Multi-layer PCB is beneficial to products because they can handle greater complexity. Computers, telephones and medical equipment are some application examples that benefit from multi-layer design. However, the use of multilayer printed circuit boards will become a key problem to connect these layers to each other. If you don’t connect each layer to the corresponding points, you will end up gluing multiple single-layer printed circuit boards together.
Input via; Our ingenious solution connects every layer vertically. However, Vias needs to know the annular ring to work properly. These rings are defined as the minimum distance between the drill hole and the edge of the via trace. The larger the ring, the larger the copper connection around the borehole.
Using a circular ring usually determines the size of the shot. When soldering to one or both sides of the circuit board, do you use Altium components for placement? For welding, you may need a larger area. Do you only use this channel as a test point without welding? The smaller annular ring size can help you.
No matter what your application of using annular ring in circuit board design is, you can easily determine the size by referring to our trusted old friend IPC-7251In this document, it is recommended that the width of the annular ring be 250μm to obtain the maximum material condition (MMC). MMC just means that you will have the most powerful solder joints. On the other hand, 150μm is the recommended width of the annular ring to achieve the minimum material condition (LMC). LMC just means that you will use the most unstable solder joints to connect and walk away.
Obviously, these are just suggestions and can (and should! ) change according to your specific application.
How to measure the annular ring.
Manufacturing tolerance of multilayer PCB design
When any combination of multiple manufacturing processes occurs in a production environment, slight overlapping errors usually occur due to incomplete tolerances here and there. Specifically, when you etch copper traces on printed circuit boards and drill holes through the traces, your drilling holes usually don’t completely align with the centers of these traces and will make you deviate slightly. But don’t be afraid; Tolerance is here!
Since you should have designed the manufacturing tolerance error, designing the ring tolerance error is no exception. Firstly, by determining the manufacturer’s specific tolerance, they will be able to accommodate errors, and by determining the minimum width that the annular ring can be safe, you can reduce the risk of the whole manufacturing process and ensure that the minimum value is always reached.
In short, I know that there will be some manufacturing errors in this process, but designing the above errors will make you higher than the minimum value, especially the annular ring for drilling through holes.
Borehole tolerance plays an important role in determining the size of annular ring.
Calculate the width of annular ring
A simple way to verify whether the width is suitable for PCB design is to calculate the maximum width after production. The following equation can be used:
((Diameter of trace pad)-(Diameter of drilling hole)) /2= (Maximum width of annular ring)
The larger the tolerance, the smaller the manufacturing error and the smaller the width of the annular ring. The larger the diameter of the drilling hole, the smaller the width of the annular ring.
Knowing the width of the annular ring should provide a strong enough connection for electrical and mechanical connection, and being able to recognize that manufacturing tolerance will keep your annular ring width at an acceptable distance, and in the case of drilling holes without even touching the trace pads (Heaven help us).
When the via hole is designed to micro-area, you will need PCB design software, which can fully specify the annular ring width and the manufacturing tolerance of the via hole. Thankfully, AltiumDesigner? Sensitive circuit board layout complexity can be easily handled through a complete check list of design rules and intuitive circuit board layout software.
