US 12,322,692 B2
Solder mask for thermal pad of a printed circuit board to provide reliable solder contact to an integrated circuit
Daniel Yap, Singapore (SG); and Hung Meng Loh, Bukit Panjang (SG)
Assigned to STMICROELECTRONICS PTE LTD, Singapore (SG)
Filed by STMICROELECTRONICS PTE LTD, Singapore (SG)
Filed on Jan. 10, 2022, as Appl. No. 17/572,247.
Application 17/572,247 is a division of application No. 16/550,775, filed on Aug. 26, 2019, granted, now 11,244,892.
Claims priority of provisional application 62/725,059, filed on Aug. 30, 2018.
Prior Publication US 2022/0130750 A1, Apr. 28, 2022
Int. Cl. H01L 23/48 (2006.01); H01L 21/48 (2006.01); H01L 23/31 (2006.01); H01L 23/495 (2006.01); H01L 23/498 (2006.01); H01L 23/52 (2006.01); H01L 29/40 (2006.01); H05K 3/34 (2006.01)
CPC H01L 23/49861 (2013.01) [H01L 21/4867 (2013.01); H01L 23/3114 (2013.01); H01L 23/49513 (2013.01); H01L 23/4952 (2013.01); H01L 23/49568 (2013.01); H05K 3/3452 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method, comprising:
forming a solder mask on a first thermal pad of a printed circuit board and leaving an unmasked portion of the thermal pad exposed from the solder mask, forming the solder mask on the thermal pad including:
forming a plurality of mask stripes extending from respective edges of the unmasked portion towards a center of the unmasked portion, each respective mask stripe of the plurality of mask stripes terminates at a respective end before extending fully across the unmasked portion of the thermal pad;
depositing solder paste on the unmasked portion of the thermal pad;
coupling a second thermal pad of an integrated circuit package to the solder paste on the first thermal pad of the printed circuit board; and
forming a solder connection by:
heating the solder paste between the first thermal pad and the second thermal pad.