We often mets clients try to reduce HDI costs. as we known, with the rapid development of 5G technology. The trend of consumer electronics is moving toward high intelligence, thinness and portability. As electronic products iterate faster , electronic designs are trying to reduce their size . while continuously improving the performance of the machine. HDI is widely used in cell phones, digital cameras, notebook computers. automotive electronics and other digital products.According to statistics, the global market size of HDI has reached USD 9.222 billion in 2018. and is expected to reach USD 11.377 billion in 2023.
So With the widespread of HDI, we frequently hear from our customers feedback. that want to know how to reduce HDI costs without sacrificing quality when purchasing HDI? In the following article, let ETE explain what HDI is ? and what factors can reduce the cost in HDI production.
HDI circuit boards with a greater wiring density than traditional printed circuit boards . PCBs with microvias, blind and buried vias, built-up laminations. and high signal performance considerations are classified as HDI PCBs . The revolution of PCB technology has paralleled the demand for smaller and faster products. resulting from the evolution of technology. HDI circuit boards have more compact vias, pads, copper traces, and spaces. So, HDIs have denser wiring, resulting in lighter, more compact, and fewer-layer PCBs. Instead of using multiple PCBs in a device. a single HDI board can house the functionality of the PCBs that were previously used.
The diameter of less than 6mil (150um) hole called micro-hole.
Buried Via Hole, buried in the inner layer of the hole, in the finished product not display. mainly for the inner layer of the line conduction. That can reduce the signal interference to maintain the continuity of the transmission line . As buried holes do not occupy the surface area of the PCB, so more components input on the surface of the PCB.
Blind Via, connecting the surface and the inner layer and not through the whole plate of the guide hole.
Traditional PCB board drilling due to the impact of the drilling tool. when the hole diameter of 0.15mm, the cost has been very high, and it is difficult to improve again. The drilling of HDI boards no longer relies on traditional mechanical drilling. but uses laser drilling technology (so sometimes called laser boards.)HDI board drilling hole diameter is generally 3-5mil (0.076-0.127mm). the line width is generally 3-4mil (0.076-0.10mm), the size of the pad can be significantly reduced. so you can get more line distribution per unit area, high-density interconnection thus.
Depending on the design requirements, HDI printed circuit boards can utilize different layering methods to achieve the desired performance. ETE PCB strongly recommends sending Board Stackup to info@excel-techn.com so that we can confirm that your desired HDI board design can be successfully manufactured.
This type of HDI board is the simplest. there is no buried holes in the multi layer board. The follow-up and multi-layer board is different from the need for laser drilling blind holes and other multiple processes. Since this laminated structure has no buried holes, then in the production. the 2nd and 3rd layers made into a core board. the 4th and 5th layers into another core board, the outer layer plus the dielectric layer and copper foil. the middle plus the dielectric layer and then pressed together in one.
This type of board structure is (1 + N + 1), (N ≥ 2, N even). this structure is the mainstream design of the PCB industry’s primary laminate. Multi-layer board with buried holes, the need for secondary press to complete.
This type of board structure is (1 +1 + N +1 +1), (N ≥ 2, N even). this structure is the current PCB industry in the design of the second laminate. multilayer board has buried holes, need three times pressed together to complete.
The structure of these boards (1+1+N+1+1), (N≥2, N even). although it is the structure of the secondary laminate. but because the location of the buried holes is not between (3-6) layers. but between (2-7) layers, this design can also reduce the press fit once. so that the secondary laminate HDI board. which requires three press fit processes, is optimized to two press fit processes. This type of board has another difficult production point. there are (1-3) layers of blind holes, split into (1-2) layers and (2-3) layers of blind holes to make. it is necessary to use the (2-3) layers of the inner blind holes to fill the production. that is, the second lamination of the inner blind holes using the filling process. usually this kind of HDI with the production of filling process. the cost is higher than that without the production of filling process.
The structure of this type of board is (1+1+N+1+1), (N≥2,N even). the inner multilayer board has buried holes, need to be secondary pressed together to complete. The main feature of this design is the stacked hole design and the blind hole design across the layers. The main feature of this design is also the need to stack the blind holes above the (2-7) buried holes. which makes the production more difficult.
In this design, the inner multilayer board has buried holes in (3-6) layers. and needs to pressed together three times to complete. Mainly there are cross-layer blind hole design, the production difficulty is higher.
High-density interconnect (HDI) PCBs are the most in-demand PCB. and are widely used in a variety of small, high-performance electronic devices. As electronic devices and their components become smaller. these printed circuit boards encapsulate more circuitry and functionality in a smaller area. They include micro vias, buried and blind vias, and through holes. In addition to this, PCB circuit boards may have coreless structures with layer pairs. passive substrate structures with no electrical connections. and connections with core less structures and layer pairs. Although the HDI PCB circuit board looks compact. it involves details and several complex elements which add to the cost. Tips on how to reduce HDI costs without compromising quality and performance?
Vias are the electrical connections between the two layers of a PCB board. The vias have two pads, which are placed adjacent to each other on two different layers of the board. Blind vias are usually exposed on a single side of the board, while buried vias are not exposed on the board, but they connect the two layers internally. Microvias are small through-holes with a hole diameter of 0.15mm. They are usually drilled using laser equipment and require high precision. It is easy to understand that microvia adds more cost compared to other through-hole types and reduce HDI costs . Therefore, it is wise to choose the type of via while keeping in mind the requirements of the application.
Stacking is one of the distinguishing features to increase the cost of components. 1-n-1, 2-n-2, and 3-n-3 are the most common types of HDI stacks. 2-n-2 layouts considered as more challenging than 1-n-1. and 3-n-3 is even more challenging than 2-n-2. This is because as the number of layers increases, the workload increases.
Glass fiber, FR4 and copper are a few of the core materials commonly used to manufacture HDI PCB . These materials have different properties and have different costs. When selecting a material focus on three properties – the material’s dimensional stability. processability and ability to withstand multiple laminations. HDI designs involve laser drilling and problematic if the material cannot withstand drilling. So, it is important to ensure that the material meets all these requirements. while still providing a price advantage and reduce HDI costs.
Stacked vias are typically filled with copper, while interleaved vias are not. No additional imaging steps are required in interleaved vias. However, stacked vias require planarization and an additional imaging step. All of this makes interleaved vias very simple compared to stacked vias. This simplicity helps to further reduce HDI costs and manufacturing costs.
This is also an important pricing factor. The conductive or non-conductive hole filling process depends on the design. Some designs require through-holes underneath surface mount assemblies. and surface mount assemblies require filling, capping or plating. The filling process often requires multiple plating and drilling steps. which can require additional time and effort.
ETE summed up the experience try to reduce HDI costs for our clients. we believe that the hole copper thickness is one of the important factors affecting the reliability and life of the PCB. if too thin, the conductive hole after high temperature or high current applications. there is a possibility to pulled off, resulting in board failure. we focus on PCB manufacturing 17 years. And ETE HDI has its own complete system, the entire process is not outsourced. all quality acceptance standards as IPC2 level standards. such as hole copper thickness ≧ 20μm. ETE with the most advanced hole-filling line. as well as the most advanced VCP horizontal plating line, resin plug hole line. Ensure that all PCBs qualities.
