While IPC 610 is the standard for PCB production, the IPC 620 standard (IPC-WHMA-A-620) prescribes practices and requirements for the manufacture of cable, wire and harness assemblies.
This post will examine the differences between the three classes IPC-620 uses to divide wiring acceptability so that you can determine which is right for your own products and communicate those requirements to your Electronics Manufacturing Services (EMS) provider.
In our previous post on IPC 610, we talked about the acceptable tolerances for the manufacture of PCBs which power three different classes of product.
- Class 1: General Electronics Products
- Class 2: Dedicated Service Electronics Products
- Class 3: High-Reliability Electronics Products
These same three classes apply to cable, wire and harness assemblies in the IPC 620 standard. They establish the different levels of quality that reflect the expected reliability and life span of different end products.
Most electrical assemblies and products include internal connections and cabling or, at least, are connected to other elements of a build with cable or wire harnesses. Cabling is clearly vital to the functioning of products, but faulty cables can be difficult to diagnose and fix, especially when they are incorporated within large and complex machinery to be used in adverse conditions (such as aerospace or automotive applications).
Obviously, no one wants their products to fail due to a fault in a wire harness, and your customers don’t want to be let down. But there are some settings where failure could have fatal consequences and failure cannot be tolerated. On the other hand, there are applications where the most exacting standards can be stripped down for efficiency and cost reasons while not presenting an unacceptable risk to consumers. These are defined as follows:
Class 1: General Electronics Products
General electronic products – such as toys and torches. The lifetime of these products is limited, they are sold cheaply and produced at high volume. While the safety of the product is an absolute requirement, their ultimate failure is not critical and longevity is not integral to their function.
Class 2: Dedicated Service Electronics Products
Dedicated service electronic products – include laptops, microwaves, and general production equipment. The lifetime of the products is longer than class 1, the amount of usage is higher, and an uninterrupted service is desirable.
Class 3: High-Reliability Electronics Products
High reliability/critical products – such as those used by the military, aerospace and medical sectors . Not only is the product lifetime extended, but the products must function without interruption. Downtime is not acceptable.
By specifying and adopting standards for internal connections and cabling you can ensure that the quality of the wiring you choose reflects these use cases and risk management requirements.
But having well-defined criteria for what is acceptable and unacceptable, also means that those repairing and maintaining products in the future are able to identify and solve problems more quickly and efficiently.
A shared language of quality
That’s why the standard is important and how it creates a shared language of quality between OEMs and EMS providers. And when it comes to the most exacting kinds of precision build, having this kind of absolute assurance around standards is the way high performance and compliant functionality is guaranteed.
Training and certification in IPC-WHMA-A-620 is recognised by ISO and auditing bodies as a major feature of compliance in certain standards. The certification standardises operations and helps manufacturers achieve operational excellence, particularly when it comes to builds where precision and quality is critical. It helps everyone involved in the processes to identify opportunities for continuous improvement.
Any EMS provider serious about compliance with IPC standards will have implemented widespread internal training programmes to ensure they are complied with. The best way to achieve this, and to maintain the standards required, is to have in-house IPC trainers who themselves will be externally re-certified.
Today’s OEMs are increasingly looking for more from their assembly provider. They need partners with expertise on everything from wire and cable, connectors and assembly, to high level assemblies, project management and regulatory standards.
Knowledgeable, highly trained professionals working against recognised industry standards are better equipped to provide the value-added services that customers need. And when we all speak the same quality language we can bring the right skills and approach to every kind of job.
