Point of Entry
Though a central PCB component library for all to use is best served by a database, there are issues that can hinder its effectiveness if they're not addressed from the start. When two or more designers are contributing to a library, it must be through a common procedure to ensure data consistency. Entering new components into the library is "the point of entry" and a consistent methodology is critical to the success of the database.
There are two ways of entering data. It can be entered directly into the database or it can be through a form. A form requires someone to design and to maintain it, whether it be a program or a web interface. In most PCB design groups, there is little time available to invest in such an activity. The alternative is to give designers direct access to the database. This a dangerous solution since most designers know little about database concepts or management. Without guidance and training, there will be no consistency. In many cases, the effort of trying to maintain a compromised database outweighs the benefit of having it in the first place.
Regardless of how one enters new components into a database, there is a thin line between severe database access restriction and no restriction. Companies that demand that only the librarian create components and add them to the libraries will create a major bottleneck in the design process. For example, if a designer asks for a 1200 pin FPGA to be created, that can take the librarian several days to complete.
As the old saying goes, "electrical designers take the path of least resistance." In cases where the point of entry is too difficult, the designers will create local libraries to keep their design moving along. All too often, these local libraries do not follow company conventions and the effort to move them into the database can be monumental. Of course, this not only impacts library development, it also becomes a major cleanup effort in the schematics and PCB design.
Databases have a delicate balance. Not only should designers have access to the database, but to contribute components they have drawn as well. But to ensure database consistency, someone must be responsible for accurate collection and validation of components into the central library (without being draconian about it).
When it comes to striking a balance, the point of entry for a new component becomes critical and where most databases fail. This is where mistakes are made, and inconsistencies are first introduced. The point of entry must guide the individual who is entering the information. This is handled in several ways:
- A good point of entry is able to search external databases like Octopart and bring in existing data from known sources. This saves time and ensures the data is correct.
- A good point of entry can create a consistent component description. The description of the component is critical. This one field of information allows the designer to identify the component's purpose without having to reference datasheets or searching the internet. A good description allows the user to search components easily when designing and placing them. It also becomes important when the designer must look at a bill of materials or check a purchaser's database when the schematic isn't readily available.
- A good point of entry can guide the user if manual information must be entered. Consistency is key, and this can only be done if users follow the same format. For example, there are several ways to write the value for a ten-thousand-ohm resistor: 10k, 10000, 10,000, 1004, 10k ohm, 10k ohms, 10000ohms, etc. The point of entry must provide a standard format.
- A good point of entry allows designers to contribute. A designer is going to keep moving forward with a project with or without a database library. Therefore, entering data must be made as simple and straightforward for the designer as possible.
- A good point of entry allows the database to immediately flag potential duplicates. Duplicates in the system lead to multiple stockings of the same component on the assembly floor. This is a perfect example of the old saying, "nip it in the bud."
- A good point of entry can cross reference other components. In some cases, a substitute can be allowed. The point of entry should be able to find similar components and provide the option to cross reference them to the new component. And in turn, cross reference the new component to the existing components.
- A good point of entry can declare a status. Because components come and go, the status informs the users if a component is new, has been evaluated, has been sunsetted, or is obsolete. Obsolete components should never be deleted. Otherwise, time and energy could be wasted by a designer reintroducing an obsolete component.
Most database libraries lack what is needed in the point of entry because the companies that develop the databases do not understand the PCB library component process. They leave the interface to the customer, therefore causing most database libraries to fail to live up to expectations. When the point of entry is difficult or lacking, inconsistencies and errors will propagate throughout the designs. The longer the delay to address the causes of the mistakes, the longer the time it takes to correct them (if even possible).
The L9 database was designed with "point of entry" in mind. It was created by individuals who not only understand the PCB design process, they also understand database concepts. Nine Dot Connects has studied, observed and implemented library flow for years. L9 is the result of these observations and efforts.