One of the most common components in electronic devices today, printed circuit boards (PCBs) have come a long way since their introduction in the early 1900s. Rising consumer demand and expectations for increased speed, functionality and features has driven much of this change. Consumers today expect their electronic devices to respond instantly, creating unique challenges for electronics manufacturers.
The Roaring 20s
Patented in 1925 by Charles Ducas, “printed wire” involved creating an electrical path directly on an insulated surface. While the concept completely eliminated the need for complex wiring, it wasn’t until 1943 that the first operational PCBs were constructed in Austria by Dr. Paul Eisler.
During the 1920s, developers constructed printed circuit boards from everyday materials like Bakelite, Masonite, layered cardboard and even thin pieces of wood. They would drill holes into the material and rivet or bolt flat brass wires onto the board. They made connections to various components by pressing the end of the brass trace onto the hollow rivet while pressing the component’s leads into the open end of the rivet. Although this didn’t create anything like the sleek, attractive and complex boards seen today, this process provided consistent results and these types of circuit boards were commonly used in gramophones and early tube-style radios.
As electricity came to homes across the country, the shift from coal, wood and oil brought unique possibilities. Homeowners around the country accepted this change readily. After all, it was much easier and cleaner to cook and heat their homes with electricity. During this time, Standard Oil, the company responsible for supplying the oil used for cooking and lighting households around the U.S. had to find a new purpose for its oil. This happened with the introduction of the automobile.
World War II
In 1947, production on the first double-sided PCB began. This unique design included through-hole plating, which allowed developers to use both sides of the printed circuit board. Copper plating on the through hole enabled electrical conductivity to travel through the board.
In 1949, Moe Abramson and Stanislaus F. Danko, members of the U.S. Army Signal Corps, developed the first PCB auto-assembly process and forever changed the way that PCBs were made. The process involved using a copper foil interconnection pattern and dip soldering technology to insert component leads onto the board. In order to create the boards, developers drew the wiring pattern and photographed it onto a zinc plate. They then created a printing plate with the zinc plate for an offset printing press. Moe Abramson and Stainslaus F. Danko patented this process in 1956.
The Introduction of Multi-Layered Circuit Boards (1950s-1970s)
During the 1950s and 1960s, the materials used to construct PCBs shifted from standard everyday materials to resins and other types of industrial materials. These new materials allowed developers to produce more PCBs in less time and at higher volumes. While printing was restricted to a single side, these boards offered more efficiency over traditional wiring methods.
In 1960, PCBs were being created with four or more layers of conductive material. These newer boards saved space and provided increased flexibility. In the 1970s, PCBs got a lot smaller. During this time, PCB manufacturers began using hot-air soldering methods for more efficient soldering and improved repair processes.
In addition to smaller PCBs, the 1970s brought the first microprocessor in the form of an integrated circuit (IC). Developed by Jack Kilby of Texas Instruments in 1958, microprocessors presented unique opportunities for electronic devices. ICs were first used in electronics manufacturing during the 1970s.
The Digital Age
Known as the Digital Age, the 1980s brought massive change to the way consumers viewed electronics. During this time, people around the United States were purchasing electronic devices at an alarming rate. Electronic stores struggled to keep shelves stocked with popular devices including compact disc machines, VHS recorders, cameras, gaming consoles, portable radios and more. As demand for electronics increased, the need for smaller PCBs with greater functionality did as well.
PCBs decreased in size again in the 1980s, thanks to the introduction of surface mount assembly. Because of lower production costs and retained functionality even with decreasing board size, surface mount assembly quickly became the method of choice over through hole components.
At this time, developers were still drawing PCBs by hand with a light board and stencils. However, when computers and electronic design automation (EDA) software arrived in the mid-80s, manufacturers quickly switched to digital design.
EDA software completely changed the way that U.S. developers designed and manufactured PCBs in the U.S., saving electronics manufacturers countless hours.
Despite the complexity and functionality of printed circuit boards increasing, the cost of production decreased considerably during the 1990s. This allowed electronics manufacturers to produce a wide range of electronic devices, as was necessary to keep up with rising consumer demand.
During the 1990s, the use of silicon became more popular with the introduction of ball grid array (BGA) packaging. Used for integrated circuits (ICs), this type of surface mount packaging provides more interconnection pins than possible on a dual in-line or flat package. Rather than just the perimeter, the entire bottom surface of the device could be used.
Although no major changes were made to PCBs during the 1990s, the design process began to change. Developers became much more focused on the IC and they began implementing Design for Test (DFT) strategies into their layouts. Instead of simply creating a one-time use board, now designers had to start planning their designs with future rework in mind. This is also the time when designers and manufacturers became two separate entities.
At this time, electronic devices were becoming more complex and individuals and businesses around the world were becoming more dependent on them. In 1995, PCB production reached a market value of $7.1 billion. This was also the year that developers began using micro-via technology when producing PCBs. This technology enabled the introduction of High-Density Interconnect (HDI) PCBs. Unlike mechanical drilling technology, which resulted in higher costs and improvement difficulties, developers use laser drilling technology to create HDI PCBs.
HDI PCB fabrication utilizes advanced multilayer technology, allowing developers to integrate several layers. Because of the board’s unique design and features, HDI PCBs have a higher circuitry density than other types of PCBs.
The Internet Age
During the early 2000s, PCBs got even smaller and more complex. Although 5-6 mil trace and space was considered normal for this time period, it wasn’t uncommon for high tech shops to fabricate boards with 3.5 to 4.5 mil trace and space.
Flexible PCBs became more common. These boards provided an affordable option, ideal for design packages where space was a primary concern. Flexible PCBs offered a wide range of motion, making it possible to use them in both bend-to-install and dynamic applications.
In 2006, the Every Layer Interconnect (ELIC) process was developed. This process uses stacked copper-filled microvias to make connections through each layer of the board. This unique process enables developers to make connections between any two layers in the PCB once stacked. Although this process increased the level of flexibility and allowed designers to maximize interconnect density, ELIC PCBs weren’t widely used until the 2010s.
Modern Day PCBs
While a printed circuit board in the 1960s might have had around 30 transistors, a single chip on a modern day motherboard may have more than one million transistors. Thanks to advanced techniques and technologies, electronics manufacturers can now include more functionality into advanced devices. By shrinking passive components such as resistors, capacitors, inductors and transformers, electronics manufacturers can increase the density of components and complexity of their PCBs.
As electronic devices have gotten smaller and more complex, assembly by hand is no longer possible. Today, PCBs include several microscopic components and assembly requires an extremely high level of precision and efficiency only available with machine assembly. It’s this shift in complexity that has paved the way for optimized electronics manufacturing.
Engineers continuously test new technologies and methods of designing and producing printed circuit boards. As the popularity and availability of 3D printers continues to grow, so does the possibility of using these printers to make complex PCBs. Using a 3D printer could enable electronics manufacturers to develop smaller and lighter antennas and circuitry. 3D printed boards will also allow for simpler packaging due to their flexible design and reduced number of cables and connectors.
Another future possibility, paper-based PCBs will offer the same functionality as boards constructed from other materials, with a fraction of the environmental impact. In addition to providing a lightweight and flexible alternative to traditional PCBs, paper-based PCBs will cost far less to produce and enable the production of a wide range of “green” electronics.
Although PCBs have undergone several changes since their introduction, we’ll likely continue to see more advancements and improvements as technology evolves.
ACDi offers a wide range of electronics manufacturing services including product engineering, PCB layout, new product introductions, testing, systems integration, cable and wire manufacturing and product lifecycle management solutions. Please contact us for information about our electronics manufacturing services.