JP2017172871A - Process of manufacture of vapor chamber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process of manufacture of a vapor chamber in which a softening of a casing even after elapsing a connecting step or a deformation caused by creep is hardly produced and both a sufficient strength and a heat transferring performance can be attained and to prevent an excessive bulky formation of crystalline particle from being produced even after passing the connecting step.SOLUTION: A process of manufacture of a vapor chamber in which after assembling the vapor chamber with several components, the components are connected through a process for heating it by more than 650°C where components 2, 3 are made of precipitation hardening type copper alloy, the precipitation hardening type copper alloy is applied with aging treatment to attain precipitation hardening without adding applying plastic working to a casing of the vapor chamber after connection.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a vapor chamber (flat plate heat pipe) by joining a plurality of components.

CPUs installed in desk-type PCs, notebook PCs, tablet terminals, mobile phones represented by smartphones, etc. are rapidly increasing in operating speed and density, and heat generated from these CPUs per unit area The amount has increased further. When the temperature of the CPU rises above a certain level, it causes malfunctions, thermal runaway, etc., so effective heat dissipation from a semiconductor device such as a CPU is a serious problem.
A heat sink is used as a heat dissipating component that absorbs heat from a semiconductor device and dissipates it into the atmosphere. Since the heat sink is required to have high thermal conductivity, copper, aluminum, or the like having a high thermal conductivity is used as a material. In the desk type PC, a method is used in which the heat of the CPU is transmitted to a heat radiating fin or the like installed on a heat sink and the heat is removed by a small fan installed in the desk type PC casing.

  However, in notebook PCs, tablet terminals, etc. that do not have space for installing fans, vapor chambers (flat plate heat pipes) have come to be used as heat dissipating parts that have a higher heat transport capacity in a limited area. It was. The heat pipe exhibits higher heat dissipation characteristics than the heat sink by cyclically performing evaporation (heat absorption from the CPU) and condensation (release of absorbed heat) of the refrigerant sealed inside. It has also been proposed to solve the heat generation problem of semiconductor devices by combining heat pipes with heat radiating components such as heat sinks and fans.

The vapor chamber further improves the heat dissipation performance of the tubular heat pipe (see Patent Documents 1 to 4). In order to efficiently condense and evaporate the refrigerant, a vapor chamber has been proposed in which fine holes are formed on the inner surface by roughening, grooving, or powder sintering, similar to a tubular heat pipe. .
In addition, a vapor chamber has been proposed that includes an external member (housing) and an internal member that is housed and fixed inside the external member. One or a plurality of internal members are arranged inside the external member in order to promote condensation, evaporation, and transport of the refrigerant, and fins, protrusions, holes, slits, and the like having various shapes are processed. A vapor chamber of this type is manufactured by arranging an internal member inside the external member and then joining and integrating the external members and the external member and the internal member by a method such as brazing or diffusion bonding. The vapor chamber is sealed by a method such as brazing after the refrigerant is put inside.

About the manufacturing method of the vapor champ, a plurality of grooves, irregularities and the like are formed on one side of the rectangular upper plate member and lower plate member, and the upper plate member and lower plate member are joined with the pattern forming surface inside. An example of manufacturing a vapor chamber will be described in detail with reference to FIG. The upper plate member and the lower plate member are components constituting a casing of the vapor chamber, and the vapor chamber does not include an internal member.
(1) In general, pure copper-based strips such as oxygen-free copper and phosphorus-deoxidized copper are used as the material for the housing of the vapor chamber. A plurality of patterns such as grooves and irregularities are formed on one side of a rectangular plate (upper plate member and lower plate member) cut out from a pure copper strip. FIG. 1A shows an upper plate member 2 (or lower plate member 3) on which a pattern 1 (shaded portion) is formed.

(2) As a means for forming the pattern 1, an etching process or a press process using a mold is used. In the case of the etching process, only the portion of the upper plate member 2 and / or the lower plate member 3 that is to be etched is exposed, and the copper of the portion to be etched is dissolved with an etchant containing a ferric chloride solution, and a predetermined pattern is formed. Form. In the case of press working, the surface property of the mold is transferred to one surface of the upper plate member 2 and / or the lower plate member 3 to form a pattern with a predetermined shape.

(3) With the pattern formation surface of the upper plate member 2 and / or the lower plate member 3 facing inward, the upper plate member 2 and the lower plate member 3 are overlapped (FIG. 1B) and joined in that state. This bonding is performed by diffusion bonding or brazing. A nozzle (small diameter tube) 4 is fitted between the upper plate member 2 and the lower plate member 3, and the nozzle 4 is also joined.

(4) In the case of diffusion bonding, as shown in FIG. 1C, a pressure of several N is applied between the upper plate member 2 and the lower plate member 3 to pressurize them (see white arrows), and in a vacuum or an inert atmosphere Usually, it is heated to a temperature of 800 ° C. or higher and held at that temperature for 30 minutes or longer. For this reason, dimensional change occurs due to softening of the material, coarsening of crystal grains, creep deformation due to pressurization, and the like. In anticipation of strength reduction and dimensional change of this material, it is necessary to set the plate thickness before diffusion bonding (both in the portion where the pattern 1 is formed and in other portions). In diffusion bonding, Cu atoms are solid-phase diffused between members, and the members (upper plate member 2, lower plate member 3, and nozzle 4) are integrated.

(5) In the case of joining by brazing, heating is performed in a reducing atmosphere or a non-oxidizing atmosphere, and brazing is performed using silver brazing (BAg), phosphor copper brazing (BCuP), or the like. Usually, the brazing point is heated to 650 ° C. or more when silver brazing is used, and to 750 ° C. or more when using phosphor copper brazing. As brazing method, insert brazing (a kind of hand brazing) or place brazing (a kind of brazing in a furnace) is applied. Need to control the brazing atmosphere. In the case of hand brazing, the time for heating to a high temperature is short, but the vapor chamber has a small mass and good thermal conductivity, so that the whole temperature rises to the brazing temperature and softens. In the case of brazing in the furnace, although it is advantageous for controlling the atmosphere, the time during which the vapor chamber is kept at a high temperature is increased, and the degree of softening of the entire material is greater than that of hand brazing.
(6) After manufacturing the vapor chamber (after joining), in a vacuum or reduced pressure atmosphere, a working fluid (water or the like) is put into the vapor chamber through the nozzle 4 to seal the nozzle 4.

Japanese Patent Laid-Open No. 2004-238672 JP 2007-315745 A JP 2014-134347 A JP-A-2015-121355

  In the manufacture (bonding) of the vapor chamber, the components constituting the vapor chamber are heated to a temperature of 650 ° C. or more at least, so that they are easily softened when made of a pure copper material having low heat resistance. When the components (the upper plate member 2 and the lower plate member 3 in the previous example) constituting the vapor chamber casing are softened, the vapor chamber is easily deformed when transported, handled, or attached to a semiconductor device. In that case, the shape and dimensions of the pattern formed inside the vapor chamber changes, or a gap is created between the vapor chamber and the semiconductor device due to the indentation, etc., and the desired heat transfer performance is demonstrated. become unable.

Further, in the diffusion bonding process, the housing of the vapor chamber is deformed by the applied pressure applied to the bonded portion. Specifically, as shown in FIGS. 2A and 2B, the joint portion between the upper plate member 2 and the lower plate member 3 is creep-deformed by the applied pressure (see the white arrow), and the thickness is reduced (t _s → t _f ) Moreover, since the upper plate member 2 and the lower plate member 3 expand by heating and try to extend in the left-right direction, while the joint portion is restrained from moving in the left-right direction by the applied pressure, the upper plate member 2 and the lower plate member 3 The thin part of the member 3 will bend inward. As a result, the dimensional accuracy of the vapor chamber also decreases, and the above problem due to softening becomes more serious.

  In addition, pure copper-based materials tend to coarsen the crystal grains when heated to a temperature of 650 ° C. or higher, and the coarsening of the crystal grains may progress as the plate thickness is penetrated (the crystal grain size is larger than the plate thickness). . In such a case, intergranular cracking occurs due to the fatigue phenomenon caused by internal pressure fluctuations (stress is applied to the housing) that is repeatedly caused by evaporation and condensation when the solder chamber is used, or when the vapor chamber is used. It has been pointed out that corrosion resistance decreases at the grain boundaries.

  The present invention solves the above-mentioned problems in manufacturing a vapor chamber, and is less likely to undergo dimensional changes due to softening or creep deformation of the casing even after the joining process, and has sufficient strength and heat transfer performance. The main object is to provide a method for manufacturing a vapor chamber. Another object is to prevent excessive coarsening of crystal grains in the housing even after the joining process.

The method of manufacturing a vapor chamber according to the present invention includes a method of manufacturing a vapor chamber by assembling a vapor chamber with a plurality of components and then joining the components through a process of heating to 650 ° C. or higher. The components constituting the vapor chamber casing are made of a precipitation hardening type copper alloy, and the precipitation hardening type copper alloy is subjected to precipitation hardening by subjecting the precipitation hardening type copper alloy to aging treatment without applying plastic working to the vapor chamber casing after joining. Features. In the present invention, there are cases where the component is composed of only components constituting the casing of the vapor chamber and other components (the internal member).
As precipitation hardening type copper alloys, known Cu-Ni-Si, Cu-Fe-P, Cu-Fe-Ni-P, Cu-Cr, and Cu-Cr-Zr-based coppers are known per se. An alloy is mentioned.

According to the present invention, by using a precipitation hardening type copper alloy as a casing material, the dimensional change due to softening or creep deformation of the casing even after the joining process, compared to a conventional vapor chamber using a pure copper-based material. Is unlikely to occur. In addition, the strength and electrical conductivity of the housing are decreasing immediately after the joining process, but the strength and electrical conductivity (thermal conductivity) of the housing are recovered (improved) by subsequently performing an aging treatment (precipitation hardening treatment). ) For this reason, it is possible to manufacture a vapor chamber having higher strength while suppressing a decrease in heat transfer performance, and further reducing the thickness of the material.
Further, according to the present invention, by using a precipitation hardening type copper alloy as a material of the casing, coarsening of crystal grains in the casing is suppressed as compared with a conventional vapor chamber using a pure copper-based material. For this reason, leakage resistance and corrosion resistance when using the vapor chamber are improved, and solder wettability is also improved.

The manufacturing method (joining method) of a vapor chamber is demonstrated, The perspective view (1A) of the housing components (upper board member or lower board member) in which pattern formation was carried out, the upper board member and lower board member which were piled up for joining It is sectional drawing (1B) of this, and sectional drawing (1C) at the time of the diffusion joining of a vapor chamber. The state of deformation of the upper plate member and the lower plate member at the time of diffusion bonding of the vapor chamber is described, and is a cross-sectional view (2A) at the start of diffusion bonding and a cross-sectional view (2B) at the end. It is a figure which shows the range of Fe and Sn content of a typical precipitation hardening type copper alloy.

Hereinafter, the manufacturing method of the vapor chamber which concerns on this invention is demonstrated in detail.
As preferable precipitation hardening type copper alloys applied to the casing of the vapor chamber, known Cu—Fe—P, Cu— (Ni, Co) —Si, Cu— (Ni, Co) —P, known per se, Cu-Cr-based and Cu-Cr-Zr-based copper alloys are exemplified. These precipitation hardening type copper alloys have a softening degree smaller than that of the conventional pure copper under high temperature heating (vapor chamber joining process), and the coarsening of the crystal grains after the high temperature heating is also higher than that of the conventional pure copper. It is suppressed in comparison. In addition, these precipitation hardened copper alloys recover (improve) strength and conductivity even when subjected to aging treatment without adding plastic working after high-temperature heating (without introducing plastic strain as a precipitation site into the material). ) The casing of the vapor chamber is not subjected to plastic working after the joining process, but by using these precipitation-hardening type copper alloys, high strength (50 MPa or more) after aging treatment can be achieved without adding plastic working after the joining process. ) And conductivity (25% IACS or higher).

The aging treatment (precipitation hardening treatment) after the joining step (after high-temperature heating) can be performed, for example, by the following method. The conditions for aging treatment (precipitation temperature range, holding time) will be described later for each alloy system.
(1) After the vapor chamber after bonding is cooled, the entire vapor chamber is reheated to the precipitation temperature range of the precipitation hardening type copper alloy, and is kept in the same temperature range for a certain period of time for precipitation hardening. In this case, the vapor chamber after bonding is rapidly cooled by water cooling or the like while it is still at a high temperature, or the vapor chamber after bonding is reheated to the solution temperature and then rapidly cooled to preliminarily precipitate the precipitation hardening type copper alloy. It is preferable.
(2) The vapor chamber after joining is kept in the precipitation temperature range for a certain time during cooling from a high temperature to precipitate and harden the precipitation hardening type copper alloy. The vapor chamber may be maintained at a constant temperature within the precipitation temperature range or may continue to be cooled within the precipitation temperature range.
(3) After the step (2), the reheating of (1) is further performed to precipitate and harden the precipitation hardening type copper alloy.

Next, each alloy system will be described.
(Cu-Fe-P system)
(1) As an example of a Cu—Fe—P based copper alloy, a copper alloy containing Fe: 0.07 to 0.7 mass% and P: 0.2 mass% or less can be given. The basic composition of this copper alloy is composed of Cu and unavoidable impurities other than Fe and P, and contains alloy elements described later as required.
In the case of this copper alloy, by performing an aging treatment after high-temperature heating (vapor chamber joining step), the 0.2% proof stress value is 100 MPa or more, and the electrical conductivity is 50% IACS or more (when Sn is included as an alloy element, 45% IACS or higher). Moreover, the average crystal grain size after high-temperature heating (vapor chamber joining step) can be suppressed to 50 μm or less by setting the Fe content to 0.25 mass% or more. The aging treatment may be carried out under conditions of holding for 5 minutes to 10 hours in a temperature range of 350 to 600 ° C.

  In this copper alloy, Fe precipitates as a simple substance of Fe or as a Fe—P compound, and has an action of improving the strength and conductivity of the copper alloy sheet after aging treatment. Fe that does not precipitate as an Fe—P compound precipitates as a simple substance of Fe, and particularly when the Fe content is 0.4 mass% or more, the amount of Fe that precipitates as a simple substance of Fe increases. If the Fe content is less than 0.07% by mass, the 0.2% yield strength after high-temperature heating and aging treatment is insufficient, and if the Fe content exceeds 0.7% by mass, the conductivity after high-temperature heating and aging treatment Does not improve. Therefore, the Fe content is set to 0.07 to 0.7% by mass. The lower limit of the Fe content is preferably 0.15% by mass, and the upper limit is preferably 0.65% by mass.

P has an action of reducing the amount of oxygen contained in the copper alloy by a deoxidation action and preventing hydrogen embrittlement when the vapor chamber is heated in a reducing atmosphere containing hydrogen. The solid solution P is heated to the deposition temperature to form an Fe—P compound, thereby improving the strength, heat resistance, and conductivity of the copper alloy. In order to precipitate the Fe—P compound, the P content needs to be 0.005 mass% or more. However, if the P content exceeds 0.2% by mass, cracking occurs when the ingot is hot-rolled and subsequent processing becomes impossible, so the upper limit of the P content is 0.2% by mass. %.
Although the P content is required to some extent due to the above action, on the other hand, the P content that does not contribute to the precipitation of the Fe—P compound is preferably as small as possible within the range where hydrogen embrittlement can be prevented. From this point, the ratio [Fe] / [P] of the Fe content (% by mass) and the P content (% by mass) is preferably in the range of 2 to 5. The lower limit value of [Fe] / [P] is more preferably 2.5, still more preferably 3.0, and the upper limit value of [Fe] / [P] is more preferably 4.5, still more preferably 4. 0.

  The said copper alloy is the range which does not impair the electrical conductivity after high temperature heating and aging treatment of the 1 type (s) or 2 types or more of the alloy elements (or alloy element group) shown to the following (a)-(c) as needed. Included within. (A) Sn: 0.006 to 1.1 mass%, (b) Zn: 1.5 mass% or less, (c) Mn: 0.1 mass% or less, Mg: 0.2 mass% or less, Si: 0.2% by mass or less, Al: 0.2% by mass or less, Cr: 0.2% by mass or less, Ti: 0.1% by mass or less, Zr: one or more of 0.05% by mass or less Is 0.5% by mass or less in total.

  Sn has the effect | action which improves the intensity | strength of a copper alloy. When the copper alloy contains Sn, the Fe and Sn contents are point A (0.1, 0.006), point B (0.5, 0.006), point C (0.05) shown in FIG. 1.1) and within the range surrounded by the point D (0.05, 0.05) (including the boundary). In this case, the lower limit of the Fe content is preferably 0.07% by mass, more preferably 0.15% by mass. Moreover, the lower limit of the Sn content is preferably 0.01% by mass, more preferably 0.02% by mass, and the upper limit is preferably 0.5% by mass, more preferably 0.4% by mass.

  Zn has the effect | action which improves the solder heat-resistant peelability and Sn plating heat-resistant peelability of a copper alloy. However, if the Zn content exceeds 1.5% by mass, the solder wettability decreases and the electrical conductivity also decreases, so the Zn content is set to 1.5% by mass or less. The upper limit of the Zn content is preferably 0.7% by mass, and more preferably 0.5% by mass. On the other hand, in order to improve the heat-resistant peelability, the lower limit of the Zn content is preferably 0.01% by mass, more preferably 0.05% by mass, and even more preferably 0.1% by mass.

  Mn, Mg, Si, Al, Cr, Ti, and Zr have the effect of improving the strength and heat resistance of the copper alloy. Mn, Mg, Si, and Al reduce the electrical conductivity of the copper alloy even if contained in small amounts, so the upper limit values are Mn: 0.1% by mass, Mg: 0.2% by mass, and Si: 0.0. 2 mass%, Al: 0.2 mass%. Cr, Ti, Zr easily forms inclusions such as oxides and sulfides of several μm to several tens of μm, and a gap is formed between the inclusions and the base material by cold rolling. When it is present on the surface, it reduces the corrosion resistance of the copper alloy. Therefore, the upper limit values of Cr, Ti, and Zr are Cr: 0.2 mass%, Ti: 0.1 mass%, and Zr: 0.05 mass%. Moreover, when a plurality of types of elements among Mn, Mg, Si, Al, Cr, Ti, and Zr are contained in the copper alloy and the total content exceeds 0.5% by mass, the conductivity of the copper alloy decreases. . Therefore, the total content of these elements is 0.5% by mass or less. On the other hand, the lower limit of the total content of one or more of these elements is preferably 0.01% by mass, more preferably 0.02% by mass, and even more preferably 0.03% by mass.

  The copper alloy (strip) having the above composition is manufactured, for example, by hot rolling an ingot and then repeating cold rolling and heat treatment (aging treatment) once or twice or more. The copper alloy manufactured under the following conditions has a 0.2% proof stress of 150 MPa or more, an elongation of 5% or more, and excellent bending workability. Also, after high-temperature heating (850 ° C. × 30 minutes), it has a 0.2% proof stress of 40 MPa or more, and then, after aging treatment, a 0.2% proof stress of 100 MPa or more, 50% IACS or more (in the case where Sn is included) 45% IACS or more). Furthermore, coarsening of crystal grains due to high temperature heating (850 ° C. × 30 minutes) is suppressed, and the average crystal grain size after high temperature heating is suppressed to 50 μm or less.

Melting and casting can be performed by ordinary methods such as continuous casting and semi-continuous casting. In addition, it is preferable to use what has little content of S, Pb, Bi, Se, As as a copper melt | dissolution raw material. In addition, it is preferable to reduce O and H by paying attention to the red heat (moisture removal) of charcoal to be coated on the molten copper alloy, bare metal, scrap raw materials, firewood, mold drying, deoxidation of the molten metal, and the like.
The ingot is preferably homogenized, and the homogenization is preferably maintained for 30 minutes or more after the temperature inside the ingot reaches 800 ° C. The holding time of the homogenization treatment is more preferably 1 hour or more, and further preferably 2 hours or more.
After the homogenization treatment, hot rolling is started at a temperature of 800 ° C. or higher. In order to prevent coarse Fe or Fe-P precipitates from being formed on the hot-rolled material, the hot-rolling is preferably completed at a temperature of 600 ° C. or higher, and then rapidly cooled by a method such as water cooling. When the rapid cooling start temperature after hot rolling is lower than 600 ° C., coarse Fe—P precipitates are formed, the structure tends to be uneven, and the strength of the copper alloy plate (product plate) is lowered.

After hot rolling, (a) hot-rolled material is cold-rolled to product thickness and subjected to aging treatment, (b) hot-rolled material is subjected to cold-rolling and aging treatment, and further cold-rolled to product thickness. Or (c) Low temperature annealing (recovery of ductility) is performed after (b).
The aging treatment (precipitation treatment) is performed under the condition of holding at a heating temperature of about 300 to 600 ° C. for 0.5 to 10 hours. When the heating temperature is less than 300 ° C., the amount of precipitation is small, and when it exceeds 600 ° C., the precipitate tends to be coarsened. The lower limit of the heating temperature is preferably 350 ° C, and the upper limit is preferably 580 ° C. The holding time of the aging treatment is appropriately selected depending on the heating temperature, and is performed within a range of 0.5 to 10 hours. When the holding time is 0.5 hours or less, the precipitation is insufficient, and even if the holding time exceeds 10 hours, the amount of precipitation is saturated and the productivity is lowered. The lower limit of the holding time is preferably 1 hour, more preferably 2 hours.

(2) As another example of the Cu-Fe-P system, a copper alloy containing Fe: 1.0 to 2.4 mass% and P: 0.005 to 0.1 mass% or less can be given. The basic composition of this copper alloy is composed of Cu and unavoidable impurities other than Fe and P, and contains alloy elements described later as required.
In the case of this copper alloy, by performing an aging treatment after high-temperature heating (vapor chamber joining step), a 0.2% proof stress value of 110 MPa or more and a conductivity of 50% IACS or more can be achieved. Further, the average crystal grain size after high temperature heating (vapor chamber joining step) can be suppressed to 50 μm or less. The aging treatment may be carried out under conditions of holding for 5 minutes to 10 hours in a temperature range of 350 to 600 ° C.

  In this copper alloy, Fe forms a single element of Fe or a compound with P and precipitates, and has an effect of improving the strength and conductivity of the copper alloy sheet after aging treatment. However, if the Fe content is less than 1.0% by mass, the 0.2% yield strength after high-temperature heating and aging treatment is insufficient. On the other hand, if the Fe content exceeds 2.4% by mass, the strength improvement ratio after high-temperature heating and aging treatment is saturated, and coarse Fe crystallized material is formed in the melt casting process, and subsequent processing steps It is difficult to extinguish with. Coarse Fe crystallized products decrease corrosion resistance, bending workability, plating properties, and the like. Therefore, the Fe content is set to 1.0 to 2.4% by mass. The lower limit of the Fe content is preferably 1.2% by mass, and the upper limit is preferably 2.2% by mass.

  P has an action of reducing the amount of oxygen contained in the copper alloy by a deoxidation action and preventing hydrogen embrittlement when the heat dissipation component is heated in a reducing atmosphere containing hydrogen. The P content necessary for preventing hydrogen embrittlement is 0.005% by mass or more. Moreover, although solid solution P reduces the electrical conductivity of a copper alloy, it heats to precipitation temperature, forms a Fe-P compound, and, thereby, the intensity | strength of a copper alloy, heat resistance, and electrical conductivity improve. However, when the content of P exceeds 0.1% by mass, the amount of P that is dissolved is increased, and the electrical conductivity is lowered. For this reason, content of P shall be 0.005-0.1 mass%.

The said copper alloy is the range which does not impair the electrical conductivity after high temperature heating and aging treatment of the 1 type (s) or 2 types or more of the alloy elements (or alloy element group) shown to the following (a)-(c) as needed. Included within. (A) Zn: 2.0 mass% or less, (b) Sn: 0.005-0.5 mass%, (c) 1 of Mn, Mg, Si, Al, Cr, Ti, Zr, Ni, Co A total of 0.5% by mass or less of seeds or two or more kinds.
Zn is added as necessary for the same reason as Zn in the copper alloy described in (1) above. The upper limit of the Zn content is preferably 0.7% by mass, and more preferably 0.5% by mass. On the other hand, the lower limit of the Zn content is preferably 0.01% by mass, more preferably 0.05% by mass, and still more preferably 0.1% by mass.

  Sn has a function of improving the strength of the copper alloy by dissolving in the copper alloy matrix. Further, the addition of Sn is also effective in improving the stress relaxation resistance. When the usage environment of the vapor chamber reaches 80 ° C. or higher, creep deformation occurs in the housing, and the contact surface with a heat source such as a CPU becomes smaller, reducing heat dissipation, but improving stress relaxation characteristics. Therefore, this phenomenon can be suppressed. In order to obtain the effect of improving the strength and the stress relaxation resistance, the Sn content is set to 0.005% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and still more preferably 0.8%. It is set to 05 mass% or more. On the other hand, if the Sn content exceeds 0.5% by mass, the electrical conductivity of the copper alloy plate after high-temperature heating and aging treatment is lowered. Therefore, the Sn content is 0.5 mass% or less.

  Since Mn, Mg, Si, Al, Cr, Ti, Zr, Ni, and Co have an action of improving the strength and heat resistance of the copper alloy, one or more of these are added as necessary. . However, when the total content of one or more of these elements exceeds 0.5% by mass, the electrical conductivity decreases. The lower limit of the total content of one or more of these elements is preferably 0.01% by mass, more preferably 0.02% by mass, and even more preferably 0.03% by mass.

  The copper alloy (strip) having the above composition can be manufactured, for example, by the same manufacturing method as the copper alloy of (1). The copper alloy produced by this production method has a 0.2% proof stress of 150 MPa or more, an elongation of 5% or more, and excellent bending workability. Also, after high-temperature heating (850 ° C. × 30 minutes), it has a 0.2% proof stress of 40 MPa or more, and after aging treatment, it has a 0.2% proof stress of 110 MPa or more and a conductivity of 50% IACS or more. become. Moreover, the coarsening of the crystal grain by high temperature heating (850 degreeC x 30 minutes) is suppressed, and the average crystal grain size after high temperature heating is suppressed to 50 micrometers or less.

(Cu- (Ni, Co) -Si system)
As an example of a Cu- (Ni, Co) -Si-based copper alloy, one or two of Ni and Co are contained in an amount of 1.0 to 4.0% by mass, and Si is contained in an amount of 0.2 to 1.2% by mass. In addition, a copper alloy having a ratio [Ni + Co] / [Si] of the total content of Ni and Co to the content of Si in the range of 3.5 to 5 can be given. The basic composition of this copper alloy consists of Cu and unavoidable impurities other than Ni or / and Co and Si, and contains the alloy elements described later as required.
In the case of this copper alloy, by performing an aging treatment after high temperature heating (vapor chamber joining step), a 0.2% proof stress value of 300 MPa or more and a conductivity of 25% IACS or more can be achieved. The aging treatment may be carried out under conditions of holding for 5 minutes to 10 hours in a temperature range of 350 to 600 ° C.

In this copper alloy, Ni and Si generate Ni ₂ Si precipitates and improve the strength of the copper alloy. However, when the Ni content is less than 1.0 mass% or the Si content is less than 0.2 mass%, the effect is small. On the other hand, when Ni content exceeds 4.0 mass% or Si content exceeds 1.2 mass%, Ni or Si crystallizes or precipitates at the time of casting, and hot workability falls. Therefore, the Ni content is 1.0 to 4.0 mass%, and the Si content is 0.2 to 1.2 mass%. The lower limit of the Ni content is preferably 1.1% by mass, and the upper limit is preferably 3.9% by mass.
In this copper alloy, part or all of Ni can be replaced with Co.
In any case, when the ratio [Ni + Co] / [Si] of the total content of Ni and Co [Ni + Co] and the Si content [Si] is less than 3.5 or more than 5, the excess Ni (and / or Or Co) or Si is dissolved, and the electrical conductivity is lowered. Therefore, the content ratio [Ni + Co] / [Si] is set to 3.5 to 5.

  The said copper alloy is the range which does not impair the electrical conductivity after high temperature heating and aging treatment of the 1 type (s) or 2 types or more of the alloy elements (or alloy element group) shown to the following (a)-(c) as needed. Included within. (A) Sn: 0.005-1.0 mass% or / and Mg: 0.005-0.2 mass%, (b) Zn: 2.0 mass%, (c) Al, Mn, Cr, Ti , Zr, Fe, P, Ag, or a total of 0.5 or less by mass.

  Sn has a function of improving the strength of the copper alloy by dissolving in the copper alloy matrix. Further, the addition of Sn is also effective in improving the stress relaxation resistance. When the usage environment of the vapor chamber reaches 80 ° C. or higher, creep deformation occurs in the housing, and the contact surface with a heat source such as a CPU becomes smaller, reducing heat dissipation, but improving stress relaxation characteristics. Therefore, this phenomenon can be suppressed. In order to obtain the effect of improving strength and stress relaxation resistance, the Sn content is set to 0.005% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more. On the other hand, when Sn content exceeds 1.0 mass%, the bending workability of a copper alloy plate will be reduced and the electrical conductivity after an aging treatment will be reduced. Therefore, the Sn content is 1.0% by mass or less, preferably 0.6% by mass or less, more preferably 0.3% by mass or less.

  Mg, like Sn, has the effect of being dissolved in the copper alloy matrix and improving the strength and stress relaxation resistance of the copper alloy. In order to obtain the effect of improving strength and stress relaxation resistance, the Mg content is set to 0.005 mass% or more. On the other hand, when the Mg content exceeds 0.2% by mass, the bending workability of the copper alloy is lowered and the conductivity after the aging treatment is lowered. Therefore, the Mg content is 0.2% by mass or less, preferably 0.15% by mass or less, more preferably 0.05% by mass or less.

  Zn has the effect | action which improves the solder heat-resistant peelability and Sn plating heat-resistant peelability of a copper alloy. However, if the Zn content exceeds 2.0 mass%, the solder wettability decreases, so the Zn content is set to 2.0 mass% or less. The upper limit of the Zn content is preferably 0.7% by mass or less, and more preferably 0.5% by mass or less. On the other hand, if the Zn content is less than 0.01% by mass, it is insufficient for improving the heat-resistant peelability, and the Zn content is preferably 0.01% by mass or more. The lower limit of the Zn content is more preferably 0.05% by mass and even more preferably 0.1% by mass.

  Al, Mn, Cr, Ti, Zr, Fe, P, and Ag have an effect of improving the strength and heat resistance of the copper alloy. However, when the total content of one or more of these elements exceeds 0.5% by mass, the electrical conductivity decreases. The lower limit of the total content of one or more of these elements is preferably 0.01% by mass, more preferably 0.02% by mass, and even more preferably 0.03% by mass.

  The copper alloy (strip) having the above composition is a standard manufacturing method, in which the ingot is soaked and hot-rolled, followed by cold rolling, recrystallization with solution treatment, cold rolling, and precipitation treatment steps. Manufactured by. A copper alloy produced under the following conditions has a 0.2% proof stress of 300 MPa or more and excellent bending workability. Further, by performing an aging treatment after high-temperature heating (850 ° C. × 30 minutes), it has a 0.2% proof stress of 300 MPa or more and a conductivity of 25% IACS or more.

Melting, casting, and homogenization are performed in the same manner as for a Cu-Fe-P-based copper alloy.
After the homogenization treatment, hot rolling is started at a temperature of 800 ° C. or higher. In order to prevent coarse (Ni, Co) -Si precipitates from being formed on the hot-rolled material, the hot-rolling is preferably completed at a temperature of 600 ° C. or higher, and then rapidly cooled by a method such as water cooling. When the rapid cooling start temperature after hot rolling is lower than 600 ° C., coarse (Ni, Co) —Si precipitates are formed, the structure tends to be uneven, and the strength of the copper alloy (product strip) is lowered.

By applying a certain strain to the copper alloy by cold rolling after hot rolling, a copper alloy having a desired recrystallized structure (fine recrystallized structure) is obtained after the subsequent recrystallization process. The processing rate of this cold rolling is preferably 5 to 35%.
The recrystallization treatment with solution treatment is performed at 650 to 950 ° C., preferably at 670 to 900 ° C. for 3 minutes or less. When the content of Ni, Co, and Si in the copper alloy is small, it is performed in a lower temperature range within the above temperature range, and when the content of Ni, Co, and Si is large, it is performed in a higher temperature region within the above temperature range. It is preferable. By this recrystallization treatment, Ni, Co, and Si can be dissolved in the copper alloy base material, and a recrystallized structure (crystal grain size of 1 to 20 μm) can be formed with good bending workability. When the temperature of this recrystallization process is lower than 650 ° C., the amount of Ni, Co, and Si dissolved decreases, and the strength decreases. On the other hand, when the temperature of the recrystallization treatment exceeds 950 ° C. or the treatment time exceeds 3 minutes, the recrystallized grains become coarse.

  After recrystallization treatment with solution, (a) cold rolling and aging treatment, (b) after cold rolling and aging treatment, and further cold rolling to product thickness, or (c) of (b) above Later, low temperature annealing (recovery of ductility) is performed. The aging treatment (precipitation treatment) may be performed under the same conditions as those of the Cu—Fe—P based copper alloy.

(Cu- (Ni, Co) -P system)
Examples of Cu- (Ni, Co) -P-based copper alloys include Ni: 0.2 to 1.0 mass% or / and Co: 0.05 to 1.0 mass%, P: 0.03 to Mention may be made of copper alloys containing 0.2% by weight. The basic composition of this copper alloy consists of Cu and unavoidable impurities other than Ni or / and Co and P, and includes Fe and other alloy elements described later as required. In this copper alloy, the total content of Ni, Co and Fe [Ni + Co + Fe] is in the range of 0.3 to 1.0% by mass, and the total content of Ni, Co and Fe and the content of P The ratio [Ni + Co + Fe] / [P] is in the range of 2-10.
In the case of this copper alloy, by performing an aging treatment after high-temperature heating (vapor chamber joining step), a 0.2% proof stress value of 120 MPa or more and a conductivity of 40% IACS or more can be achieved. The aging treatment may be carried out under conditions of holding for 5 minutes to 10 hours in a temperature range of 350 to 600 ° C.

Ni, Co, and Fe generate a P compound ((Ni, Co, Fe) -P compound) with P, thereby improving the strength and stress relaxation resistance of the copper alloy. The (Ni, Co, Fe) -P compound includes Ni-P, Co-P, Fe-P, and an MP compound containing two or more of Fe, Ni, and Co.
When the total content of Ni, Co, and Fe [Ni + Co + Fe] is less than 0.3% by mass or the P content is less than 0.03% by mass, the precipitation amount of the P compound is small, and the strength and stress relaxation resistance of the copper alloy are reduced. There is little effect to improve. On the other hand, when [Ni + Co + Fe] exceeds 1.0 mass% or the P content [P] exceeds 0.2 mass%, coarse oxides, crystallized substances, precipitates, etc. are generated and hot workability is generated. In addition, the strength, stress relaxation resistance and bending workability of the copper alloy are reduced. Moreover, the solid solution amount of Ni, Co, Fe, and P increases, and the electrical conductivity of the copper alloy decreases. Therefore, [Ni + Co + Fe] is 0.3 to 1.0 mass%, and the P content is 0.03 to 0.2 mass%.

In addition, when the individual contents of Ni, Co, and Fe are less than 0.2% by mass, less than 0.05% by mass, and less than 0.05% by mass, the strength and stress relaxation resistance of the copper alloy plate are improved. There is little effect to make. Therefore, the lower limits of the contents of Ni, Co, and Fe are 0.2% by mass, 0.05% by mass, and 0.05% by mass, respectively.
When the ratio [Ni + Co + Fe] / [P] of the total content of Ni, Co and Fe and P content is less than 2 or more than 10, the excess Ni, Co, Fe or P is dissolved. , Conductivity decreases. Therefore, the content ratio [Ni + Co + Fe] / [P] is 2-10. The lower limit value of [Ni + Co + Fe] / [P] is preferably 2.2, and the upper limit value is preferably 9.5.

  The said copper alloy is the range which does not impair the electrical conductivity after high temperature heating and aging treatment of the 1 type (s) or 2 types or more of the alloy elements (or alloy element group) shown to the following (a)-(c) as needed. Included within. (A) Sn: 0.005-1.0 mass% or / and Mg: 0.005-0.2 mass%, (b) Zn: 1.0 mass% or less, (c) Si, Al, Mn, One or more of Cr, Ti, Zr, and Ag is 0.5% by mass or less in total.

  Sn has a function of improving the strength of the copper alloy by dissolving in the copper alloy matrix. Further, the addition of Sn is also effective in improving the stress relaxation resistance. When the usage environment of the vapor chamber is 80 ° C. or higher, creep deformation occurs in the housing, and the contact surface with a heat source such as a CPU is reduced, reducing heat dissipation, but improving stress relaxation resistance. Therefore, this phenomenon can be suppressed. In order to obtain the effect of improving strength and stress relaxation resistance, the Sn content is set to 0.005% by mass or more, preferably 0.01% by mass or more, more preferably 0.02% by mass or more. On the other hand, when Sn content exceeds 1.0 mass%, the bending workability of a copper alloy plate will be reduced and the electrical conductivity after an aging treatment will be reduced. Therefore, the Sn content is 1.0% by mass or less, preferably 0.6% by mass or less, more preferably 0.3% by mass or less.

  Mg, like Sn, has the effect of being dissolved in the copper alloy matrix and improving the strength and stress relaxation resistance of the copper alloy. In order to obtain the effect of improving strength and stress relaxation resistance, the Mg content is set to 0.005 mass% or more. On the other hand, if the Mg content exceeds 0.2% by mass, the bending workability of the copper alloy plate is lowered and the electrical conductivity after the aging treatment is lowered. Therefore, the Mg content is 0.2% by mass or less, preferably 0.15% by mass or less, more preferably 0.05% by mass or less.

Zn has the effect | action which improves the solder heat-resistant peelability and Sn plating heat-resistant peelability of a copper alloy. However, if the Zn content exceeds 1.0% by mass, solder wettability decreases, so the Zn content is 1.0% by mass or less. The Zn content is preferably 0.7% by mass or less, and more preferably 0.5% by mass or less. On the other hand, if the Zn content is less than 0.01% by mass, it is insufficient for improving the heat-resistant peelability, and the Zn content is preferably 0.01% by mass or more. As for Zn content, 0.05 mass% or more is more preferable, and 0.1 mass% or more is further more preferable.
Si, Al, Mn, Cr, Ti, Zr, and Ag have an effect of improving the strength and heat resistance of the copper alloy. However, since the electrical conductivity of a copper alloy falls when there is much content of these elements, the 1st type or 2 or more types total content of these elements is restrict | limited to 0.5 mass% or less. The lower limit of the total content of one or more of these elements is preferably 0.01% by mass, more preferably 0.02% by mass, and even more preferably 0.03% by mass.

  The copper alloy (strip) having the above composition is a standard manufacturing method, in which the ingot is soaked and hot-rolled, followed by cold rolling, recrystallization with solution treatment, cold rolling, and precipitation treatment steps. Manufactured by. The conditions for each step may be performed under the same conditions as those for Cu— (Ni, Co) —Si based copper alloys. The copper alloy manufactured under these conditions has a 0.2% proof stress of 300 MPa or more and excellent bending workability. Moreover, by performing an aging treatment after high-temperature heating (850 ° C. × 30 minutes), a 0.2% proof stress of 120 MPa or more and a conductivity of 40% IACS or more are obtained.

(Cu-Cr type)
Examples of Cu-Cr-based copper alloys include Cr: 0.15-0.6 mass%, Si: 0.005-0.15 mass%, and Ti: 0.005-0.15 mass%. The copper alloy which contains seed | species or 2 types in total 0.01-0.3 mass% can be mentioned. The basic composition of this copper alloy consists of Cu and unavoidable impurities other than Cr and Si or / and Ti, and contains the alloy elements described later as required.
This copper alloy can recover strength and electrical conductivity when subjected to aging treatment without plastic working after high-temperature heating (vapor chamber joining process). Smaller than alloy. Nevertheless, a 0.2% proof stress value of 60 MPa or more and a conductivity of 45% IACS or more can be achieved. On the other hand, some precipitated particles containing Cr, Si, Ti and the like remain in high-temperature heating, which suppresses the coarsening of crystal grains due to secondary recrystallization, and suppresses the coarsening of crystal grains. For this reason, this copper alloy can suppress the average crystal grain size after high-temperature heating (bonding step of the vapor chamber) to 50 μm or less. In addition, it is preferable to carry out rapid cooling (water cooling etc.) after high temperature heating. As for an aging treatment, the conditions hold | maintained for 5 minutes-10 hours in the temperature range of 350-550 degreeC are mentioned.

  In this copper alloy, Cr precipitates as a Cr, Cr—Si compound or Cr—Ti—Si compound in the copper alloy matrix, and improves the strength and conductivity of the copper alloy after aging treatment. In addition, Cr has a small amount of solid solution in Cu even at a temperature of 700 ° C. or higher, and can prevent coarsening of crystal grains in high-temperature heating (vapor chamber joining step). However, when the Cr content is less than 0.15% by mass, the above effects are insufficient. On the other hand, if the Cr content exceeds 0.6% by mass, coarse Cr and Cr compounds are generated, and the bending workability of the copper alloy is lowered. Therefore, the Cr content is 0.15 to 0.6 mass%. The lower limit of Cr is preferably 0.2% by mass, and more preferably 0.25% by mass. The upper limit of Cr is preferably 0.5%, more preferably 0.45% by mass. In order to effectively prevent coarsening of crystal grains at a high temperature of 850 ° C. or higher, the Cr content is preferably 0.25% by mass or higher.

  Si and Ti precipitate as a Cr—Si compound or a Cr—Ti—Si compound in the copper alloy matrix, and improve the strength and conductivity of the copper alloy. In addition, the heat resistance of the copper alloy can be improved, and coarsening of crystal grains during high-temperature heating (vapor chamber joining step) can be prevented. However, when the Si content is less than 0.005% by mass, the Ti content is less than 0.005% by mass, or the total content of Si and Ti is less than 0.01% by mass, the above effects are small. On the other hand, when the content of Si or Ti exceeds 0.15% by mass, or when the total content of Si and Ti exceeds 0.3% by mass, a coarse Cr—Si compound or Cr— Ti-Si compound increases and bending workability is reduced. Therefore, the Si content is 0.005 to 0.15 mass%, the Ti content is 0.005 to 0.15 mass%, and the total content of Si and Ti is 0.01 to 0.3 mass%. To do. The lower limit of Si content and Ti content is preferably 0.01%, and the upper limit is preferably 0.1% by mass.

  The said copper alloy contains 1 type, or 2 or more types of Zn, Mg, Mn, Al, Ag, Ni, Fe, Co, and P in the range of 0.01-0.3 mass% as needed. These elements improve the strength of the copper alloy, but if the total content is less than 0.01% by mass, the effect is not sufficient, and if it exceeds 0.3% by mass, the conductivity decreases. Therefore, the total content of one or more of these elements is 0.01 to 0.3% by mass.

  The copper alloy (strip) having the above composition is manufactured by homogenizing and hot rolling an ingot, followed by cold rolling and further aging treatment. The copper alloy produced under the following conditions has a 0.2% proof stress of 300 MPa or more, an elongation of 5% or more, and excellent bending workability. Moreover, after high temperature heating (850 ° C. × 30 minutes), it has a 0.2% proof stress of 40 MPa or more, and then after aging treatment, has a 0.2% proof stress of 60 MPa or more and a conductivity of 45% IACS or more. become. Furthermore, coarsening of crystal grains due to high temperature heating (850 ° C. × 30 minutes) is suppressed, and the average crystal grain size after high temperature heating is suppressed to 50 μm or less.

The homogenization treatment is performed under the condition of maintaining the temperature at 800 to 1000 ° C. for 1 to 10 hours.
After the homogenization treatment, hot rolling is started at a temperature of 800 ° C. or higher, the processing rate is set to about 50 to 90%, and rapid cooling is performed from 700 ° C. or higher by a method such as water cooling.
Cold rolling after hot rolling is performed at a processing rate of 50 to 99%.
The aging treatment is performed under the condition that the temperature is maintained at 350 to 550 ° C. for 30 minutes to 10 hours.
After the aging treatment, cold rolling at a processing rate of 5 to 30% and subsequent strain relief annealing may be performed as necessary.
Moreover, between the cold rolling after the hot rolling of the said process and aging treatment, a solution treatment and cold rolling can be pinched | interposed as needed. In this case, cold rolling after hot rolling is performed at a processing rate of 50 to 95%, solution treatment is performed at a temperature of 700 to 900 ° C. for 5 seconds to 3 minutes, and subsequent cold rolling is performed at a processing rate. It is preferable to carry out at 50 to 95%.

(Cu-Cr-Zr system)
As an example of a Cu-Cr-Zr-based copper alloy, a copper alloy containing Cr: 0.15-0.6 mass% and Zr: 0.005-0.15 mass% can be given. The basic composition of this copper alloy is composed of Cu and unavoidable impurities other than Cr and Zr, and contains alloy elements described later as required.
This copper alloy, like the Cu-Cr-based copper alloys mentioned above, recovers strength and conductivity when subjected to aging treatment without plastic working after high-temperature heating (vapor chamber joining step). However, the recovery amount is smaller than that of the other precipitation hardening copper alloys. Nevertheless, a 0.2% proof stress value of 60 MPa or more and a conductivity of 45% IACS or more can be achieved. On the other hand, some precipitated particles containing Cr, Zr, etc. remain in high-temperature heating, which suppresses the coarsening of crystal grains due to secondary recrystallization and suppresses the coarsening of crystal grains. For this reason, this copper alloy can suppress the average crystal grain size after high-temperature heating (bonding step of the vapor chamber) to 50 μm or less. In addition, it is preferable to carry out rapid cooling (water cooling etc.) after high temperature heating. As for an aging treatment, the conditions hold | maintained for 5 minutes-10 hours in the temperature range of 350-550 degreeC are mentioned.

In this copper alloy, the reason for adding Cr is the same as that of the Cu—Cr-based copper alloy mentioned above.
Zr precipitates as a Zr-Cu compound in the copper alloy matrix and improves the strength and electrical conductivity of the copper alloy. Further, since the amount of Zr dissolved in Cu is very small, it is possible to prevent the crystal grains from becoming coarse during high-temperature heating (vapor chamber joining step). However, when the Zr content is less than 0.005% by mass, the effect is small. On the other hand, when the content of Zr exceeds 0.15% by mass, a coarse Zr compound is generated, and bending workability is lowered. Therefore, the Zr content is set to 0.005 to 0.15 mass%. The lower limit of Zr is preferably 0.01% by mass, more preferably 0.015% by mass. The upper limit of Zr is preferably 0.1% by mass, more preferably 0.08% by mass. In order to effectively prevent the coarsening of crystal grains at a temperature of 850 ° C. or higher, the Zr content is preferably 0.015% by mass or higher.

  The said copper alloy is the range which does not impair the electrical conductivity after high temperature heating and an aging treatment of the 1 type (s) or 2 types or more of the alloy elements (or alloy element group) shown to the following (a) and (b) as needed. Included within. (A) Si: 0.005 to 0.15 mass% and Ti: 0.005 to 0.15 mass%, or a total of 0.01 to 0.3 mass%, (b) Zn, Totally 0.01 to 0.3% by mass of one or more elements selected from Mg, Mn, Al, Ag, Ni, Fe, Co, Si, and P.

  The copper alloy (strip) having the above composition can be manufactured in the same process and conditions as the Cu-Cr-based copper alloy mentioned above, 0.2% proof stress is 300 MPa or more, elongation is 5% or more, And excellent bending workability. Moreover, after high temperature heating (850 ° C. × 30 minutes), it has a 0.2% proof stress of 40 MPa or more, and then after aging treatment, has a 0.2% proof stress of 60 MPa or more and a conductivity of 45% IACS or more. become. Furthermore, coarsening of crystal grains due to high temperature heating (850 ° C. × 30 minutes) is suppressed, and the average crystal grain size after high temperature heating is suppressed to 50 μm or less.

Copper alloys shown in Table 1 were cast, and copper alloy strips having a thickness of 0.40 mm were manufactured by the manufacturing methods described above. In Table 1, no. 1 and 2 are Cu-Fe-P series, 3 to 5 are Cu— (Ni, Co) —Si, 6 is a Cu- (Ni, Co) -P system, No. 6; 7 is a Cu-Cr type, No. 8 is a Cu—Cr—Zr system, 9 is a conventional OFC (Oxygen-Free Copper).
Using each manufactured copper alloy strip as a test material, 0.2% proof stress, elongation and electrical conductivity were measured in the following manner.
The plate taken from each manufactured copper alloy strip was water-cooled after heating at 850 ° C. × 30 minutes corresponding to heating in the vapor chamber joining step. Using the plate after water cooling as a test material, 0.2% proof stress and conductivity were measured in the same manner.
In addition, the plate collected from each copper alloy strip manufactured is heated at 850 ° C. for 30 minutes, which corresponds to the heating in the vapor chamber joining step, and then water-cooled, followed by aging treatment (precipitation hardening treatment) at 500 ° C. for 2 hours. ). Using the plate after aging treatment as a test material, 0.2% proof stress and conductivity were measured in the same manner, and the average crystal grain size was measured in the following manner.
The results are shown in Table 2.

(0.2% proof stress, measurement of elongation)
From each sample material, a JIS No. 5 tensile test piece was cut out so that the longitudinal direction was parallel to the rolling direction, and a tensile test was performed in accordance with JIS-Z2241, thereby measuring the yield strength and elongation. The yield strength is a tensile strength corresponding to a permanent elongation of 0.2%.
(Measurement of conductivity)
The conductivity was measured by a four-terminal method using a double bridge in accordance with a nonferrous metal material conductivity measurement method defined in JIS-H0505.
(Measurement of average crystal grain size)
The plate surface of the test material was observed, and a structure photograph was obtained with an optical microscope. The average crystal grain size is measured using a cutting method, with the direction of the line segment being parallel to the rolling direction, and four line segments each having a length of 250 μm are drawn on the structure photograph. The average of the obtained crystal grain sizes was defined as the average crystal grain size.

Tables 1 and 2 show that the conventional OFC No. In No. 9, the 0.2% proof stress after heating at 850 ° C. for 30 minutes corresponding to the vapor chamber joining step is 38 MPa, and the softening is severe. The 0.2% yield strength after heating at 500 ° C. for 2 hours corresponding to the aging treatment is also 38 MPa, and the 0.2% yield strength has not recovered. Furthermore, the crystal grains are coarsened, and it can be estimated that there is a grain boundary penetrating the plate thickness.
In contrast, no. 1 to 8 are precipitation hardening type copper alloys, which were softened by heating at 850 ° C. × 30 minutes, but the 0.2% proof stress still exceeds 50 MPa. Moreover, 0.2% yield strength and electrical conductivity were recovered by heating at 500 ° C. for 2 hours. A value of 2 or more times 9 is shown. The coarsening of the crystal grains is also suppressed, and the average crystal grain size is no. Smaller than 9, especially no. 1, 2, 7, and 8 have remarkably small average crystal grain sizes.

No. in Table 1 Copper alloys having compositions shown in 1, 3, 6, and 9 were cast, and copper alloy strips having a thickness of 1.0 mm were manufactured by the manufacturing methods described above. The manufactured copper alloy strip was used as a test material, and the 0.2% proof stress at high temperature was measured as follows. The results are shown in Table 3. In Table 3, No. 1A, 3A, 6A, and 9A have a plate thickness of 1.0 mm, and the alloy compositions are No. 1 in Table 1, respectively. It means a copper alloy strip having a composition of 1,3,6,9.
(Measurement of 0.2% proof stress at high temperature)
A JIS No. 5 tensile test piece was cut out from the test material so that the longitudinal direction was parallel to the rolling direction, held at each temperature shown in Table 3 for 30 minutes, and then subjected to a tensile test in accordance with the provisions of JIS Z2241 at the same temperature. .2% yield strength was measured. The test atmosphere was in an Ar stream to prevent the test piece from being oxidized.

  Table 3 shows that No. of the conventional example. The 0.2% proof stress of 9A is very low above 700 ° C. In contrast, No. of precipitation hardening type copper alloy. The 0.2% proof stress of 1A, 3A, and 6A is No. at 700 ° C. No. 9 at 800 ° C., 5 times or more than 9. No. 9 even at 900 ° C. more than 2 times 9. It can be seen that the strength is higher than 9 and the strength is relatively high at a high temperature, and is not easily deformed by heating in the vapor chamber joining step.

2 Upper plate member 3 Lower plate member

Claims (1)

After assembling the vapor chamber with a plurality of components, the components are bonded to each other through a process of heating to 650 ° C. or higher, and the components constituting the casing of the vapor chamber are deposited out of the components. A method of manufacturing a vapor chamber, comprising a curable copper alloy, wherein the precipitation hardened copper alloy is subjected to aging treatment and precipitation hardened without applying plastic working to a case of the vapor chamber after joining.

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