I’m looking to change an existing 1.6mm thick 2+2+2 HDI2 VIP stackup to a 0.8mm thick stackup, but the Sierra design tool doesn’t allow (or I can’t figure out how to tweak it) the layer thickness or via parameters even though they should meet the minimum capabilities.
How economical is it to use this stackup but with a core thickness of 0.2mm instead of 1.0mm? Is there a more cost effective stackup that’s close to this? The inner copper layers could be reduced to 0.5 oz and the core thickness adjusted as needed.
L1-2, L2-3, L4-5, and L5-6 microvias are 0.102mm laser drills with 0.325mm pads.
L1-6 and L2-5 through vias are 0.203mm drills with 0.457mm pads.
I have a doubt, you are calling the stackup 2–2-2 HDI-2 but the image that you have shared is the of a construction 1-4-1 HDI -1. looking at your via requirements that you have mentioned they are of the HDI-1 construction and not of HDI-2.
so i am following the via requirements that you have mentioned. also you have not mentioned what PCB material you are looking for.
Changing from 1.6mm to a 0.8mm for a 6 layer stackup should be possible and and its a matter of changing the central thick filler dielectric to a smaller one to reduce overall thickness.
In our stackup designer tool you need to explore the “HDI Stackups” on the main page. Inside the HDI stackups select the 0.031 inch option (0.8mm) and other parameters like material (i have selected FR370HR) etc and generate the stackup.
please note that the stackups that you will get on our stackup designer tool are designed for 6 mil microvias and will not support the 4 mil (0.102mm) drills but the over all construction will be similar for you as well.
I thought it was a 2-2-2 HDI2 because it required 2 additional lamination steps for each layer of blind and buried vias. From what I’ve read, the HDI type I stackup can only have blind and through vias, so anything with buried vias is HDI 2.
Regardless, thanks for confirming that the tool does not support 4 mil drills but that the construction will be similar. I had been exporing the HDI stackups but it only generates one iteration based on the inputs, and you can’t tweak it without starting all over. That would be a great future feature for the tool!
I submitted an official preliminary stackup request with Bikky, so we’ll see if Sierra can get close to the stackup mentioned above that can be used with 0.1mm microvias. And FR370HR laminate should be fine.
I understand there could be a lot of variation in HDI stackups, but it would be great if Sierra could provide a short list of some of the simplest and most common 4, 6, 8 layer HDI stackups. I’m sure that would be really helpful for a lot of people as they begin to transition to HDI PCBs.
Brian, I showed your post to one of our senior design engineers and he says he could jump on a quick phone call with you to give you advice. DM me or email me your phone number.
