Design Basics for HDI and the HDI PCB Manufacturing Process
When creating an HDI PCB, there are some basic design guidelines that need to be followed. Validating your design for the HDI manufacturing process is important. It will help you avoid costly mistakes and delays in your PCB project. A good PCB design can ensure a smooth manufacturing process from beginning to end. HDI has become an increasingly popular PCB design approach, especially amongst larger electronics companies. This is due to cost advantages, high assembly speeds, and allows for a thinner profile than traditional designs.
However, many do not understand the HDI basic design and manufacturing. To help new and existing designers better comprehend the purpose of HDI and associated HDI processes, we share some long-standing design basics for board manufacturing with you in this blog post. We hope it helps you make better decisions about your design.
HDI PCB Board Design and Manufacturing: What Is So Different?
The biggest difference between HDI PCB Board Design and Manufacturing and conventional PCB board design and manufacturing is how the boards are made. Most PCBs are made with a single-sided copper layer on both sides of the board and then plated with a layer of copper that is electrically connected to all the parts on the other side.
HDI PCBs have two layers of copper on one or both sides of the board, separated by an insulating material like fiberglass or epoxy resin. The insulating material is usually non-conductive, but sometimes it can also be conductive if you need to use a special kind of HDI board for applications like battery packs or power management systems.
HDI boards can use either single-sided or double-sided copper, depending on your design needs. Single-sided HDI boards are easy to manufacture but are not as durable as double-sided boards because they can wear out more quickly when subjected to heat or pressure over time. Double-sided HDI boards have better thermal management because they do not have exposed copper surfaces where heat can build up inside them over time. The result is smaller devices with higher speeds and better performance.
HDI PCB Design Basics
HDI PCBs can be designed with a variety of different layers and materials, but here are some basic design considerations:
- Keep signal traces on one layer as short as possible by using vias or jumpers between layers when necessary. Avoid crossing traces whenever possible since this can cause signal integrity issues.
- Minimize trace skew between adjacent layers. Skew is when one trace crosses over another at an angle other than 90 degrees. Ideally, you want all traces on one layer to be parallel with each other; this will help reduce the impedance mismatch between layers which causes reflections and thereby impedance mismatches. You can minimize skew by keeping all traces on one layer as straight as possible.
- Consider using differential pairs to reduce noise on low-speed signals such as power supply lines or I/O buses.
- Use ground planes to reduce EMI radiation and improve heat dissipation from high current devices like power supplies and motor drivers.
- HDI PCBs' lifespan is limited by how much heat they can dissipate from each layer. If you have an application requiring repeated high temperatures over time, such as an electric motor or power supply, consider using a thick copper plane on top of your ground plane layer(s). This will help keep those signals moving while reducing heat buildup over time due to electrical resistance in thinner traces.
HDI PCB Manufacturing Process: Quick Overview
PCB design is a process that involves many different phases. There are many different steps to follow, and each stage has its unique challenges.
The first step in designing a PCB is to create a schematic diagram. This is an electronic representation of the physical components used in the circuit along with their interconnections. A schematic diagram shows the layout of all electrical connections, including those between components, circuits, and systems.
After the schematic is complete, it is time to create a layout drawing of the board that will contain all of your components. The layout drawing shows where all of your components will physically be placed on your board and how they will be connected. You can also use this drawing as a guide when etching your board after it has been manufactured by using a computer-assisted milling (CAM) program such as Eagle or KiCAD.
Once you have created your layout drawing and CAM files for machining, it is time to send them off to an electronic manufacturer who specializes in making HDI printed circuit boards (PCBs). The manufacturer will receive the files from you and then convert them into a format their machinery can read. They will then send the files to a pick-and-place machine which automates the placement of components onto the board. This process is known as surface mount technology (SMT) because instead of using through-hole components that require solder reflow soldering, each component is mounted on the surface and connected with tiny gold wires soldered at each end.
Once all the components have been placed onto the board, they will be assembled into their final form and fitted with connectors for input/output devices such as buttons, LEDs, or sensors. The boards are then placed into an oven, where they will be baked at high temperatures for several minutes. This process melts solder paste between each component and its corresponding pad on the board so that it has circuits connecting all of its components when it comes out of the oven.
Next, your board will be tested using various test equipment, including oscilloscopes, multimeters, and spectrum analyzers, to ensure that all traces are functioning properly and meet industry standards for impedance resistance values.
The HDI PCB Manufacturing Process is a specialized form of PCB manufacturing, requiring more in-depth knowledge of both the PCB Manufacturing Processes, available materials, and the different design considerations. But with a little extra attention to detail, this process can produce top-quality PCBs in a reasonable time frame and at an affordable price. The key to success lies in understanding the design basics.
Hopefully, this will get you going. If you want to learn more about the HDI PCB design guidelines for manufacturing, check HemeixinPCB.