Method and apparatus for two sided solder cladded surface mounted printed circuit boards

Patent 5167361 Issued on December 1, 1992. Estimated Expiration Date:

May 16, 2011. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

Method and apparatus for solder bumping of printed circuit boards
Patent #: 4752027
Issued on: 06/21/1988
Inventor: Gschwend

Method for effecting solder interconnects Patent #: 4889275
Issued on: 12/26/1989
Inventor: Mullen, III, et al.

Inventors

Assignee

Motorola, Inc.

Application

No. 700981 filed on 05/16/1991

US Classes:

228/180.22, Lead-less (or "bumped") device228/173.3, Preforming work faying surface228/254Adherent solid layer or coating (e.g., pretinned)

Examiners

Primary: Seidel, Richard K.
Assistant: Knapp, Jeffrey T.

Attorney, Agent or Firm

Meles; Pablo

Foreign Patent References

59-39467 JP 03/12/1984

International Class

B23K 031/02

Abstract

A method of forming flat solder bumps (16 and 18) on contact areas (12 and 14) of a first side and second side of a printed circuit board (12, 14 and 10) comprises the steps of applying solder paste in a predetermined pattern and a predetermined thickness on the contact areas of the first side and the second side of the printed circuit board forming joint areas. Next, the solder paste is reflowed. Then, the solder joints on the first side are flattened (17). Before surface mounted components (20 and 26) are mounted on the printed circuit board, tack media (32) is dispensed onto the joint areas. Subsequently, the printed circuit boards is reflowed. Now the second side of the printed circuit board is flattened (19). As with the first side, tack media (34) is dispensed on the solder joints on the second side before surface mounted components (40 and 46) are mounted on the second side. Finally, the printed circuit board is reflowed again.