What is HDI technology.

The world of PCBs or printed circuit boards has seen a great deal of developments in recent times.

From their early days, one can say that the technology has undergone tremendous changes, with many variants and everything in between, to become the industry mainstay it is today.
Of the many developments that have taken place over the years, one of the most important has been that of HDI technology.
A revolutionary industry standard, it emerged fairly recently, going back about two decades or so, following the many innovative breakthroughs that were made with PCB technology.
Since then, it has found a wide array of applications, in which it has proved to be highly effective and versatile for everything from simple gadgets to high-end hardware.
Introduction To HDI Technology
To start off, the history of HDI is very much related to that of the PCB.
During the middle of the 20th century, the use of PCBs became widespread, starting around the 1950s or so. Since then, the technology improved significantly.
As time passed by, a need was found for a higher processing capacity and greater power, with the resulting efforts leading to the development of the HDI. Since then, the technology has only improved, and continues to do so, with the passage of time.
HDI is a term that stands for High Density Interconnect.
It is a circuit design, in which, as the name would suggest, the density of the circuitry is far greater than what would have been the case in traditional circuit boards.
One could say that it was a process of steady advancement and miniaturization of circuit design techniques which led to the development of HDIs. At the same time however, HDIs are more than just highly minaturized circuit designs. On the contrary, they go far beyond just making the circuit smaller, by altering the circuitry of the electronic devices themselves.
To begin with, it?s important to have a better understanding about HDI technology, and what they?re about.
As the term would suggest, HDI or High Density Interconnect are circuits which have a higher density of wiring per unit area, compared to standard PCBs.
This allow for a greater degree of electronic components, circuitry and other related elements to be integrated when used on HDI boards, and thus allowing for compact, miniaturized and well-designed gadgets and appliances.
Also, the advent of the technology proved to have several advantages for the end user. These included everything from the possibility of lightweight construction, lowered costs to some extent, versatility, performance and even flexibility.
Design Of HDI Technology
There is a lot that can be said, about what goes into the manufacture of HDI technology.
One of the initial challenges of HDI technology design is the issue of complexity. Given that the scale of it is far more than normal circuitry, the means of manufacturing the same varies as well. Some of the key points of the same are explained in the points below.
1.) Circuits ? The circuits present in HDI is fairly complex, and far finer than what you would expect in conventional PCB designs.
The development of technology and its miniaturization led to an increased demand for finer and denser components. These trends were in fact the basis of the modern day HDI technology.
It first emerged, when developers noticed that the inter-device signals had an interesting relationship with the inter-device signals. It was noticed that as the trace distance or the distance between two devices was reduced, the time required for the inter-device voltage reduced as well. A consequence of lowered capacitance and the shortened distance between the two points, it became one of the cornerstones of the circuit designs.
As for the design of the circuit tracks or signal traces, the process is fairly similar to the ones used in traditional PCBs. It is done through the etching of a metal surface on the board, which then allows for the electricity to pass through.
2.) Hole Drilling ? An important aspect of HDI technology is the use of holes, for the insertion of ?vias?, which are the electrical ?links? connecting links between the two sides of the board.
Traditional drilling techniques involves the use of a mechanized standard drill, which is not very effective when it comes to hole sizes of HDI circuit boards. In order to bypass this issue, lasers are used, typically making use of laser drills and Laser Direct Imaging or LDI, among others.
The holes are then integrated with a microvia, typically made of electroplated copper, to connect the two sides of the board. In cases where the number of layers increases the size of the microvias will vary as well.  As for the diameter of the holes, there are certainly varying standards but a widely accepted one is a diameter smaller than 150?m.
Furthermore, there is also the issue of the many layers that HDI boards tend to have, which can be a bit difficult when it comes to laser drilling. Since lasers tend to have a limited amount of drilling capacity, the boards are often drilled individually, after which they are mounted on each other.
It should also be added that there are varying designs of the holes, as well as the techniques used for their designs. Regardless, the use of laser drills have become an industry standard.
Uses & Application
As for the usage of HDI technology, there are certainly plenty of applications where its use can be found.
One of the main areas of technological growth is in the world of miniaturized gadgets and devices. With everything from MP3 players to smartphones getting smaller and more powerful, there is a high demand for compact designs, without losses in performance. It is here that HDI technology is proving to be of immense benefit.
Another place where the boards are being used is in the world of automobiles, which range from cars and ships, to aircrafts and the emerging field of space exploration.
Then there is the use of the boards in the medical industry, where they have found widespread applications in a wide range of medical devices and diagnostic equipment. One of the more interesting applications in the field, is that of electronic pills that can be swallowed, which allow for an inside view of the human intestine, which allows for an in-depth understanding of the patient?s condition.
As a whole, it can be said that the development of HDI technology, is by far one of the most important advances in recent times.
Having a decisive impact on just about everything we use, and perhaps many more which we will in the future, you could say that this was truly a revolutionary aspect of the 20th century.
Of course, there is a lot more that can be said as well, as all of the above is but an introduction to this wonderful new technological advancement, and the many benefits it offers.
Regardless, this is one piece of scientific advancement that is here to stay well into the near future.


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