DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1, 3-5, 10-15, and 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 20200098661 (Lofgreen et al) in view of US 20070238282 (Furman et al).
Concerning claim 1, Lofgreen discloses a method, comprising (Figs. 7A-7C): forming an assembly comprising multiple solid metal thermal interface materials (TIMs) (712 +770) between a first device (720) and a second device (710) placing a first solid metal TIM (770) of the solid metal TIMs, separate from the first device and the second device ([0058]), between the first device and the second device (Fig. 7A); and placing a second solid metal TIM (712)of the solid metal TIMs, separate from the first device and the second device, ([0058]) in touching relation with the first solid metal TIM between the first device and the second device ([0058]), wherein the first solid metal TIM has a first solidus temperature ([0063]-[0064]), the second solid metal TIM has a second solidus temperature above the first solidus temperature ([0063]-[0064]) a first surface of the solid metal TIMs is in touching relation with a surface of the first device (Fig. 7B), and a second surface of the solid metal TIMs opposite the first surface is in touching relation with a surface of the second device (Fig. 7C); and forming a liquid TIM alloy (740) from the solid metal TIMs by heating the assembly above the first solidus temperature . . ., wherein the liquid TIM alloy has a third solidus temperature below the first solidus temperature ([0063]-[0064]).
Lofgreen does not disclose heating the assembly above the first solidus temperature such that the first solid metal TIM becomes a first liquid met al TIM and fully dissolving the second solid metal TIM in the first liquid metal TIM. However, Furman discloses a liquid thermal interface material (102) for use in chip cooling (Figs. 1-3). Furman discloses that the thermal interface material is formed such that a first solid metal TIM (204a) of the solid metal TIMs, a second solid metal TIM (204b) of the solid metal TIMs, separate from the first device and the second device, in touching relation with the first solid metal TIM between the first device (104) and the second device (106) with a third solid metal TIM (200) between the first and second device. The first and second TIM are chosen to be at least partially formed of a small quantity of material that optionally dissolves partially or completely in the constituents of the liquid metal layer 200 (e.g., gallium, indium and tin) to permit a direct, robust metal bond between the liquid metal layer ([0022]). The thermal interface is assembled in a manner that substantially prevents reactions between materials in the liquid metal and materials in the IC chip and/or heat sink, as well as achieves sufficient wetting of the IC chip and heat sink surfaces. Thus, the thermal interface of the present invention makes deployment of the liquid metal a practical interface solution. Moreover, the present invention provides a simple, cost-effective method of deploying the liquid metal thermal interface between an IC chip and a heat sink (or between any two surfaces requiring good thermal contact). ([0039]). Therefore it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the multiple solid metal thermal interface materials of Lofgreen in order to incorporate the configuration of Furman such that the first solid metal TIM becomes a first liquid metal TIM and fully dissolving the second solid metal TIM in the first liquid metal TIM in order to prevent reactions between materials in the liquid metal and materials in the IC chip and/or heat sink.
Continuing to claim 3, Lofgreen in view of Furman discloses wherein forming the assembly further comprises placing a third solid metal TIM (Furman 200) separate from the first device and the second device, in touching relation with the first solid metal TIM or the second solid metal TIME between the first device and the second device, the third solid metal TIM having a fourth solidus temperature above the first solidus temperature of the first solid metal TIM; forming the liquid TIM alloy further comprises fully dissolving the third metal TIM in the first liquid metal TIM, wherein the third solidus temperature of the liquid TIM alloy is lower than a solidus temperature of a liquid TIM alloy that would be formed by fully dissolving only the second solid metal TIM in the first liquid metal TIM (Furman [0022]).
Considering claim 4, Lofgreen in view of Furman discloses wherein forming the assembly further comprises placing a third solid metal TIM (Furman 200) separate from the first device and the second device, a third solid metal TIM including a first metal that is not soluble in the liquid TIM alloy, the first metal controlling a bond line thickness of the assemble after the liquid TIM alloy is formed (Furman [0022]-[0024]).
Referring to claim 5, Lofgreen in view of Furman discloses the third solid metal TIM further includes a second metal that coats the first metal; and forming the liquid TIM alloy comprises further dissolving the second metal in the first liquid metal TIM (Furman Fig. 2 and [0022]-[0024]).
Pertaining to claim 10, Lofgreen discloses wherein the liquid TIM alloy comprises Ga and at least one of In, Sn, Zn, Bi, Au, Ag, Cu, W, Ni, Cr, Mo, Ti, Cd, or Pb (Furman ([0038]-[0039]).
As to claim 11, Lofgreen discloses wherein the first solid metal TIM comprises gallium or a gallium alloy (Lofgreen [0063] and Furman ([0022]).
Concerning claim 12, Lofgreen discloses wherein the second solid metal TIM comprises indium or an indium alloy (Lofgreen [0063] and Furman ([0022]).
According to claim 13, Lofgreen in view of Furman discloses wherein: the multiple solid metal TIMs comprise a third solid metal TIM comprising tin or a tin alloy; and the liquid TIM alloy comprises gallium, indium, and tin (Furman [0022] and [0038]).
Continuing to claim 14, Lofgreen discloses wherein the first device is a heat generating device, and the second device is a heat transferring device (Lofgreen [0057], note that the die is a heat generating device and the HIS is an integrated heat spreader).
Regarding claim 15, Lofgreen in view of Furman discloses the heat generating device is a. . . . heat transferring die (720), and the heat transferring device is a semiconductor package lid or heat sink (710).
Lofgreen does not disclose the die is a semiconductor die. However, Furman discloses an integrated circuit package (Figs. 1-3) in which a heat generating device (104, semiconductor die [0014]) is assembled to a heat transferring device (106, heat sink [0015]) by way of a liquid TIM composition that includes gallium, indium, and tin ([0038]). The selection of a known material based on its suitability for its intended use supported a prima facie obviousness determination in Sinclair & Carroll Co. v. Interchemical Corp., 325 U.S. 327, 65 USPQ 297 (1945). See MPEP 2144.07. It would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to form the heat generating device of a semiconductor material because it is a known material in the art that is suitable for integrated circuit packages
Regarding claim 20, Lofgreen discloses a liquid thermal interface material (TIM) alloy formed by a process (Figs. 7A-7C), the process comprising: forming an assembly comprising multiple solid metal thermal interface materials (TIMs) (712 +740) between a first device (720) and a second device (710) by placing a first solid metal TIM (770) of the solid metal TIMs, separate from the first device and the second device ([0058]), between the first device and the second device (Fig. 7A); and placing a second solid metal TIM (712)of the solid metal TIMs, separate from the first device and the second device, ([0058]) in touching relation with the first solid metal TIM between the first device and the second device ([0058]), wherein the first solid metal TIM has a first solidus temperature ([0063]-[0064]), the second solid metal TIM has a second solidus temperature above the first solidus temperature ([0063]-[0064]) a first surface of the solid metal TIMs is in touching relation with a surface of the first device (Fig. 7B), and a second surface of the solid metal TIMs opposite the first surface is in touching relation with a surface of the second device (Fig. 7C); and forming a liquid TIM alloy (740) from the solid metal TIMs by heating the assembly above the first solidus temperature . . ., wherein the liquid TIM alloy has a third solidus temperature below the first solidus temperature ([0063]-[0064]).
Lofgreen does not disclose heating the assembly above the first solidus temperature such that the first solid metal TIM becomes a first liquid metal TIM and fully dissolving the second solid metal TIM in the first liquid metal TIM. However, Furman discloses a liquid thermal interface material (102) for use in chip cooling (Figs. 1-3). Furman discloses that the thermal interface material is formed such that a first solid metal TIM (204a) of the solid metal TIMs, a second solid metal TIM (204b) of the solid metal TIMs, separate from the first device and the second device, in touching relation with the first solid metal TIM between the first device (104) and the second device (106) with a third solid metal TIM (200) between the first and second device. The first and second TIM are chosen to be at least partially formed of a small quantity of material that optionally dissolves partially or completely in the constituents of the liquid metal layer 200 (e.g., gallium, indium and tin) to permit a direct, robust metal bond between the liquid metal layer ([0022]). The thermal interface is assembled in a manner that substantially prevents reactions between materials in the liquid metal and materials in the IC chip and/or heat sink, as well as achieves sufficient wetting of the IC chip and heat sink surfaces. Thus, the thermal interface of the present invention makes deployment of the liquid metal a practical interface solution. Moreover, the present invention provides a simple, cost-effective method of deploying the liquid metal thermal interface between an IC chip and a heat sink (or between any two surfaces requiring good thermal contact). ([0039]). Therefore it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the multiple solid metal thermal interface materials of Lofgreen in order to incorporate the configuration of Furman such that the first solid metal TIM becomes a first liquid metal TIM and fully dissolving the second solid metal TIM in the first liquid metal TIM in order to prevent reactions between materials in the liquid metal and materials in the IC chip and/or heat sink.
Claim(s) 16-18 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 20200098661 (Lofgreen et al) in view of US 20070238282 (Furman et al) as applied to claim 1 above and further in view of US 20230413480 (Pokharna et al).
Continuing to claim 16, Lofgreen in view of Furman discloses heating the assembly above the first solidus temperature such that the first solid metal TIM becomes the first liquid metal TIM (Furman [0022] and [0038]))
Lofgreen in view of Furman does not disclose the process comprises: activating the heat generating device to heat the assembly above the first solidus temperature such that the first solid metal TIM becomes the first liquid metal TIM. However, Pokharna discloses the use of a thermal interface material (TIM) (130) used between two devices (120 IHS and 110 integrated die, Fig. 2, [0035]) that includes an additional solid metal TIM ([0049] nickel layer formed) and having a solidus temperature higher than the first solidus temperature of the first solid metal TIM; and forming the assembly comprises: placing the third solid metal between the first device and the second device (Fig. 2, [0045], and [0058]). Pokharna discloses that the liquid TIM being formed during operation of the heat generating device ([0038]) or by another heating operation ([0053]), and that the disclosed thermal-interface materials can be more forgiving during manufacturing and assembly than prior, conventional thermal-interface materials by providing lower thermal-resistance across a non-uniform solid- solid interface than a conventional paste, grease or foil provides, even with a relatively more uniform solid-solid interface ([0011]). Therefore it would have been obvious to one of ordinary skill in the art before the effective filing date of the invention to modify the multiple solid metal thermal interface material formation process such that the assembly is heated above the first solidus temperature such that the first solid metal TIM becomes the first liquid metal TIM by activating the heat generating device to heat the assembly above the first solidus temperature such that the first solid metal TIM becomes the first liquid metal TIM in order to achieve the aforementioned advantages of Pokharna.
Considering claim 17, Lofgreen in view of Pokharna discloses wherein: the method further comprises: deactivating the heat generating device; and the liquid TIM alloy remains in a liquid state after deactivation of the heat generating device (Pokharna [0038] and [0045]).
Regarding claim 18, Lofgreen in view of Pokharna discloses wherein the liquid TIM alloy has a solidus temperature below 20°C (Lofgreen [0040]).
Claim(s) 22-28 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 20200098661 (Lofgreen et al) in view of US 20070238282 (Furman et al) as applied to claim 1 above and further in view of US 20200203254 (Dhane et al)
Referring to claims 22-28, Lofgreen in view of Furman discloses forming the liquid TIM alloy comprising indium, gallium, and tin (Furman [0038]) and the first solid metal TIM consist of gallium (Lofgreen [0058]).
Lofgreen in view of Furman does not disclose wherein the liquid TIM alloy consists of an indium-rich non-eutectic alloy of gallium and indium, wherein the liquid TIM alloy consists of gallium and indium with a 3:1 ratio of gallium to indium, wherein the liquid TIM alloy consists of an indium-rich non-eutectic alloy of gallium, indium, and tin, wherein the liquid TIM alloy has a stoichiometry of 65.5Ga20.5In13.OSn, or wherein the liquid TIM alloy remains in a liquid state at room temperature. However, Dhane discloses a liquid thermal interface material that is suitable for use in electronic packaging “Galinstan” which is comprised of gallium, indium, and tin with an alloy that is from 62 weight (wt.) % to 95 wt. % gallium, 5 wt. % to 22 wt. % indium, and 0 wt. % to 16 wt. % indium, with the sum of weight percentages totaling 100 wt. % and melting from solid to pure liquid from 11° C. to −19° C ([0031]-[0034]). Dhane discloses that such liquid phase TIM can be sealed in a chamber between a die and an integrated heat spreader and bounded on the sides by a perimeter layer. The liquid phase TIM can be fixed in place or circulated, depending on application. The liquid phase TIM eliminates failure mechanisms present in solid phase TIMs, such as cracking due to warpage and uncontained flow out of the module (Abstract). Therefore it would have been obvious to one of ordinary skill in the art to modify the liquid TIM alloy such that consists of an indium-rich non-eutectic alloy of gallium and indium, wherein the liquid TIM alloy consists of gallium and indium with a 3:1 ratio of gallium to indium, wherein the liquid TIM alloy consists of an indium-rich non-eutectic alloy of gallium, indium, and tin, wherein the liquid TIM alloy has a stoichiometry of 65.5Ga20.5In13.OSn, and the liquid TIM alloy remains in a liquid state at room temperature in order to produce a liquid alloy TIM such as produced by Dhane that eliminates failure mechanisms present in solid phase TIMs, such as cracking due to warpage and uncontained flow out of the module.
Response to Arguments
Applicant’s arguments, see pages 7-9, filed 07/10/26, with respect to the rejection(s) of claim(s) 1 and 20 under 102 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground(s) of rejection is made in view of US 20070238282 (Furman et al).
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. US 20030112603 discloses the formation of a multi-layer TIM used between two devices (Abstract).
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to VALERIE N NEWTON whose telephone number is (571)270-5015. The examiner can normally be reached M-F 8-5.
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/VALERIE N NEWTON/Examiner, Art Unit 2897 09/16/26
/CHAD M DICKE/Supervisory Patent Examiner, Art Unit 2897
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