DE8520254U1 - Soldering device for soldering electronic flat assemblies in a soldering chamber filled with inert gas - Google Patents

Description

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Siemens Aktiengesellschaft Our mark

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Soldering device for soldering electronic Fladh assemblies in a soldering chamber filled with inert gas

The innovation relates to a soldering device for soldering electronic flat modules in an inert gas-filled IQ soldering chamber, one entry & opening and one Has outlet opening for the flat assemblies guided through the soldering chamber by means of a conveying device.

Such a soldering device known from DE-OS 33 09 648 has a soldering chamber in the form of a soldering channel which is open at both ends to the external environment. The open ends form an inlet opening and an outlet opening for printed circuit boards to be soldered, which by means of a through the soldering chamber extending conveying device successively past gas nozzles and a Schwallötbad inside the soldering chamber will. Heated shielding gas flows through the gas nozzles onto the soldering sides of the flat modules that are passed by these reach the wave solder bath. The protective gas preferably consists of a nitrogen-hydrogen mixture that Has an oxygen-reducing effect and thus enables flux-free soldering of the flat modules. The fed The gas flow is dimensioned so that there is a constant slight overpressure compared to the inside of the soldering chamber The outside atmosphere prevails, so that the protective gas flows outwards at the inlet and outlet openings and so flows in Ingress of ambient air into the interior of the soldering chamber is prevented.

From the magazine "welding technology", 1980, issue 3, page 109, Fig. 1, it is known in a similarly structured

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Brazing furnace for brazing workpieces in a protective gas atmosphere the protective gas flowing out of the corresponding inlet and outlet openings of the soldering furnace to be diverted harmlessly by means of trigger devices and to torch.

Due to the open design of the known soldering devices, it can be particularly in the areas of entry and Exit opening for the formation of explosive air-protective gas mixtures. The aim is to solve the problem of a Specify soldering device for soldering printed circuit boards in a protective gas atmosphere, in which a formation such air / protective gas mixtures is excluded.

To solve this problem, in the soldering device of the type specified at the outset, the input opening is according to the invention a lock device upstream and a further lock device downstream of the outlet opening; every Lock device each has a lock chamber with an inner lock gate to the soldering chamber and an outer one The lock gate to the outer environment of the soldering device opens, and the lock chambers are in with a vacuum pump Link.

The main advantage of the soldering device according to the invention is that the interior of the soldering chamber compared to the outer environment of the soldering device is sealed gas-tight via the lock chambers, so that a mixture formation is excluded from the protective gas in the soldering chamber and the outside air. Despite this encapsulation of the soldering chamber a continuous passage for the PCBs to be soldered through the According to the innovation soldering device through made possible by the lock chambers alternately over their respective outer Lock gate to the outside environment and via the respective inner lock gate to the soldering chamber are opened, wherein

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meanwhile each lock chamber when it is closed Lock gates is evacuated by means of the vacuum pump connected to it. In the lock chambers they change Atmospheres between ambient air and protective gas * without

I 5 there is a mixture formation.

i üede lock device advantageously contains each j a transport device for the flat modules, which i within the respective lock chamber between the

i 10 is arranged extending over both lock gates. the

ί transport devices enable the transport of the \ PCBs by the respective lock means f through it, so that the direction in cooperation with the Förderyor- \ within the soldering chamber a continuous

I 15 Passage of the flat modules through the renewal

j soldering device is guaranteed through. The transport! · Devices in the two lock devices can ί well as the conveyor in the soldering chamber in a manner I have known way rails, where motör-

I 20 driven transport chains are running.

In an advantageous embodiment of the I-soldering device according to the invention, each lock gate is the lock device each connected to an electric motor via a toggle lever arrangement and a reduction gear.

This ensures that the lock gates both in one by the vacuum pump in the respective lock chamber generated negative pressure as well as an overpressure of the protective gas in the lock chamber in question this safe 30 ″ by arranging the toggle lever arrangement in this way is that it is approximately in a dead position when the lock gate is closed and therefore the drive torque of the Electric motor converts into a very high closing force of the lock gate in question. The reduction gear for 35 Reduction of the motor speed to the toggle lever arrangement can, for example, consist of a self-locking screw

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transmission exist.

The soldering chamber is advantageously via a pressure relief valve Connected to a gas storage tank. This enables the flat modules transported in the soldering chamber With a constant supply of protective gas to flow through nozzles, whereby to maintain a constant Internal pressure in the soldering chamber, the amount of gas corresponding to the protective gas supplied from the soldering chamber via the The pressure relief valve in the gas storage tank escapes without mixing with the outside air. Due to the overpressure inside The soldering chamber also provides an additional seal between the soldering chamber and the external environment.

Safe operation of the soldering device according to the innovation is achieved with only little control effort in advantageously achieved in that the lock chambers are connected to one another via a pipeline, that the pipeline via a ventilation valve with the external environment and via a suction valve with the Vacuum pump is in connection and that the soldering chamber is connected to the pipeline via a pressure compensation valve. With this valve arrangement, safe start-up and safe operation of the innovation according to the invention is always essential Allows soldering device. So when you switch on the soldering device according to the innovation by opening the Pressure equalization valve and the suction valve when the lock gates are closed, both the lock chambers as also evacuate the soldering chamber in order to remove any residual gas mixtures that may be present. While the According to the innovation soldering device, the lock chambers can be opened by opening the ventilation valve at the same time with closed pressure equalization valve and closed suction valve, fill with air until the pressure is equal to the external environment exists, so that the respective outer lock gates of the two lock chambers are opened

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can; A PCB to be soldered can then be transported into one lock chamber, while a already soldered flat module can be removed from the further lock chamber. After both Lock chambers are closed again, they can be opened by closing the ventilation valve and opening the suction valve evacuated and then filled with protective gas by closing the suction valve and opening the pressure compensation valve will. Now the inner lock gates of the two lock chambers can be opened so that the one to be soldered Flat module from one lock chamber into the soldering chamber and a completely soldered flat module from the Soldering chamber can be transported into the further lock chamber.

In a preferred development of the soldering device according to the innovation, the ventilation valve is the suction valve and the pressure compensation valve each electromagnetic valves which are connected to outputs of a program control device are connected; the electric motors for the lock gates are connected to further outputs of the program control device connected, the lock gates are each assigned limit switches, each at the inputs of the Program control device are connected, and the lock chambers are via a measuring pipe with a Pressure sensor device connected, the output side connected to further inputs of the program control device is. The program control device enables simple and reliable control and monitoring of the innovation according to the invention Soldering device, the respective positions of the lock gates by means of the limit switches and by means of the Pressure sensor device detects the internal pressure conditions of the soldering device and in the form of input signals fed via the inputs or further inputs of the program control device * Depending on the program control device controls these input signals

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management via their outputs or other outputs Electric motors to set the lock gates and the electromagnetic valves to exchange the atmospheres in the lock chambers between air and protective gas.

The pressure sensor device advantageously contains a vacuum switch, an atmospheric pressure switch and a Overpressure switches which are each connected to the measuring pipe at their pressure connections and at their switching outputs are each connected to one of the further inputs of the program control device. The Vacuum switch for detecting the evacuated state of the two lock chambers, the atmospheric pressure switch responds to a pressure equalization between the interior of the lock chambers and the external environment, and the Overpressure switch is used for feedback when the pressure of the protective gas is open to the soldering chamber when the lock chambers are open exceeds a specified overpressure value. To further increase the security of the soldering device according to the innovation single pressure switches and limit switches can be duplicated and in the program control device are monitored for equivalent switching behavior in each case.

To explain the innovation, see

Fig. 1 shows a preferred embodiment of the soldering device according to the innovation in section shown.

Fig. 2 shows a lock gate with an associated toggle lever arrangement, reduction gear and Electric motor,

Fig. 3 shows a further preferred embodiment for a lock gate,
and in

4 shows a diagram of the soldering device according to the invention.

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The exemplary embodiment of the soldering device according to the invention shown in FIG. 1 has a soldering chamber 1 with an inlet opening 2 and an outlet opening 3 for electronic flat assemblies to be soldered, in particular printed circuit boards with components. The soldering chamber 1 is connected at its inlet opening 2 to an upstream lock device 4, and a further lock device 5 is arranged downstream of the soldering chamber 1 at the outlet opening 3. The soldering chamber .1 consists of three individual chambers 6, 7 and B, of which a first individual chamber directly adjoining the lock device 4 is designed as a gassing chamber 6; A soldering space 7 adjoins the gassing chamber 6 as a second individual chamber, and an angular compensation chamber 8 is arranged downstream of the soldering space 7 as a third individual chamber. Through the soldering chamber 1 through a conveying device 9, which serves to transport the not shown electronic printed circuit board assemblies from the voltage Eintrittsöf ^f 2 by the soldering chamber 1 through up to the Austrittsöffnuny 3 extends. A plurality of gas nozzles 10, which are connected to a protective gas container 11 via valves (not shown here), are arranged in the middle part of the gassing chamber 6. The protective gas container 11 contains a protective gas which is under excess pressure and which preferably consists of a nitrogen-hydrogen mixture. The gas nozzles 10 are arranged in such a way that the protective gas flowing out of them hits the soldering sides of the flat modules passed by the conveying device 9. The protective gas flowing out of the gas nozzles 10 can be heated to high temperatures above the soldering temperature by heating coils (not shown here) on the gas nozzles 10. The soldering room 7 contains a height-adjustable soldering trough 12 with a wave soldering bath 13. Within the soldering room 7, the conveying device 9 is arranged at an angle of inclination of a few degrees to the horizontal, so that the flat modules to be soldered are guided past the wave soldering bath 13 with their soldering side at this angle of inclination .

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In the downstream angle compensation chamber 8, the goes Course of the conveyor 9 back into the horizontal. The lock devices 4 and 5 each exist from a lock chamber 14 or 15, which leads to the soldering chamber 1 through an inner lock gate 16 and 17, respectively are lockable and each have an outer lock gate 18 or 19 have. Each of the two lock chambers 14 and 15 contains a transport device 20 and 21, respectively Transport of the flat modules within the respective Lock chamber 14 and 15 between its two lock gates 16 and 18 or 17 and 19. In the illustrated embodiment of the innovation according to the soldering device, the lock device 4 has a before Outer lock gate 18 arranged, upwardly and forwardly open input chamber 22 for inserting the to be soldered PCBs on; the further lock device 5 accordingly has one behind its outer lock gate 19 arranged, upwardly and rearwardly open output chamber 23 for removing completely soldered flat modules.

The lock devices 4 and 5 and the individual chambers 6, 7 and 8 of the soldering chamber 1 each consist of rectangular ones Pipe flange pieces that are screwed together using rubber seals.

Fig. 2 shows a drive for one of the lock gates 16 to 19. The respective lock gate (e.g. 18) consists essentially of a flap which is pivotable about an axis of rotation 30. At the lock gate 18 engages a toggle lever arrangement 31 with a lever arm 32 which is attached to a bearing end 33 at a distance from the axis of rotation 30 is mounted on the lock gate 18 and is mounted on its other bearing end 34 on the circumference of a gear wheel disk 35.

The axis 36 of the gear wheel 35, the bearing ends 33 and 34 of the lever arm 32 and the axis of rotation 30 of the lock gate 18

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form joints of the toggle lever arrangement 31 (four-bar linkage). The toothed wheel disk 35 is also a component at the same time a reduction gear 37, which is designed as a worm gear and in addition one in the gear wheel 35 engaging worm wheel 38 has. The worm wheel 38 is connected to the shaft 39 of an electric motor 40 tied together. The toggle lever arrangement 31 is designed such that the bearing ends 33 and 34 of the lever arm 32 and the axis 36 of the gear wheel disk 35 with the lock gate 18 closed lie approximately in a line, so that the toggle lever arrangement 31 is in a dead position and therefore the drive torque of the electric motor 40 in a very high closing force of the lock gate 18 implements.

Fig. 3 shows an example of a preferred embodiment of the Lock gates 16 to 19 the lock gate 16 of the lock chamber 14 both in the open and in the closed Position. The pivoting range of the lock gate 16 is indicated by a double arrow. The lock gate 16 has a Closure plate 100 for a corresponding opening 101 of the lock chamber 14 to the soldering chamber 1. The locking plate 100 is held on a lever arm 102 which is firmly connected to a drive shaft 103. The drive shaft 103 the soldering device is arranged laterally offset to the opening 101 and traverses transversely and - not shown here on its shaft end protruding from the soldering device via a reduction gear (e.g. worm gear) connected to an electric motor. On the back of the closure flap 100 are two locking parts 104 and 105 each arranged pivotably about an axis of rotation 106 or 107. Each locking member 104 and 105 is respectively provided with an approach 108 or 109, which with the lock gate 16 closed and in the locked position of the two locking parts 104 and 105 each have one of two projections 110 and arranged on both sides of the opening 101 111 reaches behind. The two locking parts 104 and 105

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are via a hook stitch assembly 112 to the free end 115 of the lever arm 102 connected. The knee lever arrangement comprises two at the free end 103 of the lever arm 102 articulated levers 114 and 115 which, at their free ends, are attached to one of the two locking parts 104 and 105 attack and are connected there with a tension spring. When the lock gate 16 is open, the Tension spring 116 the locking parts 104 and 105 in an unlocked position. To close the lock gate the closure plate 100 is pivoted against the opening 101 with the aid of the lever arm 102. With further pivoting of the lever arm 102, the locking parts 104 and through the toggle lever assembly 112 against the force of Tension spring 116 is pivoted into a locking position in which the lugs 108 and 109 the projections 110 and 111 reach behind. As soon as during the pivoting movement of the lever arm 102 its connection point with the toggle lever | arrangement 112 crosses the line of action of the tension spring 116, the tension spring 116 acts to support the Lock so that the lock gate 16 closes securely.

As FIG. 4 shows in a schematic representation of the exemplary embodiment of the soldering device according to the invention according to FIG. 1, the lock chambers 14 and 15 are connected to one another via a pipeline 41. The pipeline 41 is connected to the external environment of the soldering device via a ventilation valve 42 and to a vacuum pump 44 via a suction valve 43. The pipeline 41 is also connected to the interior of the soldering chamber 1 via a pressure equalization valve § 45. Like Fig. 4; also shows, five gas nozzles 10 are provided for gassing the soldering chamber 1, each of which is connected to the protective gas container 11 via valves 46 and a common main valve 47. The main valve 47 is designed as a control valve for the continuous control of the gas flow rate. The soldering chamber 1 is also via an additional I.

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Valve 48 and a pressure relief valve 49 are connected to a gas reservoir 50. The interior of the two lock chambers 14 and 15 is connected to a pressure release device 52 via a measuring pipe 51. The pressure sensor device 52 contains a vacuum switch 53 with a response pressure of 1 mbar, an atmospheric pressure switch 54 with a response pressure of 1 bar and an overpressure switch 55 with a response pressure of 1.25 bar. In addition, another vacuum switch 56 with a response pressure of 1 mbar, another overpressure switch 57 with a response pressure of 1.25 bar and two additional overpressure switches 58 and 59 each with a response pressure of 1.4 bar via a further measuring pipe 60 with the interior of the Soldering chamber 1 connected. An additional vacuum switch 61 with a response pressure of 1 mbar is connected to the second lock chamber 15. Each of the lock gates 16 to 19 is each driven by an electric motor 62 to 65 via a reduction gear with a toggle lever arrangement, indicated here only by a dashed line of action. Two limit switches 66 to 73 are assigned to each lock gate 16 to, whereby the limit switches 66, 68, 70 and 72 are operated when the lock gates 16 to 19 are closed and the limit switches 67, 69, 71 and 73 are operated when the lock gates 16 to 19 are open will. A further redundant limit switch 74, 75, 76 and 77 is assigned to each of the limit switches 66, 68, 70 and 72. The limit switches 66 to 77 are each connected to inputs 78 of a program control device 79. The pressure switches (vacuum switches, 30 switches, atmospheric pressure switches and overpressure switches) are connected to further inputs 80 of the program control device 79 at their respective switching outputs. The individual valves 42 to 47 and 48 are electromagnetic valves which are each connected to outputs 81 of the program control device 79; the electric motors 62 to

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65 for the lock dead 1-6 to 19 are connected to further outputs 87 of the program control device 79.

When the soldering device is switched off, all valves and all ° 5 lock gates closed. After switching on the

According to the soldering device according to the innovation, the lock chambers are evacuated by the vacuum pump 44 with the suction valve 43 open until the vacuum switches 53 and 61 respond. \ Subsequently the soldering chamber 1 is evacuated at an open-printed iO a'jsgleichsventil 45, respond to the vacuum switch 53, I and 56th Thereafter, it is ensured that the proper soldering device j renewal of residual gas mixtures is freed I. The soldering chamber 1 is then opened by opening the

Valves 46 and the main valve 47 filled with the protective gas 15; the pressure relief valve 49 causes at constantly After the protective gas flows inside the soldering chamber 1, there is a constant overpressure of about 0.3 bar. At the start of a lock cycle, the lock chambers 14 and 14 are ventilated by opening the vent valve 42 for as long 20 until the atmospheric pressure switch 54 responds. Then 1 the ventilation valve 42 is closed and the external

Ϊ Lock gates 18 and 19 of lock chambers 14 and

* 15 opened to allow printed circuit boards to enter the lock chamber 14

'into or out of the further lock chamber 15 out

25 transport. After closing the outer lock gates ti and 19, the lock chambers 14 and 15 are evacuated,

:] by opening the suction valve 43 until the

ί Respond vacuum switches 53 and 61. The

|; Lock chambers 14 and 15 filled with protective gas by the

I 3.0 pressure equalization valve 45 with the suction valve now closed

I valve 43 is opened until both lock chambers

I 14 and 15 and the soldering chamber 1 evenly with protective gas

I are filled and the overpressure switches 55 and 57 respond,

$ Now the inner lock gates 16 and 17 of the

I 35 lock chambers 14 and 15 are opened to the Flachet
I assemblies from the lock chamber 14 into the soldering chamber

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4 figures
7 claims

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Claims (6)

New protection claims 1 to 6 Our reference number G 85 20 254.1 5 1. Soldering device for soldering electronic flat modules in a soldering chamber filled with inert gas, which has an inlet opening and an outlet opening for the means of a Has conveyor device guided through the soldering chamber flat modules, characterized that a lock device (4) is attached to the inlet opening (2) of the soldering chamber (1), that at the outlet opening (3) of the soldering chamber (1) a further lock device (5) is attached, that each Lock device (4, 5) each have a lock chamber (14, 15) with an inner lock gate (16, 17) for Has soldering chamber (1) and an outer lock gate (18, 19) to the external environment of the soldering device and that the Lock chambers (14, 15) each have a connection for connection to a vacuum pump (44). 2. Soldering device according to claim 1, characterized in that each lock device (4, 5) each ^ ine transport device (20, 21) for the flat modules that are located within the respective lock chamber (14, 15) between the two Lock gates (16, 18 or 17, 19) is arranged extending. 3. Soldering device according to one of the preceding claims, characterized in that each Lock gate (16 to 19) of the two lock devices (4 and 5) each via a toggle lever arrangement (31) and a Reduction gear (37) is connected to an electric motor (40). Il ill »« ■ ti <1 til * · • I I I I ι t I I * I ** ttt -III Il • * 4 * 1 1 i it dt • * * · I I I · • Ι * Γ · Γ · 1 · ·· ιι · tea arei ■ · ■ · · «· ft 1 ι m - 2 - VPA 85 G 4056 DE 4. Soldering device according to one of the preceding claims, characterized in that the The soldering chamber (1) has a connection with a pressure relief valve (49). 5. Soldering device according to one of the preceding claims, characterized in that between the lock chambers (14, 15) they are connected to one another Pipe (41) runs that on pipe (41) a ventilation valve (42) for connection with the sweetener Environment and a suction valve (43) for connection to the Vacuum pump (44) is attached and that between the soldering chamber (1) and the pipeline (δι) a pressure compensation valve (45) lies. 6. Soldering device according to claim 5 in conjunction with claim 3, characterized in that the ventilation valve (42), the suction valve (43) and the pressure compensation valve (45) are each electromagnetic valves, that the lock gates (16 to 19) each limit switch (66 to 72) and that a measuring pipe (51) is continued from at least one lock chamber (14, 15), at the end of which there is a pressure sensor device (52). HH »t i · it II t * I III It t till *