB, you can create electronic devices and components of much smaller sizes and designs.

You will not have to design your product to accommodate your circuit; your circuit will be small and efficient enough to be easily incorporated in your design. Medical equipment, implants, aerospace applications, smartphones, smart devices, and robotics are just a few areas where HDI Rigid-Flex PCBs can work their magic.

We use Polyimide to make our Rigid-Flex PCBs. Our drills are capable of producing microvias down to 0.05 mm in diameter. Our design capabilities include ELIC (Every Layer Inter Connection), stacked, skipped, and telescopic microvias, lines and spaces as fine as 35 micrometers and 40 micrometers respectively. We can also accommodate a laser-drilled pad diameter as small as 150 micrometers. Even with mechanical drilling for through-holes, we can drill pads as small as 250 micrometers in diameter.

We can accommodate PCB buildups 1+N+1, 2+N+2, 3+N+3, and 4+N+4. For advanced network requirements, we use Megatron 6 and Megatron 4 materials.

We can deliver your HDI PCB within 10 days of your order. You can design your device with as much flexibility and freedom as you want since your circuit can be as efficient and as compact as you wish it to be. We promise robust, extremely efficient, well designed, durable and dependable HDI Rigid-Flex PCBs that can be used in a number of avenues, such as in devices as delicate as tiny medical implants, or rugged wearable for very harsh environmental conditions.