JPH07253440A - Flow velocity measuring jig of jet of melted solder - Google Patents

Abstract

PURPOSE:To accurately measure with high accuracy a flow velocity of a jet of melted solder. CONSTITUTION:A lower end of a sensor arm 11 is dipped in melted solder 40 which becomes a jet discharged from above a jet nozzle 22, and the end of the arm 2 is rotated in a jet direction of the solder 40. An operating rod 17 is integrally rotated by the rotation of the arm 11, and a load applied to the end of the rod 17 is measured by a load cell 16 coupled to the end of the rod 17. The rod 17 transmits a force of the jet of the solder 40 to be applied to the end of the arm 11 to a load detector 16 in an enlarged state. The detector 16 accurately detects a load to be applied to the rod 17 based on a flowing speed of the jet of the solder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms a jet flow when soldering an electronic component to a printed circuit board by applying molten solder discharged upward from a jet nozzle into a jet flow to the printed circuit board. The present invention relates to a flow velocity measuring jig used to measure the flow velocity of molten solder.

[0002]

2. Description of the Related Art When soldering an electronic component to a printed circuit board, molten solder is usually discharged upward from a jet nozzle to form a jet, and the printed board is conveyed along the jet flow to thereby print the printed board. Molten solder is applied to the lower surface of the. As described above, when the molten solder is applied, there is a problem that the quality of the molten solder applied to the printed circuit board largely changes due to the flow rate of the molten solder that has become a jet flow.

For example, when the flow rate of the molten solder increases with respect to the conveying speed of the printed circuit board, the flow rate of the molten solder flowing down along the lower surface of the printed circuit board in the conveying direction of the printed circuit board increases, and a cavity is formed in the molten solder. There is a possibility that a defect called a "tunnel" may occur. Conversely,
When the flow rate of the molten solder becomes smaller than the conveying speed of the printed circuit board, the flow rate of the molten solder flowing down along the lower surface of the printed circuit board in the conveying direction of the printed circuit board becomes smaller, and the molten solder that has adhered to two adjacent points of the printed circuit board becomes There is a possibility that defects such as “touch” in which the two are adhered to each other or “flicker” in which the molten solder adhering to the printed board hangs down may occur.

For this reason, it is necessary to measure the flow rate of the molten solder that has become a jet flow and adjust the jet flow of the molten solder to a predetermined flow rate with respect to the conveyance speed of the printed circuit board.

For example, in Japanese Utility Model Publication No. 2-37493, an impeller is immersed in a molten solder that has become a jet and rotated, and the flow velocity of the molten solder that has become a jet is measured based on the rotation of the impeller. A device is disclosed.

[0006]

However, the jet of molten solder ejected from the jet nozzle is usually in a state where an oxide film is formed on the surface, and in the flow rate measuring device disclosed in the above publication, The impeller is adhered to the oxide film formed on the surface of the molten solder, and the impeller does not rotate smoothly. Therefore, the flow velocity of the jet of molten solder can be detected accurately and highly accurately. There is a problem that you cannot do it.

An apparatus for measuring the flow velocity of the jet flow of the molten solder by electromagnetic force, electric current, etc. has also been developed. Again, the oxide film formed on the surface of the molten solder accurately and highly accurately The flow velocity cannot be measured.

The present invention solves such a problem, and an object thereof is to accurately measure the flow velocity of a molten solder that has become a jet even if an oxide film is formed on the surface of the molten solder. It is to provide a jig for measuring a flow velocity.

[0009]

A jig for measuring the flow velocity of a jet flow of molten solder of the present invention has a lower end portion immersed in the molten solder discharged upward from a jet nozzle to form a jet, and the upper end portion is A vertical sensor arm whose center is pivoted at the lower end in the direction of the molten solder jet, and an operation rod whose base end is attached to the upper end of the sensor arm so as to rotate integrally. And a load detector connected to the tip portion of the operating rod so as to detect the load on the tip portion due to the rotation of the operating rod. To be achieved.

[0010]

In the jig for measuring the flow velocity of the molten solder jet of the present invention, the lower end portion of the sensor arm is immersed in the molten solder discharged upward from the jet nozzle to form a jet, It is rotated in the jet direction of the molten solder.
The operation rod is integrally rotated by the rotation of the sensor arm, and the load applied to the tip of the operation rod is measured by the load detector connected to the tip of the operation rod. The operating rod transmits the force of the molten solder jet applied to the lower end of the sensor arm to the load detector in an expanded state, and the load detector applies the load applied to the operating rod based on the flow velocity of the molten solder jet. Can be detected accurately and with high accuracy. Then, the flow velocity is calculated based on the detection result of the load detector.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a jig for measuring the flow velocity of a molten solder jet of the present invention, FIG. 2 is an enlarged front view of the jig for measuring the flow velocity, and FIG. 3 is a cross section taken along line XX of FIG. It is a figure.

As shown in FIG. 1, the jig 10 for measuring the flow velocity of the molten solder jet of the present invention is arranged above a molten solder bath 21 in which the molten solder 40 is accommodated. Molten solder bath 2
In No. 1, the jet nozzle 22 is arranged in the central portion with the discharge port 22a facing upward. And the jet nozzle 2
The printed circuit board 30 to which the molten solder is applied is conveyed above the second discharge ports 22a in the direction indicated by the arrow A, for example, by a chain conveyor in a substantially horizontal state.

The molten solder 40 is continuously supplied to the lower portion of the jet nozzle 22 in the molten solder tank 21, and the molten solder 40 is ejected as a jet from the ejection port 22a of the jet nozzle 22. There is. The printed circuit board 30 has a discharge port 2
The lower surface is brought into contact with the jet of molten solder discharged from 2a.

The flow rate measuring device 10 of the present invention provided above the molten solder bath 21 has a discharge port 22a of a jet nozzle 22.
It has a vertical sensor arm 11 whose lower end is immersed in a jet of molten solder 40 discharged from the. The upper end of the sensor arm 11 is supported by a rotating shaft 13 so as to be rotatable along the jet direction of the molten solder 40. The rotating shaft 13 is attached to the lower end of the bracket 12 on the printed circuit board. It is supported in a substantially horizontal state orthogonal to the transport direction of 30.

As shown in FIGS. 2 and 3, at the lower end of the sensor arm 11, there is provided a blade portion 11a which is immersed in the jet of the molten solder 40. When the plate portion 11a is immersed in the jet of the molten solder 40,
The sensor arm 11 has a flat plate shape orthogonal to the jet direction of the molten solder 40 so that the sensor arm 11 can be reliably rotated by the molten solder 40. The blade portion 11a has a rectangular shape and has a depth D (m) in the molten solder 40,
It is immersed over the width W (m).

As shown in FIG. 3, the bracket 12 has a bifurcated lower part, and the bifurcated part is
A rotating shaft 13 is installed. And this rotating shaft 13
The upper end of the sensor arm 11 is fitted to the. Further, a base end portion of an operation rod 17 extending in the jet direction of the molten solder 40 in a state substantially orthogonal to the sensor arm 11 is attached to the rotating shaft 13.

The bracket 12 is attached to the lower part of the rotation adjusting tool 15. The rotation adjusting tool 15 is rotatably attached to a support shaft 14 that is parallel to the rotation shaft 13 provided on the bracket 12. The support shaft 14 is fixed to a ceiling or the like, and the rotation adjusting tool 15 includes a sensor arm 11 attached to the rotation adjusting tool 15 via a bracket 12 and a rotation shaft 13 so that the molten solder 40 is jetted in the direction of the jet. The sensor arm 1 is rotated and fixed with respect to the support shaft 14 so as to be orthogonal to the sensor arm 1.
The entire rotation adjusting tool 15 is rotated with respect to the support shaft 14 and is fixed to the support shaft 14 so that 1 does not come into contact with the printed circuit board 30 conveyed onto the jet solder bath 21. .

A load cell 16 as a load detector is fixed to the lower part of the rotation adjusting tool 15. The load cell 16 is disposed adjacent to the bracket 12 in the extending direction of the operation rod 17 described above, and the pressing pin 16a projects downward. This push pin 1
When the lower end of the sensor arm 12 is rotated along the jet flow of the molten solder 40, 6a is pressed upward by the tip of the operation rod 17 that rotates together with the sensor arm 12. , Is connected to the tip of the operating rod 17.

The operation rod 17 has a length B (m) from the axis of the rotating shaft 13 to the axis of the pressing pin 16a of the load cell 16 below the axis of the rotating shaft 13 in the sensor arm 11. It is sufficiently shorter than the length L (m) to the end face.

The flow velocity measuring jig 10 having such a structure is
It is used as follows. For example, before the printed circuit board 30 to which the electronic components are soldered is conveyed onto the molten solder bath 21, the rotation adjusting tool 15 is rotated and the blade portion 11 a provided on the lower end portion of the sensor arm 11 is rotated. Are immersed in the jet of the molten solder 40 discharged from the discharge port 22a of the jet nozzle 22. And the rotation adjusting tool 1
5 is fixed in such a state.

The blade portion 11a of the sensor arm 11
However, when immersed in the jet of the molten solder 40, the sensor arm 11 is rotated in the jet direction of the molten solder 40. With the rotation of the sensor arm 11, the operation rod 17 is also rotated in the same direction, and the tip of the operation rod 17 presses the pressing pin 16a of the load cell 16 upward. As a result, the load cell 16 measures the load applied to the pressing pin 16a.

At this time, as shown in FIG.
The distance B from the axis of the rotary shaft 13 to the axis of the pressing pin 16a of the load cell 16 is sufficiently short with respect to the length L of the sensor arm 11 from the axis of the sensor arm 11 to the lower end of the blade portion 11a. Therefore, the force F ₁ applied to the blade portion 11a by the molten solder 40 becomes a large force F ₂ that pushes the pressing pin 16a upward in a greatly expanded state. Therefore, the load cell 16 detects a large force F ₂ proportional to the force F ₁ applied to the sensor arm 11 by the jet flow of the molten solder 40.

The measurement result of the load cell 16 is input to an arithmetic unit (not shown), and the arithmetic unit calculates the flow velocity of the jet flow of the molten solder 40 based on the force F ₂ detected by the load cell 16. Has become. The calculation by the calculation device is performed as follows, for example.

As described above, when the rectangular lower portion of the blade portion 11a is immersed in the jet of the molten solder 40 over the depth D (m) and the width W (m), the blade portion 11a is formed.
A force F ₁ is applied to the central portion of the nozzle by the jet flow of the molten solder 40. The density of the molten solder 40 is ρ, and the molten solder 4 is
If the flow velocity of the jet flow of 0 is V (m / min), the force F ₁ applied to the blade portion 11a is expressed by the following equation.

F ₁ = ρ × D × W × V ² (1) The rotational moment M ₁ of the sensor arm 11 due to the force F ₁ applied to the blade portion 11a is expressed by the following equation.

M ₁ = F ₁ × (L−D / 2) = ρ × D × W × V ² × (L−D / 2) (2) The operating rod 17 is controlled by the rotational moment M ₁ of the sensor arm 11. Rotates, but the rotational moment M ₂ of the operating rod 17 at this time is due to the pressing pin 16 of the load cell 16.
When the force F ₂ applied to a is expressed by the following equation.

M ₂ = F ₂ × B (3) Since the equations (2) and (3) are the same, the molten solder 4
The flow velocity V of 0 is calculated by the following equation.

Ρ × D × W × V _s ² × (L−D / 2) = F ₂ × B V _s ² = F ₂ × B / ρ × D × W × (L−D / 2) V _s = √ {F ₂ × B / ρ × D × W × (L−D / 2)} (4) Therefore, the load (force) measured by the load cell 16
The jet velocity V of the molten solder 40 discharged from the jet nozzle 22 is calculated based on F ₂ .

When the flow velocity V of the jet flow of the molten solder 40 discharged from the discharge port 22a of the jet nozzle 22 is calculated in this way, the rotation adjusting tool 15 is rotated around the support shaft 14. The sensor arm 11 is fixed at a position where it does not come into contact with the printed circuit board 30 being conveyed. In such a state, the printed circuit board 30 is transported at an optimal transport speed for the calculated jet flow velocity of the molten solder.

FIG. 4 is a schematic view showing a state in which the molten solder 40 is applied to the lower surface of the printed circuit board 30 by the jet flow of the molten solder 40. The quality of the molten solder 40 applied to the lower surface of the printed circuit board 30 is usually the horizontal flow velocity V _{Rh of} the molten solder 40 flowing down the lower surface of the printed circuit board 30,
It is determined based on the relative velocity difference between the jet flow of the molten solder 40 and the horizontal flow velocity V _Sh .

The transport speed of the printed circuit board 30 is V _t , the inclination angle of the printed circuit board 30 with respect to the horizontal is α (usually the transport angle with respect to the horizontal of the conveyor for transporting the printed circuit board 30), and the jet flow of the molten solder 40 is When the inclination angle with respect to the horizontal is β and the flow rate V _{p of} the molten solder 40 flowing down the lower surface of the printed circuit board 30, the horizontal flow rate V _{Rh of} the molten solder 40 flowing down the lower surface of the printed circuit board 30 and the molten solder 40 The horizontal flow velocity V _Sh in the jet is
Each is as follows.

V _Rh = (V _t −V _p ) × cos α (5) V _Sh = V _s × cos α (6) The horizontal flow velocity of the molten solder 40 flowing down the lower surface of the printed circuit board 30. When V _Rh is substantially equal to or slightly larger than the horizontal flow velocity V _Sh in the jet of the molten solder 40,
The molten solder 40 applied to the lower surface of the printed circuit board 30 is
"Touch" that adheres like a bridge, "Turara" that hangs down, "Tunnel" that forms a cavity inside
Almost no such defective state occurs, and the molten solder 40 can be applied well. On the other hand, the horizontal flow velocity V _Rh of the molten solder 40 flowing down the lower surface of the printed circuit board 30 is the horizontal flow velocity V in the jet flow of the molten solder 40.
When it is smaller than _Sh, the number of "tunnels" in which cavities are formed in the molten solder 40 attached to the printed circuit board 30 is increased, whereas "touch" and sagging in a bridge shape occur. The number of defective states such as “flicker” is reduced, and conversely, the horizontal flow velocity V _{Rh of} the molten solder 40 flowing down the lower surface of the printed circuit board 30 is 4
When the flow velocity V _Sh in the horizontal direction in the jet flow of 0 is larger, the defective states of “touch” and “crawler” increase, whereas the defective state of “tunnel” decreases.
As a result, the horizontal flow velocity V _Rh of the molten solder 40 flowing down on the lower surface of the printed circuit board 30 is made substantially equal to or slightly larger than the horizontal flow velocity V _Sh in the jet flow of the molten solder 40, so that the printed circuit board 30 is exposed. Thus, the molten solder 40 can be applied well.

In this way, based on the measurement result of the load cell 16, the flow velocity V in the jet of the molten solder 40 is
For example, the horizontal flow velocity V _Rh of the molten solder 40 flowing down the lower surface of the printed circuit board 30 calculated by a calculation device is substantially equal to or slightly larger than the horizontal flow velocity V _Sh in the jet flow of the molten solder 40. The jet speed of the molten solder discharged from the jet nozzle 22 is adjusted with respect to the transport speed of the printed circuit board 30.

Although the load cell is used as the load detector in the above embodiment, a strain gauge, a displacement sensor or the like can also be used.

[0036]

As described above, the jig for measuring the flow velocity of the molten solder jet according to the present invention, when the lower end portion of the sensor arm is rotated by the molten solder jet, the rotation is expanded to the operation rod. The load that is transmitted and applied to the tip of the operating rod is detected by the load detector, so even if an oxide film is formed on the surface of the molten solder, the sensor arm can be reliably discharged by the jet of molten solder. Rotate. Then, the flow velocity of the molten solder can be accurately and precisely obtained based on the detection result of the load detector.
Therefore, the molten solder can be favorably applied to the printed circuit board.

[Brief description of drawings]

FIG. 1 is a front view showing an example of a jig for measuring the flow velocity of a molten solder jet of the present invention.

FIG. 2 is an enlarged view of a main part of a jig for measuring the flow velocity of the jet flow of the molten solder.

3 is a sectional view taken along line XX of FIG.

FIG. 4 is a schematic diagram for explaining a coating state of molten solder on a printed circuit board by a jet flow of molten solder.

[Explanation of symbols]

 10 Flow rate measuring jig 11 Sensor arm 11a Blade part 12 Bracket 13 Rotating shaft 14 Support shaft 15 Rotating adjusting tool 16 Load cell 16a Pressing pin 17 Operating rod 21 Jet solder tank 22 Jet nozzle 22a Discharge port 30 Printed circuit board 40 Molten solder

Claims (1)

[Claims] 1. A vertical shape in which a lower end is immersed in molten solder discharged upward from a jet nozzle into a jet, and the lower end is rotated around the upper end in the jet direction of the molten solder. A sensor arm, an operation rod whose base end is attached to the upper end of the sensor arm so as to rotate integrally, and an operation rod for detecting the load of the tip end due to the rotation of the operation rod. A load detector connected to the tip of the rod, and a jig for measuring the flow velocity of a jet flow of molten solder, comprising: