What is the design tolerance of multilayer PCB in our company?

Multilayer PCBs are beneficial to products because they can handle greater complexity. Computers, telephones and medical devices are some examples of applications that benefit from multi-layer design. However, using multilayer printed circuit boards to connect these layers to each other becomes a key issue. If you do not connect each layer to the corresponding point, you will eventually glue multiple single-layer printed circuit boards together.

Input vias; Our ingenious solution connects each layer vertically. However, Vias needs to know about the ring to work properly. These rings are defined as the minimum distance between the drilled hole and the through hole trace edge. The larger the ring, the larger the copper connection around the hole.

Using a ring usually determines the size of the shot. When pcbs are soldered to one or both sides of a circuit board, do you use Altium components for placement? In order to weld, you may need a larger area. Do you only use this channel as a test point without welding? The smaller ring size can help you.

No matter what application of ring ring you use in circuit board design, you can easily determine the size by referring to our trusted old friend IPC-7251. This document recommends a ring width of 250 μ m. To obtain the maximum material condition (MMC). MMC simply means that you will have the most powerful solder joints. On the other hand, 150 μ M is the recommended width of the ring to achieve the minimum material condition (LMC). LMC just means that you will use the most unstable solder joint connection to go away.

Obviously, these are just suggestions and can (and should!) Make changes based on your specific application.

How to measure the ring.

Hunan Multilayer PCB Design

Manufacturing tolerance of

When any combination of multiple manufacturing processes occurs in a production environment, minor overlap errors usually occur due to incomplete tolerances here and there. Specifically, when you are etching copper traces on a printed circuit board and drilling through the traces, your drilling usually does not exactly align with the center of these traces and will make you slightly deviate. But don't be afraid; The tolerance is here!

Since you should have designed and manufactured tolerance errors, designing circular tolerance errors is no exception. First, by determining the manufacturer's specific tolerance, they will be able to accommodate errors, and by determining the minimum safe width of the ring, you can reduce the risk of the entire manufacturing process and ensure that the minimum value is always reached.

In short, you know that there will be some manufacturing errors in this process, but the design of the above errors will make you higher than the minimum value, especially the annular ring for drilling through holes.

Drilling tolerance plays an important role in determining the ring size.

Calculate ring width

A simple way to verify that the width is suitable for PCB design is to calculate the maximum width of the run after production. The following equation can be used:

((diameter of trace pad) - (diameter of drilling hole))/2=(maximum annular ring width)

The larger the tolerance, the smaller the manufacturing error, and the smaller the ring width. The larger the hole diameter, the smaller the width of the ring.

Know that the width of the ring should be able to provide a strong enough connection for electrical and mechanical connection, and be able to realize that the manufacturing tolerance will keep your ring width at an acceptable distance, and when drilling holes without even touching the trace pad (heaven helps us).

When vias are designed to micro areas, you will need PCB design software, which can fully specify the annular ring width and the manufacturing tolerance of vias. Fortunately, AltiumDesigner? Sensitive board layout complexity can be easily handled through a complete design rule checklist and intuitive board layout software.