Issue link: https://iconnect007.uberflip.com/i/1533085
MARCH 2025 I DESIGN007 MAGAZINE 59 opportunity to communicate with them. Do some designers build a relationship with a field applications person? at field applications engineer may stop answer- ing questions aer a year (laughs). It's likely the FA has never done any design work themselves, but at least they can teach you. I would tell cus- tomers to start laying out their BGA first, then send it off to the field apps guy for quick DFM feedback. e FA might give them guidance on adjusting lines and spaces and so forth. To start that BGA layout, use what is required internally to route it out, then ask the fabrica- tor for their standard line and space, and then default to those outside the BGA. Design a stackup, and then the FA can run all the imped- ance and recommend who to select materials for the dielectrics. But when you specify the exact dielectrics, we're confined and might have to say no to your job if they do not have a free dielectric center of the design to adjust the overall thickness. Something will have to give here because we will be over thickness or under thickness or whatever. Dack: We have customers who dial in a "rec- ipe" for the board, then they'll document it on the fab drawing. Their position is, "Just make the board like this. As long as the board is made like this, we don't have to specify any- thing." Off it goes to volume production. What would you warn them against? Remember that not all fabricators are made equal. If you're doing an advanced technol- ogy, not a vanilla type of board, the first thing you ask the fabricator is, "Can you build this technology?" When he says yes, the designer's second question should be, "How many times