How HDI PCBs Can Help Create Smaller, More Streamlined Electronics
Using HDI PCBs can help you create high-quality electronics with smaller, more streamlined packages. They’re especially ideal for products where size, weight, and reliability are crucial.
This technology uses blind and buried vias to reduce the distance between components, which improves electrical performance. These benefits include lower power consumption, faster signal transmission, and improved reliability.
Build-up structure
An HDI PCB has a high-density wiring layout that allows it to be used in smaller products than traditional printed circuit boards. It can be used in a wide range of applications, including mobile devices, digital video equipment and computerized medical equipment. HDI PCBs can reduce the overall size of a product by using fewer layers and shorter trace lengths. They can also improve signal integrity, control impedance and thermal performance.
There are many types of HDI PCBs, each with different layer stack-up structures. The most common is the 1+N+0 design, which includes two sequential laminations on either side of the core and a single copper layer. The next is the 2+N+2 design, which uses two consecutive build-up layers and adds four copper layers to the structure. This type of structure is a better choice for high-pin-count ball grid arrays (BGAs).
Whether you are designing an HDI PCB or a standard one, it’s important to know the maximum routing density your fabricator can produce. In addition to determining the layer stack-up, you should consider the type of vias and where they will be located. For example, if you use laser-drilled vias, they can replace through-holes and offer more routing space on the layers below them. This will save you time and money. You can also choose to move the GND and power planes to the bottom of the layer stack-up if they don’t require components or traces.
Microvias
Microvias are used to connect the copper layers in an HDI PCB. They are usually made using laser drilling technology, which produces a high-impact beam that can cut through metal and glass, creating tiny via holes. These holes are then filled with a non-conductive material or plated closed. Depending on the type of microvia, the manufacturing process may require additional steps to ensure the integrity of the holes. This is due to the high aspect ratio of these vias, which increases the chance of failure during reflow and thermal/mechanical shocks.
Moreover, the smaller via size allows for more connections and wire routing hdi pcb density in a PCB. This leads to shorter signal transmission distances, resulting in better electrical performance. It also reduces the time it takes to design a circuit board, allowing for faster prototyping.
There are two main types of vias: buried and blind. Buried vias pass through all the outer layers but do not pierce through the inner layers. They are hidden from view, but they can still provide a connection to the outer layer. Blind vias, on the other hand, are visible only from one side of the circuit board and can connect to any inner layers.
The reliability of microvias is impacted by the mismatch of coefficients of expansion between copper and dielectric. This problem occurs because the copper expands more than the dielectric, which can result in cracking or debris-based ICD (insulation damage). To prevent this, a close-to-pad technique is used to avoid this issue.
Drilling process
The drilling process used in an HDI PCB is different from conventional PCBs. This process involves using a computer-controlled machine that drills holes into the board. The machine uses a drill bit that rotates at a high speed and can create a hole as small as 6 mils. This type of drill produces good quality holes, but it also leaves a burr on the edge of each hole. This burr causes poor copper plating and other defects, such as barrel cracks and blowholes. It also increases the cost of manufacturing the circuit board because it requires a greater number of deburring operations.
The manufacturing of an HDI PCB requires a special procedure to ensure the quality of the vias. The process begins with etching and then separating the layers with partially cured HDI PCB Supplier laminates, called prepregs. Then the PCB goes through a lamination cycle, and the prepregs are heated to liquify them. This process is known as sequential lamination.
Conventional PCBs rely on mechanical drill bits for PTH drilling, but HDI circuit boards have smaller vias that are harder to make with mechanical tools. In addition, mechanical drilling can cause the edges of holes to be rough, which reduces signal transmission. To solve this problem, an HDI PCB manufacturer can use a microvia-in-pad design style to improve reliability. This technique places a small trace section near the microvia, which completes the connection to an internal layer in case of drill wander.
Layout
HDI PCBs use buried and blind vias to cut down on space, which allows for higher component density. These features can significantly reduce the board’s size while improving its performance. They can also reduce signal interference. This makes them ideal for high-performance electronic devices such as smartphones and tablets.
HDI PCB prototypes are a great way to evaluate your designs before committing to a larger batch of manufactured boards. These prototypes are simple models of the manufactured boards, and they can help you determine which design is best for your application. They can also help you choose the right type of vias, stackup, and material. These factors can all influence the manufacturing process and cost.
The type and amount of vias, through-holes, and microvias in your HDI PCB can have a big impact on its price. For example, smaller vias will be more expensive than larger ones. The number of layers in your stackup will also affect the price. It is best to opt for fewer layers, as these will decrease assembly costs and production duration.
When choosing the number of layers in your HDI PCB, make sure to follow the manufacturer’s guidelines. You should also consider signal integrity when selecting the layer count. This will ensure that the board’s impedance meets signaling standards. Finally, it’s important to select a good layout for the board, which will minimize EMI and improve signal routing.
