Issue link: https://iconnect007.uberflip.com/i/1166358
28 PCB007 MAGAZINE I SEPTEMBER 2019 • We would not be able to secure the correct quality level • We would not be able to compare "like-for-like" products or factories • A guaranteed time to market would be based on chance rather than good factory selection and good design Now that we can all agree that we need standards, are IPC standards effective? Yes! Through the implementation of IPC standards, the designer, manufacturer, and end customer see some of the benefits in Figure 2. One of the most important things to notice is that using IPC standards as the minimum benchmark helps save the designer and manu- facturer time before the product is built, during the manufacturing process, and after the final product is assembled, which results in saving money. There are multiple documents within IPC standards, and when used together, these documents should lead both manufacturer and customer to consistent terms of quality and ac- ceptability. These documents also allow the customer and manufacturer to work together to set the criteria for acceptance of products that use newer technologies. If you're reading this and wondering how to start understanding standards and accept- ability, there are many resources to help you. IPC's website can help you learn more about the organization and how to become a mem- ber. Also, engineers at NCAB Group can help you to learn which IPC standards you should consider depending on your end application. We have certified IPC Trainers to teach your engineers about the acceptability of printed boards, and you can work with NCAB to pro- duce your next PCB. Based on the 120+ mil- lion PCBs we ship annually, we've identified multiple steps in our PCB production process where we go beyond IPC specifications (we will discuss some of those specifics later). Risk/Awareness When we look at what can happen from fail- ing to require, reference, or follow specifica- tions, there are a few considerations. The ma- terial produced can suffer from poor reliabili- ty. The cost to produce the PCB can be higher than needed, or subsequent builds of the same design can be inconsistent. It is critical to ref- erence relevant industry specifications such as those released by IPC. Designs must contain a complete and concise specification that does not allow for interpretation as well as an ade- quate baseline to make sure that both the cus- tomer and supplier are on the same page. A common example we see is a requirement for copper weights not referencing IPC mini- mums as detailed in the IPC-6012 and IPC- 600 specifications. For instance, a fabrication drawing for a six-layer design has copper re- quirements of 2 oz. for all layers. No additional information for copper thicknesses is detailed or external specification referenced. This fab- rication data goes to the manufacturer to be built, and some of the delivered PCBs show failures post-assembly. During root-cause anal- ysis of the failures, it is noticed there is vari- ance in the copper thicknesses delivered. This could potentially be caused by failure to ref- erence the IPC copper thickness chart for in- ternal and external conductor thickness in the fabrication data, allowing your manufacturer to interpret the requirement. Theoretically, this could result in external copper thickness rang- ing from 47.9 µm to 78.7 µm, depending on what the fabrication house considers as 2 oz. finished copper. As a minimum, general specifications—like the ones issued by IPC—should be referenced in fabrication data to prevent a consistent base- line for building. We also recommend creating Figure 2: Benefits of users who implement IPC standards. (Source: TechValidate survey of IPC users, January 2018)