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`US009820374B2
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`a2) United States Patent
`US 9,820,374 B2
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`Nov. 14, 2017
`(45) Date of Patent:
`Bois et al.
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`Notice:
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`USE OF HYBRID PCB MATERIALSIN
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`PRINTED CIRCUIT BOARDS
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`Inventors: Karl J. Bois, Fort Collins, CO (US);
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`Ramon R. Campa, Tomball, TX (US)
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`Assignee: Hewlett Packard Enterprise
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`Development LP, Houston, TX (US)
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`Subject to any disclaimer, the term ofthis
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`patent is extended or adjusted under 35
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`U.S.C. 154(b) by 1717 days.
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`Appl. No.:
`13/061,493
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`PCTFiled:
`Aug. 30, 2008
`PCT No.:
`PCT/US2008/074943
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`§ 371 (€)(),
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`Feb. 28, 2011
`(2), (4) Date:
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`PCT Pub. No.: WO2010/024823
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`PCT Pub. Date: Mar. 4, 2010
`Prior Publication Data
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`US 2011/0157842 Al
`Jun. 30, 2011
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`Int. Cl.
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`HOS5K 1/00
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`HOS5K 1/02
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`HIO5SK 3/46
`US. Cl.
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`CPC oc. HO5K 1/024 (2013.01); HOSK 3/4688
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`(2013.01); HOSK 3/4626 (2013.01)
`Field of Classification Search
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`USPC ooccee eee 361/748, 360, 361; 174/250
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`See application file for complete search history.
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`CN
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`EP
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`References Cited
`U.S. PATENT DOCUMENTS
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`4,925,024 A
`5/1990 Ellenberger et al.
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`5,652,055 A
`7/1997 King et al.
`6,890,635 B2
`5/2005 Lin et al.
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`7,265,181 B2
`9/2007 Linet al.
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`7,378,598 B2
`5/2008 Boiset al.
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`7,416,972 B2
`8/2008 Japp et al.
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`7,470,990 B2
`12/2008 Japp et al.
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`7,730,613 B2*
`6/2010 Vasoya ween 29/852
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`7,989,895 B2*
`8/2011 White et al ow. 257/379
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`8,242,380 B2
`8/2012 Boiset al.
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`2003/0098177 AL*
`5/2003 Cheng we 174/261
`2005/0183883 Al
`8/2005 Boiset al.
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`(Continued)
`FOREIGN PATENT DOCUMENTS
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`1658734 A
`8/2005
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`1838855 A
`9/2006
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`1705974
`9/2006
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`OTHER PUBLICATIONS
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`Rick Hartley, “Designing PCBs with Mixed Materials,” Printed.
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`Circuit Design and Manufacture Magazine, Mar. 30, 2006, 4 pages
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`http://pedandf.com/cms/index2php?option=com.
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`(Continued)
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`Primary Examiner — Andargie M Aychillhum
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`(74) Attorney, Agent, or Firm — Conley Rose, P.C.
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`(57)
`ABSTRACT
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`A apparatus comprising a printed circuit board (“PCB”). The
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`PCB comprises a first insulating layer and a second insu-
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`lating layer. The first insulating layer is made ofa first
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`material and the second insulating layer is made of a second
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`material. The first material has a lower dissipation factor
`than the second material. The first material and second
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`material have substantially similar dielectric constants.
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`17 Claims, 4 Drawing Sheets
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`Page 1 of 9
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`SAMSUNG EXHIBIT 1028
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`Page 1 of 9
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`SAMSUNG EXHIBIT 1028
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`US 9,820,374 B2
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`References Cited
`U.S. PATENT DOCUMENTS
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`2005/0218524 Al
`10/2005 Jappetal.
`2007/0040626 Al*
`2/2007 Blair et al. wee 333/1
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`2007/0040689 Al*
`2/2007 Reynolds oe. 340/572.7
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`2007/0090894 Al*
`4/2007 Phan et al. wwe 333/33
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`2007/0182016 Al
`8/2007 Japp et al.
`2008/0196933 Al
`8/2008 Boiset al.
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`2010/0323477 AL* 12/2010 Aral et al. wo. 438/121
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`OTHER PUBLICATIONS
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`International Search Report and Written Opinion, dated Mar. 13,
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`2009, 11 pages.
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`* cited by examiner
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`Page 2 of 9
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`U.S. Patent
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`Sheet 1 of 4
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`US 9,820,374 B2
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`Nov. 14, 2017
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`U.S. Patent
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`Nov. 14, 2017
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`Sheet 2 of 4
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`US 9,820,374 B2
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`Figure 2
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`U.S. Patent
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`Nov. 14, 2017
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`Sheet 3 of 4
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`US 9,820,374 B2
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`Figure 3
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`A
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`U.S. Patent
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`Sheet 4 of 4
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`US 9,820,374 B2
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`Figure 4
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`Manufacture a First POB Layer
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`using Low Dielectric Constant,
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`Low Dissipation Factor Material
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`Manufacture a Second POB
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`Layer using Material with a
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`Similar Dielectric Canstant, yet
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`Higher Dissipation Factor than
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`‘First PCB Layer Material
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`Manufacture a Third PCB Layer
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`using Same Material as. the First
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`FCB Layer
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`Manufacture a Fourth PCS Layer
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`using Same Material as the
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`Bond All PCS Layers Together to
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`Second PCB Layer
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`\
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`Page 6 of 9
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`US 9,820,374 B2
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`1
`USE OF HYBRID PCB MATERIALSIN
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`PRINTED CIRCUIT BOARDS
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`BACKGROUND
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`Virtually every electronic device includes one or more
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`varieties of printed circuit boards (“PCBs”) (also referred to
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`as printed wiring boards or “PWBs”). PCBs are relatively
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`thin, layered substrates upon which integrated circuits and
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`other electronic components are mounted. A printed circuit
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`board typically includes a plurality of electrically conductive
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`and insulating layers arranged in a sandwich-like fashion.
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`Conductive layers generally have conductive pathsor traces,
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`which are chemically or mechanically etched outof the bulk
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`conductive layer, thus isolated from one another by insulat-
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`ing material and routed within a plane. These traces are
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`generally designed to electrically contact conductive por-
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`tions of the electronic components mounted on the PCB,
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`forming electrical interconnects. Insulating layers electri-
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`cally isolate conductive layers from one another. The prin-
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`ciple structure of conductive traces and layers of insulating
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`material is also used on a smaller scale within a packaged
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`microchip having a PCB-like package substrate.
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`The insulating layers typically are made of preimpreg-
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`nated (prepreg) materials such as FR-2 (Phenolic cotton
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`paper), FR-3 (Cotton paper and epoxy), and FR-4 (Woven
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`glass and epoxy). FR-4 is the material of choice in the
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`building of PCBs usedin high-end industrial, consumer, and
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`military electronic equipmentdueto its ability to absorb less
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`moisture, its strength and stiffness, and its flame resistance.
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`Numerous variations of FR-4 are available on the market,
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`such as FR-408 and Polyclad 370HR. FR-408 has a lower
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`dissipation factor at high frequencies than many other mate-
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`rials makingit desirable for use in PCBs requiring the use of
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`high speed signals. However, FR-408 and other insulating
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`materials that have low dissipation factors at high frequen-
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`cies have higher costs. It would be desirable to manufacture
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`a PCBat lower cost while maintaining the capabilities of
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`the term “couple” or “couples” is intended to mean either an
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`indirect, direct, optical or wireless electrical connection.
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`Thus, if a first device couples to a second device,
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`connection may be through a direct electrical connection,
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`through an indirect electrical connection via other devices
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`and connections, through an optical electrical connection, or
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`through a wireless electrical connection.
`DETAILED DESCRIPTION
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`The following discussion is directed to various embodi-
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`ments of the invention. Although one or more of these
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`embodiments may bepreferred, the embodiments disclosed
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`should not be interpreted, or otherwise used, as limiting the
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`scope of the disclosure, including the claims. In addition,
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`one skilled in the art will understand that the following
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`description has broad application, and the discussion of any
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`embodiment is meant only to be exemplary of that embodi-
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`ment, and not intended to intimate that the scope of the
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`disclosure, including the claims, is limited to that embodi-
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`FIG.1 illustrates an electronic device 100 in accordance
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`with embodiments of the invention. As shownin FIG.1, the
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`electronic device 100 comprises a chassis 102, a display
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`104, and an input device 106. The chassis 102 is coupled to
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`the display 104 and the input device 106 to enable the user
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`to interact with electronic device 100. The display 104 and
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`the input device 106 may together operate as a user inter-
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`face. The display 104 is shown as a video monitor, but may
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`take many alternative forms such as a printer, a speaker, or
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`other means for communicating information to a user. The
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`input device 106 is shown as a keyboard, but may similarly
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`take many alternative forms such as a button, a mouse, a
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`keypad, a dial, a motion sensor, a camera, a microphone or
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`other means for receiving information from a user. Both the
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`display 104 andthe input device 106 may beintegrated into
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`The chassis 102 may comprise a processor, memory, and
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`information storage devices which are coupled to a printed
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`circuit board (“PCB”) 108. PCB 108 provides a base for
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`interconnecting semiconductor components,
`input/output
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`connectors and/or other electronic components and may be
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`representative of a motherboard. At least some of the elec-
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`tronic components inside the electronic device 100 are
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`soldered to PCB 108. The chassis 102 may further comprise
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`a network interface (not shown) that allows the system 100
`to receive information via a wired or wireless network.
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`Although electronic device 100 is representative of a
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`desktop computer, alternative embodiments may vary with
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`respect to size, shape, computing capacity and/or features.
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`Examples of such electronic devices include, but are not
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`limited to,
`laptop computers, DVD players, CD players,
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`game systems, personal digital assistants (“PDAs”), cellular
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`phones, smart phones, GPS devices, user input devices
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`(mouse, keyboard)or other electronic devices having PCBs.
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`FIG.2 illustrates an exploded view of an exemplary PCB
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`subcomponent 200 of PCB 108 in accordance with embodi-
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`ments of the invention. PCB subcomponent 200 includes
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`conductive layer 210 and an insulating layer 220 surround-
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`ing conductive layer 210. Although a single conductive and
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`insulating layer is depicted for ease of discussion, it will be
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`appreciated that numerous layers are possible.
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`Conductive layer 210 is generally made of a metal with a
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`high electrical conductivity, such as copper (Cu) or tungsten
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`(W). These metallic conductive layers are used to provide
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`power and ground planes for PCB subcomponent 200, or
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`alternatively, they are patterned to form conductive paths,
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`For a detailed description of exemplary embodiments of
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`the invention, reference will now be made to the accompa-
`45
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`nying drawings in which:
`FIG.1 illustrates ah electronic device in accordance with
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`embodiments of the invention;
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`FIG. 2 illustrates an exploded view of an exemplary
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`printed circuit board layer in accordance with embodiments
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`of the invention;
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`FIG. 3 illustrates an exploded view of an exemplary
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`printed circuit board in accordance with embodiments of the
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`invention; and
`FIG.4 illustrates a method in accordance with embodi-
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`ments of the invention.
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`NOTATION AND NOMENCLATURE
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`55
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`50
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`Certain terms are used throughout the following descrip-
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`tion and claimsto refer to particular system components. As
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`one skilled in the art will appreciate, computer companies
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`mayrefer to a componentby different names. This document
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`does not
`intend to distinguish between components that
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`differ in name but not function. In the following discussion
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`and in the claims, the terms “including” and “comprising”
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`are used in an open-ended fashion, and thus should be
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`interpreted to mean “including, but not limited to... .” Also,
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`Page 7 of 9
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`US 9,820,374 B2
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`3
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`such as traces 202 and pads 205A-B, which enable signals
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`to flow from one point of PCB subcomponent 200 to
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`Trace 202 and pads 205A-B are organized or patterned
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`using various methods. For example, patterning occurs by
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`way of chemical vapor deposition (“CVD”), through a series
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`of etching steps, or by printing a layer of metallic ink using
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`an ink-jet printer.
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`Some pads couple to trace 202 while other pads do not.
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`For example, pad 205A couple to trace 202. Thus, pad 205A
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`couples the trace to which it
`is attached to additional
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`conductive layers.
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`Insulating layer 220 is preferably disposed about conduc-
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`tive layer 210 to surround trace 202 and pads 205A-B
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`preventing traces and pads from making contact with each
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`other. Insulating layers, such as insulating layer 220, are
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`generally made of a ceramic, such as alumina, or other
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`dielectric material, such as TEFLON® (by Du Pont), or
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`FR-4 (a glass epoxy resin widely used in PCB fabrication).
`20
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`Suitable vendors of FR-4 include Isola (formerly Polyclad),
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`Nelco, Arlon, Allied Signal, and Gore.
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`There are a variety of specific materials that may be used
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`to fabricate FR-4 insulating layer 220 in accordance with
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`various embodiments. For example, FR-408 is a high-
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`performance FR-4 epoxy resin used for advanced circuitry
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`applications. FR-408 has a low dielectric constant (approxi-
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`mately 3.65) and a low dissipation factor (approximately
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`0.012) making it an ideal material for circuit designs requir-
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`ing faster signal speeds or improvedsignal integrity. Another
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`variety of FR-4 is Polyclad 370HR. Polyclad 370HR has a
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`low dielectric constant (approximately 4.04), similar to
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`FR-408’s dielectric constant; however, Polyclad 370 HR has
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`a dissipation factor (approximately 0.021) which is higher
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`than FR-408’s dissipation factor. Thus, Polyclad 370HR is
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`inferior to FR-408 for circuit designs requiring fast signal
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`speeds. However, Polyclad 370HR is significantly less
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`expensive than FR-408 and is a satisfactory material for
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`fabricating insulating layer 220 for circuit designs contain-
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`ing powerplanes or designs requiring slowersignals. It will
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`be understood by those skilled in the art that other FR-4
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`materials may be used to make up insulating layer 220 as
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`well, such as Polyclad 250HR, Polyclad 254, FR-402,
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`FR-406, IS 400 and others.
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`FIG. 3 illustrates an exploded view of exemplary PCB
`45
`108 in accordance with embodiments of the invention. PCB
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`108 comprises PCB subcomponents 200, 310, 320, and 330
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`bonded together. Although four PCB subcomponents are
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`shown in FIG. 3, PCB 108 may contain more or less PCB
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`subcomponents. As explained above, PCB subcomponent
`50
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`200 contains an insulating layer 220 and conductive layer
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`210 used to provide power and groundplanes for PCB 108,
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`or alternatively, conductive layer 210 is patterned to form
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`conductive paths which enable signals to flow from one
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`point of PCB 108 to another. Conductive layer 210 is
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`surrounded by insulating material on all sides,
`including
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`above and below. PCB subcomponents 310, 320, and 330
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`also contain insulating layers 340, 350, and 360 and con-
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`ductive layers 315, 325, and 335 in a similar manner as PCB
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`subcomponent 200. PCB subcomponents 310, 320, and 330
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`have conductive layers 315, 325, and 335 capable of being
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`used to provide power and ground planes for PCB 108, or
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`alternatively, patterned to form conductive paths which
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`enable signals to flow from one point of PCB 108 to another.
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`In some embodiments, two different materials comprise
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`the insulating layers (e.g., insulating layer 220 from FIG. 2
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`and insulating layers 340, 350, and 360 from FIG. 3) of PCB
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`108. However, each insulating layer 220, 340, 350, and 360
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`4
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`of each PCB subcomponent 200, 310, 320, and 330 may
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`comprise only one material. For example, insulating layer
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`220 of PCB subcomponent 200 may comprise FR-408,
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`while insulating layer 340 of PCB subcomponent 310 may
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`comprise Polyclad 370HR. Thus, PCB 108 is a hybrid PCB
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`(comprised of more than one material).
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`Asstated above, it is preferable that a material with a low
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`dielectric constant and a low dissipation factor, such as
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`FR-408, comprise the insulating layer (e.g., insulating layer
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`220 from FIG. 2 and insulating layers 340, 350, and 360
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`from FIG. 3) of any PCB subcomponent 220, 310, 320, or
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`330 which is designed to require fast signal speeds or
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`improved signal integrity. Other insulating layers 220, 340,
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`350, or 360 of PCB 108 may be comprised of a lower cost
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`material, such as Polyclad 370HR,so long as the lower cost
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`material has a dielectric constant similar to the highercost,
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`low dielectric constant, low dissipation factor material. If the
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`two materials have a significantly different dielectric con-
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`stant, the embodimentandelectrical advantages remain the
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`same; however, more care is needed to tune the vertical
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`connectivity because of the changesin electrical impedance
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`due to the change in materials. These practices are well
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`known to those skilled in the art, or could be extrapolated
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`from current techniques. Thus, PCB 108 is less expensive to
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`produce than a PCB manufactured entirely of a low dielec-
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`tric constant,
`low dissipation factor material,
`such as
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`FR-408. Thus, made from a combination of FR-408 and
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`Polyclad 370HR, PCB 108 provides increased performance,
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`especially for the critical high-speed signal layers, than if
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`manufactured entirely out of a lower cost, low dielectric,
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`high dissipation factor material, such as Polyclad 370HR.
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`FIG.4 illustrates an exemplary flow diagram of a method
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`400 implemented in accordance with embodiments of the
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`invention. The method begins in block 402 with the manu-
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`facture of a first PCB subcomponent(e.g., PCB subcompo-
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`nent 200 from FIG. 2) with ah insulating layer 220 com-
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`posed of a material with a low dielectric constant and a low
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`dissipation factor, such as FR-408. In block 404, a second
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`PCB subcomponent (e.g., PCB subcomponent 310 from
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`FIG. 3) is manufactured with an insulating layer 340 com-
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`posed of a material with a similar dielectric constant as that
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`of the first insulating layer 220’s material, yet a higher
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`dissipation factor than thefirst insulating layer 220’s mate-
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`rial, such as Polyclad 370HR. In block 406, a third PCB
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`subcomponent (e.g., PCB subcomponent 320 from FIG. 3)
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`is manufactured using the same material as insulating layer
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`220 (e.g., FR-408) for insulating layer 350. The method
`continues with the manufacture of a fourth PCB subcom-
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`ponent(e.g., PCB subcomponent330 from FIG.3) using the
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`same material for insulating layer 360 as used in the manu-
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`facture of insulating layer 340 (e.g., Polyclad 370HR).
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`As stated above, the PCB subcomponents 200 and 320
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`comprising insulating layers 220 and 350 madefrom the low
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`dielectric constant,
`low dissipation factor material (e.g.,
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`FR-408) are designed for high speed signals. However, the
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`PCB subcomponents 310 and 330 comprising insulating
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`layers 340 and 360 made from the low dielectric constant,
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`high dissipation factor material (e.g., Polyclad 370HR) are
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`designed for power and groundplanes as well as for slow
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`speed signals. In block 406, the PCB subcomponents manu-
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`factured in blocks 402, 404, 406, and 408 are bonded
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`together to make PCB 108.
`The above discussion is meant to be illustrative of the
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`principles and various embodiments of the present inven-
`tion. Numerous variations and modifications will become
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`apparentto those skilled in the art once the above disclosure
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`

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`US 9,820,374 B2
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`5
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`is fully appreciated. It is intended that the following claims
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`be interpreted to embrace all such variations and modifica-
`tions.
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`6
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`9. The apparatus of claim 1, further comprising:
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`a processor mounted to the PCB.
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`10. A system comprising:
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`a first printed circuit board (‘PCB’) subcomponent com-
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`prising a first insulating layer and a first conducting
`Whatis claimed is:
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`layer; and
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`1. An apparatus, comprising:
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`a second PCB subcomponent comprising a second insu-
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`a printed circuit board (“PCB”) comprising a first insu-
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`lating layer and a second conducting layer;
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`lating layer and a secondinsulating layer,
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`wherein the first insulating layer is made fromafirst
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`wherein the first insulating layer is made of a first
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`10
`material and the second insulating layer is made
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`material and the secondinsulating layer is made of a
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`from a second material;
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`second material;
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`whereinthefirst material has a lowerdissipation factor
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`whereinthefirst material has a lowerdissipation factor
`than the second material; and
`wherein the first material and second material have
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`than the second material; and
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`wherein the first material and second material have
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`substantially similar dielectric constants.
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`substantially similar dielectric constants.
`11. The system of claim 10, wherein thefirst material is
`FR-408.
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`2. The apparatus of claim 1, wherein the first material is
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`FR-408.
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`12. The system of claim 10, wherein the second material
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`is Polyclad 370HR.
`3. The apparatus of claim 1, wherein the second material
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`13. The system of claim 10, further comprising a third
`is Polyclad 370HR.
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`PCB subcomponent comprising a third insulating layer and
`4. The apparatus of claim 1, wherein the PCB further
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`a third conducting layer,
`comprises a third insulating layer,
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`wherein the third insulating layer is made of the first
`wherein the third insulating layer is made of the first
`material.
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`material.
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`14. The system of claim 13, further comprising a fourth
`5. The apparatus of claim 4, wherein the PCB further
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`PCB subcomponent comprising a fourth insulating layer and
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`comprises a fourth insulating layer,
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`a fourth conducting layer,
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`wherein the fourth insulating layer is made of the second
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`wherein the fourth insulating layer is made of the second
`material.
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`material.
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`6. The apparatus of claim 1, wherein the first insulating
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`15. The system of claim 10, wherein the first conducting
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`layer contains a conductive layer that carries high speed
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`layer carries high speed signals.
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`signals.
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`16. The system of claim 10, wherein the second conduct-
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`7. The apparatus of claim 1, wherein the second insulating
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`ing layer comprises one or more poweror ground planes.
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`layer comprises one or more poweror groundplanes.
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`17. The system of claim 10, wherein the second conduct-
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`8. The apparatus of claim 1, wherein the second insulating
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`ing layer carries low speedsignals.
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`layer contains a conductive layer that carries low speed
`*
`*
`*
`*
`*
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`signals.
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`20
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`25
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`30
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`Page 9 of 9
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`Page 9 of 9
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