The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.

The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.

Date of Patent:
Aug. 25, 2020

Filed:

Oct. 28, 2018
Applicant:

Indium Corporation, Utica, NY (US);

Inventors:

Fengying Zhou, Suzhou, CN;

Fen Chen, Suzhou, CN;

Ning-Cheng Lee, New York, NY (US);

Assignee:

INDIUM CORPORATION, Utica, NY (US);

Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H01L 21/44 (2006.01); H01L 21/56 (2006.01); B23K 35/24 (2006.01); H05K 3/30 (2006.01); H01L 23/498 (2006.01); H01L 23/00 (2006.01); H05K 3/34 (2006.01);
U.S. Cl.
CPC ...
H01L 24/11 (2013.01); H01L 24/17 (2013.01); H05K 3/3436 (2013.01); H01L 2924/15311 (2013.01);
Abstract

The disclosure describes techniques for eliminating or reducing non-wet open (NWO) defect formation by using a low activity flux to prevent a solder paste from sticking to ball grid array (BGA) solder balls during reflow soldering. The low activity flux may be configured such that: i) it creates a barrier that prevents the solder paste from sticking to the solder balls of the BGA; and ii) it does not impede the formation of solder joints during reflow. In implementations, a solid coating of the low activity flux may be formed over balls of the BGA, and the BGA may then be bonded to a PCB during reflow. In implementations, the balls of a BGA may be dipped in a low-activity creamy or liquid flux prior to reflow. In some implementations, the flux may applied on a solder paste printed on pads of the PCB, followed by placement of a BGA.


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