When we think of a library, the first thing that comes to mind is a building that holds materials of some kind. In April 1800, when the seat of the government moved from Philadelphia to Washington, one of the first acts of President Monroe was to allocate $5,000 to purchase books for Congress to use. With the establishment of the Library of Congress, it held 740 books and three maps.
It now contains 32 million cataloged books and other print materials in 470 languages, and more than 61 million manuscripts. It is the most extensive rare book collection in North America, and by far, the most extensive library in the entire world. For anyone who has ever visited the Library of Congress, it is incredible when you consider the tremendous amount of knowledge and materials in those walls. However, what I find even more astounding is how all that material is kept organized enough to find something quickly.
For PCB designers, it is not a building but rather a collection of information or data used to build a PCB design. The most common part of the library is the collection of components used in the PCB design process. But, I have seen some libraries have other information, including a resource area—a group of documents, standards, and articles. Basically, it can have anything you want.
It is essential to make sure the library is structured so that it is easy to expand and grow with the company. Unfortunately, some organize their library for their present needs with no consideration of the future.
So, it is easy to organize a library for, let's say, the 1,000 components you have now, but how would you manage 50,000 components? The hope is that your companies will grow and, of course, stay on the cutting edge of technology. That means bringing in the latest components.
Furthermore, it is vital to have that information readily available to find what is needed quickly. Although every library is different, each one has the basic foundation to ensure that it is successful. They include singularity, managed, architecture, reviewable, and traceability (SMART).
Importance of the PCB Library
Everything begins and ends with the library, which includes a design's success or failure. With all the detailed steps involved in every PCB design, I fully believe that the PCB library is by far the most crucial part. Therefore, a rule I follow is to always be excellent friends with your PCB librarian. They are underappreciated most of the time, but they hold the most critical position on any PCB design team.
In the past, we have seen how there is a “parents and children” document. We also have noticed that sometimes a document can be both a parent and child, like the schematic it is a parent of the PCB and the BOM. But, it is also a child because it is the library's parent. Everything starts right there. If you have a lousy library, there is no recovery from that. That library represents money to your company, and it can fall in either the profit or loss column.
Some of the information collected in the library is static, meaning that it won't ever change. But there is also dynamic information, so it will constantly be changing. This brings up a couple of points, mainly that the library is a living, breathing thing, and must be maintained.
The Danger of Rogue Libraries
A PCB library should be an item known as a Single Source of Truth (SSOT). Singularity is the first foundation of every successful library. When working with a team that is working from different data and procedures, it doesn't take a psychic to determine the results of that. There is absolutely no way to control the results. Multiple people starting at different locations, going in different directions, with all other maps ending up at the exact location? Nope. Not a good plan.
More times than I wish to count, I have seen the problems caused by what is called "rogue libraries." They are libraries with components that are not managed or verified. Consider the massive amounts of work to prepare a PCB design. There is the engineering, layout, fabrication process, and then as you get into assembly, the notorious unwanted phone calls begin, letting you know that they were hitting "snags," such as parts not going onto the PCB because of wrong footprints or other components tombstoning or falling off entirely. Uou start to investigate the issue, only to find that a “rogue library” got used, resulting in scrapping the entire fabrication. At this point, you begin that long walk to the manager's office to explain the situation—not a good feeling.
Several years back, I joined a well-established, successful company. However, the PCB design area had no structure or organization. It would be an understatement to say it was in total disarray, which was evident by the multiple numbers of boards spins. I remember going over to one of the designers who opened a desk drawer filled with bare PCB boards. He let me know that those were the designs that did not make it through assembly due to some problem. When I investigated further, I found that 1,123 PCB libraries were used. All different kinds and sizes, of course. Multiple footprints with the same name. Every designer with their personal library. No wonder there were problems.
Our hope that every design has, to use a single word, integrity. What is meant by that? Integrity is “the state of being whole and undivided.” That is an excellent mental picture of a PCB design—to be unbroken and undivided. I like that. When we were working from a thousand libraries, we were starting from a possible thousand different places and possible problems. Even worse, we were not starting from what would be considered reliable and verified data for designs and an SSOT.
There is a saying, "To get something you have never had, you need to do something you have never done." I knew the solution to fix the problem, although it was a radical step. My answer was simple. On a Friday evening, after everyone went home, I went onto the server and deleted all the libraries. I must say that was an exciting Monday morning. Within a short amount of time, we began to see vast improvements in the PCB designs. It started with getting control of the source of information and making it singular. The moral of the story is to have integrity in the PCB designs, and we first had to have integrity in our information and process. That meant integrity in our components and the libraries.
John Watson, CID, is a customer success manager at Altium.