US 12,269,106 B2
Two-step solder-mask-defined design
Koustav Sinha, Boise, ID (US); and Hyunsuk Chun, Boise, ID (US)
Filed by Lodestar Licensing Group LLC, Evanston, IL (US)
Filed on Dec. 21, 2021, as Appl. No. 17/558,546.
Application 17/558,546 is a continuation of application No. 16/664,627, filed on Oct. 25, 2019, granted, now 11,207,744.
Prior Publication US 2022/0111457 A1, Apr. 14, 2022
Int. Cl. B23K 1/20 (2006.01); H01L 23/49 (2006.01); H01L 23/498 (2006.01); B23K 101/40 (2006.01); B23K 101/42 (2006.01)
CPC B23K 1/20 (2013.01) [H01L 23/49816 (2013.01); B23K 2101/40 (2018.08); B23K 2101/42 (2018.08)] 12 Claims
OG exemplary drawing
 
1. An apparatus, comprising:
a solder masked defined (SMD) mounting pad, the SMD mounting pad having a first SMD area comprising a first aperture in a solder resist layer and a second SMD area comprising a second aperture in a buffer layer, the buffer layer being disposed on top of the solder resist layer, the first aperture exposing at least a portion of an underlying pad and the second aperture having an interface diameter that is larger than an interface diameter of the first aperture by a value in a range of 0.5% to 5%, wherein a thickness of the solder resist layer is in a range of 5 microns to 50 microns and a thickness of the buffer layer is in a range of 5 microns to 50 microns; and
a solder ball disposed on the SMD mounting pad such that the solder ball contacts a sidewall of the buffer layer exposed by the second aperture and contacts a sidewall of the solder resist layer exposed by the first aperture and has a diameter that is larger than the interface diameter of the second aperture, wherein the sidewall of the solder resist layer or the sidewall of the buffer layer, or both, comprises a taper forming a slope.