Issue link: https://iconnect007.uberflip.com/i/1529411
20 PCB007 MAGAZINE I NOVEMBER 2024 used a pre-certified material in the first place. At that point, who pays for the test or replacement? In your experience, what else will negatively affect PCB total build cost? Excessive plating is another potential cost adder. Your plated through-hole (PTH) has certain specific plating requirements. When a PCB goes through the production process, you will not have the same amount of copper in all places, but rather variation across your PCB panel. It's no problem if you need stan- dard IPC Class 2 or Class 3 with 20–25 aver- age microns of copper in your PTH, but if you require 35–50 µm, that is a delicate range. It is more difficult to control and will increase your costs. Some manufacturers do a double-plat- ing process for this. Essentially, you're paying for another plating process. If possible, try to work around excessive plating requirements. Tolerance is an issue. IPC suggests ±0.003" (76.2 µm) tolerance for a PTH if using HASL. But sometimes customers want ±50 µm with HASL. at process isn't secure for this. You need to go to immersion tin or something sim- ilar; use a different surface finish process. Finally, make it clear in the documentation. A standard tolerance on PTH is 0.1 millimeter or about 004". If you need something tighter, document that clearly. If anything is a bit out of the norm, above or below the normal spec, you need to be very clear about what you're trying to achieve. By and large, documentation seems to be something designers can improve on. Of course, the other side is that you also need to be careful not to over-specify things. A delicate balance of providing enough direction but allowing people to do what they need to do per their expertise. is is a quick list of what should be included in a data package and the accompanying docu- mentation: a type description of the PCB (multi- layer, flex, rigid, etc.); the acceptability and per- formance specification: Class 2 or 3; the PCB size or dimensions, making sure those are consistent with your data; the rough trace thickness you're expecting; the material you're expecting to be used, and note whether you need a compara- tive tracking index and voltage or glass transition temperature at minimum; and surface finish. If you need some kind of specific solder mask layer, for instance a peelable mask, you need to call it out. If you have some kind of special screen print layer, state clearly what you're expecting: specific production markings, via plug, counter sinks, and depth milling. Provide a sketch because drawings help. Sometimes these very simple things pre- vent expensive mistakes for everyone. Your data files matter, even the format. In China, for instance, not everyone can work with ODB++. If you use Gerber files, please send a netlist file. Right, the netlist is critically important. If you provide an IPC-D356 netlist in addi- tion to sending the Gerber data, we can catch an error, like missing layers in the data. Maybe they sent data for a four-layer board but the netlist clearly shows six layers. e manufac- turer can detect that because he will create his own netlist from the Gerber data and compare them. He will see that something's off. Richard, what is the greatest communication challenge between the customer or PCB designer and the manufacturer? I feel like we've been talking about this for 30 years and it gets only marginally better. Communicate what you're trying to achieve. For example, if your PCB is an odd shape, it helps when you explain what you will do with that board, what it's going into, and its purpose. Explain the problem you're trying to solve so we can see it from your perspective and imme- diately rule out any bad ideas we might have. Very simple, but very wise. ank you. Richard, this has been interesting. Thank you for your time. PCB007