JP2017119740A - Method for joining metal member and resin member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for joining a metal member and a resin member which enables a metal member and a resin member to be more strongly joined together.SOLUTION: The method for joining a metal member and a resin member is provided which comprises a coupling agent application step, a coupling agent layer formation step, an exposure step and a resin member formation step, and in which a temperature T of a high humidity atmosphere in the exposure step is 0°C or higher and 100°C or lower, a relative humidity RH in the high humidity atmosphere is 15% or more and 100% or less, and in the exposure step, an exposure time t (h) at which a coupling agent layer 200 formed on the surface of a metal member 100 under high humidity atmosphere is exposed is 1 second or more and 48 hours or less, and the high humidity atmosphere is an atmosphere satisfying conditional expressions (1) and (2). In conditional expression (1) and (2), K represents is a coefficient of water vapor exposure, and Mis an amount of saturated water vapor (g/m).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a method for joining a metal member and a resin member, and more particularly, to a method for joining a metal member and a resin member using a coupling agent.

  Patent Document 1 describes a method for joining a metal member and a resin member using a silane coupling agent. Patent Document 1 describes that high adhesion is achieved by adjusting the material composition and solution concentration of the silane coupling agent applied to the metal surface.

Japanese Patent Laid-Open No. 2015-013474

  However, even if the material composition and solution concentration of the coupling agent are adjusted, there is a possibility that the metal member and the resin member cannot be bonded with sufficient bonding strength.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a method for joining a metal member and a resin member, which can more strongly join the metal member and the resin member. is there.

ここで、Ｋは、水蒸気暴露係数であり、Ｍ_{ｗ＿ｍａｘ}は、飽和水蒸気量（ｇ／ｍ^３）であり、ＲＨは、高湿雰囲気の相対湿度（％）であり、ｔは、前記暴露時間（ｈ）であり、Ｔは、高湿雰囲気の温度（℃）である。 The method for joining a metal member and a resin member according to the present invention includes a step of applying a coupling agent containing an organic compound having an amino group to the surface of the metal member, and the coupling agent applied to the surface of the metal member. A step of forming a coupling agent layer on the surface of the metal member, a step of exposing the coupling agent layer formed on the surface of the metal member to a high humidity atmosphere, and a surface of the metal member Forming a resin member directly on the coupling agent layer formed on the substrate. The temperature of the high humidity atmosphere is 0 ° C. or higher and 100 ° C. or lower, and the relative humidity of the high humidity atmosphere is 15% or higher and 100% or lower. In the step of exposing the coupling agent layer to the high humidity atmosphere, the exposure time for exposing the coupling agent layer to the high humidity atmosphere is 1 second to 48 hours. The high humidity atmosphere is an atmosphere that satisfies the following conditional expressions (1) and (2).

Here, K is a water vapor exposure coefficient, M _{w_max} is a saturated water vapor amount (g / m ³ ), RH is a relative humidity (%) in a high humidity atmosphere, and t is the exposure time ( h), and T is the temperature (° C.) of the high humidity atmosphere.

  According to the method for joining a metal member and a resin member according to the present invention, the coupling agent layer formed on the surface of the metal member is exposed to a high humidity atmosphere, whereby the surface of the coupling agent layer is subjected to the cup. The functional group that reacts with the resin member formed immediately above the ring agent layer is oriented. Thereby, the reaction efficiency of the functional group of the coupling agent layer and the resin member is improved. Therefore, the metal member and the resin member can be bonded more firmly. Therefore, the joining method of the metal member and resin member which can join a metal member and a resin member more firmly can be provided.

1 is a cross-sectional view schematically showing a power card according to a first embodiment. FIG. 3 is a process diagram illustrating a method for joining a metal member and a resin member according to the first embodiment. In an Example and a comparative example, it is sectional drawing explaining the method of investigating the joint strength of a metal member and a resin member. It is a graph which shows the joint strength of the metal member joined by the joining method concerning an Example, and the joining method concerning a comparative example, and a resin member.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing a power card 1 according to the first embodiment of the present invention. The power card 1 according to the first embodiment is manufactured using the joining method of the metal member and the resin member according to the first embodiment. This method will be described later. As shown in FIG. 1, the power card 1 according to the first embodiment has a double-sided heat dissipation structure in which a power semiconductor element 12 and an electrode 13 are sandwiched between a pair of lead frames 11 and 14 that function as a heat dissipation plate.

  Specifically, the power card 1 according to the first embodiment includes a lead frame 11, a power semiconductor element 12, an electrode 13, a lead frame 14, a bonding wire 15, solder layers 21, 22, 23, a lead frame 11, and a coupling. The agent layer 30 and the mold resin 40 are provided.

The lead frame 11 is made of Ni plated copper or the like.
Further, the power semiconductor element 12 is soldered to an element mounting portion (reference numeral omitted) of the lead frame 11.
The electrode 13 is made of a copper block or the like and is soldered to the power semiconductor element 12.
The lead frame 14 is made of Au plated copper or the like and is soldered to the electrode 13.
Further, the power semiconductor element 12 and the plurality of leads 11 </ b> L of the lead frame 11 are electrically connected via bonding wires 15.

In the power card 1, the pair of lead frames 11 and 14 that sandwich the power semiconductor element 12 and the electrode 13 can function as a heat sink.
The illustrated power card 1 is merely an example, and the design can be changed as appropriate.

  The mold resin 40 is made of a thermosetting resin including an epoxy resin. Further, the mold resin 40 seals the element laminate 10 including the power semiconductor element 12, the electrode 13, and a pair of lead frames 11 and 14 sandwiching them.

  In the element stack 10, the electrode 13 and the pair of lead frames 11 and 14 are metal members. The mold resin 40 is a resin member. The element laminate 10 including the electrode 13 that is a metal member and the pair of lead frames 11 and 14 and the mold resin 40 that is a resin member are heterogeneously bonded. In other words, the element laminate 10 and the mold resin 40 are bonded using the bonding method between the metal member and the resin member according to the first embodiment.

Specifically, a coupling agent layer 30 is formed between the element laminate 10 and the mold resin 40 in order to improve the bondability of the dissimilar bonding.
The coupling agent layer 30 is a layer formed using a coupling agent containing an organic compound having an amino group.

Next, a method for manufacturing the power card 1 will be described.
First, the power semiconductor element 12 is soldered to the element mounting portion of the lead frame 11 made of Ni-plated copper or the like. Next, the power semiconductor element 12 and the plurality of leads 11 </ b> L of the lead frame 11 are electrically connected via bonding wires 15.

Next, an electrode 13 made of a copper block or the like is soldered on the power semiconductor element 12.
Next, a lead frame 14 made of Au-plated copper or the like is soldered on the electrode 13.
As described above, the element stack 10 including the power semiconductor element 12, the electrode 13, and the pair of lead frames 11 and 14 sandwiching them is obtained.

  Next, the element laminate 10 and the mold resin 40 are bonded using the method for bonding the metal member and the resin member according to the first embodiment. Specifically, an aqueous solution of a coupling agent containing an organic compound having an amino group is applied to at least a portion of the exposed surface of the element laminate 10 where the mold resin 40 is formed (coupling agent application step). Next, the aqueous solution of the coupling agent applied to the exposed surface of the element laminate 10 is dried to form the coupling agent layer 30 (coupling agent layer forming step). Next, the coupling agent layer 30 formed on the exposed surface of the element laminate 10 is exposed to a high humidity atmosphere (exposure process). Next, the mold resin 40 is formed immediately above the coupling agent layer 30 formed on the exposed surface of the element laminate 10 (resin member forming step). As described above, the power card 1 is manufactured.

  Next, with reference to FIG. 2, the joining method of the metal member and resin member concerning this Embodiment 1 of this invention is demonstrated concretely. As shown in FIG. 2, the method for joining the metal member and the resin member according to the first embodiment includes a coupling agent application step, a coupling agent layer formation step, an exposure step, and a resin member formation step. Here, for simplicity of explanation, the Ni-plated copper substrate 100 will be described as an example of the metal member.

  First, in the coupling agent application step, a coupling agent 200 containing an organic compound having an amino group is applied to the surface of the Ni-plated copper substrate 100 as a metal member. Specifically, as shown in FIG. 2, the Ni-plated copper substrate 100 is immersed in an aqueous solution 201 of a silane coupling agent 200 as a coupling agent containing an organic substance having an amino group. Thereby, the silane coupling agent 200 is applied to the Ni-plated copper substrate 100. The method for applying the aqueous solution 201 of the coupling agent to the Ni plated copper substrate 100 is not limited to the above method. However, a method of immersing the Ni-plated copper substrate 100 in the aqueous solution 201 of the coupling agent is preferable.

  Next, in the coupling agent layer forming step, the silane coupling agent 200 applied to the surface of the Ni plated copper substrate 100 is dried to form the silane coupling agent layer 200 on the surface of the Ni plated copper substrate 100. Specifically, the aqueous solution of the silane coupling agent 200 on the surface of the Ni-plated copper substrate 100 is thinly extended by a spin coating method so as to have a substantially uniform film thickness. Thereafter, the silane coupling agent 200 on the surface of the Ni-plated copper substrate 100 is dried. Thereby, the silane coupling agent layer 200 is formed on the surface of the Ni-plated copper substrate 100. The method for drying the coupling agent 200 applied to the Ni-plated copper substrate 100 is not particularly limited. For example, heat drying, vacuum drying, and vacuum heating drying are preferable. Further, the thickness of the coupling agent layer 200 after drying is not particularly limited. For example, a thickness of about 10 to 2000 nm is preferable.

  Next, in the exposure step, the silane coupling agent layer 200 formed on the surface of the Ni-plated copper substrate 100 is exposed to a high humidity atmosphere. Specifically, a silane coupling agent layer is formed on the surface for an exposure time of 1 second to 48 hours in an atmosphere of a temperature range of 0 ° C. to 100 ° C. and a relative humidity range of 15% to 100%. The Ni-plated copper substrate 100 on which 200 is formed is left to stand.

ここで、Ｋは、水蒸気暴露係数であり、Ｍ_{ｗ＿ｍａｘ}は、飽和水蒸気量（ｇ／ｍ^３）であり、ＲＨは、高湿雰囲気の相対湿度（％）であり、ｔは、暴露時間（ｈ）であり、Ｔは、高湿雰囲気の温度（℃）である。なお、当該水蒸気暴露係数Ｋは、本願発明者が独自に発明した指標である。 The high humidity atmosphere satisfies the following conditional expressions (1) and (2).

Here, K is a water vapor exposure coefficient, M _{w_max} is a saturated water vapor amount (g / m ³ ), RH is a relative humidity (%) in a high humidity atmosphere, and t is an exposure time (h T is the temperature (° C.) of the high humidity atmosphere. The water vapor exposure coefficient K is an index uniquely invented by the present inventor.

  Next, in the resin member forming step, the resin member 300 is formed immediately above the silane coupling agent layer 200 formed on the surface of the Ni-plated copper substrate 100. Specifically, the resin member 300 is formed immediately above the silane coupling agent layer 200 formed on the surface of the Ni-plated copper substrate 100 by a transfer molding method. Thereafter, the Ni-plated copper substrate 100 on which the resin member 300 is formed is heated to perform post-cure processing. The resin member 300 is formed from, for example, a thermosetting resin including an epoxy resin. In addition, the method of forming the resin member 300 directly on the silane coupling agent layer 200 is not limited to the above-described method, and a known method can be appropriately selected.

  In addition, it does not restrict | limit especially as a coupling agent containing the organic compound which has an amino group, A well-known thing can be used. For example, as a coupling agent, a silane coupling agent is preferable.

The silane coupling agent includes an organic functional group capable of reacting or interacting with an organic substance in one molecule (hereinafter, this group is expressed as “—Y”) and a hydrolyzable group (hereinafter, this group). Is represented as “—OR”, where —OR is —OCH ₃ , —OC ₂ H ₅ , OCOCH _3, etc.).
The hydrolyzable group (—OR) becomes a hydroxyl group in an aqueous solution. This hydroxyl group can react or interact with a functional group such as a hydroxyl group present on the surface of the metal body.
Silane coupling agents can react or interact with both metals and resins to improve their bondability.
In Embodiment 1, a silane coupling agent (hereinafter also referred to as “aminosilane”) in which the organic functional group (—Y) is an amino group can be used.
The aminosilane may contain either an aliphatic amino group or an aromatic amino group.
Examples of aminosilane include N-2- (aminoethyl) -3-aminopropyltrimethoxysilane and 3-aminopropyltrimethoxysilane.

The aqueous solution of the coupling agent containing an organic compound having an amino group contains at least a coupling agent and water, and may contain one or more optional components as necessary.
As a solvent of the aqueous solution of the coupling agent, a mixed solvent of water and ethanol is preferable.

Examples and Comparative Examples Next, examples and comparative examples according to the present invention will be described with reference to FIGS.

  First, the silane coupling agent 200 was apply | coated to the surface of the Ni plating copper substrate 100 as a metal member in the coupling agent application | coating process. As a silane coupling agent, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, “KBM-603” manufactured by Shin-Etsu Silicone Co., Ltd.) was used. Moreover, the mixed solvent which mixed water and ethanol by mass ratio 1: 1 was used as a solvent. Then, the aminosilane was dissolved in the solvent to prepare an aqueous solution 201 of a silane coupling agent 200 having a concentration of 10%. And the Ni plating copper substrate 100 was immersed in the aqueous solution 201 of the silane coupling agent 200 of normal temperature (20-25 degreeC) for 1 minute.

  Next, in the coupling agent layer forming step, the Ni-plated copper substrate 100 is taken out, excess liquid is removed, and then the silane coupling agent 200 on the surface of the Ni-plated copper substrate 100 is substantially removed by spin coating. The film was extended so as to have a uniform film thickness. As a result, a thin film of the silane coupling agent 200 was formed on the surface of the Ni-plated copper substrate 100. Thereafter, the silane coupling agent 200 was immobilized on the surface of the Ni-plated copper substrate 100 by heating at 100 ° C. for 15 minutes, thereby forming a coupling agent layer 200 having a thickness of 200 nm.

Next, in the exposure step, the silane coupling agent layer 200 formed on the surface of the Ni-plated copper substrate 100 is exposed to a high humidity atmosphere. The temperature T (° C.), the relative humidity RH (%), the exposure time t (h), the amount of saturated water vapor M _{w_max} (g / m ³ ), and the water vapor exposure in Examples 1 to 7 and Comparative Examples 1 to 4 The coefficient K is shown in Table 1.

  Next, in the resin member forming step, the resin member 300 was formed immediately above the coupling agent layer 200 using an epoxy resin that is a thermosetting resin by transfer molding. As shown in FIG. 2, the resin member 300 has a truncated cone shape. Further, the diameter of the bottom surface of the truncated cone is 3.7 mmφ, the diameter of the top surface is 2.7 mmφ, and the height is 4 mm. The molding conditions are 175 ° C. and 7 MPa. Thereafter, the Ni-plated copper substrate 100 on which the resin member 300 was formed was heated at 180 ° C. for 2 hours, and post-curing treatment of the epoxy resin (resin member 300) was performed.

  Next, the bonding strength between the Ni-plated copper substrate 100, which is a metal member, and the resin member 300 is measured. Specifically, the shear strength between the Ni-plated copper substrate 100 and the resin member 300 was measured using a “force gauge” manufactured by Aiko Engineering Co., Ltd. as a measuring device.

  More specifically, as shown in FIG. 3, by pressing the block 400 against the side surface of the resin member 300, the direction parallel to the joint surface between the Ni-plated copper substrate 100 and the resin member 300 (indicated by the arrow shown in FIG. 3). Direction) at a moving speed of 6 mm / min. And the magnitude | size of the load when the resin member 300 peels from the Ni plating copper substrate 100 is made into the shear strength of the Ni plating copper substrate 100 and the resin member 300, and Ni plating copper substrate 100 and resin are based on the said shear strength. The bonding strength with the member 300 was estimated. The separation distance between the block 400 and the coupling agent layer 200 was 0.1 mm.

Table 1 shows the shear strength of Examples 1 to 7 and Comparative Examples 1 to 4. FIG. 4 shows the relationship between the shear strength and the water vapor exposure coefficient K of Examples 1 to 7 and Comparative Examples 1 to 4. Here, when the shear strength was 25 (MPa), it was determined that the Ni-plated copper substrate 100 and the resin member 300 were joined with sufficient strength.
As shown in FIG. 4, in Example 1 in which the water vapor exposure coefficient K is 3190.47, the shear strength is 30.9 (MPa), which is larger than 25 (MPa), and a sufficient bonding strength is obtained. Yes. On the other hand, in Comparative Example 1 in which the water vapor exposure coefficient K is less than 5, the shear strength is 23.5, which is less than 25 (MPa), indicating that the bonding strength is weak.

  When a coupling agent containing an organic compound having an amino group as a hydrophilic organic functional group (—Y) such as a silane coupling agent is used, the coupling agent 200 is exposed to hydrophilicity in a high-humidity atmosphere. The organic functional group (—Y) is selectively oriented on the surface side of the coupling agent layer 200 that contacts the high-humidity atmosphere. In other words, the hydrophilic organic functional group (—Y) is selectively oriented on the outermost surface of the coupling agent layer 200. Thereby, the reaction point of the said organic functional group (-Y) of the coupling agent layer 200 and the resin member 300 can be increased. Therefore, the Ni-plated copper substrate 100 and the resin member 300 can be bonded more firmly.

  However, if the degree of exposure of the coupling agent 200 to the high-humidity atmosphere is too high, in other words, if the water vapor exposure coefficient K is greater than 7000, the coupling agent 200 becomes fragile due to water supply and swelling. The coupling between the hydrolyzable groups (—OR) inside the ring agent layer 200 is broken by hydrolysis, and the coupling agent layer 200 becomes brittle. Therefore, after the resin member 300 is formed immediately above the coupling agent 200, the Ni-plated copper substrate 100 and the resin member 300 are easily peeled off because the coupling agent layer 200 is brittle.

  Further, if the degree of exposure of the coupling agent 200 to a high humidity atmosphere is too low, in other words, if the water vapor exposure coefficient K is smaller than 5, the water vapor does not sufficiently act on the coupling agent layer 200. Therefore, the hydrophilic organic functional group (—Y) is not selectively oriented on the surface side of the coupling agent layer 200 that contacts the high humidity atmosphere. Therefore, the reaction point between the organic functional group (—Y) of the coupling agent layer 200 and the resin member 300 cannot be increased. Therefore, the bonding strength between the Ni-plated copper substrate 100 and the resin member 300 cannot be improved.

そして、絶対水蒸気量Ｍ_ｗが高すぎると、単位体積当たりの水分子の量が多いため、水分子がカップリング剤層２００に接触する機会（単位時間当たりの回数）が過多になる。そのため、カップリング剤層２００の膨潤を引き起こしたり、加水分解性基（−ＯＲ）同士の結合の加水分解を引き起こしたりする。
一方、絶対水蒸気量Ｍ_ｗが低すぎると、単位体積当たりの水分子の量が少ないため、水分子がカップリング剤層２００に接触する機会（単位時間当たりの回数）が過少になる。そのため、親水性の有機官能基（−Ｙ）のカップリング剤層２００の最表面への配向が不十分になる。 Moreover, when the absolute water vapor amount is M _w (g / m ³ ), the absolute water vapor amount M _w is represented by the following equation (3).

If the absolute water vapor amount _Mw is too high, the amount of water molecules per unit volume is large, so that the opportunity for water molecules to contact the coupling agent layer 200 (the number of times per unit time) becomes excessive. Therefore, swelling of the coupling agent layer 200 is caused, or hydrolysis of a bond between hydrolyzable groups (—OR) is caused.
On the other hand, if the absolute water vapor amount _Mw is too low, the amount of water molecules per unit volume is small, so the opportunity for water molecules to contact the coupling agent layer 200 (number of times per unit time) becomes too small. Therefore, the orientation of the hydrophilic organic functional group (—Y) to the outermost surface of the coupling agent layer 200 becomes insufficient.

In addition, if the exposure time t (h) is too long, the opportunity (the number of times per unit time) for water molecules to contact the coupling agent layer 200 becomes excessive. Therefore, swelling of the coupling agent layer 200 is caused, or hydrolysis of a bond between hydrolyzable groups (—OR) is caused.
On the other hand, when the exposure time t (h) is too short, the opportunity (the number of times per unit time) for water molecules to contact the coupling agent layer 200 becomes too small. Therefore, the orientation of the hydrophilic organic functional group (—Y) to the outermost surface of the coupling agent layer 200 becomes insufficient.

On the other hand, if the temperature T (° C.) of the high-humidity atmosphere is too high, the thermal motion of water molecules becomes intense. In other words, the mean free path of water molecules becomes longer. Thereby, the opportunity (number of times per unit time) for water molecules to contact the coupling agent layer 200 becomes excessive. Therefore, swelling of the coupling agent layer 200 is caused, or hydrolysis of a bond between hydrolyzable groups (—OR) is caused.
On the other hand, if the temperature T (° C.) of the high humidity atmosphere is too low, the thermal motion of water molecules becomes poor. In other words, the mean free path of water molecules is shortened. Thereby, the opportunity (number of times per unit time) for water molecules to contact the coupling agent layer 200 becomes too small. Therefore, the orientation of the hydrophilic organic functional group (—Y) to the outermost surface of the coupling agent layer 200 becomes insufficient.

That is, depending on the numerical value of the water vapor exposure coefficient K depending on the combination of the absolute water vapor amount M _w (g / m ³ ), the exposure time t (h), and the temperature T (° C.) of the high humidity atmosphere, Ni The bonding strength between the plated copper substrate 100 and the resin member 300 is determined.

  According to the method for joining the metal member 100 and the resin member 300 according to the first embodiment described above, the coupling agent layer 200 formed on the surface of the metal member 100 (Ni-plated copper substrate 100) has a high humidity atmosphere. By exposing to the bottom, the organic functional group (—Y) that reacts with the resin member 300 formed immediately above the coupling agent layer 200 is oriented on the surface of the coupling agent layer 200. Thereby, the reaction efficiency of the organic functional group (-Y) of the coupling agent layer 200 and the resin member 300 is improved. Therefore, the metal member 100 and the resin member 300 can be joined more firmly. Therefore, the joining method of the metal member 100 and the resin member 300 which can join the metal member 100 and the resin member 300 more firmly can be provided.

Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in Embodiment 1 described above, a high-humidity atmosphere is defined by the numerical value of the water vapor exposure coefficient K. However, elements constituting the water vapor exposure coefficient K, such as the absolute water vapor amount M _w (g / m ³ ), _{Some elements of the} saturated water vapor amount M _{w — max} (g / m ³ ), the relative humidity RH (%), the exposure time t (h), and the temperature T (° C.) of the humid atmosphere are set to constant values, An embodiment in which the numerical value range of elements is limited to the numerical value range of the water vapor exposure coefficient K of the present application is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Power card 10 Element laminated body 11 Lead frame (metal member)
11L Lead 12 Power semiconductor element 13 Electrode (metal member)
14 Lead frame (metal member)
15 Bonding wire 30 Coupling agent layer 40 Mold resin (resin member)
100 Ni plated copper substrate (metal member)
200 Coupling agent layer 300 Resin member 400 Block

Claims (1)

Applying a coupling agent containing an organic compound having an amino group to the surface of the metal member;
Drying the coupling agent applied to the surface of the metal member to form a coupling agent layer on the surface of the metal member;
Exposing the coupling agent layer formed on the surface of the metal member to a high humidity atmosphere;
Forming a resin member directly on the coupling agent layer formed on the surface of the metal member;
With
The temperature of the high humidity atmosphere is 0 ° C. or more and 100 ° C. or less, and the relative humidity of the high humidity atmosphere is 15% or more and 100% or less,
In the step of exposing the coupling agent layer to the high-humidity atmosphere, the exposure time for exposing the coupling agent layer to the high-humidity atmosphere is 1 second to 48 hours,
The high-humidity atmosphere is an atmosphere that satisfies the following conditional expressions (1) and (2).

Here, K is a water vapor exposure coefficient, M _{w_max} is a saturated water vapor amount (g / m ³ ), RH is a relative humidity (%) in a high humidity atmosphere, and t is the exposure time ( h), and T is the temperature (° C.) of the high humidity atmosphere.

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