JPH0145754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molten wax application control section of a wax processing apparatus that sprays molten wax onto a printed circuit board on which electronic components to be soldered are mounted to temporarily fix the wax.

FIG. 1 is a block diagram showing an example of a conventional soldering device. 1 shows the entire soldering device;
2 is a preliminary soldering processing device, 3 is a cutting device, and 4 is a finishing soldering processing device. In these devices, 5, 9 are flux processors, 6,
10 is a preheater, 7 is a dip type soldering bath,
8 and 12 are coolers, and 11 is a jet type solder bath.

FIG. 2 is a partial side cross-sectional view showing how electronic components are mounted on a printed circuit board, 13 is a printed circuit board, 14 is an electronic component such as a resistor, capacitor, IC, etc., and 15 is a lead wire ( or lead terminal), 16 is a through hole through which the lead wire (or lead terminal) 15 is inserted.

In this way, in the conventional soldering device, the printed circuit board 13 is heated twice to attach molten solder to the printed circuit board 13 and the final soldering process, which results in a lot of solder consumption. The components 14 are affected by heat, and the lead terminals 15 of the IC components are connected to the printed circuit board 1.
When performing the final soldering process after inserting it into the through hole 16 of No. 3, the force of the jet solder
There were drawbacks such as IC parts lifting up.
In addition, since the preliminary soldering device 2 has the same equipment as the final soldering device 4, the entire soldering device 1 becomes large, and a large space is required to install the soldering device 1, which reduces costs. There were such shortcomings.

One way to solve these shortcomings is to
A method has been proposed in which electrical components are temporarily fixed to a printed circuit board by spraying molten wax and solidifying it (see Japanese Patent Laid-Open No. 52-3164). However, since no particular consideration was given to the wax treatment section, there was a problem in that the wax was not evenly sprayed onto the printed circuit board.

The present invention was made to solve these problems, and provides a wax processing section of a soldering device that can spray molten wax uniformly over the entire width of a printed circuit board. The present invention will be explained below based on the drawings.

FIG. 3 is a schematic configuration diagram showing an embodiment of the present invention, and numeral 21 indicates the entire carrierless soldering processing apparatus. 22A is a fixed side conveyance chain, 22
Reference numeral B designates a conveyance chain on the movable side, 23 a waxing processing device, 24 a wax processing section, and 25 a molten wax that has been turned into a liquid by heating. Also, the first
The same reference numerals as in FIG. 2 and FIG. 2 indicate the same parts.

Next, the operation shown in FIG. 3 will be explained.

An electronic component 14 is mounted on a printed circuit board 13, and a lead wire 15 is made to protrude downward.

Next, the printed circuit board 13 is processed in the wax processing section 24.
Molten wax 25 is sprayed onto the upper surface, and then the sprayed molten wax 25 is transferred to the cooler 8.
The electronic components 14 are covered with the solidified wax and fixed on the printed circuit board 13. Further, in the case of an IC component, the molten wax 25 also penetrates between the lead terminal 15 and the through hole 16 and is fixed.

Next, the lead wire 15 is cut by the cutting device 3, and soldered by the final soldering device 4 through the processing steps of a flux processor 9, a preheater 10, a solder bath 11, and a cooler 12.

4a and 4b show the wax processing section 24 of FIG. 3, FIG. 4a is a partially cutaway perspective view, and FIG. 4b is an enlarged side sectional view taken along the line X-X of FIG. 4a. It is. In these figures, the same reference numerals as in FIG. 3 indicate the same parts, 26 is a wax tank main body for storing the molten wax 25, and 27 is a wax tank main body 2 for pressurizing and sending out the molten wax 25.
6 is a gear pump provided below, 28 is a motor that drives the gear pump 27, 29 is a control valve that adjusts the flow rate and pressure of the molten wax 25, 30 is a passage for the molten wax 25, and 31 is a motor for driving the molten wax 25. 25 is a filter for removing dust mixed in the molten wax 25; 32 is a passage through which the molten wax 25 filtered by the filter 31 passes; 33 is a plurality of pipes branched from the passage 32 and connected in parallel; 34;
is a flexible tape heater wrapped around the outer circumference of the pipe 33, which heats the molten wax 25 passing through the pipe 33 so that it does not solidify. 3
5 is a heat insulating material that covers the outer periphery of the tape heater 34;
Reference numeral 36 denotes an injection device for injecting the molten wax 25, which is attached to each of the plurality of pipes 33 via a connecting fitting 37, and is connected to the conveying chains 22A, 22 of the soldering device 21 in FIG.
A plurality of them are arranged in a direction perpendicular to the running direction of the printed circuit board 13 carried by the motor B. 38
is a thermostat that detects the temperature of the molten wax 25 in the wax tank body 26.
Note that 39 is a removable lid for removing dust and the like from the filter 31, and 40 is a control panel.

In the gear pump 27, 41 is a drive shaft connected to the motor 28. 42 is a driven shaft. In FIG. 4b, 43 is the gear pump 2
A guide shaft that serves as a guide for assembling 7, 4
4 is a semicircular fixture used to fix the gear pump 27 to the wax tank body 26; 45 is a disk-shaped upper case; 46 and 47 are a pair of spur gears; They mesh with each other at the hatched part in the middle, and the spur gear 46 is connected to the drive shaft 41, and the spur gear 46 is connected to the drive shaft 41.
7 is fixed to the driven shaft 42. 48 is a gear case that surrounds and stores the sides of the spur gears 46 and 47 on the lower surface of the upper case 45, 49 is a disc-shaped base on which the gear case 48 is placed, and 50 is a fixture for assembling the gear pump 27. It's a screw. Also, 4
4a is the molten wax 2 formed on the fixture 44;
5, the introduction port 45a and 48a are the introduction port 44a.
Supply holes 48b and 49a supply the molten wax 25 from the spur gears 46 and 47 to the spur gears 4
6 and 47 are delivery holes for sending out the pressurized molten wax 25; 51 is a supply hole for supplying the molten wax 25 from the gear pump 27 to the passage 30;
b, 52 are return holes for the molten wax 25 to be returned from the passages 30, 32 via the control valve 29.

Next, the operations shown in FIGS. 4a and 4b will be explained.

The solid wax charged into the wax tank body 26 is heated by a heater (not shown) to become molten wax 25, the temperature is detected by a thermostat 38, and maintained at a constant temperature by operation on a control panel 40. .

When the motor 28 is driven and the pair of spur gears 46 and 47 of the gear pump 27 rotate, the molten wax 25 in the wax tank body 26 is sucked into the inlet 4.
4a, passes through supply holes 45a and 48a (arrow A), is pressurized by spur gears 46 and 47, and further passes through delivery holes 48b and 49a and supply hole 51 into passage 30 (arrow B).

The molten wax 25 in the passage 30 passes through the filter 31
After entering the inside of the building and removing trash etc.
2 (arrow C), the liquid branches into a plurality of pipes 33 (arrow D), and is injected from each injection device 36 to spray the entire printed circuit board 13 and electronic components 14 mounted on its upper surface.

On the other hand, the flow rate and pressure of the molten wax 25 in the passages 32 and 30 are controlled by the control valve 29.
2, 30 through the control valve 29 as shown by arrows E and F in FIG.
2 and is returned to spur gears 46 and 47.

FIG. 5 is an enlarged perspective view showing the gear pump 27 in an exploded manner, in which the same parts as in FIGS. 49c is a support hole for the drive shaft 41, 44d and 45d are insertion holes through which the driven shaft 42 is rotatably inserted, and 49d is a support hole for the driven shaft 42.
The support hole 46c is connected to the spur gear 46 on the drive shaft 41.
A fixing hole 47c for fixing the driven shaft 4
A fixing hole for fixing the spur gear 47 to 2, 44
e, 45e, 48e, 49e are the guide shafts 43
Insertion holes for inserting, 44f, 45f, 48f, 4
9f is an insertion hole through which the fixing screw 50 is inserted.

When assembling, drive shaft 41, driven shaft 4
2. Attach the guide shaft 43 to the base 49, then mesh the spur gears 46 and 47 and fix it to the drive shaft 41 and the driven shaft 42. Next, the gear case 48 is attached to the base 4.
9 and then store the spur gears 46 and 47. Next, the upper case 45 is placed over the top of the gear case 48 to seal the spur gears 46 and 47, and then the fixing tool 4
4 is placed and the whole is tightened with fixing screws 50 to form a gear pump 27, which is attached to the wax tank body 26, and the drive shaft 41 is connected to the motor 28.

Note that the operation of the gear pump 27 shown in FIG. 5 has been explained in FIGS. 4a and 4b, and will therefore be omitted here.

FIG. 6 is an enlarged side sectional view showing details of the control valve 29, in which the same reference numerals as in FIG. 4b indicate the same parts, and 61
is the valve box of the control valve 29, and the wax tank body 26
is mated to. Reference numeral 62 denotes an adjustment valve screwed into the valve box 61, which adjusts the flow rate of the molten wax 25 by rotation. 63 is a safety valve, melting wax 2
5. Automatically adjust the pressure. 64 is the valve seat of the regulating valve 62, 65 is the valve seat of the safety valve 63, 66
6 is a spring that presses the safety valve 63 against the valve seat 65;
7 is an introduction hole on the regulating valve 62 side provided at one longitudinal end of the valve box 61, 68 is an introduction hole on the safety valve 63 side provided at the other longitudinal end of the valve box 61, and 69 is each of the introduction holes. Reflux hole 5 provided between 67 and 68
The discharge hole 70 on the second side is an O-ring for stopping water.

Next, the operation shown in FIG. 6 will be explained.

The molten wax 25 pressurized by the rotation of the spur gears 46 and 47 of the gear pump 27 passes through the supply hole 51 and the passage 30, passes through the filter 31 shown in FIG.
2. It is injected from the injection device 36 through each pipe 33, but if you want to adjust the injection amount, turn the adjustment valve 62 to open a gap between the adjustment valve 62 and the valve seat 64, and the passage 32 will melt. A portion of the wax 25 is diverted and enters the valve box 61 through the introduction hole 67, and is further sent to the reflux hole 52 via the valve seat 64 and the discharge hole 69. On the other hand, if the pressure of the molten wax 25 becomes higher than a predetermined value due to flow rate adjustment, stopping of injection, etc., a part of the molten wax 25 in the passage 30 is diverted and enters the introduction hole 68, and the safety valve 63 is closed by the spring 66.
It is pressed against the pressing force of
Sent to 2.

FIG. 7 is an enlarged side sectional view showing details of one of the injection devices 36 in FIG. 4a, where the same reference numerals as in FIG. They are screwed together by a portion 72. 73
is the molten wax 25 provided on the side of the valve box 71.
74 is the valve shaft, 75 is the valve, 76 is the valve seat,
Reference numeral 77 includes a connection fitting that includes the valve seat 76 and engages with one end of the valve box 71; 78 and 79 refer to outlet fittings; 80 is a nozzle; 81 is a mounting fitting for the nozzle 80; 82
83 is a gasket; 84 is an air cylinder;
A piston 85 is fixed integrally with the valve shaft 74 protruding from the other end of the valve box 71.

Next, the operation shown in FIG. 7 will be explained.

Gear pump 2 of wax tank body 26 in Fig. 4a
The molten wax 25 pressurized in step 7 passes through a passage 30, a filter 31, and a passage 32, and then flows into the pipe 3 in FIG.
3 and from the introduction hole 73 in the valve box 71 to the valve box 7.
Go inside 1.

When the printed circuit board 13 passes below the injection device 36, pressurized air is introduced into the air cylinder 84 by detection by a detector such as a phototube (not shown), and the piston 85 is actuated to apply the pressing force of the spring 82 to the valve stem 74. The valve 75 is released from the valve seat 76 by pressing against it. When the valve seat 76 is opened, the molten wax 25 in the valve box 71 is injected from the nozzle 80 through the nozzle fittings 78 and 79, and is sprayed onto the printed circuit board 13.

Note that the nozzle 80 may be directly attached to the valve seat 76 of the connecting fitting 77.

FIG. 8 shows the wax application control section of the wax application processing device 23, which is the main part of the present invention.
First, to explain the outline, in the wax processing section 24 shown in FIG. The injectors 36 are maintained in an operable state by turning on the limit switches corresponding to the required number of injectors 36;
Further, the molten wax 25 is sprayed after detecting the passage of the printed circuit board 13. The details will be explained below based on FIG.

In FIG. 8, the same reference numerals as in FIGS. 2, 3, and 4 a indicate the same parts, 22A is a fixed conveyance chain, and 22B is a conveyor chain movable in a direction perpendicular to the running direction of the printed circuit board 13. The conveyor chains 36 ₁ , 36 ₂ , . . . , 36 _o on the movable side are connected to the injection device 3
6 is shown. Reference numeral 91 denotes a holding claw for the printed circuit board 13, which is fixed integrally with the transport chains 22A, 22B. 92 is a screw rod for moving the conveyance chain 22B, 93 is the conveyance chain 22B,
The operating contact piece 94 that moves together with the holding claw 91 is a limit switch, and 94 ₁ , 94 ₂ , ..., 94 _o indicate each of the limit switches 94, and are connected to the injection devices 36 ₁ , 36 ₂ , ..., 36 _o , respectively. They operate in a corresponding manner and are aligned in the same direction.

Next, the operation will be explained.

By turning a handle (not shown) serving as an adjustment means for adjusting the interval between the holding claws 91 of the soldering device 21, the conveyance chain 22B is moved, and the printed circuit board 1 is moved.
3 is attached to the holding claw 91.

At this time, the actuating contact piece 93 changes depending on the width of the printed circuit board 13, for example, as shown in FIG.
When the four air cylinders 4 ₁ to 94 ₄ are contacted and turned on, the air cylinders 84 (see FIG. 7) of the injection devices 36 ₁ to 36 ₄ are maintained in an operable state.

Next, when the printed circuit board 13 travels and comes in front of the injection devices 36 ₁ to 36 ₄ , the air cylinder 84, which is ready for operation, is activated by detection by a detector (not shown) such as a phototube, and the injection devices are activated. 36 ₁ ~
The molten wax 25 is sprayed from the four pieces ₃₆₄ and sprayed onto the printed circuit board 13.

In addition, since the limit switches ₉₄₅ to _94o of the above-mentioned injection devices ₃₆₅ to _36o are not turned on, the air cylinder 84 is not maintained in the operating state even if the printed circuit board 13 passes the detector and is detected. Therefore, the air cylinder 84 does not operate and the molten wax 25 is not injected.

As explained above, the present invention includes a wax tank main body that stores molten wax, a gear pump provided in the wax tank main body that sends out the molten wax, and a control system that controls the flow rate and pressure of the molten wax sent out from the gear pump. In the wax processing unit, which includes a control valve that controls
In order to operate each injection device individually, a limit switch is provided corresponding to each injection device, and a holding claw on the printed circuit board that moves according to the width of the board to which molten wax is applied works in conjunction with the limit switch to turn on the required limit switch. The wax application control unit of the soldering machine is formed by the molten wax application control unit equipped with an actuating contact piece, so that the molten wax can be spouted at a preset constant pressure, and can be applied over the entire width of the printed circuit board. It can be sprayed evenly onto the surface of the screen, and electronic components can be reliably temporarily fixed. Furthermore, when the printed circuit board is attached to the holding claws of the transfer chain, the actuation contact turns on the required number of limit switches, so molten wax can be automatically injected from the same number of injection devices as the limit switches turned on. Therefore, the molten wax can be automatically applied according to the width of the printed circuit board, which has the advantage that the labor required for these adjustments can be saved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional soldering device, FIG. 2 is a partial side sectional view showing how electronic components are mounted on a printed circuit board, and FIG. 3 is a schematic diagram showing an embodiment of the present invention. Configuration diagram, Figure 4 a, b
4 shows the wax treatment section in FIG. 3, FIG. 4 a is a partially cutaway perspective view, and FIG.
Figure 5 is an enlarged perspective view showing the gear pump exploded, Figure 6 is an enlarged side sectional view showing details of the control valve, Figure 7 is an enlarged side view showing details of the injection device. The side sectional view and FIG. 8 are configuration diagrams showing the wax application control section of the wax application processing apparatus, which is the essential part of the present invention. In the figure, 3 is a cutting device, 4 is a finishing soldering processing device, 8 is a cooler, 9 is a flux processing device, 10 is a preheater, 11 is a soldering bath, 13
is a printed circuit board, 14 is an electronic component, 15 is a lead wire (or lead terminal), 16 is a through hole,
21 is a soldering device, 22A and 22B are conveyance chains, 23 is a waxing processing device, 24 is a wax processing section, 25 is a melting wax, 26 is a wax tank body, 27 is a gear pump, 28 is a motor, 2
9 is a control valve, 30 and 32 are passages, 31 is a filter, 33 is a pipe, 34 is a tape heater, 35 is a heat insulating material, 36 is an injection device, 37 is a connecting fitting, 38
is the thermostat, 39 is the lid, 40 is the control panel, 4
1 is a drive shaft, 42 is a driven shaft, 43 is a guide shaft, 4
4 is a fixture, 45 is an upper case, 46 and 47 are spur gears, 48 is a gear case, 49 is a base, 50 is a fixing screw, 51 is a supply hole, 52 is a return hole, 61 is a valve box, 62 is an adjustment Valve, 63 is a safety valve, 64, 65 is a valve seat, 66 is a spring, 67, 68 is an introduction hole, 69 is a discharge hole, 71 is a valve box, 72 is a threaded part, 73 is an introduction hole, 74 is a valve stem, 75 is a valve, 76 is a valve seat, 80 is a nozzle, 82 is a spring, 84 is an air cylinder, 85
is a piston, 91 is a holding claw, 92 is a screw rod, 93
94 is an operating contact piece, and 94 is a limit switch.

Claims (1)

[Claims] 1 A wax tank body that stores molten wax;
A gear pump provided in the wax tank body to send out the molten wax, a control valve to control the flow rate and pressure of the molten wax sent out from the gear pump, and a control valve arranged in sequence in a direction perpendicular to the running direction of the printed circuit board. In a wax processing unit equipped with a plurality of spraying devices, a limit switch is provided corresponding to each of the spraying devices to operate each spraying device, and a limit switch is provided corresponding to each spraying device, and a limit switch is provided according to the width of the printed circuit board to which the molten wax is applied. A molten wax application control section of a wax application apparatus, characterized in that it comprises an operating contact piece that is linked with a moving holding claw of the printed circuit board and turns on a required one of the limit switches.