NOTE: This disposition is nonprecedential.

United States Court of Appeals 

for the Federal Circuit ______________________ 

POLYGROUP LIMITED MCO,

Plaintiff-Appellant

v.

WILLIS ELECTRIC COMPANY, LTD,

Defendant-Appellee

______________________ 

2018-1748, 2018-1749, 2018-1750

______________________ 

Appeals from the United States Patent and Trademark Office, Patent Trial and Appeal Board in Case Nos. 

IPR2016-01615, IPR2016-01616, and IPR2016-01617. 

______________________ 

Decided: January 28, 2019

______________________ 

 ROBERT A. ANGLE, Troutman Sanders LLP, Richmond, 

VA, argued for appellant. Also represented by DABNEY 

JEFFERSON CARR, IV, CHRISTOPHER FORSTNER, LAURA 

ANNE KUYKENDALL; DOUGLAS SALYERS, Atlanta, GA.

 LARINA A. ALTON, Fox Rothschild LLP, Minneapolis, 

MN, argued for appellee. 

______________________ 

Before DYK, REYNA, and HUGHES, Circuit Judges.
2 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

HUGHES, Circuit Judge. 

This is a patent case involving lighted artificial trees.

Polygroup Ltd. MCO petitioned for inter partes review of 

U.S. Patent No. 8,936,379. The Patent Trial and Appeal 

Board instituted review of all challenged claims. The 

Board determined that Polygroup had not established the 

unpatentability of any of the challenged claims. Polygroup now appeals. Because the Board did not err in 

finding that Korengold does not teach an “interference fit” 

under the broadest reasonable interpretation of that term,

we affirm the Board’s determination that claims 12, 15, 

and 32 were not shown to be unpatentable. But, we find 

that the Board erred in construing “modular artificial 

tree” and erred in finding that Polygroup failed to establish a motivation to combine the asserted prior art. As a 

result, we vacate the Board’s determination that claims 

1–6, 8, 10–11, 13–14, 16–17, and 28–29 were not shown to 

be unpatentable. On remand, the Board should consider 

whether those claims are unpatentable under a proper 

construction. 

I 

A.

Willis Electric Co., Ltd. owns the ’379 patent, which is

directed to a lighted artificial tree. The tree is comprised 

of “separable, modular tree portions mechanically and 

electrically connectable between trunk portions.” ’379

patent col. 1 ll. 13–15. The hollow trunk portions contain

electrical wiring and electrical connectors that provide a 

source of electricity for light strings draped over the 

branches. The connectors are designed so that mechanically connecting trunk portions during assembly also

creates an electrical connection between the trunk portions. The connectors form an electrical connection regardless of the rotational alignment of the trunk portions. 

These features simplify tree assembly by removing the 

need for “significant manipulation and handling of the 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 3

tree sections to securely align and couple the sections 

together.” ’379 patent col. 2 ll. 26–28.

The ’379 patent relates to the patents at issue in our 

companion case, Polygroup Ltd. v. Willis Elec. Co., No. 18-

1745, slip op. (Fed. Cir. Jan. 28, 2019), but the ’379 patent 

focuses more specifically on the structure and positioning 

of the mechanical-electrical connectors within the trunk 

sections. Independent claims 1 and 5 are representative

of the challenged claims and are reproduced below.

1. A modular artificial tree, comprising:

a first trunk portion having a first elongated 

trunk body defining a first cavity for receiving a 

first wiring harness including a first electrical 

wire and a second electrical wire;

a second trunk portion having a second elongated 

trunk body defining a second cavity for receiving a 

second wiring harness including a first electrical 

wire and a second electrical wire;

a first trunk connector insertable into the first 

trunk body along a central vertical axis, and securable to the first trunk body in at least four rotational alignment positions about the central 

vertical axis, including at a final insertion position, the first trunk connector being entirely located within the first cavity at the final insertion 

position[;]

a first electrical contact set including a first electrical contact and a second electrical contact engaged with the first trunk connector and 

electrically connected to the first electrical wire 

and the second electrical wire of the first wiring 

harness, respectively;

a second trunk connector insertable into the second trunk body along the central vertical axis, and 
4 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

securable to the second trunk body in at least four 

rotational alignment positions about the central 

vertical axis, including at a final insertion position;

a second electrical contact set including a first 

electrical contact and a second electrical contact 

engaged with the second trunk connector and 

electrically connected to the first electrical wire 

and the second electrical wire of the second wiring 

harness, respectively; and

wherein connecting the first and second trunk 

portions causes the first electrical contact set to be 

electrically connected to the second electrical contact set.

’379 patent col. 23 l. 63–col. 24 l. 30 (emphasis added).

5. A lighted modular artificial tree, comprising:

a first tree section including a first elongated 

trunk defining a vertical axis, a plurality of 

branches coupled to the first trunk, and a first 

plurality of lights, the first elongated trunk enclosing a first wiring harness configured to supply 

power to the first plurality of lights;

a second tree section including a second elongated 

trunk, a plurality of branches coupled to the second trunk, and a second plurality of lights, the 

second elongated trunk housing a second wiring 

harness;

a connector assembly configured to connect the 

first tree section to the second tree section along 

the vertical axis, the connector assembly including 

a first trunk connector located at least partially 

within the first trunk, a second trunk connector 

located at least partially within the second trunk, 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 5

a first pair of electrical contacts electrically connectable to a second pair of electrical contacts;

a top tree section including a vertically extending 

top portion, a plurality of branches coupled to the 

top portion, and a third plurality of lights, and a 

top connector connecting the top tree section to 

the second tree section and including:

a top connector body having a first portion insertable into the second trunk, a flanged portion coupled to the first portion, and a receiving port for 

receiving a portion of the vertically extending top 

portion, and

wherein the first plurality of lights are electrically 

connected to the second plurality of lights through 

the connector assembly, and the second plurality 

of lights are electrically connected to the third 

plurality of lights and,

wherein the flanged portion of the top connector 

body is outside the second trunk body and abutting a top edge of the second trunk portion.

’379 patent col. 24 l. 51–col. 25 l. 16 (emphasis added). 

The preamble of each challenged claim recites a 

“modular artificial tree.” Claims 1, 17, and 29 require 

that the connector fit into the trunk body “in at least four 

rotational alignment positions about the central vertical 

axis.” ’379 patent col. 24 ll. 20–21; see also id. at col. 26 ll. 

3–5; id. at col. 28 ll. 33–34. Although none of the claims 

here recite the “tree portion” limitation at issue in our 

companion case, see Polygroup, No. 18-1745, slip op. at 4, 

claim 5 recites multiple “tree sections.” And the Board 

construed “tree section” identically to “tree portion.” See 

id. at 7 (noting that the Board construed “tree portion” to 

mean “a mechanically and electrically connectable modular and unitary portion of an artificial tree”). Claims 12, 

15, and 32 depend from claims 1, 5, and 28 respectively, 
6 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

and each adds the limitation of an “interference fit” 

formed between the trunk connector and the trunk body. 

B.

Polygroup Ltd. filed three petitions for IPR of the ’379

patent alleging obviousness based on different combinations of prior art references. The Board instituted review 

on all challenged grounds in three separate IPR proceedings. 

Polygroup’s petitions rely on six prior art references, 

three of which are relevant here: U.S. Patent No. 

4,072,857 (DeVicaris), U.S. Patent No. 2,229,211 (Korengold), and U.S. Patent Application Publication No. 

2007/0230174 A1 (Hicks).

Polygroup relies on DeVicaris for each of its asserted 

grounds. DeVicaris is directed to an artificial tree with 

hollow trunk sections that contain electrical wiring and 

have electrical-mechanical connectors for attaching the 

trunk sections. During assembly, the trunk sections must 

be aligned in a single rotational position about the vertical axis. The branches in DeVicaris are detachable from 

the trunk sections, and the tree is assembled by first 

connecting the trunk sections, and then attaching the 

branches to the trunk. 

Polygroup relies on Korengold to teach both the

“interference fit” limitation in claims 12, 15, and 32, and 

the “four rotational alignment positions” limitation in

claims 1, 17, and 29. Korengold is directed to an electrical 

connector used to supply power between conduit pipe 

sections in an electrical device with multiple tubular 

parts, such as a modular lamp. The external diameter of 

the connector is “substantially equivalent” to the internal

diameter of the pipe, which allows the connectors to form 

a “snug fitting” when inserted into the pipe. J.A. 1100. 

Polygroup argues that Korengold’s “snug fit[]” is equivalent to the “interference fit” in the ’379 patent. Polygroup 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 7

also argues that a person of ordinary skill in the art 

would have been motivated to apply the type of connection taught by Korengold to the connectors in DeVicaris, 

resulting in a “connector . . . securable to the [] trunk body 

in at least four rotational alignment positions.” ’379 

patent col. 24 ll. 18–21.

Polygroup relies on Hicks for the obviousness of

claims 5, 10, 11, and 15–17. Hicks discloses an artificial 

tree with hollow trunk members that house the light 

wiring system. Hicks also teaches removable branches, 

each having its own electrical connector. Electricity is 

provided to the light strings on each branch individually, 

so that a branch can be removed and replaced without 

affecting lights on other branches. 

C.

The Board issued a consolidated decision for the three 

IPRs challenging the ’379 patent. A majority of the Board 

found that Polygroup failed to prove by a preponderance 

of the evidence that any of the challenged claims are 

unpatentable.1 

The Board first addressed the construction of “modular artificial tree” recited in the preamble of each claim. 

The Board found the preamble to be limiting, and it 

construed “modular artificial tree” to mean “a tree constructed of modular portions, each modular portion being 

a separate tree section.” J.A. 14. Crediting the testimony 

of Willis’s expert, the Board found that a “person having 

ordinary skill in the art ‘recognizes modular’ as a ‘distinct’ 

type of artificial tree with tree sections that come ‘with 

branches pre-attached to the trunk’ so that assembly is 

‘quick and easy.’” J.A. 19. Accordingly, the Board found 

 

1 A single member of the Board dissented and 

would have found all challenged claims unpatentable as 

obvious under 35 U.S.C. § 103. 
8 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

that neither DeVicaris nor Hicks teaches a “modular 

artificial tree” because the branches of each are separately attached to the trunk sections. Because every challenged claim recites a “modular artificial tree,” and 

Polygroup failed to provide a prior art reference teaching 

that limitation, the Board found that Polygroup failed to 

prove that any of the challenged claims are unpatentable.

As an alternate basis for its patentability determinations as to claims 12, 15, and 32, the Board found that 

Korengold fails to teach an “interference fit” as required 

by those claims. The Board construed “interference fit” to 

mean “an engineered connection where two components or 

parts to be connected are manufactured to be of different 

dimensions such that when one component is pressed into 

the other, they interfere and deform to force a connection.” J.A. 30. The Board concluded that Polygroup failed 

to show that Korengold’s “snug fit” between two parts 

with “substantially equivalent” diameters teaches a fit 

where parts “interfere to force a connection so as to secure 

the connection.” J.A. 47. 

As an alternate basis for its patentability determinations as to claims 1, 2–4, 6, 8, 13, 14, 17, and 29, the 

Board found that Polygroup failed to establish that a 

skilled artisan would have been motivated to combine 

DeVicaris with Korengold. Polygroup argued a person of 

ordinary skill would have been motivated to combine the 

references because the “ease of assembly [of DeVicaris] is 

improved because of the rotational freedom afforded by 

Korengold’s interference-fit connection.” J.A. 39. According to the Board, Polygroup failed to show that Korengold 

teaches rotational freedom. Additionally, because Korengold does not teach an “interference fit,” the Board concluded that a skilled artisan would not look to Korengold 

for such a fit. 

Polygroup now appeals. We have jurisdiction under 

28 U.S.C. § 1295(a)(4)(A).
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 9

II

We first consider the Board’s claim constructions of 

“modular artificial tree” and “interference fit.” We review 

the Board’s ultimate claim construction de novo and any 

underlying factual determinations involving extrinsic 

evidence for substantial evidence. In re Cuozzo Speed 

Techs., LLC, 793 F.3d 1268, 1280 (Fed. Cir. 2015). Substantial evidence requires that “a reasonable mind might 

accept the evidence to support the finding.” In re Giannelli, 739 F.3d 1375, 1379 (Fed. Cir. 2014). 

During IPR of an unexpired patent, the Board gives 

the claims their broadest reasonable interpretation in 

light of the specification. 37 C.F.R. § 42.100(b). Under 

this standard, claim terms are generally given their 

ordinary and customary meaning, as would be understood 

by a skilled artisan in the context of the entire disclosure. 

See In re Translogic Tech., Inc., 504 F.3d 1249, 1257 (Fed. 

Cir. 2007). 

For the reasons below, we find the Board erred in its 

construction of “modular artificial tree,” but it did not err 

in its construction of “interference fit.” 

A.

The Board found the recitation of “modular artificial 

tree” in the preamble of each claim to be limiting because 

it “provides necessary context at least for the terms ‘trunk 

portion’ and ‘tree section,’ and how they interface with 

each other.” J.A. 12. The Board then construed “modular 

artificial tree” to mean “a tree constructed of modular 

portions, each modular portion being a separate tree 

section.” J.A. 11. Relying on the testimony of Willis’s 

expert, Dr. Brown, the Board concluded that a modular 

tree is “a ‘distinct’ type of artificial tree with tree sections 

that come ‘with branches pre-attached to the trunk.’” J.A. 

19. This conclusion was error because the Board’s con-
10 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

struction does not represent the broadest reasonable 

interpretation of “modular artificial tree.”

First, we note that other than claim 5, none of the independent claims of the ’379 patent recite branches. We 

find no support for reading such a limitation into the 

claims as the Board did here. See Phillips v. AWH Corp., 

415 F.3d 1303, 1320 (Fed. Cir. 2005) (cautioning against 

reading limitations from the specification into the claims).

Additionally, while the ’379 patent’s specification discloses “modular tree portions” in the Field of Invention, 

see ’379 patent col. 1 l. 14, it also describes other aspects 

of the tree as “modular” throughout the specification, such 

as the connector assembly and light system, see id. at col. 

18 l. 36 (noting the “modularity and detachability of 

connector assembly 200”); id. at col. 20 ll. 50–53 (discussing the “modularity” of the lighting system). Given these

disclosures, we are not persuaded that the broadest 

reasonable interpretation of “modular artificial tree” 

requires a tree with “tree sections that come ‘with 

branches pre-attached to the trunk.’” J.A. 15. Instead, 

we find Polygroup’s proposed construction, “an artificial 

tree with elements capable of being easily joined or arranged with other parts or units,” to be more consistent 

with the entire disclosure of the ’379 patent. J.A. 11.

To the extent the Board relied on Dr. Brown’s testimony in reaching its construction, the Board erred in 

doing so. While it can be proper to rely on expert testimony “to establish that a particular term in the patent . . . 

has a particular meaning in the pertinent field[,] . . . 

conclusory, unsupported assertions by experts as to the 

definition of a claim term are not useful” during claim 

construction. Phillips, 415 F.3d at 1318. Dr. Brown’s 

statement is a conclusory and unsupported assertion, and 

we find it to be inconsistent with the intrinsic record. So, 

his testimony does not provide substantial evidentiary 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 11

support for the Board’s conclusion that a modular tree is 

one with “branches pre-attached to the trunk.” J.A. 15. 

Because the Board’s determinations on the patentability of claims 1–6, 8, 10–11, 13–14, 16–17, and 28–29 relied 

solely on its erroneous construction of “modular artificial 

tree,” we vacate those determinations and remand to the 

Board for consideration of whether those claims are 

obvious under a proper construction.2 

B.

The Board construed “interference fit” to mean “an 

engineered connection where two components or parts to 

be connected are manufactured to be of different dimensions such that when one component is pressed into the 

other, they interfere and deform to force a connection.” 

J.A. 30. The Board emphasized that the key to an interference fit is that the difference in dimensions forces a 

connection that “is strong enough to cause the two pieces 

to remain fixed relative to each other.” J.A. 22. The 

Board rejected Polygroup’s proposed construction, “a fit 

between two parts in which the external dimension of one 

part slightly exceeds the internal dimension of the part 

into which it has to fit,” J.A. 22, because it is “unconcerned with whether the two parts are fixed relative to 

each other, and is only concerned with whether they are 

somewhat different in size.” J.A. 23.

 

2 The Board also found that Hicks does not disclose 

the “tree section” limitation of claim 5. The Board construed “tree section” to have the same meaning as “tree 

portion,” a limitation in the related patents at issue in our 

companion case. See Polygroup, No. 18-1745, slip op. at 7. 

Because we found that the Board erred in construing “tree 

portion” in that case, id. at 10, we find that the Board 

erred in construing “tree section” here.
12 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

We find that the Board’s construction reflects the 

broadest reasonable interpretation of “interference fit” 

given the ’379 patent’s specification. The specification 

describes the “interference fit” between the connector and 

the trunk wall as one where “force is exerted” so that the 

parts are “held together.” See ’379 patent col. 12 l. 66–col. 

13 l. 2; see also id. at col. 13 ll. 62–65. The specification 

also explains that the parts or components “deform” in 

order to fit the connector “inside [the] base-trunk portion,” 

and that “[s]uch deformation or compression” forms an 

“interference fit.” Id. at col. 16 ll. 1–4. Thus, we agree 

with the Board that the key consideration for an “interference fit” is the connection generated between the parts

and whether the parts deform to force a connection, not 

whether the difference in their diameters is slight or 

substantial. 

Because we find no error in the Board’s claim construction of “interference fit,” we also find that the 

Board’s determination that Korengold does not teach an 

“interference fit” is supported by substantial evidence. 

Korengold teaches a “snug fit[]” formed by parts with 

“substantially equivalent” diameters. J.A. 1100. Nothing 

in its disclosure teaches that the parts “interfere [and 

deform] to force a connection.” See J.A. 47. Nor does 

Korengold require that the external diameter of the 

connector exceeds the internal diameter of the pipe. 

Thus, Korengold fails to teach an interference fit even 

under Polygroup’s proposed construction, which requires 

that the external dimension of one part “slightly exceeds” 

the internal dimension of the part into which it is to fit. 

See J.A. 22.

III

 Next, we consider the Board’s finding that Polygroup 

failed to establish that a skilled artisan would have been 

motivated to combine DeVicaris with Korengold. A party 

asserting that a claimed invention is obvious “must 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 13

demonstrate . . . that a skilled artisan would have had 

reason to combine the teaching of the prior art references 

to achieve the claimed invention, and that the skilled 

artisan would have had a reasonable expectation of success from doing so.” PAR Pharm., Inc. v. TWI Pharm, 

Inc., 773 F.3d 1186, 1193 (Fed. Cir. 2014) (internal quotation marks omitted). Whether a person of ordinary skill

would have been motivated to combine the prior art is a 

factual question reviewed for substantial evidence. 

Intercontinental Great Brands LLC v. Kellogg N. Am. Co., 

869 F.3d 1336, 1343 (Fed. Cir. 2017); see also In re Giannelli, 739 F.3d at 1379. 

In its petition, Polygroup argued that a skilled artisan

would have been motivated to enhance the tree from 

DeVicaris with the “interference fit-type connection” 

taught by Korengold. J.A. 160. According to Polygroup, 

“[t]he rotational freedom afforded by Korengold’s interference fit-type connection would permit the . . . electrical 

connectors of DeVicaris to be inserted into, and secured 

within, respective trunk sections in any rotational alignment position.” Id. 

The Board rejected Polygroup’s proposed motivation. 

The Board found that Korengold does not teach rotational 

freedom because “an electrical connector assembly within 

a conduit pipe . . . does not in itself teach rotational freedom.” J.A. 40. Further, because the Board determined 

that Korengold does not teach an “interference fit,” it 

found that a skilled artisan would not look to Korengold 

for such a fit. The Board also found that a person of 

ordinary skill would not have been motivated to replace 

the connectors in DeVicaris with the connectors in Korengold. Given the record before us, we conclude that the 

Board’s rejection of Polygroup’s proposed motivation is 

not supported by substantial evidence for three reasons. 

First, the Board’s determination that a skilled artisan

would not replace the connectors in DeVicaris with the 
14 POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD

connectors from Korengold is irrelevant to the motivation 

actually proposed by Polygroup. Polygroup suggested 

enhancing DeVicaris with the connection used to insert 

Korengold’s connectors into the conduit pipe, not the 

connectors themselves. Because most of the Board’s 

analysis, and the expert testimony it relied upon, focused 

on the motivation to replace DeVicaris’s connector with 

Korengold’s connector, neither that analysis nor the 

expert testimony provides substantial evidentiary support 

for the Board’s rejection of Polygroup’s proposed motivation. See J.A. 41–43 (focusing on the finding that replacing DeVicaris’s connector with Korengold’s connector

would make tree assembly more difficult).

Second, the fact that Korengold does not teach an “interference fit” as that term is used in claims 12, 15, and 

32 is also irrelevant to the motivation to combine analysis. Polygroup argues that a skilled artisan would look to 

Korengold’s connection because it teaches rotational 

freedom. Polygroup’s choice to refer to Korengold’s connection as an “interference fit-type connection” has no 

bearing on whether Korengold teaches rotational freedom, 

so it also has no bearing on whether a skilled artisan

would have been motivated in the manner Polygroup 

proposes. That Korengold does not teach an “interference 

fit” is only relevant to the patentability of claims 12, 15, 

and 32, which include that limitation.

Finally, the Board’s determination that Korengold 

fails to teach rotational freedom is not supported by 

substantial evidence. Korengold discloses a cylindrical 

connector that is inserted into a cylindrical pipe with a 

“substantially equivalent” diameter such that the two 

parts form a “snug fitting.” J.A. 1100. Such an arrangement would allow the connector to be inserted in “any

rotational alignment position,” as Polygroup’s expert 

asserted. J.A. 1020. Nowhere does Korengold suggest 

that its connectors require a particular rotational alignment. Thus, no reasonable fact finder could conclude that 
POLYGROUP LTD MCO v. WILLIS ELEC. CO., LTD 15

Korengold fails to teach a connection with rotational 

freedom. And we agree with Polygroup that a person of 

ordinary skill would have been motivated to enhance 

DeVicaris with Korengold because Korengold’s rotational 

freedom would improve the ease of assembly of the DeVicaris tree.

IV

We have considered the parties’ remaining arguments 

and find them unpersuasive. We conclude that the Board 

erred in its construction of “modular artificial tree” and

that Polygroup established a sufficient motivation to 

combine DeVicaris with Korengold. Therefore, we vacate 

the Board’s determination that Polygroup failed to prove 

that claims 1–6, 8, 10–11, 13–14, 16–17, and 28–29 are 

not unpatentable. On remand, the Board should consider 

whether those claims are unpatentable under a proper 

construction. We affirm the Board’s determination that 

Polygroup failed to prove that claims 12, 15, or 32 are 

unpatentable because Korengold fails to teach an “interference fit” under the broadest reasonable interpretation 

of that term. 

AFFIRMED-IN-PART, VACATED-IN-PART, AND

REMANDED

COSTS

No costs.