Issue link: https://iconnect007.uberflip.com/i/1401769
AUGUST 2021 I PCB007 MAGAZINE 33 Max Clark: Too late now. Holden: Designers need information rapidly at particular points in design. If it's not there they do the best they can and they move forward because they can't stop and run around wait- ing for a question to be answered. Schedules any more don't allow that. It's not just commu- nication, but we don't have tools and visibility of assembly, fabrication, test, things like that, made available to designers in the right form at the right time. Max Clark: at's an interesting concept. In a sense, you're saying what the fabricators want to do in terms of shiing their process capa- bilities is to not just shi the process capabili- ties, but also provide a relative cost. It doesn't have to be a finite cost, but a relative cost, if that particular item is violated. Let's say you have a particular via size, and if you go below this via size you would like to have the design- er knocked on his head, saying, "You can do this, but you need to know when everything is said and done this is going to add an addition- al cost." Holden: At HP, we created a relative cost index (RCI). We created a hypothetical currency because we found that nobody wanted to give Max Clark: at's a good question. When the fabricator puts their stuff up there it's even kept from me. I don't even know. e stuff is encrypted. We didn't look at it to the degree to start doing that kind of comparison. Obvi- ously, it's probably possible, but everybody's facility is a little bit different, and they all have their own way of doing things. So I can't tell you if I notice a similarity. Say you had three manufacturers that were your options. In theo- ry, it's possible to run an analysis once and look across all three to see who has the most likely capabilities to build this with the least number of issues. We have customers that say, "Even with this kind of knowledge I might be able to tweak a few things in the design and move it from our high-end fabricator into our mid- range fabricator. I reroute three traces and bin- go, I go from $1 a board to $0.80 a board, just like that." Matties: Happy calls this the cost drivers that the designer needs to be aware of. Happy, would you talk a little bit about this? Happy Holden: ere's a set of design rules that are considered a commodity in that they're built into the process and the chemistry such that you can price boards based on the num- ber of layers and the square inches. But when you get to the limit of those commodities, there starts to be a cost slope, like if the diam- eter of a drilled hole goes under 10 or 12 mils, then we've got to get a drill bit, we've got to not stack as high, etc. Now there's a slope that, depending on how many of these are in your design, we add a cost to the commod- ity price. If you go under 75 micron there's an extra cost because of a yield loss. e hor- izontal commodity hits a slope, then the slope ends with our next capability. Beyond this we can't accept this design at all. But de- signers are not specifically aware of the cost drivers, and the slope of the cost drivers. e poor designers just have to guess or do the best they can.