1. Field of the Invention
The present invention relates to a method of bonding parts to a substrate using a solder paste such that the parts are disposed at the same position and are aligned in the same direction, and more particularly, to a method of bonding chips to a substrate using a Au—Sn alloy solder paste such that the chips are disposed at the same position and are aligned in the same direction.
Priority is claimed on Japanese Patent Application No. 2008-154003, filed Jun. 12, 2008 and Japanese Patent Application No. 2008-221633, filed Aug. 29, 2008, the content of which is incorporated herein by reference.
2. Description of Related Art
In general, for example, a Au—Sn alloy solder paste has been used to bond a substrate and a semiconductor chip, such as an LED (light emitting diode) chip, a GaAs optical chip, a GaAs high-frequency chip, or a heat transfer chip. A Au—Sn alloy solder paste has been known which is obtained by mixing Au—Sn eutectic alloy gas-atomized powder having a composition including 15 mass % to 25 mass % of Sn (preferably, 20 mass % of Sn) and the balance composed of Au and inevitable impurities with a commercial flux including rosin, an activator, a solvent, and a viscosity improver.
When the Au—Sn alloy solder paste is used to bond the chip and the substrate, there are the following advantages. Since a Au—Sn alloy solder bonding layer is made of a Au—Sn solder alloy, the thermal conductivity and bonding reliability are high. Since the Au—Sn alloy solder paste is paste, it is possible to collectively supply the Au—Sn alloy solder paste to a plurality of bonding portions and collectively perform a heat treatment thereon. In addition, during a reflow process, since a flux covers the surface of the Au—Sn solder alloy, an oxide film is less likely to be formed. Therefore, the fluidity of a molten Au—Sn solder alloy is high during bonding and the wettability thereof is high. Therefore, it is possible to use the entire surface of the chip as a bonding surface. Further, it is not necessary to apply an excessive load to the chip during bonding.
In order to bond the substrate and the chip using the Au—Sn alloy solder paste, first, as shown in a longitudinal cross-sectional view of
[Patent Citation 1]
Japanese Unexamined Patent Application, First Publication No. 2007-61857
In particular, in order to industrially solder the chip 4 to the substrate, a plurality of metallization layers is formed in a line on a wide substrate. A Au—Sn alloy solder paste is mounted or applied to the plurality of metallization layers and chips are regularly mounted on the Au—Sn alloy solder paste. In this state, the chips are put into a heating furnace and the chips are soldered to the substrate by one reflow process. During the reflow process, the chips are rotated and soldered to the substrate while being inclined with respect to the arranged metallization layers of the substrate so as to deviate from the central of the metallization layer in a random direction, which is not preferable as a product to be shipped. In addition, when a package size is further reduced in the future and the distance between the chips is short, the chips are likely to contact each other.
In order to solve the above-mentioned problems and achieve an object of the present invention, the present invention uses the following methods.
(1) According a method of bonding a part to a substrate using a solder paste in a first aspect of the present invention, the method includes mounting or applying the solder paste between a metallization layer formed on the substrate and a metallization layer formed on the part, and soldering the part and the substrate by performing a reflow process in a non-oxidizing atmosphere, wherein the metallization layer formed on the surface of the substrate is planar and includes a metallization layer main portion that has an area smaller than that of the metallization layer of the part and a solder guide portion that protrudes from a periphery of the metallization layer main portion.
(2) The solder paste may be a Au—Sn alloy solder paste obtained by mixing a flux with a Au—Sn alloy solder powder including 20 mass % to 25 mass % of Sn and the balance composed of Au and inevitable impurities.
(3) The solder paste may be a Pb—Sn alloy solder paste obtained by mixing a flux with a Pb—Sn alloy solder powder including 35 mass % to 60 mass % of Pb and the balance composed of Sn and inevitable impurities.
(4) The solder paste may be a Pb—Sn alloy solder paste obtained by mixing a flux with a Pb—Sn alloy solder powder including 90 mass % to 95 mass % of Pb and the balance composed of Sn and inevitable impurities.
(5) The solder paste may be a Pb-free solder paste obtained by mixing a flux with a Pb-free alloy solder powder including 40 mass % to 100 mass % of Sn and the balance composed of one or more kinds of metal selected from a group consisting of Ag, Au, Cu, Bi, Sb, In, and Zn and inevitable impurities.
(6) The part may be a chip.
(7) The metallization layer formed on the substrate may be an electrode film.
(8) According to a method of bonding a part to a substrate using a solder paste in a second aspect of the present invention, the method includes mounting or applying the solder paste between a metallization layer formed on the substrate and a metallization layer formed on the rectangular part, and soldering the part and the substrate by performing a reflow process in a non-oxidizing atmosphere. The metallization layer formed on the surface of the substrate is planar and includes a metallization layer main portion that has an area smaller than that of the metallization layer of the part, and at least two solder guide portions that protrude from the periphery of the metallization layer main portion, and the angle between two adjacent solder guide portions in the longitudinal direction is equal to an intersection angle between the diagonal lines of the part.
(9) The rectangular part may include a square part.
(10) According to a metallization layer formed on a surface of a substrate in a third aspect of the present invention, the metallization layer is planar and includes a metallization layer main portion and a solder guide portion protruding from the periphery of the metallization layer main portion.
(11) In the metallization layer according to (10), the metallization layer formed on the substrate may be an electrode film.
(12) According to a substrate having a metallization layer formed thereon in a fourth aspect of the present invention, the metallization layer is planar and includes a metallization layer main portion and a solder guide portion protruding from the periphery of the metallization layer main portion.
(13) In the substrate according to (12), the metallization layer may be an electrode film.
(14) According to a solder paste in a fifth aspect of the present invention, the solder paste may be a mixture of an alloy solder powder including at least Sn and a flux.
(15) According to a bonded body of a part and a substrate in a sixth aspect of the present invention, the part and the substrate are bonded by the method of bonding according to any one of (1) to (9).
(16) According to a method of producing a bonded body of a part and a substrate in a seventh aspect of the present invention, the bonded body of the part and the substrate is produced using the method of bonding according to any one of (1) to (9).
According to a method of bonding a substrate and a part in the present invention, it is possible to solder all parts at desired positions and in a desired direction.
The inventors have conducted a study on a bonding method capable of soldering a chip to a substrate such that the chip is constantly disposed at the same position with respect to a metallization layer of the substrate and is aligned in a given direction. As a result, it was found that the position and direction of the chip after soldering was able to be aligned in the following embodiments.
(i) As shown in a longitudinal cross-sectional view of
The thickness of the metallization layer 12 is not particularly limited, but it is preferable that the thickness of the metallization layer 12 be, for example, equal to or more than 0.02 μm and equal to or less than 50 μm. It is more preferable that the thickness of the metallization layer 12 be, for example, equal to or more than 0.05 μm and equal to or less than 10 μm. A material forming the outermost surface of the metallization layer 12 is not particularly limited, but it is preferable that the outermost surface of the metallization layer 12 be made of, for example, Au, Ag, or Cu in terms of the wettability of solder. The metallization layer is formed by, for example, a plating method, a sputtering method, or a coating method. The width W1 of the solder guide portion 12B is not particularly limited. However, for example, the width W1 of the solder guide portion 12B is preferably in the range of 5% to 50% of the length of one side of the main portion 12A, and more preferably in the range of 10% to 40% of the length. When the width W1 is too small or too large, the effect of positioning the chip 14 is reduced. As shown in
A Au—Sn alloy solder paste 13 is mounted on the metallization layer main portion 12A. The amount of paste 13 may be equal to that in the conventional method. Specifically, the thickness of the solder bonding layer after soldering is preferably in the range of 1 μm to 25 μm and more preferably in the range of 1 μm to 10 μm. The chip 14 with an area more than that of the metallization layer main portion 12A is mounted on the Au—Sn alloy solder paste 13 in an arbitrary direction. At that time, in the present invention, even though an accurate positioning process is not performed, it is possible to align the direction of the chip 14 after soldering using the solder guide portion 12B. Therefore, it is possible to reduce a production cost corresponding to a reduction in the positioning accuracy during assembly.
In this state, when a reflow process is performed in an inert gas atmosphere, the solder paste 13 is melted, and the chip 14 is rotated and moved to a relative position (
(ii) The metallization layer main portion 12A and the solder guide portion 12B protruding from the metallization layer main portion 12A may be used as an electrode film of a semiconductor chip, such as an LED (light emitting diode) chip, a GaAs optical chip, a GaAs high-frequency chip, or a heat transfer chip.
(iii) The phenomenon shown in (i) is not limited to the substrate and the chip, but also occurs in a general part mounted on the substrate. Therefore, the present invention may be applied to a general part.
(iv) It is preferable that the solder paste be a Au—Sn alloy solder paste. However, instead of the Au—Sn alloy solder paste, the following solder paste may be used: a Pb—Sn alloy solder paste obtained by mixing a flux with Pb—Sn alloy solder powder including 35 mass % to 60 mass % of Pb and the balance composed of Sn and inevitable impurities; a Pb—Sn alloy solder paste obtained by mixing a flux with Pb—Sn alloy solder powder including 90 mass % to 95 mass % of Pb and the balance composed of Sn and inevitable impurities; or a Pb-free solder paste obtained by mixing a flux with Pb-free alloy solder powder including 40 mass % to 100 mass % of Sn and the balance composed of one or more kinds of metal selected from a group including Ag, Au, Cu, Bi, Sb, In, and Zn and inevitable impurities. In this case, the same effect as that when the Au—Sn alloy solder paste is used is obtained.
Other embodiments of the present invention are shown in
It is preferable that the shape of the metallization layer main portion formed on the substrate be the same as that of the chip, but the shape of the metallization layer main portion is not particularly limited. For example, as shown in
The solder guide portion may protrude from any position of the periphery of the metallization layer main portion. For example, as shown in
(v)
(vi) When a chip 24 with a rectangular shape is used, as shown in
(vii) The phenomenon shown in (v) is not limited to the substrate and the square chip, but also occurs when a general square part is mounted on the substrate. In addition, the phenomenon shown in (vi) is not limited to the substrate and the rectangular chip, but also occurs when a general rectangular part is bonded to the substrate. Therefore, it is possible to apply this phenomenon to the bonding between the substrate and a square part or the bonding between the substrate and a rectangular part, thereby soldering the part to the substrate at a given position and in a given direction.
As shown in the embodiment of
It is preferable that the solder guide portion have a strip shape with a constant width, as shown in
It is preferable that the number of solder guide portions be four, as shown in
As shown in
Au—Sn alloy solder powder having a composition including 20 mass % of Sn and the balance composed of Au and having an average particle diameter D50 of 11.1 μm and a maximum particle diameter of 20.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Au—Sn alloy solder powder such that a composition including 8.0 mass % of RMA flux and the balance composed of Au—Sn alloy solder powder was obtained, thereby producing a Au—Sn alloy solder paste with a paste viscosity of 85 Pa·s. In addition, the Au—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 LED chips each having a dimension of a length of 400 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 400 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers shown in
In the 50 metallization layers each having the metallization layer main portion and the solder guide portion, 0.03 mg of Au—Sn alloy solder paste was applied onto the center of the metallization layer main portion by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Au—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 300° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviation of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the y-axis direction was calculated as the standard deviation of the average y-axis position. As a result, it was found that the deviation of the chip central position in the y-axis direction was ±4.2 μm, and the position accuracy of the chip was very high.
Pb—Sn alloy solder powder having a composition including 37 mass % of Pb and the balance composed of Sn and having an average particle diameter D50 of 11.4 μm and a maximum particle diameter of 14.5 μm was used as a solder alloy. A commercial RMA flux was mixed with the Pb—Sn alloy solder powder such that a composition including 11.0 mass % of RMA flux and the balance composed of Pb—Sn alloy solder powder was obtained, thereby producing a Pb—Sn alloy solder paste with a paste viscosity of 120 Pa·s. In addition, the Pb—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
The dispenser was used to apply 0.02 mg of Pb—Sn alloy solder paste onto 50 metallization layers each having the metallization layer main portion and the solder guide portion manufactured in Example 1. The previously prepared 50 LED chips were mounted on the Pb—Sn alloy solder paste. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 220° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviation of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the y-axis direction was calculated as the standard deviation of the average y-axis position. As a result, it was found that the deviation of the chip central position in the y-axis direction was ±5.8 μm, and the position accuracy of the chip was very high.
Pb—Sn alloy solder powder having a composition including 95 mass % of Pb and the balance composed of Sn and having an average particle diameter D50 of 11.7 μm and a maximum particle diameter of 14.8 μm was used as a solder alloy. A commercial RA flux was mixed with the Pb—Sn alloy solder powder such that a composition including 10.0 mass % of RA flux and the balance composed of Pb—Sn alloy solder powder was obtained, thereby producing a Pb—Sn alloy solder paste with a paste viscosity of 80 Pa·s. In addition, the Pb—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
The dispenser was used to apply 0.03 mg of Pb—Sn alloy solder paste onto 50 metallization layers each having the metallization layer main portion and the solder guide portion manufactured in Example 1. The previously prepared 50 LED chips were mounted on the Pb—Sn alloy solder paste, and a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 330° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviation of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the y-axis direction was calculated as the standard deviation of the average y-axis position. As a result, it was found that the deviation of the chip central position in the y-axis direction was ±6.7 μm, and the position accuracy of the chip was very high.
Pb-free solder powder having a composition including 96.5 mass % of Sn, 3.0 mass % of Ag, and the balance composed of Cu and having an average particle diameter D50 of 10.8 μm and a maximum particle diameter of 14.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Pb-free solder powder such that a composition including 12.5 mass % of RMA flux and the balance composed of Pb-free solder powder was obtained, thereby producing a Pb-free solder paste with a paste viscosity of 72 Pa·s. In addition, the Pb-free solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
The dispenser was used to apply 0.02 mg of Pb-free solder paste onto 50 metallization layers each having the metallization layer main portion and the solder guide portion manufactured in Example 1. The previously prepared 50 LED chips were mounted on the Pb-free solder paste, and a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 240° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviation of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the y-axis direction was calculated as the standard deviation of the average y-axis position. As a result, it was found that the deviation of the chip central position in the y-axis direction was ±5.1 μm, and the position accuracy of the chip was very high.
Au—Sn alloy solder powder having a composition including 20 mass % of Sn and the balance composed of Au and having an average particle diameter D50 of 11.1 μm and a maximum particle diameter of 20.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Au—Sn alloy solder powder such that a composition including 8.0 mass % of RMA flux and the balance of Au—Sn alloy solder powder was obtained, thereby producing a Au—Sn alloy solder paste with a paste viscosity of 85 Pa·s. In addition, the Au—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 LED chips each having a dimension of a length of 400 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 400 μm, and a width of 400 μm was formed on entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers shown in
0.03 mg of Au—Sn alloy solder paste was applied onto the center of each of the 50 metallization layers, which were the composite metallization layers, by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Au—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 300° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviation of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the y-axis direction was calculated as the standard deviation of the average y-axis position. As a result, it was found that the deviation of the chip central position in the y-axis direction was ±38.2 μm, and the position accuracy of the chip was low.
Au—Sn alloy solder powder having a composition including 20 mass % of Sn and the balance composed of Au and having an average particle diameter D50 of 11.1 μm and a maximum particle diameter of 20.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Au—Sn alloy solder powder such that a composition including 8.0 mass % of RMA flux and the balance composed of Au—Sn alloy solder powder was obtained, thereby producing a Au—Sn alloy solder paste with a paste viscosity of 85 Pa·s. In addition, the Au—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 square LED chips each having a dimension of a length of 400 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 400 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers having a planar shape shown in
In the 50 metallization layers each having the metallization layer main portion and the solder guide portion, 0.03 mg of Au—Sn alloy solder paste was applied onto the center of the metallization layer main portion by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Au—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 300° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviations of the central positions of the bonded 50 LED chips in the y-axis direction and the x-axis direction were calculated as the standard deviation of the average y-axis position and the standard deviation of the average x-axis position, respectively. As a result, it was found that the deviation of the chip central position in the x-axis direction was ±4.8 μm, and the deviation of the chip central position in the y-axis direction was ±5.2 μm. Accordingly, the position accuracy of the chip was very high.
Pb—Sn alloy solder powder having a composition including 37 mass % of Pb and the balance composed of Sn and having an average particle diameter D50 of 11.4 μm and a maximum particle diameter of 14.5 μm was used as a solder alloy. A commercial RMA flux was mixed with the Pb—Sn alloy solder powder such that a composition including 11.0 mass % of RMA flux and the balance composed of Pb—Sn alloy solder powder was obtained, thereby producing a Pb—Sn alloy solder paste with a paste viscosity of 120 Pa·s. The Pb—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 rectangular LED chips each having a dimension of a length of 200 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 200 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers having a planar shape shown in
In the 50 metallization layers each having the metallization layer main portion and the solder guide portion, 0.02 mg of Pb—Sn alloy solder paste was applied onto the center of the metallization layer main portion by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Pb—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 220° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviations of the central positions of the bonded 50 LED chips in the x-axis direction and the y-axis direction were calculated as the standard deviation of the average x-axis position and the standard deviation of the average y-axis position, respectively. As a result, it was found that the deviation of the chip central position in the x-axis direction was ±7.1 μm, and the deviation of the chip central position in the y-axis direction was ±6.8 μm. Accordingly, the position accuracy of the chip was very high.
Pb—Sn alloy solder powder having a composition including 95 mass % of Pb and the balance composed of Sn and having an average particle diameter D50 of 11.7 μm and a maximum particle diameter of 14.8 μm was used as a solder alloy. A commercial RA flux was mixed with the Pb—Sn alloy solder powder such that a composition including 10.0 mass % of RA flux and the balance composed of Pb—Sn alloy solder powder was obtained, thereby producing a Pb—Sn alloy solder paste with a paste viscosity of 80 Pa·s. The Pb—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 rectangular LED chips each having a dimension of a length of 200 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 200 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers having the planar shape shown in
In the 50 metallization layers each having the metallization layer main portion and the solder guide portion, 0.03 mg of Pb—Sn alloy solder paste was applied onto the center of the metallization layer main portion by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Pb—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 330° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviations of the central positions of the bonded 50 LED chips in the x-axis direction and the y-axis direction were calculated as the standard deviation of the average x-axis position and the standard deviation of the average y-axis position, respectively. As a result, it was found that the deviation of the chip central position in the x-axis direction was ±6.6 μm, and the deviation of the chip central position in the y-axis direction was ±7.2 μm. Accordingly, the position accuracy of the chip was very high.
Pb-free solder powder having a composition including 96.5 mass % of Sn, 3.0 mass % of Ag, and the balance composed of Cu and having an average particle diameter D50 of 10.8 μm and a maximum particle diameter of 14.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Pb-free solder powder such that a composition including 12.5 mass % of RMA flux and the balance composed of Pb-free solder powder was obtained, thereby producing a Pb-free solder paste with a paste viscosity of 72 Pa·s. The Pb-free solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 square LED chips each having a dimension of a length of 400 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 400 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers having the planar shape shown in
In the 50 metallization layers each having the metallization layer main portion and the solder guide portion, 0.02 mg of Pb-free solder paste was applied onto the center of the metallization layer main portion by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Pb-free solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 240° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviations of the central positions of the bonded 50 LED chips in the x-axis direction and the y-axis direction were calculated as the standard deviation of the average x-axis position and the standard deviation of the average y-axis position, respectively. As a result, it was found that the deviation of the chip central position in the x-axis direction was ±9.3 μm, and the deviation of the chip central position in the y-axis direction was ±8.9 μm. Accordingly, the position accuracy of the chip was very high.
Au—Sn alloy solder powder having a composition including 20 mass % of Sn and the balance composed of Au and having an average particle diameter D50 of 11.1 μm and a maximum particle diameter of 20.1 μm was used as a solder alloy. A commercial RMA flux was mixed with the Au—Sn alloy solder powder such that a composition including 8.0 mass % of RMA flux and the balance composed of Au—Sn alloy solder powder was obtained, thereby producing a Au—Sn alloy solder paste with a paste viscosity of 85 Pa·s. In addition, the Au—Sn alloy solder paste was filled in a syringe and the syringe was mounted in a dispenser (model number: ML-606GX manufactured by Musashi Engineering, Inc.).
In addition, 50 LED chips each having a dimension of a length of 400 μm, a width of 400 μm, and a height of 100 μm were prepared; and a Au film having a dimension of a thickness of 3 μm, a length of 400 μm, and a width of 400 μm was formed on the entire one surface of each of the LED chips by plating.
An alumina substrate was prepared, and 50 metallization layers, which were composite metallization layers each including a Cu layer having a dimension of a length of 500 μm, a width of 500 μm, and a thickness of 10 μm; a Ni layer having a dimension of a length of 500 μm, a width of 500 μm, and a thickness of 5 μm; and a Au layer having a dimension of a length of 500 μm, a width of 500 μm, and a thickness of 0.1 μm; were formed in a line on the surface of the alumina substrate at an interval of 600 μm.
0.03 mg of Au—Sn alloy solder paste was applied onto the center of each of the 50 metallization layers, which were the composite metallization layers, by a previously prepared dispenser. The previously prepared 50 LED chips were mounted on the Au—Sn alloy solder paste by a mounter. In this state, a reflow process of maintaining the chips under the conditions of a nitrogen atmosphere, and a temperature of 300° C. was performed for 30 seconds. Then, a cooling process was performed and the central positions of the 50 LED chips arranged in a line were measured by a three-dimensional measuring machine (NEXIV VMR-3020 manufactured by Nikon). Here, the deviations of the central positions of the bonded 50 LED chips, which were arranged in a line in the x-axis direction, in the x-axis direction and the y-axis direction was calculated as the standard deviation of the average x-axis position and the standard deviation of the average y-axis position, respectively. As a result, it was found that the deviation of the chip central position in the x-axis direction was ±42.1 μm, and the deviation of the chip central position in the y-axis direction was ±37.5 μm. Accordingly, the position accuracy of the chip was low.
While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.
The present invention provides a method of bonding parts to a substrate using solder paste such that the parts are disposed at the same position and are aligned in the same direction, particularly, a method of bonding chips to a substrate using a Au—Sn alloy solder paste such that the chips are disposed at the same position and are aligned in the same direction. Therefore, the present invention has industrial applicability.
Number | Date | Country | Kind |
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2008-154003 | Jun 2008 | JP | national |
2008-221633 | Aug 2008 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2009/060785 | 6/12/2009 | WO | 00 | 11/30/2010 |