Appeal No. 1999-0725
Application 08/476,475
Obviousness
It is necessary to begin with a definition of "solder ball," as
defined in the specification (p. 11, lines 2-8):
It should be noted that the term "solder ball" as used in
conjunction with this invention means that the lead and tin
have been combined and gone through at least one reflow cycle
and formed a "solder ball". Therefore, it should be clear to a
person skilled in the art that the invention is an improvement
of these already formed solder balls or C4s.
The reflow cycle brings the solder to a spherical shape as shown in
Appellants' figure 1 due to the surface tension of the solder.
In claim 1, the step of "(a) forming said solder ball on a
substrate" is not found in the '346 reference and is not accounted
for in the Examiner's rejection. The '346 reference4 shows a high
melting point metal 24 deposited on a pad 22 on the ceramic
substrate 21 via a metal mask 23 at a thickness of 100 :m
(translation, p. 7). Then a low melting point metal 25 is deposited
on material 24 at a thickness of 20 :m via the mask 23 (translation,
p. 7). This results in a solder "bump" consisting of a high melting
point metal layer 24 and a low melting point metal layer 25.
Respective solder bumps on a semiconductor chip 26 and a ceramic
substrate 21 are mounted to face each other and the low melting point
4 Figure 3 in the '346 reference appears to be the same as
figure 6-20b of Microelectronics.
- 7 -
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 Next
Last modified: November 3, 2007