the part ordering number LTM4634IY-ND, is NOT Non-Lead RoHS (R estriction of Hazardous Substances): Linear Technology introduced eutectic SnPb (tin-lead) ball BGA package options for 53 μModule power products, now being acquired by ADI.
We will update our product part landing pages accordingly.
SnPb BGA μModule products can be distinguished by the package top mark (e0) complying with JEDEC standard J-STD-609.
You can download their BGA manufacturing guidelines for PCB assembly (attached and available online via this link:
www.analog.com/media/en/technical-documentation/product-information/l2_bga-assy_09-27-2016.pdf).