KR20010011385A - A method of heat treating a workpiece by at least one heat transfer liquid, and a condensation oven for implementing the mehtod - Google Patents

Abstract

PURPOSE: A method for heat treating a work piece using at least one heat transfer liquid and an oven for performing the same are provided to continuously perform a processing work in a manufacturing line and to perform a uniform and excellent heat transfer therein. CONSTITUTION: In the method for heat treating a work piece using at least one heat transfer liquid, the work piece(2) is laid in the oven(1) and thereafter at least one door(8,9) mounted to the oven(1) is completely sealed. At this time, an internal structure(5) is formed in the oven(1) and at least one heat transfer liquid is injected into the oven(1). The oven(1) is heated at a predetermined temperature above a boiling point of the liquid. In the oven(1), at least one heat transfer liquid is evaporated during the operation of the oven(1) and a part of vapor resulting from the evaporation of heat transfer liquid is condensed on the work piece(2). A sealed structure(7) in the oven(1) is filled with the vapor. After condensing of the vapor, the remaining vapor in the oven(1) is exhausted from the oven(1). Finally, the processed work piece(2) is drew out of the oven(1).

Description

A METHOD OF HEAT TREATING A WORKPIECE BY AT LEAST ONE HEAT TRANSFER LIQUID, AND A CONDENSATION OVEN FOR IMPLEMENTING THE MEHTOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the technical field related to the treatment by heat transfer liquid, and is a processing method applied to all kinds of workpieces, and is made by a filler material deposited locally with a tab of a component fixing function. It relates to the processing of workpieces formed on supports on which electronic, electrical, mechanical or mechanical components are mounted.

Particularly advantageous applications of the present invention relate to processing techniques involving the combination of components by polymer or component bonding and to the combination of components by polymerisation, and also reflow techniques in which the filler is composed by alloys. (reflow technique).

In the preferred technical field of the present invention, various types of devices are known for melting the filler material to fix the components on the support. Therefore, it is known to use a joining device for rapidly and uniformly heating the temperature of the support and the component to a temperature slightly above the melting point of the filling material, thereby making the bonding material obtained by bonding or polymerizing the filling material.

In the first classification of the prior art, means are provided for manufacturing a device in the form of a convection oven, an infrared oven or a forced convection oven and optionally providing a controlled atmosphere. The main advantage of using an oven is that the oven is configurable inside the manufacturing line. Similarly, workpieces can be processed continuously by an oven. However, the main drawbacks of the treatment methods by ovens are the relatively long treatment times, poor heat transfer to the workpiece being processed, high cost, and the use of inert gas for ovens operating in a controlled atmosphere.

In the second classification of the prior art, there is a method of treating using steam of a heat transfer liquid. Therefore, the steam treatment apparatus is composed of a container containing a fluorocarbon type liquid, and the container is designed to be raised to the boiling point by heating means so as to form a main steam having a saturated and inert property in the bonding area or the bonding area. The temperature of the main steam is slightly higher than the melting point of the fill material. An adhesive or bonding region extends between the surface of the liquid and the heat exchange coil for condensing the first vapor. The bonding zone or bonding zone is optionally mounted by a cooling zone or a preheating zone occupied by another steam.

At the top of the container, the container has a through opening, the opening having a lid and the opening being designed such that components which are joined onto the support for insertion into the container can be mounted on the support. The support is used by an apparatus for moving the support and then fixing the support in the preheating zone, the bonding zone and the cooling zone. Therefore, after the support is fixed in the preheating zone for a predetermined time, the support comes into contact with the main steam so that latent heat generated during condensation is transferred to the support and the coupled components. The heat supply causes the temperature of the support and the components to rise quickly and uniformly to the temperature of the main steam, so that the filler material melts and, as a result, the coupling parts are supported by a bonding action or a polymer forming action, depending on the technology associated with the application. Is bonded to.

This type of device has an undeniable advantage in terms of uniformity and condition with respect to heat transfer and requires a lower investment than the cost required for the oven. However, this type of device has disadvantages such as the consumption of heat transfer liquid, difficulty in installing the device inside a manufacturing line, and consequently difficulty in continuously performing the processing work.

In reviewing the prior art, no completely satisfactory treatment machine has been provided to date.

An object of the present invention is to solve the above problems by combining the advantages of the prior art, avoiding the disadvantages, and providing a method for heat treatment on a workpiece.

Accordingly, an object of the present invention is to provide a method of heat treatment to a workpiece by heat transfer liquid, which is performed continuously by the processing work is integrated in the manufacturing line, and a uniform and good heat transfer action is provided according to the above method.

According to the present invention for this purpose, in a method in which a heat treatment is performed on a workpiece by one or more heat transfer liquids having a boiling point of a given value, the workpiece to be processed in the oven is placed, and the internal structure of the oven Forming a sealed structure accessible and sealed through the door, making the internal structure of the oven at a temperature suitable for condensation on the workpiece to which a portion of the vapor obtained by evaporating the heat transfer liquid is to be treated; An operation in which the closed structure of the oven is occupied by the steam so that a portion of the steam is condensed on the workpiece to be treated, extracting the steam remaining in the closed structure of the oven, and taking the work out of the oven. A method is characterized in that a method is provided.

In addition, according to the present invention, in the condensation oven for heat treatment to the workpiece, one closed structure accessible by one or more doors and forming a sealing state is formed by the inner structure and composed of the inner structure A case, a heating means for heating the internal structure to a temperature suitable for condensation on the workpiece to be treated with a portion of the vapor obtained by evaporating the heat transfer liquid, and the vapor obtained by evaporating the liquid occupy the interior of the closed structure Condensation oven, comprising a system for condensing on the workpiece to be treated a portion of the steam, and the extraction device for extracting the steam occupying the interior of the closed structure constituted in the oven and the sealing state This is provided.

Various other features will become apparent from the following description with reference to the drawings, which illustrate embodiments of the invention by way of non-limiting example.

1 is a longitudinal schematic sectional view of an embodiment of an oven according to the present invention;

FIG. 2 is a sectional view taken along the line II-II in FIG. 1. FIG.

* Code Description

1 ... oven 2 ... workpiece

4 ... Case 5 ... Internal Structure

8 ... entrance door 9 ... exit door

11 ... bottom plate 12 ... sidewalls

13 ... ceiling 14 ... front wall

15 ... rear wall 16 ... heating means

18 ... pipe 22 ... suction circuit

23 ... condensing unit 26 ... conveying means

1 and 2, an embodiment of an oven 1 in accordance with the invention and generally for applying heat treatment to the workpiece 2 is shown. According to the preferred embodiment below, the workpiece 2 is supported by a support that fits into all types of components, such as electronic, electrical, mechanical or mechanical components, which are suitably configured to perform a particular function for a particular use. It is composed. In an embodiment, the oven 1 is designed to melt the filler material and attach the components to the support, which is deposited locally in combination with the tabs of the components. According to an easy method, the filling material is constituted by a polymer or an alloy. The support is constituted, for example, by a printed circuit which constitutes a card or workpiece 2 when fitted with various components.

The oven 1 according to the invention consists of a "high temperature" internal structure 5 and a case 4 fitted with a lagging 6 of thermal insulation. Internal structure 5 by means of a hermetic seal 7 which is accessible and sealed by two doors 8 and 9 having an inlet and an outlet as shown in at least one door embodiment and which is sealed. ) Is formed inside.

In the illustrated embodiment, the internal structure 5 has one bottom plate 11, which consists of two side walls 12 which are vertically formed and finished at the ceiling 13 from the bottom plate 11. do. In the illustrated embodiment, the front wall 14 and the rear wall 15, which are configured in the inlet and outlet doors 9 and 9, respectively, are also constructed in the inner structure 5, the doors being shown (in the figure). It is fitted with automatic opening and closing means according to the prior art (not shown). When the doors are closed, the interior of the internal structure 5 consisting of the bottom plate 11, side wall 12, ceiling 13 and front wall 14, rear wall 15 is a sealed structure forming a sealing state Form. The various components constituting the internal structure 5 are made of a material having good performance for heat conduction or heat transfer function. For example, the bottom plate 11, the side wall 12, the ceiling 13 and the front wall 14, and the rear wall 15 are metal plate shaped components.

Heating means 16 for heating the internal structure 5 are mounted to the oven 1 so that the oven 1 reaches a predetermined temperature. For example, the heating means 16 is constituted by the outer surface of at least a part of the components constructed in the internal structure 5 and the electrical resistors mounted on all the components. The heating means 16 may of course also be constructed using other methods, for example using a circuit through which the heat transfer fluid is circulated. Insulating lagging 6 is provided on the outside of the internal structure 5 to limit heat loss. It is known to the person skilled in the art and the lagging 6 is configurable in a suitable way for covering the various parts constituting the internal structure 5.

According to the invention, a system 17 is mounted in the oven 1 in which the interior of the enclosed structure 7 can be occupied by steam obtained by evaporating a heat transfer liquid having a given temperature or boiling point. In applications for joining components, the boiling point of the liquid is higher than the melting point of the fill material. According to a preferred feature of the invention, the system 17 for the internal space of the internal structure to be occupied by steam is provided by a supply circuit 18 for supplying a heat transfer liquid contained in a tank 19. It is composed. The liquid supply circuit 18 is opened on the bottom plate 11 of the oven and can accommodate the liquid diffused on the bottom plate by the inner surface of the oven. In order to convert the liquid into steam, the bottom plate 11 of the oven is heated to a temperature above the boiling point of the liquid. The bottom plate 11 of the oven is designed to maintain a temperature above the boiling point of the liquid even while the liquid is supplied onto the inner surface of the oven. For this purpose, the bottom plate 11 has sufficient heat accumulation so that the liquid in contact with the inner surface of the oven is evaporated. A system 17 for the interior space of the closure structure 7 to be occupied by steam may be provided in the form of a system for supplying steam to the interior space of the closure structure 7. The vapor may be provided outside the enclosure by suitable means to evaporate the heat transfer liquid. According to the invention steam is provided inside the closure structure 7 so that at least part of the steam can be condensed on the workpiece 2 to be treated.

According to another feature of the invention, an extraction apparatus 21 is formed in the oven 1 for extracting steam which forms a sealing state and occupies the internal space of the hermetically sealed structure 7. According to a preferred embodiment, the extraction device 21 is constituted by a suction circuit 22 which opens toward the bottom of the sealing structure 7, and the extraction device 21 condenses to condense the sucked vapor. The unit 23 is connected to the outside of the oven. A return pipe 24 is formed in the condensing unit 23 which opens into the sealed structure 7 in a sealed state for delivering air, which is previously sucked in and discharged with the steam. The extraction device 21 is constituted by a closed circuit for condensing steam contained in the sealed structure 7 in a sealed state. It is preferred that a feedback circuit 24a for returning the liquid to the tank 19 is mounted to the condensation unit 23.

Other forms of vapor extraction device 21 may be provided. For example, the extraction device may be constituted by a condenser installed inside the sealed structure 7 of the oven, in order to condense the vapor in the sealed structure in a sealed state. In this embodiment, means for extracting the heat transfer liquid to empty the closure structure may be configured in the closure structure.

It is preferred that a control device (not shown) for controlling the various components constituting the oven upon application of the following treatment cycle is mounted to the oven 1 of the present invention.

The method of constructing a condensing oven according to the invention is immediately understood from the above description.

The processing operation of the oven 1 is directly performed on the work piece 2 delivered to the internal space of the oven 1 by a known delivery means 25, and the delivery means 25 delivers the work piece 2. It is mounted on the internal transfer means 26 of the prior art. The inlet door 8 and the outlet door 9 are closed to form a sealed structure 7 in a sealed state. The internal structure 5 of the oven is reached by means of the heating means 16 to a temperature condensable on the work piece 2 to which a portion of the vapor obtained by evaporating the heat transfer fluid is to be treated. It is preferred that the internal structure 5 of the oven reach a temperature above the boiling point of the liquid. For example, an apparatus may be provided wherein the internal structure reaches a temperature of about 240 ° C. for a liquid having a boiling temperature of about 215 ° C. In contact with the bottom plate 11, the heat transfer liquid is supplied by the pipe 18 so that the heat transfer liquid turns into vapor almost instantaneously in the sealed structure in a sealed state. As a result, steam generation occurs in the sealed structure, and the amount of steam content gradually rises until the steam content reaches saturation in the sealed structure. According to a feature of the preferred embodiment, all the internal structures 5 are raised to a temperature above the boiling point of the heat transfer liquid, so that steam does not condense on the internal structures. By definition, not only the components constituting the case 4 and forming the enclosed structure 7 but also all the components located inside the oven are included in the internal structure 5. In particular, it should be understood that the liquid supply pipe 18, the suction circuit 22 and the delivery means 26 are included in the internal structure 5.

The steam occupying the closed structure 7 by the condensation process transfers the thermal energy of the steam to the workpiece 2 to be treated. The latent heat of the evaporation process is transferred by the vapor to the workpiece at a temperature below the boiling point of the liquid. In the joining operation of the component according to the embodiment, a temperature slightly above the melting point of the previously deposited fill material is formed in the saturated steam and inert steam together with the tabs of the fixed function configured in the components. As a result, the components are assembled to the support of the workpiece.

After the assembling work, the extraction device 21 is operated to suck the vapor remaining in the sealed structure 7 in the sealed state. The air from which steam is removed is returned by the extraction device 21 to the sealed structure 7 in a sealed state through the pipe 24. When the sealed structure 7 no longer contains steam, the exit door 9 is opened so that the work piece 2 is taken out of the oven and transferred by the delivery device 27. The oven 1 can then be used again to process another work piece 2.

With the oven 1 according to the invention, the workpieces can be treated in an inert atmosphere by steam having a temperature higher than the boiling point of the heat transfer liquid. As long as the inner structure 5 of the case is heated up to a temperature higher than the boiling point of the heat transfer liquid in the hermetically sealed structure 7 and steam occupies the inner structure 7, the steam is at the boiling point of the heat transfer liquid. It is heated above.

A relatively limited amount of the liquid can be introduced into the closure structure 7 so that a corresponding amount of steam can be obtained. For example, it is suitable to add 15 grams of liquid per liter to the volume of the closure structure. In view of the advantages of the oven 1 according to the invention, it is operated with a limited amount of liquid which is recycled in each process. The liquid is discontinuously steam converted, ie continuously converted only during the treatment time. In this connection, by the formation of steam inside the closed structure by the system 17, a control unit for controlling each workpiece processing operation is started, and then the extraction device 21 controls by extracting the steam. The unit continues to operate.

In the description of the operation of the oven, it has been assumed that the amount of steam that the workpiece penetrates completely into the steam is present in the enclosure. By adjusting the amount of the liquid introduced into the bottom plate 11, the amount of vapor in the sealed structure can be adjusted. In addition, for controlling the temperature of the system, it is possible to select the liquid from a plurality of heat transfer liquids having different boiling points. In this connection, a plurality of tanks and pipes 18 each containing a different heat transfer liquid are connected by valves. It is a further advantage of the present invention that the condensation oven can be integrally constructed in a manufacturing line where the workpieces must be processed continuously. In this regard, during the processing operation, the workpiece to be processed is supported in a single plane which is continuous with the plane of the delivery device located before and after the oven.

The oven according to the invention is suitable for simultaneously processing one or two or more workpieces 2. In addition, a porthole for checking the progress of the processing operation can be mounted in the oven.

In this connection, the port holes mounted in the ceiling 13 of the oven and mounted in the form of a glass plate to form a sealed state of the assembly are advantageous because they are used to pass infrared rays. By the oven of the present invention, a short- or medium-wave infrared source can be provided which makes the thermal characteristics of the oven modifiable. According to a feature of the invention, since each heating mode (by convection, radiation and condensation) is available alone or in combination, an oven provided with another radiation mode in relation to the processing operation is further provided. It is readily available.

The present invention is not limited to the above embodiments and can be modified in various forms without departing from the spirit of the present invention.

Claims (14)

In a method in which a workpiece is heat treated with one or more heat transfer liquids having a boiling point of a given value, Placing a workpiece to be processed inside the oven and forming a closed structure in which the internal structure of the oven is accessible through at least one door and is in a sealed state, Making the internal structure of the oven at a temperature suitable for condensation on the workpiece to be treated with a portion of the vapor obtained by evaporating the heat transfer liquid; An operation in which the enclosure of the oven is occupied by the steam such that a portion of the steam condenses on the workpiece to be treated, Extracting the steam remaining in the sealed structure of the oven, A method characterized by the operation of taking out a workpiece from an oven. 2. A method according to claim 1, consisting of the operation of placing the internal structure of the oven at a temperature above the boiling point of the liquid. 3. A method according to claim 2, consisting of the operation of placing all internal structures constructed in the oven at a temperature above the boiling point of the liquid. 2. A method according to claim 1, characterized by the operation of injecting a given amount of liquid into the oven and onto the bottom plate so that the liquid is evaporated so that the closure structure of the oven is occupied by steam. 2. A method according to claim 1, characterized by the operation of injecting a given amount of steam into the oven such that the enclosure of the oven is occupied by steam. 2. The method of claim 1 wherein the steam is moved outside of the oven to condense the steam to extract steam from the enclosure of the oven. The method of claim 1, wherein the steam is condensed within the sealed structure and the liquid is extracted from the sealed structure in order to extract steam from the sealed structure of the oven. In the oven of the condensation function for the heat treatment to the workpiece, A case formed by the inner structure and formed by the inner structure, wherein one sealing structure is accessible by at least one door and is in a sealed state; Heating means for heating the internal structure to a temperature suitable for condensation on the workpiece to be treated with a portion of the vapor obtained by evaporating the heat transfer liquid; A system for vapor condensing on the workpiece, wherein the vapor obtained by evaporating the liquid occupies an interior of the enclosure and a portion of the vapor is to be treated; Condensation function oven, characterized in that configured to the extraction device for extracting the steam occupying the interior of the closed structure constituted in the oven. 9. The condensation oven of claim 8, wherein a system is provided in which the interior of the hermetic structure is occupied with steam by a liquid supply circuit which opens on the bottom plate of the oven to evaporate the liquid. 10. The condensation function oven according to claim 9, wherein the vapor extraction device is constituted by a vapor suction circuit in which a condensation unit having an outlet port connected to the internal structure is mounted. 11. The condensation oven of claim 10, wherein a tank for recirculating heat transfer liquid is provided with a condensation unit, and a supply circuit for supplying liquid to the inside of the sealed structure is connected to the tank. 9. The condensation function oven according to claim 8, wherein the vapor extraction device is constituted by means for extracting heat transfer liquid from inside the closed structure and a condenser installed inside the closed structure of the oven. 9. The condensation oven of claim 8, wherein a series of tanks filled with heat transfer liquids having different values of boiling points are provided in a system in which the interior of the closure structure is occupied by steam. 9. The condensation oven according to claim 8, wherein a port hole through which infrared radiation of short wavelength or intermediate wavelength provided by the infrared source is passed is mounted to the case.