Here's a side view of flip chip in a ball grid array. So this is the die, this is the actual chip, okay? And it's IOs, they may be around the outside of the peripheral of the chip where the IOs may be spread across the whole surface of the chip, or around a band around the outside of the chip. There's various ways you can place the IO cells on your silicon. But they turn it over. And they have these tiny, tiny, tiny, little balls. Under these tiny little, I guess they call them, yeah, they call them bumps. And this takes the inputs and outputs of those pads, those IO cells on the chip, and provide it a path to the substrate. So this section is this packet substrate right here. Then the signal is then routed out to these much bigger balls, sodder bumps, that get sodder balls, that get soddered on to your prints circuit board. So thermal stressing a component, cooling it down, putting it in a chamber, okay? Cool it down, heated up, cool down, heated up across your range. And, then you take it out of there, and you saw another product under your print's finger board, and you test it. And you see if it works or not. When I worked at Seeker Engineering here, they're an aerospace satellite company here, worked there for about a year. They were buying a standard component. I don't remember what it was, and I believe it was a relatively small component that was, I don't know if it's a flip chip, or a wire bond inside, but it had, I was a ball grader a like this. I had a bunch of solder balls on it that got soddered onto the board, and they used them for years. And then, One day, they started having failures, and they were scratching their heads. We've got this product, isn't working, this board isn't working. When we tested it, it's failing, so we used X-rays to try and figure out what's going on. So you X-ray it from the top, and you X-ray it from the side. And anyways, they determined that some of these sodder ball connections were cracking after they had been soddered onto the board, and they were put in the thermal chamber in there, but they were thermal cycling their product, heating it up and down, and up and down, and these balls were cracking, causing an open. And unbeknownst to them, the size of die originally was pretty big, like this, and provided mechanical stability for the package. What is, we've moved from 65 to 45, to 40 to 32, to 28 to 21, to 19 to 16, to 14. I don't know what process node, but we've been getting smaller, and smaller, and smaller over time. A die was getting smaller, and no, this was never communicated to the customers. At least, it wasn't communicated to seeker. And so, when they went through, when the die was big, it provided mechanical stability. And when the die got smaller, and smaller, and smaller, this part would start to flex during a thermal stressing. It puts stress on the exciter balls, causing a crack. And it took them, got everybody's attention, it was hot, [LAUGH], a hot issue. Why is this part failing, why is this part failing? Eventually, they figured out a way to mitigate this, I don't know what the solution was. But this just gives you an example of how thermal stressing of component can be a good deal. And it's important to include that. And the higher your product volumes are, the more and more important it becomes to stress your product, in as many ways as you possibly can. Thermal stressing of printed circuit boards. So this is a side view of a printed, some. Printed circuit board. Who's familiar with the term, through hole via? Heard that term before? Yeah, okay. So this is a side view of through hole via. This is the most mechanically sound, durable interconnect between layers. There's a lot of, generally, it's copper, there's a lot of copper here in these survive thermal stressing, very, very well through hole vias. Okay, a Blind Via is available on the outside, and on the top or bottom surface of the printed circuit board, and goes down to one of the buried layers inside of the printed circuit boards. A simple circuit board's two layers, right? It's just an insulator, and it's got conductors on one side and the other. But real products, you end up needing to, you have so many signals to route that you have to start stacking up layers. So this is called the Blind Via. And this one here is called the Buried Via. You have no visibility to this at all. And as it's been explained to [INAUDIBLE] and mechanical people that I've worked with, these are the most durable. These are a little less durable, and these can crack the easiest when they undergo thermal stressing. And again, it's just another mode of failure. Put your product in a thermal chamber, and cycle it back and forth. Be hard on it, be harder than your customers will be hard on it. So it's better for you to find a product problem with your product, and their customer find a problem with your product.
