Development of multilayer pcb

Development of Ultra-Multilayer PCBs

Printed Circuit Boards were a revolutionary idea when they were introduced. It would be a way of sophisticated wiring only easier. In the early 1900s Charles Ducas, the real pioneer of Printed Circuit Boards, panted a design where an electrical path would be made on an insulated surface, this surface is now commonly referred to as a substrate. Charles Ducas’ idea was revolutionary, the complexity with circuit wiring had been done would now be possible but with a consistency in the results it provided. A large margin of error had been done away with but that is theoretically. It was not until after the end of World War II a real functional Printed Circuit Board was made. Dr. Paul Esler from Austria was the first to start making functional Printed Circuit Boards around the year of 1943. Point to point construction was phased out when PCBs went in to mass production. The point to point constructions mostly used large bulky components and wiring that was manually done thus increasing the possibility of error as connections were solely dependent on the person joining them together. Printed Circuit Boards developed from being made on thin strips of wood and the single layered electrical connections made from brass to the ultra-multilayered ones that go up 80 layers.

Evolution of PCBs

The evolution of PCBs has been over a long period of time and it has not been all glorious. The concept of the printed electrical paths between connections was a strong one for it was either that or the point to point connections that had components that required constant changing due to wearing out and short circuiting. The technology for manufacture of these Printed Circuit Boards has also come a long way from simple drilling on the wooden pieces, where the electrical components would be on one side while the printed wire strips would be on the other and the connections made through the drilled holes known as vias. The possibility that PCBs could practically be made out of anything pushed the concept all along its developmental stages. The earliest devices commonly known to have used the PCB technology were gramophones and radios.

Invention of Ultra multilayer PCBs

Since the year 1956, when the United States patent office granted the United States military a patent to assemble circuit boards there happened a boom in the industry that prompted the growth of very many sectors involving information communication technology. It had been noted that the utilization of Printed Circuit Boards had not been fully exploited, although the cost of material initially was acting as a deterrent of its progress. The patent forwarded by the United States military combined the use of acid insoluble ink, the drawing of the circuit pattern, photographing it on a zinc plate and using acid to etch out the pattern on the board using copper wires. This form of innovation was the basis for the rest of the creators. Copper is a better conductor of electricity and is also a stable compound. By the late 1970s scientists had come up with four layered Printed Circuit Boards. This helped to lower costs in the industry as they had learned to reduce the material used and the multiple layers on the same board proved to be very efficient. By the end of the 1980s the multilayered PCBs were being used on digital cameras. Around the same time Japanese scientists had developed Liquid Photo Image-able masks. The evolution of the multilayered PCBs ensured that the short circuiting that had been witnessed with various other models was eliminated together with the human error factor.

Presently these circuit boards can be found on nearly all devices. Scientists have even come up with a contact lens that has a printed circuit that measures the glucose levels in the body. Most of these devices comprise mp3 players, personal computers, smart skin, prosthetic limbs, and wearable devices such as clothes, watches, car computers, televisions, security systems, machinery and a lot more. Gradually PCBs have driven the size reduction of electronic devices to miniature sizes for example; radios that used to be large devices have now become so small that they fit perfectly of any person’s palms.Innovation and change in production of PCBs is a major contributing factor coupled with the fact that the use of printed circuit boards seems to be the present and the future of most of the devices people currently use.

Manufacture and Composition

The development of ultra-multilayered circuit boards was driven by the market need for increased memory and little or no size changes. Currently the most number of layers on a semiconductor board is 80 layers. Generally a printed circuit board is a connection of electrical paths in which they are connected to components that are embedded in the substrate. Drilled holes in the substrate from where the electric paths and electrical components meet, increases the PCBs efficiency.

The production of ultra-multilayered circuit boards meant that the technology used to laminate the copper on to the board would need to be changed. It would not be possible to use the same equipment or technology that is used to etch up to 40 layers. Thus new innovations would be needed. The size of the board is one of the elements that would immediately change, this is due to the increased layers, and another element that changes is the surface upon which the board is placed on during the etching of the layers. To support the many layers the thickness of the board that is usually in the range of about 1.2mm to about2.0 mm, increases up to about 6 mm. Thicker drills ensure that making holes through the thicker board is more precise and avoids breaking of the drill which will in turn distort the shape which will lead to viasthat cause damage to the copper layers. The plating technology must also be able to cope with thicker diameters. The aspect ratios must be very high. The impedance control characteristic technology should also increase the transmission speeds that come with lowered losses.

Ultra-multilayered Printed Circuit Boards are necessitated by the need for increased memory holding capability. They are an improvement on an already efficient system.

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