Ex Parte Müller et al

Patent Trial and Appeal Board

Sep 28, 2018

15155152 (P.T.A.B. Sep. 28, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
15/155, 152 05/16/2016
146730 7590 10/02/2018
Wendy W. Koba
II -VI Incorporated
PO Box 556
Springtown, PA 18081
FIRST NAMED INVENTOR
Jurgen Muller
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www .uspto.gov
ATTORNEY DOCKET NO. CONFIRMATION NO.
LE-003 6467
EXAMINER
NIU, XINNING
ART UNIT PAPER NUMBER
2828
NOTIFICATION DATE DELIVERY MODE
10/02/2018 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
wendykoba@usa.net
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte JURGEN MULLER,
RAINER BATTIG, REINHARD BRUNNER,
and STEP AN WEISS
Appeal2018-003209
Application 15/155, 152 1
Technology Center 2800
Before ADRIENE LEPIANE HANLON, CHRISTOPHER C. KENNEDY, and
DEBRA L. DENNETT, Administrative Patent Judges.
HANLON, Administrative Patent Judge.
DECISION ON APPEAL
A. STATEMENT OF THE CASE
The Appellants filed an appeal under 35 U.S.C. § 134(a) from an Examiner's
decision finally rejecting claims 1-17 under 35 U.S.C. § 103(a) as unpatentable
over Krejci et al. 2 in view of Roff et al. 3 We have jurisdiction under 35 U.S.C.
§ 6(b).
1 The real party in interest, and the Applicant, is said to be II-VI Laser Enterprise
GmbH. Appeal Brief dated October 5, 2017 ("App. Br."), at 1.
2 US 2009/0104727 Al, published April 23, 2009 ("Krejci").
3 US 9,450,377 Bl, issued September 20, 2016 ("Roff').
Appeal2018-003209
Application 15/155, 152
We REVERSE.
The claimed subject matter is directed to a diode laser bar assembly.
According to the Appellants:
Diode bars are high-power semiconductor lasers containing a
one-dimensional array of broad-area emitters or, alternatively,
subarrays containing 10-20 narrow stripes. Diode bars typically
contain between 20 and 50 emitters, each being about 100 µm wide.
A typical commercial device may comprise a laser resonator length on
the order of 1-5 mm, with a width of about 10 mm. This size of
device is capable of generating tens to hundreds of watts of output
power without much difficulty. Power levels up to 250W continuous
output power are commercially available.
Spec. ,r 3.
The Appellants disclose that the need to operate diode bars at high powers
results in a significant quantity of heat being generated. Spec. ,r 5. In order to
maintain acceptable performance of the diode laser over a reasonable lifetime (e.g.,
20 kh or more), the Appellants disclose that the diode bar needs to be mounted
onto a heatsink or provided in an arrangement with a low thermal resistance. Spec.
The Appellants disclose that conventional heatsink materials, such as
copper, exhibit a coefficient of thermal expansion (CTE) that is different from the
CTE of the diode laser bar itself. Spec. ,r 5. This mis-match in CTE is said to
create mechanical stress between the heatsink and the diode laser bar during the
high-temperature process of attaching the diode laser bar to the heatsink. Spec.
,r 5. According to the Appellants, that stress results in the formation of a curvature
along the lateral extent of the diode laser bar which is referred to as a "smile."
Spec. ,r 6; see also Appellants' Fig. 4. A smile artifact is said to have detrimental
effects on the ability to focus beams from diode bars. Spec. ,r 6.
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Application 15/155, 152
The Appellants' Figure 5, reproduced below, illustrates a diode laser bar
assembly that is said to address the smile artifact problem in prior art diode laser
bar assemblies.
Appellants' Figure 5 is an exploded, isometric view of
an exemplary diode laser bar assembly
using a sandwich of platelets.
The inventive diode laser bar assembly comprises a pair of platelets 12, 14,
disposed above and below the diode laser bar 10, respectively, forming a
"sandwich" structure. Spec. ,r,r 9, 40. The bottom platelet 14 is disposed between
the heatsink (cooler) 16 and the diode laser bar 10. Spec. ,r,r 9, 40. The Appellants
disclose that "[ t ]he combination of the top and bottom platelets provides the ability
to create various configurations and designs that best accommodate stress
conditions for a particular situation." Spec. ,r 9.
Independent claim 1 is reproduced below from the Claims Appendix to the
Appeal Brief. The limitation at issue is italicized.
1. A diode laser bar assembly comprising
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Appeal2018-003209
Application 15/155, 152
a bar of semiconductor laser diodes including an array of
emitter regions disposed in a lateral direction across a front facet of
the bar, the bar including a bottom major surface and an opposing top
major surface, the front facet extending orthogonally between the top
and bottom major surfaces;
a heatsink;
a bottom platelet disposed between the heatsink and the bottom
major surface of the bar of semiconductor laser diodes, the bottom
platelet comprising a material and thickness chosen to create a low
thermal resistance path between the bar of semiconductor laser diodes
and the heatsink, providing heat flow from the bar of semiconductor
laser diodes to the heatsink in a direction perpendicular to the major
surfaces of the bar of semiconductor laser diodes, with the bottom
platelet affixed in place using a suitable solder material; and
a top platelet disposed over and affixed to the top major surface
of the bar of semiconductor laser diodes, the dimensions and
materials of the top platelet chosen to manage mechanical stress
conditions within the assembly and reduce curvature across the array
of emitter regions.
App. Br. 11
B. DISCUSSION
The Examiner finds Krejci discloses an assembly comprising a bar of
semiconductor laser diodes, a heatsink (cooler), and a bottom platelet (submount)
disposed between the heatsink and the bottom major surface of the bar of
semiconductor laser diodes. Final Act. 5. 4 Krejci Figure 2, reproduced below,
illustrates an embodiment of the diode laser bar assembly.
4 Final Office Action dated May 30, 2017.
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Appeal2018-003209
Application 15/155, 152
Cc~,i:~r ~x.---:..,1::::-~
·-..... GTf'-'· ·::6 ): -~i;:1~:: K··:
(-!~A~ ~-;;,;::.-:t~c E3.8r:
{: n:~ t~ .~.:.:· ~ (f.: K ·;
"::1·:.~,::r~}',s M-:x~m.J~: S-:} (:P~:
Krejci Figure 2 is a general view of an
embodiment of the diode laser bar assembly.
Krejci discloses that "one major problem when manufacturing industrial
laser bars is the large thermal mismatch between the commonly used laser diodes
and the cooler." Krejci ,r 3. Krejci discloses that there are three common
technologies for mounting industrial laser bars on copper coolers, two of which
include forming a bar-on-submount structure. Krejci ,r,r 4--6. Krejci discloses that
these mounting technologies, however, suffer from the same "smile" problem
described in the Appellants' Specification. Krejci ,r 8.
Krejci discloses that the "smile" problem may be solved by pre-stressing the
submount. Krejci discloses that
this is done either by deforming, e.g. bending, the submount before or
during assembly or by building up stress within the submount/laser
bar subsystem during assembly of the latter. In other words, rather
than matching the CTEbar of the laser bar, the submount is designed
with a structure with "tailored tensile strength" ....
Krejci ,r 23.
The Examiner finds that Krejci does not disclose "a top platelet disposed
over and affixed to the top major surface of the bar of semiconductor laser diodes,
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Appeal2018-003209
Application 15/155, 152
the dimensions and materials of the top platelet chosen to manage mechanical
stress conditions within the assembly and reduce curvature across the array of
emitter regions" as recited in claim 1. Final Act. 5.
The Examiner, however, finds Roff discloses a laser diode chip formed
between two submounts. Final Act. 5. The Examiner concludes that it would have
been obvious to one of ordinary skill in the art to modify Krejci's assembly "by
adding a second platelet affixed to the top major surface of the bar of
semiconductor laser diodes in order to further cool the laser diode bar." Final
Act. 5 ( emphasis added).
The Appellants argue that "the 'laser diode chip' of Roff is not a 'bar of
semiconductor laser diodes including an array of emitter regions' as defined by
independent claim 1." App. Br. 5 (emphasis added). Rather, the Appellants argue
that Roff defines a "laser diode chip" as comprising "a single broad area emitting
laser light" which is not packaged to any heatsink. App. Br. 6 ( citing Roff, col. 1,
11. 12-24) (original emphasis omitted); see also Roff, col. 2, 11. 56-57 (disclosing
that "[a] laser diode chip is herein defined as single emitter laser diode").
The Appellants argue that Roff discloses mounting a plurality of laser diode
chips vertically onto a cooling surface with a sub-mount on both the P-side and the
N-side of the emitter laser diode chip. App. Br. 6 (citing Roff, col. 2, 11. 51-54).
The Appellants direct our attention to Roff Figure 4, reproduced below, which
illustrates a plurality of laser diode chips 403 perpendicular to the surface of base
401.
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Application 15/155, 152
40b
402
Roff Figure 4 depicts an embodiment of
the invention.
Roff discloses:
In FIG. 4, each laser diode chip 403 has two opposing bonding
surfaces that are perpendicular to the surface of the carrier base 401.
Each one of the two opposing bonding surfaces are attached to one of
the plurality of sub-mounts. Thus, considering laser diode chip 403,
one of its bonding surfaces is attached to the sub-mount 402 and
another is attached to the sub-mount [ 404].
Roff, col. 11, 11. 16-22 (emphasis omitted); see also Roff, col. 11, 11. 9-10
(describing sub-mounts 402 and 404); App. Br. 8 (citing Roff, col. 11, 11. 16-26).
The Appellants argue:
It is clear that each individual laser diode chip in Roff is
disposed orthogonal to a substrate, with a pair of separate "sub-
mounts" disposed on opposing, exposed surfaces of each individual
laser diode chip. Roff does not disclose or suggest any "top platelet"
disposed across an array of emitter regions, as defined by Appellant'
[sic] independent claim 1 and shown in FIG. 5. Without teaching this
structure, the combination of Roff with Krejci is still lacking an
essential element of independent claim 1.
App. Br. 8.
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Appeal2018-003209
Application 15/155, 152
In response, the Examiner maintains that Roff discloses a laser diode chip
formed between two submounts which "sandwich" a laser emitter disposed
orthogonal to a substrate. Ans. 3, 4. 5 The Examiner concludes:
Given that Krejci already teaches a diode laser bar structure with a
bottom platelet in contact with the diode laser bar, one of ordinary
skill in the art would find it obvious to modify Krejci given the
teachings of Roff by disposing an additional platelet above the diode
laser bar so that the diode laser bar is further cooled by the additional
platelet/submount.
Ans. 3 (emphasis added); see also Ans. 4. The Examiner finds that "[t]he device
of Krejci as modified by Roff teaches the dimensions and materials of the top
platelet chosen to manage mechanical stress conditions within the assembly and
reduce curvature across the array of emitter regions" as recited in claim 1. Ans. 4--
5.
The Appellants argue that "Roff does not discuss 'mechanical' problems.
Indeed, mechanical problems such as curvature of an array of emitter regions is
only a problem with diode laser bars, since the plurality of emitter regions are
formed within a single 'bar' of material." Reply Br. 2. 6 The Appellants argue that:
[T]he "top platelet" element of independent claim 1 is particularly
defined as comprising materials and dimensions "to manage
mechanical stress conditions ... and reduce curvature across the
array of emitter regions". Without discussing "mechanical problems"
or issues associated with "curvature" across an array of emitter
regions, Appellant fails to see the relevance of Roff' s teaching to the
laser diode bar structure of Krejci.
Reply Br. 2.
5 Examiner's Answer dated January 25, 2018.
6 Reply Brief dated February 1, 2018.
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Appeal2018-003209
Application 15/155, 152
The Appellants' arguments are persuasive of reversible error. Claim 1
recites that the dimensions and materials of the top platelet "manage mechanical
stress conditions within the assembly and reduce curvature across the array of
emitter regions." App. Br. 11. The Examiner has failed to show, in the first
instance, that the dimensions and materials of Roff's sub-mount 402 or 404 would
be capable of managing mechanical stress conditions within Krejci's diode laser
bar assembly and reduce curvature across the array of emitter regions as recited in
claim 1. See In re Oetiker, 977 F.2d 1443, 1445 (Fed. Cir. 1992) (examiner bears
the initial burden of presenting a prima facie case ofunpatentability). To the
extent that Roffs sub-mounts are capable of cooling Krejci's diode laser bar, the
Examiner has failed to direct us to any evidence that correlates cooling a diode
laser bar with managing mechanical stress conditions within a diode laser bar
assembly and reducing curvature across an array of emitter regions as recited in
claim 1.
For the reasons set forth above, the obviousness rejection on appeal is not
sustained.
C. DECISION
The Examiner's decision is reversed.
REVERSED
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