Issue link: https://iconnect007.uberflip.com/i/1339822
84 PCB007 MAGAZINE I FEBRUARY 2021 solder smear transfer to the dielectric surface, flux residue and other contaminants that affect life, ability to assemble and serviceability." Also note: "ere shall be no evidence of any liing or separation of platings from the sur- face of the conductive pattern, or of the con- ductor from the base laminate in excess of that allowed. ere shall be no loose plating slivers on the surface of the printed board." As written, there is a requirement here; not measureable, but it's still quite clear. But are we missing something here? In my daily work with suppliers, we oen discuss what is acceptable. We read the related standards, explain, and give examples. We try to agree on how to understand the specific re- quirement or a combination of several require- ments. en we inspect the related boards and agree on what we observe. Some years ago, the defects we found were functional, such as open circuit, short circuit, and via hole, that will cause functional problems. The Difference Between Cosmetic Issues and Cosmetic Failure Today's factories have better process control and improved functional testing, meaning that most of the claims are what can be called cos- metic. e challenge is knowing what is cos- metic, and what is purely a cosmetic issue that could lead to a failure in the application. is leads me back to the standard, and the sen- tence that many PCB suppliers oen overlook: "Printed boards shall be ee of non-conformanc- es in excess of those allowed in this specification." e last revision of the standard, and still written in IPC-6013 and IPC-6018, says: "Printed boards shall be ee of defects in excess of those allowed in this specification." e word defect has then, if we are kind to the reader, been understood as functional: • What is a defect? • Is a cosmetic imperfection a defect? e next revision uses the term non-confor- mance, and we hope that helps. Here, it must be understood as any imperfection to the PCB design. Before we discuss this further, it is important to understand that even an up-to-date PCB factory will have some handling, and smaller cosmetic issues will occur. It is very important that the user understands and does not reject fully functional products. For further understanding I suggest reading my April 2020 column, keeping in mind what I discussed last year that it is still important for the PCB supplier to understand the standard and have a goal to reduce such cosmetic issues. Workmanship: What Does the Standard Really Say? What the standard says about workmanship is, in reality, that the PCB shall be free of any imperfection not allowed in this specification. But what are we talking about? I would say that more than 60% of customer claims are related to solder mask in one way or the other. Let me give some examples: 1. Scratches in the solder mask All of us producing and using PCBs know that handling in production will lead to scratches in the solder mask. But what is the criteria to ac- Figure 1: An unwanted particle in solder mask not violating general rules but still not allowed by the workmanship requirement.