I think you're getting steered in the wrong direction, with the exception of DaveF's link. By the way, I'm a PCB fabricator, just to avoid any backlash.
IPC 4101 is the IPC guideline for raw materials. It has 6 slash sheets for lead-free capable materials, which fall into 3 main classifications. The materials you are most used to seeing fit within IPC 4101/126 and /129 (typically 370HR, IS410, SM750, IT188, etc..). The lowest slash sheets are /101 and /121, with the primary thermal description change being a min Td of 310C. These materials aren't commonly found in the states, but perhaps one day we will get there.
Going back to your scoring issue. As BoardHhouse mentioned, a 0.015" web is typical for 0.062". While you can drop it to 0.012", you risk having your arrays fall apart on you during assembly, especially if you have heavier components on them. If it were me, I'd first verify that you're actually getting 0.015" web to begin with. The reason is that these 180Tg/340Td materials are phenolic materials, which are not just harder, but more brittle. When we first started using them, the surface would look like a zipper after scoring due to the material fracturing as the blade went through. An easy way to avoid this was by reducing the depth of the blade, which increases the web thickness. However, this results in issues like those that you are seeing. At the end of the day, we ended up changing our scoring parameters like RPM and feed, as well as shortening the life of our scoring blades.
If the web checks out, then it would be wise to invest in depaneling equipment such as those made by CAB and FKN.
At the end of the day, these are just bandaids to deal with materials that cost a lot of money but still have a lot of issues. We're seeing more and more customers convert to the middle IPC categories of /99 and /124, which tend not to be phenolic cured materials. This thread is getting long enough so I won't get into more details. We did a webinar on these materials (beneftis, etc.) that you might want to spend 30 minutes to look at. It's at http://www.saturnelectronics.com/webinar_leadfree_signup.htm. You may find it helpful. Thanks!
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