Appeal No. 2003-2136 Page 3 Application No. 09/562,952 thus made features "a high bonding strength and a small thermal stress, and thereby durability of the spark plug is improved." (Id. at 19.) A further understanding of the invention can be achieved by reading the following claim. 7. A method of manufacturing a spark plug for an internal combustion engine, the spark plug including an insulator having a through- hole formed therein, a center electrode made of a nickel-based alloy disposed at one end of the through-hole, a metal housing holding the insulator therein, and a ground electrode connected to the metal housing and disposed to face the center electrode, forming a spark gap therebetween, the manufacturing method comprising steps of: attaching a noble metal chip directly on a flat end surface of the center electrode, the noble metal chip being made of an iridium alloy containing iridium and a noble metal having a melting point in a range from 1,500 to 2,100 °C and a linear expansion coefficient in a range from 8 x 10-6 to 11 x 10-6/°C, the iridium alloy having a melting point equal to or higher than 2,200 °C, a surface area of the flat end surface of the center electrode, to which the noble metal chip is directly attached, being larger than a surface area of the noble area [sic; metal] chip which is directly attached to the flat end surface of the center electrode; and radiating a laser beam on the noble metal chip in a direction substantially perpendicular to an axial direction of the center electrode, thereby forming a molten bond containing more than 1-weight-percent noble metal having a melting point in a range from 1,500 to 2,100 °C and a linear expansion coefficient in a range from 8 x 10-6 to 11 x 10-6/°C between the center electrode and the noble metal chip. Claims 7-15 and 17 stand rejected under 35 U.S.C. § 103(a) as obvious over U.S. Patent No. 5,440,198 ("Oshima '198"); U.S. Patent No. 6,094,000 ("Osamura");Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 NextLast modified: November 3, 2007