JP2004141907A - Tool for removing molten oxide on molten solder surface, and device and method for manufacturing electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the degree of removing molten oxide films from a molten solder surface and to suppress occurrence of the void. <P>SOLUTION: A molten oxide removing tool 4 is fitted to a tip of a robot arm with a fitting part 4b, and brought into contact with the molten solder surface by the robot arm. Small recesses 4a are distributed in a lattice on a lower surface in which the molten oxide removing tool 4 is brought into contact with the molten solder surface. The small recesses 4a suck molten oxides by utilizing the surface tension of the molten oxides, and remove the molten oxide film from a face side of the molten solder. A projection portion 4c can be fitted to the molten oxide removing tool 4, and the contact height is controlled with high accuracy by the projection portion 4c. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for removing a molten oxide present on the surface of a molten solder.
[0002]
2. Description of the Related Art In many cases, an electronic device is manufactured by soldering a bottom surface of a second component (for example, a chip element) to a surface of a first component (for example, a lead frame or a ceramic substrate). Usually, the solder on the surface of the first component is heated and melted in a reducing atmosphere. Even if a reducing atmosphere is used, the molten oxide floats on the surface of the molten solder and is covered with a film of the molten oxide. This molten oxide film reduces the wettability of the solder to components (such as chip elements). If the solder is not sufficiently wetted by the component, air bubbles (voids) may be generated between the solder surface and the component. When voids are generated, the joining strength between components decreases. In addition, the electric characteristics are deteriorated. Since the molten oxide film floating on the surface of the molten solder causes voids and leads to poor quality of the electronic device, it is necessary to remove the molten oxide film from the surface of the molten solder.
Conventionally, in order to remove the molten oxide film, a technique to remove the molten solder while maintaining it in a reducing atmosphere, or to remove the molten oxide film floating on the surface of the molten solder using a chip element adsorbed and held on a jig A technique of stirring and pulverizing is known (for example, Patent Document 1). In addition, Patent Documents 2 to 5 also introduce techniques for taking measures against a molten oxide film floating on the solder surface.
[0003]
[Patent Document 1]
JP-A-9-17811 [Patent Document 2]
JP-A-3-8347 [Patent Document 3]
JP-A-64-74730 [Patent Document 4]
JP-A-5-269576 [Patent Document 5]
JP-A-10-325853
However, in the prior art, the degree of removal of the molten oxide film was low, and the generation of voids was not sufficiently suppressed.
[0005]
In the present invention, a technique for increasing the extent to which the molten oxide film is removed from the surface of the molten solder and for sufficiently suppressing the generation of voids is created.
[0006]
In order to achieve the above object, the present invention has created a jig for removing molten oxide. This jig is characterized in that fine recesses for sucking the molten oxide using the surface tension of the molten oxide are dispersedly arranged on the surface in contact with the surface of the molten solder.
On the surface of the jig in contact with the surface of the molten solder, fine recesses for sucking the molten oxide by utilizing the surface tension of the molten oxide are dispersedly arranged. Therefore, when the jig is brought into contact with the surface of the molten solder, the molten oxide existing on the surface of the molten solder is sucked into the fine recess and removed from the surface of the molten solder. According to the technology that removes the molten oxide by sucking it into the micro recesses, the technology that removes the molten oxide by maintaining the molten solder in a reducing atmosphere, or the method that stirs and grinds the molten oxide film that floats on the surface of the molten solder The degree of removal can be improved as compared with the technique which performs the removal.
[0007]
In the present invention, an apparatus for manufacturing an electronic device in which the bottom surface of the second component is soldered to the surface of the first component has also been created. In this apparatus, means for heating and melting the solder on the surface of the first component in a reducing atmosphere and fine recesses for sucking the molten oxide using the surface tension of the molten oxide are dispersedly arranged. A jig, a means for bringing the jig into contact with the surface of the molten solder and then separating the jig, and a means for bringing the bottom surface of the second component into contact with the molten solder from which the molten oxide has been removed.
In this device, an electronic device is manufactured by soldering a bottom surface of a second component (for example, a chip element) to a surface of a first component (for example, a lead frame or a ceramic substrate). For this purpose, the device comprises means for heating and melting the solder on the surface of the first component in a reducing atmosphere. In addition, a jig in which fine recesses for sucking the molten oxide by utilizing the surface tension of the molten oxide are dispersed is provided. Further, there is provided means for bringing the jig into contact with the surface of the molten solder and then separating the jig. By bringing the jig into contact with the molten solder surface, the molten oxide present on the molten solder surface is sucked into the fine recess, and by separating the jig sucking the molten oxide into the fine recess from the molten solder surface, The molten oxide can be effectively removed from the surface of the molten solder. A means for contacting the bottom surface of the second component with the molten solder from which the molten oxide has been removed from the surface allows soldering so that voids are not generated between the bottom surface of the second component and the solder It becomes.
According to the manufacturing apparatus of the present invention, since the second component is soldered after removing the molten oxide present on the surface of the molten solder, it is possible to prevent the generation of voids and stably produce a good quality electronic device. Can be manufactured.
[0008]
Further, in the present invention, a method for manufacturing an electronic device by soldering the bottom surface of the second component to the surface of the first component has been created. In this method, a step of heating and melting the solder on the surface of the first component in a reducing atmosphere, a step of using the surface tension of the molten oxide to suck the molten oxide into the fine recess, Contacting the bottom surface of the second component with the molten solder from which the molten oxide has been removed.
According to this method, the second component can be soldered after the molten oxide is removed from the surface of the molten solder, and a high-quality electronic device without voids can be manufactured.
[0009]
DESCRIPTION OF THE PREFERRED EMBODIMENTS The main features of the embodiment described below are listed.
(Embodiment 1) On the surface of the molten oxide removing jig that is in contact with the surface of the molten solder, spot-shaped recesses having a square, rectangular, or circular cross section are dispersed and arranged in a grid. In this case, the length of the wall forming the recess per unit area of the jig surface can be secured long, and a large amount of the molten oxide can be sucked and removed into the recess group.
(Mode 2) Each recess is formed by a linearly extending groove, and a plurality of grooves are arranged in parallel. Since this jig can be manufactured by processing a linearly extending groove, it can be manufactured at low cost.
(Embodiment 3) Each recess is formed by a groove extending linearly, and a plurality of grooves are radially arranged. Since this jig can be manufactured by processing a linearly extending groove, it can be manufactured at low cost. Further, the surface of the molten solder has a dome shape, and a large amount of molten oxide floats at the top of the molten solder. A large amount of molten oxide can be sucked near the radiation center where the density of the arrangement of the suction grooves is high, by locating the radiation center of the suction grooves and the top portion in correspondence.
(Embodiment 4) Each recess is formed by a through hole. The through holes are easy to process, and jigs can be manufactured at low cost. Further, it is easy to clean the sucked oxide. However, each recess does not need to penetrate the jig, and the upper part may be closed.
(Mode 5) The jig is made of a material having a low bonding strength with the solidified solder while a strong surface tension acts between the jig and the molten solder.
[0010]
Next, a first embodiment according to the present invention will be described in detail with reference to FIGS. In the first embodiment, an electronic device manufacturing apparatus having a robot arm is used. At the tip of the robot arm, a holder (a collet or the like) for holding a molten oxide removing jig or a chip element (a second component in the claims) can be attached. In addition, a solder foil is heated and melted to join the components, and a chip element (a second component in the claims) is mounted on a substrate (a first component in the claims) via the heated and melted solder.
First, a solder foil 2 is set on a substrate 1 as shown in FIG. At this time, the solder foil 2 is solidified, and the entire surface is covered with the oxide film 2a.
Next, as shown in FIG. 2, the substrate 1 is placed in a reflow furnace (not shown) in a reducing atmosphere, the substrate 1 is placed on a heater 66, and the solder foil 2 is heated via the substrate 1. The heating melts the solder foil 2 to form a molten solder 3. The surface of the molten solder 3 has a dome shape due to surface tension. The bottom surface 3b of the molten solder 3 is in close contact with the surface of the substrate 1. The oxide film 2a covering the surface of the solder foil 2 is heated and melted. When the oxide film 2 a covering the lower surface of the solder foil 2 melts, the molten oxide floats because the specific gravity is lower than that of the molten solder 3. No oxide or void remains between the bottom surface 3b of the molten solder 3 and the surface of the substrate 1. The dome-shaped surface of the molten solder 3 has a floating molten oxide derived from the oxide film 2 a covering the lower surface of the solder foil 2, and an oxidized surface covering the upper surface of the solder foil 2. It is covered with the molten oxide derived from the material coating 2a (this is referred to as a molten oxide coating 3a).
Next, as shown in FIG. 3, the molten oxide removing jig 4 attached to the tip of the arm 60 of the robot 62 of the electronic device manufacturing apparatus is lowered from above, and the flat lower surface of the molten oxide removing jig 4 is The molten solder 3 is brought into contact with the top of the dome-shaped surface.
FIG. 4A is a diagram in which the lower surface of the molten oxide removing jig 4 is viewed from below, and FIG. 4B is a BB cross-sectional view. As shown in FIG. 4, on the lower surface of the molten oxide removing jig 4, recesses 4a having a square cross section are dispersedly arranged in a lattice. The cross section of each of the recesses 4a is sufficiently small, and the molten oxide is sucked into the recess 4a by the surface tension acting between the wall forming the recess 4a and the molten oxide, and rises up the recess 4a. It is configured to have a size that allows a capillary action to occur. The molten oxide removing jig 4 is made of a material (for example, carbon or glass) having a low bonding strength with the solidified solder while a strong surface tension acts on the molten solder. By arranging the recesses 4a in a lattice shape, it is possible to sufficiently secure the length of the wall forming the recesses 4a that comes into contact with the molten solder per unit area of the lower surface of the molten oxide removing jig 4. . Therefore, a sufficient amount of the molten oxide can be sucked into the recesses 4a.
Each recess 4a penetrates from the lower surface to the upper surface of the molten oxide removing jig 4, and the sucked oxide can be easily cleaned by an air jet. Since the molten oxide removing jig 4 is made of a material having a low bonding strength with the solidified solder, it can be easily cleaned by an air jet.
The group of recesses 4a can be processed by physical processing or chemical processing. For example, the group of recesses 4a can be processed by mechanical processing using die punching or scribing, laser processing using excimer laser, etching, or the like.
Projections 4c adjusted to a predetermined length extend from four corners of the lower surface of the molten oxide removing jig 4. For this reason, the height (distance from the surface of the substrate 1) of the lower surface of the molten oxide removing jig 4 when the molten oxide removing jig 4 is brought close to the substrate 1 by the robot arm 60 is determined by the protrusion 4c. It is controlled precisely. Further, the molten oxide removing jig 4 includes a mounting portion 4 b connected to the tip of the robot arm 60.
As shown in FIG. 5, when the molten oxide removing jig 4 comes into contact with the top of the molten solder 3, surface tension acts between the molten oxide and the surface of the molten oxide removing jig 4. That is, surface tension acts between the wall forming the recess 4a and the molten oxide, and the molten oxide film 3a is sucked into the recess 4a group by the capillary action. As a result, the molten oxide film 3a on the surface of the molten solder 3 is removed.
When all of the molten oxide film 3a covering the surface of the molten solder 3 is sucked, the molten oxide removing jig 4 is raised and separated from the molten solder 3 as shown in FIG. The molten oxide film 3a is removed from the surface of the molten solder 3, and no molten oxide remains on the surface of the molten solder 3. Since the above processing is performed in a reducing atmosphere, the surface of the molten solder from which the molten oxide film 3a has been removed does not oxidize again.
Next, as shown in FIG. 7, the bottom surface of the chip element 5 held by a holding jig such as a collet 64 attached to the tip of the robot arm 60 of the electronic device manufacturing apparatus is brought into contact with the molten solder 3 at that position. Hold. The molten solder 3 is cooled and solidified, and the chip element 5 is joined to the substrate 1 by the solder. According to the above steps, since the molten oxide 3a is removed from the surface of the molten solder 3 and the chip element 5 is positioned therefrom, no void is generated between the solidified solder 3 and the chip element 5. Therefore, a high-quality electronic device is manufactured. Further, the molten oxide can be removed by a simple method of attaching the molten oxide removing jig 4 to the tip of the robot arm 60 which has been conventionally used.
As shown in FIG. 8, the molten oxide removing jig 4 sucking the molten oxide film 3a is cleaned by an air jet ejected from an air jet ejection port 6 provided at an upper part of the reflow furnace. The oxide 3 a separated from the molten oxide removing jig 4 is dropped on an oxide reservoir 8 along an inclined plate 7 provided below, and is discarded from a pipe 9.
[0011]
(Second embodiment of jig for removing molten oxide)
In the molten oxide removing jig 14 of the second embodiment, as shown in FIG. 9A, the recesses 14a having a square cross section are dispersedly arranged in a lattice, and as shown in FIG. 9B. Thus, the upper part of each recess 14a is covered. That is, it does not penetrate to the upper surface of the molten oxide removing jig 14. The recess may penetrate like the recess 4a shown in FIG. 4B, or may not penetrate like the recess 14a shown in FIG. 9B.
[0012]
(Third embodiment of molten oxide removing jig)
In the molten oxide removing jig 24 of the third embodiment, as shown in FIG. 10A, each recess 24a extends in a stripe shape, and a large number of groove-shaped recesses 24a are parallel at equal intervals. Are located in The groove width is set to a width at which the molten oxide rises in each recess 24a by the capillary phenomenon. Each recess 24a penetrates from the lower surface to the upper surface of the molten oxide removing jig 24 as shown in FIG. This molten oxide removing jig 24 can be easily machined and manufactured at low cost.
(Fourth embodiment of a jig for removing molten oxide)
In the molten oxide removing jig 34 of the fourth embodiment, as shown in FIG. 11A, each recess 34a extends in a stripe shape, and a large number of groove-shaped recesses 34a are parallel at equal intervals. Are located in The groove width is set to a width at which the molten oxide rises in each recess 34a by the capillary phenomenon. Each recess 34a does not penetrate to the upper surface of the molten oxide removing jig 34 as shown in FIG. The recess may penetrate like the recess 24a shown in FIG. 10B, or may not penetrate like the recess 34a shown in FIG. 11B. The molten oxide removing jig 34 can be easily machined and manufactured at low cost.
(Fifth embodiment of the molten oxide removal jig)
In the molten oxide removing jig 44 of the fifth embodiment, as shown in FIG. 12A, each recess 44a is formed by a groove extending linearly, and a plurality of groove-like recesses 44a are formed radially. Are located in The groove width is set to a width at which the molten oxide rises in each recess 44a by the capillary phenomenon. Each recess 44a penetrates from the lower surface to the upper surface of the molten oxide removing jig 44 as shown in FIG. The molten oxide removing jig 44 can be easily machined and manufactured at low cost. Further, by positioning the radiation center 44d at the top of the dome-shaped molten solder 3, a large amount of molten oxide can be sucked in the vicinity of the radiation center 44d where the groove-shaped recesses 44a are arranged at a high density. .
(Sixth embodiment of a device for removing molten oxide)
In the molten oxide removing jig 54 of the sixth embodiment, as shown in FIG. 13A, each recess 54a is formed by a groove extending linearly, and a plurality of groove-like recesses 54a are formed radially. Are located in The groove width is set to a width at which the molten oxide rises in each recess 54a by a capillary phenomenon. Each recess 54a does not penetrate to the upper surface of the molten oxide removing jig 54 as shown in FIG. The recess may penetrate like the recess 44a shown in FIG. 12B or may not penetrate like the recess 54a shown in FIG. 13B. The molten oxide removing jig 54 can be easily machined and manufactured at low cost. Also, by positioning the radiation center 54d at the top of the dome-shaped molten solder 3, a large amount of molten oxide can be sucked in the vicinity of the radiation center 54d where the groove-shaped recesses 54a are arranged at a high density. .
[0013]
As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above.
In addition to the techniques shown in the above application examples, various modified and modified techniques can be used as follows.
-The electronic device manufacturing apparatus of the present embodiment is provided with a robot arm to which a molten oxide removing jig can be attached at the tip. However, the present invention is not limited to this, and may be any electronic device manufacturing apparatus provided with means such as a shaft to which a molten oxide removing jig is attached.
In this embodiment, the electronic device is manufactured by soldering the chip element and the substrate. However, the present invention is not limited to these, and can be used for any combination of components constituting an electronic device such as an electronic element, a terminal, a heat sink, and a housing.
In this embodiment, the solder foil placed on the first component is heated and melted, but is not limited to this. For example, molten solder may be supplied from a supply nozzle onto the first component.
In the present embodiment, the height is controlled by the protrusion attached to the molten oxide removing jig itself, but the present invention is not limited to this. For example, a method for controlling the height of the robot arm may be adopted without providing a portion for controlling the height in the molten oxide removing jig itself. The molten oxide removing jig 54 of FIG. 13 does not have a projection for adjusting the height.
In the present embodiment, the molten oxide removing jig is cleaned by the air jet, but is not limited to this. For example, the oxide may be sucked out using a vacuum.
In the present embodiment, as the molten oxide removing jig, recesses having a square cross section are dispersedly arranged in a lattice, and each recess is formed by a groove extending linearly. The ones arranged in parallel and the ones in which each recess is formed by a groove extending linearly and these grooves are arranged radially are cited. However, the recesses are not limited to these forms, and may be rectangular, circular, etc., as long as they exhibit the action of capillary action, or may be arranged in any manner.
In the present embodiment, the recess of the molten oxide removing jig is provided on the entire lower surface, but is not limited to this, and may be provided at least in a portion in contact with the solder surface.
In the present embodiment, the lower surface of the molten oxide removing jig has a square shape, but the present invention is not limited to this.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. The technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.
[0014]
As described above, according to the present invention, the molten oxide generated on the surface of the molten solder can be completely removed. Therefore, a high-quality electronic device can be manufactured.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a first stage of a manufacturing process of an electronic device.
FIG. 2 is a diagram illustrating a second stage of the manufacturing process of the electronic device.
FIG. 3 is a diagram illustrating a third stage of the manufacturing process of the electronic device.
FIG. 4 is a view showing a first embodiment of a molten oxide removing jig.
FIG. 5 is a diagram showing a fourth stage of the manufacturing process of the electronic device. .
FIG. 6 is a view showing a fifth stage of the manufacturing process of the electronic device.
FIG. 7 is a view showing a sixth stage of the manufacturing process of the electronic device.
FIG. 8 is a view showing a cleaning process of the molten oxide removing jig.
FIG. 9 is a view showing a second embodiment of a molten oxide removing jig.
FIG. 10 is a view showing a third embodiment of a molten oxide removing jig.
FIG. 11 is a view showing a fourth embodiment of a molten oxide removing jig.
FIG. 12 is a view showing a fifth embodiment of a molten oxide removing jig.
FIG. 13 is a view showing a sixth embodiment of a molten oxide removing jig.
[Explanation of symbols]
1: substrate,
2: Solder foil,
3: molten solder,
3a: molten oxide coating 4: molten oxide removal jig,
5: chip element,
6: Air jet spout,
7: inclined plate,
8: Oxide reservoir,
9: Pipe

Claims (3)

A jig for removing the molten oxide on the surface of the molten solder,
A jig in which fine recesses for sucking the molten oxide by utilizing the surface tension of the molten oxide are dispersedly arranged on a surface in contact with the surface of the molten solder. A device for manufacturing an electronic device in which the bottom surface of the second component is soldered to the surface of the first component,
Means for heating and melting the solder on the surface of the first component in a reducing atmosphere;
A jig in which fine recesses for sucking the molten oxide using the surface tension of the molten oxide are dispersedly arranged,
Means for bringing the jig into contact with the molten solder surface and then separating,
Means for bringing the bottom surface of the second component into contact with the molten solder from which the molten oxide has been removed from the surface. A method of manufacturing an electronic device by soldering the bottom surface of the second component to the surface of the first component,
Heating and melting the solder on the surface of the first component in a reducing atmosphere;
A step of sucking the molten oxide into the fine recess using the surface tension of the molten oxide,
Bringing the bottom surface of the second component into contact with the molten solder from which the molten oxide has been removed from the surface.

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