JP7555774B2 - Blower and electronic component mounting device - Google Patents

Description

The present invention relates to a blower and an electronic component mounting device.

Mounting machines that mount electronic components such as semiconductor chips onto boards must be carried out in a highly clean space to prevent mounting defects. For this reason, such mounting machines are provided with a cover that covers the mounting machine, and a downflow, an air current that flows downward from the ceiling, is generated inside the cover to exhaust dust and other particles generated from the mechanism, preventing dust from adhering to the electronic components.

The configuration for creating this downflow is such that a pressurized chamber is provided above the space in which the downflow is to be generated, and air is drawn into the pressurized chamber using a fan, blower, etc. to increase the air pressure inside the chamber, and then the air is blown downwards through a flow resistance imparting member provided at the bottom of the pressurized chamber. Also, in order to increase the cleanliness of the air being supplied, it is common to supply air into the pressurized chamber through a fan filter unit such as HEPA.

The flow resistance imparting member provides sufficient flow resistance to make the pressure distribution in the pressurized chamber more uniform and generate a downflow. In addition to mesh materials, punched metal plates with through holes are commonly used as flow resistance imparting members.

Japanese Patent Application Laid-Open No. 62-288433

In recent years, the mounting of electronic components has also come to require a clean environment with Class 1 (ISO 3) cleanliness, the same as the front-end process of semiconductor manufacturing, and extremely fine control has become necessary to prevent the stirring up of dust. For example, in 3D packaging and hybrid bonding, which increase the degree of integration by arranging semiconductor chips in multiple layers, it is necessary to bond electrodes with a very narrow pitch. For this reason, greater precision, for example, precision on the submicron order, is now required when mounting electronic components on a board.

Furthermore, during mounting, errors caused by the operation of the mounting mechanism and dust generated by the operation can lead to poor bonding. However, even if a downflow is created using a fan filter unit as described above, unacceptable amounts of dust can still be stirred up in the required clean environment.

The present invention has been proposed to solve the problems described above, and its purpose is to provide a blower and electronic component mounting device that can create a downflow that can prevent dust from being stirred up.

である。
The blower of the present invention is provided above a chamber and comprises at least one fan filter unit, a pressurizing chamber into which gas from the fine filter unit flows, and a vent plate which constitutes at least a part of the bottom surface of the pressurizing chamber and has a plurality of vent holes through which the gas from the pressurizing chamber passes and which directly faces the chamber, the thickness of the vent plate, which is the vertical length of at least some of the vent holes, being between two-fifths and four-fifths of the diameter of the vent holes,
When the arrangement density of the vent holes is (the number of arranged vent holes)/(the arrangement area of the vent holes) and the opening ratio of the vent holes is {π (diameter of the vent hole)2/4}×(arrangement density of the vent holes), the thickness of at least a part of the vent plate ^is :

It is.

The electronic component mounting device of the present invention has a chamber with the air blower at its top, and a mounting machine that is provided within the chamber and mounts electronic components.

The present invention aims to provide a blower and electronic component mounting device that can create a downflow that can prevent dust from being stirred up.

1 is a partial cross-sectional view showing a schematic configuration of a mounting device to which a blower according to a first embodiment is applied; FIG. 13 is a graph showing the average lateral wind speed in the downflow region for an opening ratio of 10%. 13 is a graph showing the average lateral wind speed in the downflow region for an opening ratio of 20%. 13 is a graph showing the average lateral wind speed in the downflow region when the opening ratio is 50%. 13 is a graph showing the average lateral wind speed in the downflow region for an opening ratio of 70%. 1 is a graph showing an optimum ratio of the thickness of the vent plate and the diameter of the vent hole according to the opening ratio of the vent plate. FIG. 13 is an explanatory diagram showing the change in wind direction in the downflow area when the thickness of the ventilation plate is changed. FIG. 13 is an explanatory diagram showing the airflow when the ventilation plate is made thinner than the optimum value. FIG. 13 is an explanatory diagram showing the airflow when the ventilation plate is made thicker than the optimum value. FIG. 13 is an explanatory diagram showing the airflow when the ventilation plate is set to the optimum value. FIG. 13 is an explanatory diagram showing the airflow when the FFU is installed in the center of the pressurized chamber. 1A is a cross-sectional view showing a mounting device according to a second embodiment, and FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[First embodiment]
[composition]
1, the blower 1 of the present embodiment includes a fan filter unit (FFU) 10, a pressurizing chamber 20, and a ventilation plate 30. The blower 1 is provided in an upper portion of a chamber 40 configured as a clean room.

Although not shown, the fan filter unit (hereafter referred to as FFU) 10 has a ULPA filter installed downstream of the fan, and supplies air purified through the ULPA filter to the pressurized chamber 20. The pressurized chamber 20 is a space into which gas from the FFU 10 flows and the air pressure is increased. The pressurized chamber 20 is a rectangular parallelepiped whose vertical sides are shorter than their horizontal sides.

The ventilation plate 30 constitutes the bottom surface of the pressurized chamber 20. As shown in FIG. 2, the ventilation plate 30 has a plurality of ventilation holes 31 through which gas from the pressurized chamber 20 passes. The ventilation holes 31 are cylindrical through-holes with an axis in the vertical direction. In this embodiment, the ventilation holes 31 are provided at equal intervals on the surface of the ventilation plate 30. The ventilation plate 30 can be, for example, a punched plate in which the ventilation holes 31 are formed by punching a metal or resin plate.

The thickness t of the ventilation plate 30, i.e., its length in the vertical direction, is preferably 3 mm to 7 mm. However, in order to reduce deflection, it is more preferable to set it to 5 mm to 6 mm. The relationship between the thickness t of the ventilation plate 30 and the diameter D of the ventilation hole 31 will be described later.

The chamber 40 is a rectangular parallelepiped container that houses an electronic component mounter 50 inside. A blower 1 is provided at the top of the chamber 40, and the ventilation plate 30 of the pressurized chamber 20 forms the ceiling of the chamber 40. An exhaust port 41 is provided at the bottom of the chamber 40. Therefore, the gas inside the chamber 40, together with dust, is exhausted from the exhaust port 41 at the bottom of the chamber 40. The mounter 50 is installed on a stand 60 that is installed on the floor F of a factory or the like.

である。通気孔３１の配置面積は、通気孔３１が形成された領域を囲う面積であり、通気板３０の全体に均等に通気孔３１が設けられている場合、配置面積は、通気板３０の全体の面積と同等である。 [Thickness of vent plate and diameter of vent hole]
The thickness t of the ventilation plate 30 is 2/5 to 4/5 of the diameter of the ventilation hole 31. In addition, when the arrangement density of the ventilation holes 31 is (the number of arranged ventilation holes)/(arrangement area of the ventilation holes), the cross-sectional area of each ventilation hole 31 perpendicular to the axis is {π(diameter of the ventilation hole) ^2/4 } (π is the circular constant), and the opening ratio of the ventilation holes 31 is {π(diameter of the ventilation hole) ^2/4 }×(arrangement density of the ventilation holes), the thickness t of at least a part of the ventilation plate 30 is

The arrangement area of the ventilation holes 31 is the area surrounding the region in which the ventilation holes 31 are formed, and when the ventilation holes 31 are evenly provided over the entire ventilation plate 30, the arrangement area is equal to the entire area of the ventilation plate 30.

The inventor discovered that the airflow that flows through the through-holes of the conventionally used punched plate is affected by the direction of the airflow in the pressurized chamber. In other words, the airflow in the pressurized chamber above the punched plate does not necessarily flow vertically downward. For example, due to the convenience of the equipment to be installed, there are cases where air must be blown horizontally through a duct, that is, in a direction that intersects with the vertical direction. In this way, if the airflow contains a horizontal flow component, it will also be affected by the horizontal flow and will become a downflow with a large inclination to the vertical direction.

To address this issue, even if a fan filter unit is placed directly above the center of the punching plate, the airflow direction becomes more horizontal the further away from the center of the punching plate, resulting in the same phenomenon as above. It is also possible to place a large number of fan filter units so that air is supplied vertically toward the entire punching plate. However, there is a limit to the amount of equipment that can secure such space above the punching plate, and preparing a large number of fan filter units is problematic in terms of cost. Also, if the pressure loss in the punching plate is increased to supply air vertically toward the entire punching plate, a sufficient downflow rate cannot be obtained, and dust cannot be sufficiently discharged.

The inventors focused on the thickness t of the ventilation plate 30, which had not previously been considered in relation to airflow, as well as the ratio of the thickness t to the diameter D and the opening rate of the ventilation holes 31. They then investigated a value that would allow the thickness t of the ventilation plate 30, which is a simple punched plate, to withstand actual use while still producing a nearly vertical downflow.

The results are shown in Figs. 3 to 6. Figs. 3 to 6 are graphs plotting the average wind speed of the crosswind generated in the downflow region where the airflow becomes a downflow by changing the opening ratio of the air holes 31, with the thickness t of the ventilation plate 30 on the horizontal axis and the diameter D of the ventilation holes 31 on the vertical axis, as shades of hatching. A positive value of the wind speed m/s indicates that the direction is the same as the horizontal direction above the ventilation plate 30, and a negative value indicates that the direction is the opposite horizontal direction. The wind speed was calculated using a three-dimensional finite element method. The "average wind speed of the crosswind generated in the downflow region" is the average wind speed at a cross section downstream four times the length of the thickness t or the pitch of the ventilation holes 31, whichever is greater, from the ventilation plate 30. In each figure, the downflow flow rate per 1 ^m2 of horizontal area is set to 30 ^m3 /min.

3 shows an aperture ratio of 10%, FIG. 4 shows an aperture ratio of 20%, FIG. 5 shows an aperture ratio of 50%, and FIG. 6 shows an aperture ratio of 70%. In each figure, (A) and (B) show different angles at which the airflow in the pressurized chamber 20 hits the vent hole 31 with respect to the vertical direction. (A) is 80°, and (B) is 60°. In other words, the angle of the airflow flowing into the vent hole 31 in (A) is closer to horizontal and shallower. The allowable crosswind is the absolute value of the wind speed of 0.1 m/s or less, that is, the region where the crosswind speed is between -0.1 and +0.1 m/s. In the figure, the "OK" range shown by the dotted line and two-way arrow is the approximate allowable condition region for crosswinds. For this reason, it is preferable to select a vent plate 30 with performance that satisfies such a condition region. Note that the jaggedness of the boundary between the light and dark shades of the hatching is due to errors in numerical calculations.

As shown in Figures 3 to 6, if the airflow is tilted more sharply relative to the vertical direction, i.e., if the angle of the airflow relative to the surface of the ventilation plate 30 is small, the range of acceptable conditions becomes narrower.

If the pressure chamber 20 is made large and the height is secured, the airflow flowing from the pressure chamber 20 into the air vent 31 can be made closer to vertical. However, since the space of the pressure chamber 20 is limited, there is a limit to how much it can be expanded in the height direction. For this reason, we thought of taking measures to ensure that the inflow angle is at least about 80° or more.

Therefore, we focus on the graphs in Figures 3 to 6 (A). In these graphs, the region of allowable conditions is the range inside the straight line passing through the origin, shown by the dotted line. Therefore, in order to keep the crosswinds occurring in the downflow region within an allowable range, it is necessary to set the ratio of thickness t to diameter D (t/D) to a unique value that satisfies the region of allowable conditions.

The optimal value of t/D is around 3/5 (0.6) in all of Figures 3(A) to 6(A). For example, in Figure 6, when the thickness t of the ventilation plate 30 is 3 mm and the diameter of the ventilation hole 31 is 7 mm, this is one of the conditions for tolerating crosswinds. In other words, t/D = 3/7 = 0.43. Also, in Figure 3, when the thickness t of the ventilation plate 30 is 3 mm and the diameter of the ventilation hole 31 is 4 mm, this is one of the conditions for tolerating crosswinds. In other words, t/D = 3/4 = 0.75.

3 and 6, the opening ratio is different, and therefore it can be seen that the conditions under which cross winds can be tolerated differ depending on the opening ratio. This relationship can be expressed by the following approximate formula 1.

The relationship between the optimum value of t/D and the aperture ratio α is shown in Figure 7. The airflow incidence angle is 80°, the downflow flow rate is 30 ^m3 /min, and the plotted points and their range were determined from Figures 3 to 6 under the allowable conditions of the allowable lateral wind speed being ±0.1 m/s or less. Approximation formula 1 was obtained from these determined points. The dotted line is the approximation value of formula 1.

FIG. 8 shows a schematic diagram of the change in wind direction in the downflow area when the vent plate 30 has a different thickness t. The thickness t is 2 mm for (a), 3 mm for (b), 4 mm for (c), 6 mm for (d), 10 mm for (e), 20 mm for (f), and 50 mm for (g). The diameter D of the vent hole 31 is 5 mm, the arrangement pitch of the vent hole 31 is 10 mm (hole opening ratio 19.635%), and the downflow flow rate per 1 ^m2 of horizontal area is 30 ^m3 /min. The angle (incident angle) at which the airflow in the pressurizing chamber 20 hits the vent hole 31 is 80°. The graph shown in the center of FIG. 8 is the same as FIG. 4(A).

8(b), when the thickness t is within the optimal t/D range, a vertical downflow can be generated even if the angle at which the airflow in the pressurizing chamber 20 hits the vent hole 31 is close to horizontal. The direction of the airflow in the chamber 40 in this case can be shown, for example, by the white arrow in FIG. 11 described later. On the other hand, as shown in FIG. 8(a), when the thickness t is thinner than the optimal t/D range, the crosswind in the pressurizing chamber 20 is transmitted to the downflow area in the same direction. The direction of the airflow in the chamber 40 in this case can be shown, for example, by the white arrow in FIG. 9 described later. On the other hand, as shown in FIG. 8(c) to (f), when the thickness t is thicker than the optimal t/D range, the airflow hits the side of the vent hole 31 and is reflected, so that an airflow in the opposite direction to the airflow in the pressurizing chamber 20 is generated. The direction of the airflow in the chamber 40 in this case can be shown, for example, by the white arrow in FIG. 10 described later. In order to suppress the reverse airflow that occurs when the air collides with the side of the vent hole 31, it is necessary to use a very thick vent plate 30, as shown in Figure 8 (g). In other words, it is necessary to prepare a very thick and heavy punched plate, and such conditions are not realistic. Even if there were nozzles that were only vent holes, it would be difficult to arrange a large number of nozzles.

[effect]
This embodiment has an FFU 10, a pressurized chamber 20 into which gas from the FFU 10 flows, and a ventilation plate 30 that forms at least a part of the bottom surface of the pressurized chamber 20 and has a plurality of ventilation holes 31 through which gas from the pressurized chamber 20 passes, and the thickness t of the ventilation plate 30 is two-fifths to four-fifths of the diameter D of the ventilation holes 31.

である。 In addition, when the arrangement density of the ventilation holes 31 is (the number of ventilation holes)/(the arrangement area of the ventilation holes) and the opening ratio of the ventilation holes 31 is {π(diameter of the ventilation hole) ² /4}×(arrangement density of the ventilation holes), the thickness t of the ventilation plate 30 is

It is.

With this configuration, regardless of the direction of the airflow in the pressurized chamber 20, i.e., regardless of cross wind or asymmetric airflow, a downflow airflow with sufficient flow speed and little cross wind can be blown by passing through the air vents 31 in the ventilation plate 30. This suppresses eddies and stagnation of the airflow in the downflow area, reduces the amount of dust that is stirred up, and improves cleanliness. In addition, this can be achieved with a simple structure such as a punched plate.

[Modification]
It should be noted that the FFU 10 cannot always be disposed above the pressurizing chamber 20. In other words, as shown in Figures 9 to 11, due to restrictions in the height direction, air may be supplied from the FFU 10 from the side via a duct. In this case, the duct portion becomes the pressurizing chamber 20.

In such a case, the air supply will mostly have a horizontal component. For example, as shown in FIG. 9, when a vent plate 30 (t/D is 0.3) thinner than the optimal thickness shown in this embodiment is used, a downflow will occur in the chamber 40 with an inclination in the same direction as the airflow in the pressurized chamber 20. As a result, a strong upturned airflow (vortex airflow) will occur on the inside (upstream direction of the airflow in the pressurized chamber 20). Also, as shown in FIG. 10, when a vent plate 30 (t/D is 1.5) thicker than the optimal thickness shown in the embodiment is used, a downflow will occur in the chamber 40 with an inclination in the opposite direction to the airflow in the pressurized chamber 20. As a result, a strong upturned airflow (vortex airflow) will occur on the outside (downstream direction of the airflow in the pressurized chamber 20). On the other hand, when the vent plate 30 (t/D is 0.6) of this embodiment is used, a nearly vertical downflow can be generated in the chamber 40 as shown in FIG. 11. As a result, the air currents that rise up beside the downflow are weak.

As shown in FIG. 12, even if the FFU 10 is provided in the center of the pressurized chamber 20, a nearly vertical downflow can be generated in the area Ra directly below the FFU 10, but in the peripheral area Rb, the airflow becomes more inclined the further away from the center. For this reason, this embodiment may not be applied to the area of the ventilation plate 30 directly below the FFU 10, but may be applied only to the peripheral area Rb.

Second Embodiment
As a second embodiment, a mounting device 2 to which the above-mentioned blower 1 is applied will be described with reference to Fig. 13. In this embodiment, as shown in Fig. 13(A), exhaust paths 51a, 60a continuing from the ventilation plate 30 in a downward direction are provided in the mounting machine 50 and the stand 60. In addition, an exhaust path 40a continuing from the ventilation plate 30 in a downward direction is provided between the stand 60 and the inner wall of the chamber 40. The exhaust path 51a is a hole formed in the bottom of the main body of the mounting machine 50 and penetrating in the vertical direction. This hole is preferably located at least near mechanical parts such as a motor and a sliding part that are sources of dust generation.

The mounting machine 50 mounts, for example, a semiconductor chip on a substrate. The mounting of the semiconductor chip can be face-up bonding, in which the circuit surface of the semiconductor chip faces upward. It can also be face-down bonding, in which the circuit surface faces the substrate. In this case, so-called flip-chip bonding is performed.

The exhaust path 60a is provided on the top surface of the stand 60 and has a through hole that is continuous with the exhaust path 51a, a gap provided inside the stand 60, and a through hole provided in the bottom of the stand 60. The gap inside the stand 60 is left with only the wiring remaining, and anything that would obstruct the airflow, such as a control device, is removed to the outside as much as possible.

In this embodiment, the nearly vertical downflow from the blower 1 is exhausted from the exhaust port 41 on the floor surface F via the exhaust paths 51a, 40a, and 60a. This makes it possible to suppress the up-flooring of dust and achieve highly clean mounting.

As mentioned above, mounting equipment is now also required to have a clean environment that can provide Class 1 (ISO 3) cleanliness, the same level as the front-end of semiconductor manufacturing.

Conventionally, in order to increase the cleanliness of mounting equipment, a typical structure has been to install a HEPA or other FFU on the top, and exhaust the downflow from the FFU from an exhaust fan installed on the back of the mounting equipment cover. However, this can sometimes generate localized fast air currents, creating vortex air currents that stir up dust. This makes it difficult to achieve Class 1. An example of a vortex air current is the air current near the side wall inside chamber 40 in Figures 9 to 11.

In this device, a nearly vertical downflow flows from the FFU 10, which is a ULPA, through the ventilation holes 31 in the ventilation plate 30, and the downflow is guided to the exhaust on the floor surface F side without using an exhaust fan, via exhaust paths 51a, 60a provided on the mounting machine 50 and the stand 60, and exhaust path 40a provided between the stand 60 and the inner wall of the chamber 40. This prevents dust from being stirred up by vortex currents, achieving Class 1.

As shown in FIG. 13B, the FFU 10 is not disposed in an area where the entire interior of the chamber 40 is directly below it. Even in such a case, by applying the ventilation plate 30 shown in the above embodiment, the lateral airflow can be made into a nearly vertical downflow. Also, as described above, the thickness t and diameter D of the ventilation plate 30 may be applied only to areas other than those directly below the FFU 10.

Furthermore, if there is an area of the ventilation plate 30 where it is desired to tilt the downflow in a desired direction relative to the vertical direction, this embodiment may be applied only to that area without applying this embodiment to that area. That is, as described above, the direction of the airflow passing through the ventilation plate 30 can be determined from the thickness t of the ventilation plate 30, the diameter D of the ventilation hole 31, and the aperture ratio α. For this reason, for example, at a position very close to the side wall in the chamber 40, the thickness t of the ventilation plate 30, the diameter D of the ventilation hole 31, and the aperture ratio α can be set so that the airflow is directed toward the side wall and along the side wall. In this way, the airflow that is blown up along the side wall in the chamber 40 can be more effectively suppressed, and dust can be discharged more smoothly.

In addition, depending on the shape of the components such as the mounting machine 50 and the stand 60 installed in the chamber 40 of the mounting device 2, it may be possible to prevent dust from being stirred up by creating an airflow that avoids the components rather than a straight downflow from directly above them. In such cases, the thickness t of the ventilation plate 30, the diameter D of the ventilation hole 31, and the opening rate α can be set to obtain the desired airflow.

The material of the ventilation plate 30 is not important. It can be metal, resin, or ceramic, as long as it has the necessary rigidity and weight.

Furthermore, in the above embodiment, the cross-sectional shape of the ventilation hole 31 is circular. This makes it easier to manufacture. However, any shape, such as elliptical or polygonal, may be used, as long as the effective diameter of the opening through which air can pass is within the range shown in the above embodiment. In this case, the cross-sectional area perpendicular to the axis of each ventilation hole 31 (each hole) used to calculate the opening ratio is the area of the respective shape, such as an ellipse or polygon.

[Other embodiments]
Although the embodiment of the present invention and the modified examples of each part have been described above, these embodiments and the modified examples of each part are presented as examples and are not intended to limit the scope of the invention. These novel embodiments described above can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims.

1 Blower 2 Mounting device 10 Fan filter unit (FFU)
20 Pressurizing chamber 30 Ventilating plate 40 Chamber 60 Stand 51a, 60a, 40a Exhaust path D Diameter F Floor surface t Thickness

Claims (7)

Provided at the top of the chamber,
At least one fan filter unit;
a pressurizing chamber into which gas from the fan filter unit flows;
a ventilation plate that constitutes at least a part of the bottom surface of the pressurizing chamber and has a plurality of ventilation holes through which gas from the pressurizing chamber passes and directly faces the chamber;
having
The thickness of the ventilation plate, which corresponds to the vertical length of at least some of the ventilation holes, is between two-fifths and four-fifths of the diameter of the ventilation hole;
When the arrangement density of the vent holes is (the number of arranged vent holes)/(the arrangement area of the vent holes) and the opening ratio of the vent holes is {π (diameter of the vent hole)2/4}×(arrangement density of the vent holes), the thickness of at least a part of the vent plate ^is :

A blower characterized by: The ventilation plate has an area with a different opening ratio,
In each region having a different opening rate, the thickness of the ventilation plate is

2. The blower according to claim 1 , In an area other than the area directly below the fan filter unit, the thickness of the ventilation plate is

2. The blower according to claim 1 , 4. The blower according to claim 1 , wherein the thickness of the ventilation plate is 3 to 7 mm. A chamber having an upper portion including the blower according to any one of claims 1 to 4 ;
a mounting machine provided in the chamber for mounting electronic components;
An electronic component mounting device comprising: the mounting machine is supported by a stand provided in the chamber,
6. The electronic component mounting apparatus according to claim 5 , wherein the base and the mounting machine are provided with an exhaust path that is continuous from the ventilation plate downward. 7. The electronic component mounting apparatus according to claim 6, further comprising an exhaust path extending downward from said ventilation plate between said stand and an inner wall of said chamber.

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