JPH0623943Y2 - Heater for mass flow controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to a heater of a mass flow controller for controlling a mass flow rate of glass used in a semiconductor manufacturing process or the like.

Conventional technology and its problems Gas measurement and control have been performed by a conventional volume flow meter (roller meter), but recently, due to automation of manufacturing equipment and computerization, all operations are performed by electric signals. Many mass flow controllers have become popular.

An example of such a mass flow controller 10 'is shown in FIG. An inlet fitting 13 having an inflow side joint 12a is attached to the metal base portion 14 '. The intermediate flow rate detection unit includes a sensor unit 17 and a bypass unit 18. The sensor unit 17 is a thermal mass flow sensor, and a pair of resistance heating elements (not shown) are wound around the outside of the sensor tube 19, and the heating resistors are deprived of heat by the passage of gas to become the resistance heating elements. There is a temperature difference. This temperature is detected as a resistance value change in a bridge circuit (not shown) and taken out as an output.

In the mass flow controller 10 ', liquefied easy gas at around room _{temperature, SiCl 4, SiH 2 Cl 2} , BCl 3, NH 3
When measuring and controlling the above, there is a case that the gas-liquid equilibrium peculiar to the gas is broken and the gas is liquefied due to the pressure change generated in the valve 16, the sensor unit 17, etc., and stable flow rate measurement cannot be performed. Therefore, a rubber heater, a ribbon heater, or the like is adhered to the base portion 14 ', or a hole is opened in the base portion 14' to insert a cartridge heater or the like to heat the mass flow controller 10 'to raise its temperature and cope with it. There is.

However, the former has problems such as deterioration of maintainability due to complexity of mounting means to the mass flow controller and instability of temperature control due to variations in the position of the temperature measuring means and heat radiation situation.

On the other hand, the latter has a problem that it is difficult to mount the cartridge heater after the mass flow controller is installed and replace the heater when a failure occurs.

Moreover, in any case, since the temperature rising part is exposed,
There is much diffusion and radiation of generated heat to the atmosphere, which causes heat loss, lacks stability in temperature control of the mass flow controller, and may cause burns due to accidental contact.

Means for Solving the Problems The present invention provides a mass flow controller by fastening the fastening metal fittings of a pair of heater units having fastening metal fittings at both ends in the longitudinal direction of a plate equipped with heating means with a detachable means. By the heater for the mass flow controller, which is designed to sandwich the front and back of the base part of
The above problems were solved.

Action The plate is heated by the heating means, and the heat is transferred to the base portion which is in close contact with the plate to heat the plate.

To attach the heater, a pair of heater units need only be applied to the front and back surfaces of the base portion, and the fastening metal fittings can be fastened with the detachable means, so that the heater can be easily attached and detached.

Example FIG. 1 is a perspective view showing the relationship between the heater of the present invention and the mass flow controller in a disassembled state.

The mass flow controller 10 includes a joint 12 a for gas inflow and a joint 1 for gas outflow in the longitudinal direction of the base portion 14.
2b is provided. The heater 20 is composed of a pair of heater units 36a and 36b that sandwich the front and back surfaces of the mass flow controller 10. The heater 20 is attached by tightening the fastening fittings 22a and 22b with screws 24a and 24b.

FIG. 2 is a front view when the heater is assembled, and has a heating means 28 substantially at the center of an aluminum plate 26 having good thermal conductivity. The heating means 28 is a rod-shaped cartridge heater, in which a coil-shaped heat element is fitted in a cylindrical metal sheath in proximity to the inner peripheral surface of the sheath and is filled with a heat conductive electrical insulator. It was done. A temperature sensor 30 is provided on the plate 26. The size of this plate 26 is
It is almost equal to the front and back surfaces of the base portion 14 of the mass flow controller 10. Since the heater 20 is mainly used to prevent liquefaction of gas, the sensor 30 uses the valve 16 which is a temperature detection target.
It is desirable to be provided in the plate portion near the.

3 and 4 are a top view and a right side view of the heater 20. The plate 26 is the mass flow controller 1
The surface opposite to the base portion 14 of 0 is covered with a heat insulating layer 32 such as urethane foam, and the outer surface of the heat insulating layer 32 is covered with a heat insulating cover 34 made of stainless steel having both strength and heat insulating properties. The heat insulating layer 32 may be an air layer.
The plate 26, the heat insulating layer 32, and the heat insulating cover 34 are
Configure the heater unit.

One heater unit 36a has a pair of fastening metal fittings 22a at both ends in the longitudinal direction, and the other heater unit 36a.
A pair of tightening fittings 22b are attached to b.
The tightening metal fittings 22a and 22b have an inverted L shape, and when the heater units 36a and 36b are attached to the mass flow controller 10, they have an inverted U shape as shown in FIG. 4 and interfere with the joints 12a and 12b. There is nothing to do.

Attach the pair of clamps 22a, 22b with screws 24b,
Then, the screw 24a is adjusted and screwed, and a moment is applied to the tightening metal fittings 22a and 22b to firmly tighten them, so that the plate 26 is brought into close contact with the base portion 14 of the mass flow controller 10. Also, the tightening fitting 22
A spring surrounding the screw 24a (or replacing the screw 24a) may be interposed between a and 22b so that the plate 26 elastically clamps the base portion 14. It should be noted that these exemplify specific examples of the “detachable means”, and it goes without saying that the detachable means may have other modified examples such as a coil spring instead of the screw 24b. Is.

Each of the heating means 28 is insulated with a silicon compound at the connecting portion with the lead wire in the plate 26, and is connected in parallel to the two-pole connector 38. And the sensor 30
Then, the heating means 28 is adjusted by a temperature controller (not shown) to control the temperature of the mass flow controller 10.

When the heating means 28 is energized, the plate 26 is heated. Since the plate 26 is made of aluminum, which is a good heat conductor, even if heat is locally taken away, the heat transfer coefficient is high and a uniform temperature distribution can be obtained. Further, since the outer surface is covered with the heat insulating layer 32 and the heat insulating cover 34, the heat generated by the heating means 28 is efficiently transferred to the base portion 14 which is in close contact with the inside.

When the heater needs to be removed, screws 24a, 24b
The heater 20 is removed from the mass flow controller 10 by opening each heater unit and the fastening metal fitting. The removal work is the same as when installing the screw 24a,
Since it is performed only by 24b, a large space and a mounting man-hour are not required.

In addition, the tightening metal fittings may be integrally formed with the heat insulating cover to provide attachment strength and improve heat insulating performance.

Further, the heating means described above is an example, and the present invention is not limited to this.

Effect of the Invention The present invention can be firmly and easily attached by the detachable means so that the base portion requiring heating can be sandwiched even after the mass flow controller is installed, and the installation work is also easy. Space is fine. Therefore, even when the heater needs to be replaced or repaired, the work can be easily performed.

In addition, if the tightening metal fittings have an inverted U-shape when mounted, they can be mounted closely without interference with the joint, and if the outer surface is covered with a heat insulating layer, heat transfer from the plate Can be efficiently performed mainly on the base portion.

[Brief description of drawings]

FIG. 1 is a perspective view showing a relationship between a heater and a mass flow controller by disassembling a heater according to an embodiment of the present invention, FIG. 2 is a front view of a heater assembled, and FIG. 3 is a top view of FIG.
FIG. 4 is a right side view of FIG. 2 showing a part in section, and FIG. 5 is a sectional view of the mass flow controller. 10 ... Mass flow controller 14 ... Base part 16 ... Valve 20 ... Heater 22a, 22b ... Tightening metal fittings 24a, 24b ... Screw (detachable means) 26 ... Plate 28 ... Heating means 30 ... Temperature Sensor 32 ... Insulation layer 34 ... Heat insulation cover 36a, 36b ... Heater unit

Claims (1)

[Scope of utility model registration request] 1. A front surface and a back surface of a base portion of a mass flow controller are fixed by attaching and detaching the fastening metal fittings of a pair of heater units having fastening metal fittings at both longitudinal ends of a plate provided with heating means. A heater for a mass flow controller, which is characterized by being sandwiched.