JPH0481273A - Cream solder dispernser - Google Patents

Abstract

PURPOSE:To stabilize the amt. of cream solder by providing a feedback control system which compensates the pressure fluctuation of an air pressure supply source and subjects the secondary side pressure of a pressure regulator to control with fixed set-point to a set pressure in a pneumatic pipeline. CONSTITUTION:An electropneumatic regulator (to regulate the setter of the secondary pressure in correspondence to the electric signal from the outside, more specifically an impressed voltage) is adopted for the pressure regulator 7. The feedback system takes the detected value of the pressure sensor 12 detected on the secondary side of the pneumatic pipeline 8 on the downstream of the pressure regulator as a feedback signal into a controller 5. The controller compares the feedback signal and the set pressure valve and applies the control signal corresponding to this deviation to the pressure regulator 7, thereby making the control with fixed set-point of the secondary side pressure to the set pressure. The casual main pressure fluctuation of the air pressure supply source 9 is compensated in this way and the air pressure to be introduced into a syringe 1 is maintained always under a prescribed pressure. The discharge rate of the cream solder supplied onto printed wirings from the syringe is stabilized and the reflow soldering of electronic parts is executed in a normal state.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention targets hybrid integrated circuits, and is a method for soldering surface-mounted electronic components such as flat package ICs to printed wiring boards. The present invention relates to a cream solder dispenser that applies cream solder to the mounting position of the electronic component specified above.

[Conventional technology]

First, the control system and solder application operation of a conventionally used cream solder dispenser will be explained with reference to FIG.

In the figure, 1 is a syringe with a plunger 1a containing cream solder 2, and the tip of the syringe 1 is equipped with a nozzle 3. Such a syringe 1 has an X for positioning.
- It is mounted on the Y movement operation unit 4 and is operated to move in the X and Y axis directions by commands from the controller 5. Also,
The syringe 1 is connected to an air pressure supply source 9 via a pneumatic circuit 8 connected to a solenoid valve 6 and a pressure regulator 7 (pressure reducing valve).

Next, the operation of the cream solder dispenser will be explained. First, the air pressure introduced into the syringe 1 is set in advance using the pressure regulator 7 (the pressure on the secondary side is set by manually operating the pressure adjustment handle). Next, the printed wiring board 10 is supplied to the dispenser, and the controller 5 (the controller stores component data files regarding the shape, size, lead pitch, etc. of various electronic components) is loaded with information such as the type of mounted components, mounting position, etc. When inputting the data and giving a start command, the X-Y movement operation unit 4 moves the syringe 1 in response to a command from the controller 5.
Move to the solder application starting point corresponding to the component mounting position,
From here, x along the specified solder application pattern 11,
While moving in the Y-axis direction, solder application pattern 1
The solenoid valve 6 is controlled to open and close according to the timing. As a result, when the solenoid valve 6 opens, the syringe 1 receives the secondary pressure of the pressure regulator 7 and discharges the cream solder from its tip nozzle 3, and the cream solder is applied along the solder application pattern 11 on the printed wiring board. Apply. When the solder application for one mounted component is completed by the above operation, the syringe 1 is subsequently moved to the mounting position of another mounted component and applies cream solder in the same manner.

The illustrated solder application pattern 11 is a flat package I in which lead rows are drawn out from the four sides around the package.
A solder application pattern corresponding to C is shown.

[Problem to be solved by the invention]

By the way, in the conventional dispenser described above, if the source pressure of the air pressure supply source 9 (for example, a multi-purpose air pressure source installed in a factory) fluctuates during use, the secondary pressure of the pressure regulator 7 fluctuates. Therefore, the amount of cream solder discharged from the syringe 1 varies.

Figure 3 is an operating characteristic diagram showing this situation, and shows that the pressure regulator's secondary pressure is set to 3 kg/ctff and the original pressure of the air pressure supply source is 5 kg/cdl. Assuming that the pressure decreases to 4 kg/cdl, the pressure on the secondary side of the pressure regulator also decreases, causing a fluctuation of ΔQ in the amount of cream solder discharged from the syringe. As a result,
It was not possible to apply the appropriate amount of cream solder on the printed wiring board, and when reflow soldering the electronic components mounted on the printed wiring board in the next process, the insufficient amount of solder application caused soldering defects. cause. Further, when the source pressure of the air pressure supply source increases, the amount of cream solder discharged becomes excessive, and a solder bridge occurs during reflow soldering. Furthermore, fluctuations in the air pressure applied to the syringe.

In other words, it is possible to consider a method of optimizing the amount of solder applied to the printed wiring board by adjusting the moving speed of the syringe in response to changes in the amount of cream solder discharged, but such control is extremely difficult.

The present invention has been made in consideration of the above points, and an object of the present invention is to provide a dispenser that can always maintain a constant amount of cream solder discharged from a syringe by compensating for pressure fluctuations in a pneumatic supply source. do.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a feedback control system for the pneumatic circuit connected to the syringe, which compensates for pressure fluctuations in the pneumatic supply source and controls the secondary pressure of the pressure regulator to a set pressure. do.

[Effect]

In the above configuration, an electro-pneumatic regulator (which adjusts the set value of the secondary pressure according to an external electrical signal, specifically an applied voltage) is used as the pressure regulator, and the feedback system uses the pressure regulator as the pressure regulator. The detected value of the pressure sensor detected on the secondary side of the pneumatic circuit further downstream is input to the controller as a feedback signal, and the controller compares the feedback signal with the pressure set value and gives a control signal corresponding to the deviation to the pressure regulator. Controls the secondary pressure at a fixed value to the set pressure.

This makes it possible to compensate for unexpected fluctuations in the source pressure of the air pressure supply source and to always maintain the air pressure introduced into the syringe at a predetermined pressure, thereby stabilizing the amount of cream solder discharged from the syringe onto the printed wiring board. .

〔Example〕

FIG. 1 is a control system diagram of a cream solder dispenser according to an embodiment of the present invention, and the same parts corresponding to those in FIG. 2 are given the same reference numerals.

In FIG. 1, an electro-pneumatic regulator is adopted as the pressure regulator 7 connected to the pneumatic circuit 8 together with the solenoid valve 6, and a pressure sensor 12 connected to the secondary side downstream of the pressure regulator 7, a variable resistor 13 and the variable A feedback control system 16 for the pressure regulator is configured with the controller 5, including an applied voltage adjustment section 15 of the electropneumatic regulator 7 combined with an adjustment operation motor 14 (stepping motor) of the resistor 13. Here, the controller 5 is given a set value of the secondary pressure in advance, compares the detected value from the pressure sensor 12 with the set value, and adjusts the pressure regulator via the voltage regulator 15 based on the deviation. The voltage applied to the pump is adjusted and constant value control is performed to maintain the secondary pressure at the set value.

By performing the feedback control described above, even if the source pressure of the air pressure supply source 9 fluctuates while the dispenser is in use, the secondary pressure of the pressure regulator 7 is always maintained at the set pressure. 1 to the printed wiring board 10 becomes stable.

Note that, as in the illustrated embodiment, the variable resistor 13. Instead of using the voltage regulator 15 combined with the motor 14, the controller 5 outputs a control voltage corresponding to the deviation,
This can also be applied directly to the pressure regulator to control the secondary pressure.

〔Effect of the invention〕

As described above, according to the present invention, even if the source pressure of the pneumatic pressure supply source fluctuates, the secondary side pressure of the pressure regulator introduced into the syringe through the pneumatic circuit can always be maintained at the set pressure. In the solder application process, the amount of cream solder supplied from the syringe to the printed wiring board can be stabilized, and electronic component glue flow soldering in the subsequent process can be performed in a normal state.

[Brief explanation of the drawing]

1 and 2 are control system diagrams of an embodiment of the present invention and a conventional cream solder dispenser, respectively.
The figure is a characteristic diagram showing the relationship between the source pressure fluctuation of the pneumatic supply source and the amount of cream solder discharged by a conventional dispenser. In the figure, 1: syringe, 2: cream solder, 5: controller, 6: solenoid valve, 7: pressure regulator, 8: pneumatic circuit, 9: pneumatic supply source, 10 niblint wiring board, 12: pressure sensor, 16: fift one

Claims (1)

[Claims] 1) A cream solder dispenser that applies cream solder to the specified mounting position of electronic components on a printed wiring board, and a solenoid valve and pressure regulator are installed in the pneumatic circuit that connects the syringe containing the cream solder and the pneumatic pressure supply source. Connect the syringe, move the syringe along the solder application pattern, open and close the solenoid valve during the movement process, introduce the pressure regulator's secondary pressure into the syringe, and apply cream solder onto the printed wiring board from the tip nozzle. The pneumatic circuit is characterized by being equipped with a feedback control system for compensating for pressure fluctuations in the pneumatic supply source and controlling the secondary pressure of the pressure regulator to a set pressure at a constant value. Cream solder dispenser.