Abstract
A system for connecting electronic assemblies, in particular a soldering and/or sintering system, has a transport device for conveying the assemblies through the system, with a plurality of gas-tightly separable modules for connecting the assemblies to one another. At least one module is a soldering and/or sintering module and one module is a cooling module. Between the soldering/sintering and the cooling module, a further module is a soft cooling module for cooling between a process temperature of the soldering or sintering module and an intermediate temperature, in particular below a solder solidification temperature. In a soldering or sintering module in a gas-tightly sealable process chamber, in particular in the soft cooling module, at least one heat source is contactable with the assemblies for heating the assemblies and at least one cold trap is arranged, having in operation a surface temperature which is lower than a heat source operating temperature.
Claims
1.-31. (canceled)
32. A soldering and/or sintering system for connecting electronic assemblies, comprising: a transport device for conveying the electronic assemblies through the system, comprising; a plurality of gas-tightly separable modules for connecting the electronic assemblies to one another; wherein at least one of the plurality of modules is designed as a soldering and/or sintering module and one of the plurality of modules is designed as a cooling module; wherein; the soldering and/or sintering system comprises a higher-level control for controlling the plurality of modules; between the at least one soldering or sintering module and the cooling module, a further module is arranged that is designed as a soft cooling module for cooling between a process temperature of the at least one soldering or sintering module and an intermediate temperature below a solder solidification temperature; in the soft cooling module, a heating and/or a cooling device is comprised for controlled temperature adjustment and cooling down of the electronic assemblies from 500° C. or below to the intermediate temperature below the solder solidification temperature, which is in the range from 220° C. to 150° C.; in the soft cooling module, a gas purging device for purging the electronic assemblies, in particular using cold gas, preferably with cold nitrogen gas, is comprised.
33. The soldering and/or sintering system according to claim 32, wherein the soft cooling module is configured to provide a positive pressure for a process atmosphere of 1 bar, in particular up to 4.5 bar.
34. The soldering and/or sintering system according to claim 32, wherein the soft cooling module is configured to provide a negative pressure of below 1 bar, in particular a vacuum.
35. The soldering and/or sintering system according to claim 32, wherein the soft cooling module is designed as a positive pressure chamber and/or vacuum chamber.
36. The soldering and/or sintering system according to claim 32, wherein the heating and/or a cooling device is designed as a heatable and/or coolable contact plate.
37. The soldering and/or sintering system according to claim 36, wherein: the contact plate is designed as a heating plate; and the cooling device is designed as a gas cooling device for cooling down the contact plate by means of a gas flow, in particular a nitrogen gas flow, from a side of the heating plate facing away from the electronic assemblies.
38. The soldering and/or sintering system according to claim 36, wherein: the contact plate is mechanically movable, in particular can be brought into contact with and kept at a distance from the electronic assemblies; and/or the contact plate comprises a gas rack preferably designed in meandering form.
39. The soldering and/or sintering system according to claim 32, wherein an inlet valve for admitting the gas into a process chamber of the soft cooling module is comprised on the soft cooling module.
40. The soldering and/or sintering system according to claim 32, further comprising a gas collection container outside a process chamber of the soft cooling module, which is connected to the inlet valve and is designed to receive the gas extracted from the process chamber of the soft cooling module.
41. The soldering and/or sintering system according to claim 32, wherein a positive pressure valve for checking a positive pressure and/or a quick bleed valve is comprised on the soft cooling module.
42. The soldering and/or sintering system according to claim 32, wherein a positive pressure of 4 to 6 bar prevails in the soft cooling module.
43. The soldering and/or sintering system according to claim 32, wherein the cooling down from a temperature below the solder solidification temperature to room temperature takes place in the cooling module, in particular from a temperature below 200° C. to room temperature.
44. The soldering and/or sintering system according to claim 32, wherein a normal pressure or negative pressure, in particular a vacuum, prevails in the cooling module.
45. The soldering and/or sintering system according to claim 32, further comprising a further module connected in front of the soldering or sintering module, that is designed as a preheating module.
46. The soldering and/or sintering system according to claim 32, further comprising a cold trap in the process chamber of the soft cooling module, in particular as a gas cooler in a gas outlet path of the process chamber.
47. The soldering and/or sintering system according to claim 32, wherein a separation of the gas-tightly separable modules is achieved using vacuum insertable gate valves, wherein a tightness of the vacuum insertable gate valves increases as the pressure increases and/or pressure equalization using the vacuum insertable gate valves takes place when the pressure is too high.
48. The soldering and/or sintering system according to claim 32, wherein in the module designed in particular as the soldering or sintering module or as the soft cooling module in a gas-tightly sealable process chamber at least one heat source contactable with the electronic assemblies for heating the electronic assemblies and at least one cold trap are arranged, the at least one cold trap having in operation a surface temperature which is lower than an operating temperature of the heat source.
49. The soldering and/or sintering system according to claim 48, wherein a specific process atmosphere is provided in the process chamber, wherein the cold trap and the heat source are arranged relative to one another such that at least during a specific operating phase currents are present in the process atmosphere solely due to convection, which is generated by a temperature difference between the cold trap and the heat source.
50. The soldering and/or sintering system according to claim 48, wherein the surface temperature of the cold trap is between −196° C. (77 k) and 150° C., in particular 16° C. to 25° C., and wherein a cascadable surface temperature of the cold trap is preferably providable.
51. The soldering and/or sintering system according to claim 48, further comprising at least one additional heat source for heating the process chamber.
52. The soldering and/or sintering system according to claim 51, wherein the operating temperature of the heat source and/or of the additional heat source is between 150° C. and 400° C., or preferably between 200° C. and 300° C.
53. The soldering and/or sintering system according to claim 48, wherein at least one and in particular a plurality of assemblies is arranged on a workpiece carrier and preferably at a distance therefrom in a direction of the cold trap at least at times, such that the distance of the assemblies to the cold trap is less than a distance of the workpiece carrier to the cold trap.
54. The soldering and/or sintering system according to claim 48, wherein at least one partial area of the process chamber, in particular at least one wall surface of the process chamber and/or a surface of a transport device arranged in the process chamber and provided to insert and/or remove assemblies, is designed as a temperature adjustment zone, wherein said temperature adjustment zone has during operation a temperature between the surface temperature of the cold trap and the operating temperature of the heat source, wherein the temperature of the temperature adjustment zone is preferably between 50° C. and 150° C., in particular between 80° C. and 120° C.
55. The soldering and/or sintering system according to claim 48, wherein the process chamber is connected or connectable via a pipeline to an evacuation device, wherein an outlet of the pipeline into the process chamber is provided immediately adjacent to the cold trap.
56. The soldering and/or sintering system according to claim 48, wherein the cold trap has a plurality of cooling fins preferably extending in a vertical direction.
57. The soldering and/or sintering system according to claim 48, further comprising a collection device provided underneath the cold trap to collect condensate generated at the cold trap.
58. The soldering and/or sintering system according to claim 53, wherein the heat source and/or the workpiece carrier with the assemblies are adjustable in their distances relative to one another in the direction of the cold trap.
59. The soldering and/or sintering system according to claim 53, wherein the workpiece carrier is separately heatable.
60. The soldering and/or sintering system according to claim 48, further comprising a speed-controlled extraction vacuum pump with a liquid separator provided for creating a negative pressure in the process chamber.
61. The soldering and/or sintering system according to claim 48, further comprising at least one heatable vacuum insertable gate valve, in particular two heatable vacuum insertable gate valves at two opposite sides of the process chamber, provided for insertion and/or removal of the assemblies.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] Further advantages are revealed by the appended drawings and the descriptions of the drawing. The drawing shows exemplary embodiments of the invention. The drawing and, description contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.
[0075] In the Figures:
[0076] FIG. 1 is an embodiment of a system in accordance with the invention in an isometric view;
[0077] FIG. 2 a sectional representation of a further embodiment of a system in accordance with the invention;
[0078] FIG. 3 a circuit diagram of an embodiment of a system in accordance with the invention;
[0079] FIG. 4 an embodiment of a cold trap;
[0080] FIG. 5 a circuit diagram of a further embodiment of a system in accordance with the invention;
[0081] FIG. 6 a plan view onto a process chamber;
[0082] FIG. 7 a sectional view of the process chamber of FIG. 6;
[0083] FIG. 8 a further view of the process chamber of FIG. 6;
[0084] FIG. 9 a cold trap with cooling fins;
[0085] FIG. 10 a further embodiment of a cold trap with cooling fins;
[0086] FIG. 11 a side view of a further cold trap;
[0087] FIG. 12 a possible cooling circuit in a cold trap;
[0088] FIG. 13 a receiving element for the cold trap of FIG. 12;
[0089] FIG. 14 a collection device of a cold trap;
[0090] FIG. 15 a plan view onto a module of the soldering system with robot;
[0091] FIG. 16 an embodiment of a workpiece carrier;
[0092] FIG. 17 a further embodiment of a cold trap;
[0093] FIG. 18 an embodiment of a receiving element for the cold trap of FIG. 17;
[0094] FIG. 19 a side view of the receiving element with cold trap of FIGS. 17 and 18;
[0095] FIG. 20 a further view of the embodiment of FIG. 19;
[0096] FIG. 21 a sectional view of the embodiment of FIG. 19;
[0097] FIG. 22 a detailed view of the embodiment of FIG. 20;
[0098] FIG. 23 an isometric representation of the receiving element with opening element;
[0099] FIG. 24 a sectional representation through a process chamber;
[0100] FIG. 25 a further embodiment of a workpiece carrier; and
[0101] FIG. 26 a further view of the embodiment of FIG. 25.
DETAILED DESCRIPTION OF THE INVENTION
[0102] Identical or similar components are given the same reference signs in the figures.
[0103] FIG. 1 shows an embodiment of a system 10 in accordance with the invention in an isometric view. The system 10 can be designed as a soldering system 10a and comprise a plurality of modules 16. In this embodiment, the system 10 comprises at least five modules 16, wherein the first and the last module 16 can each be subdivided again. The middle three modules 16 form a preheating module 14, a soldering or sintering module 18 and a soft cooling module 22. The soft cooling module is arranged between the soldering or sintering module 18 and the cooling module 20. The cooling module 20 forms the last module 16 of the system 10 in the embodiment shown. Furthermore, an unloading module can be downstream of the cooling module 20 in an embodiment not shown. The module 16 on the left in the representation can accordingly be designed as a loading module.
[0104] FIG. 2 shows a sectional representation of a further embodiment of a system 10 in accordance with the invention. The vacuum insertable gate valves 44 between the individual modules 16 are discernible here. The housing is, unlike in the embodiment of FIG. 1, not shown. This embodiment shows four modules 16, a preheating module 14, a soldering or sintering module 18, a soft cooling module 22 and a cooling module 20. The modules 16 are arranged one behind the other in the sequence described. The soft cooling module 16 is spatially separated from the soldering or sintering module 18 and from the cooling module 20 by a vacuum insertable gate valve 44 in each case. A heating plate can be arranged in the soft cooling module 16, wherein the heating plate can be cooled from underneath with cold gas, in particular nitrogen. This permits cooling of the electronic assemblies to just below the solder solidification temperature.
[0105] FIG. 3 shows a circuit diagram of an embodiment of a system 10 in accordance with the invention. The soft cooling module 22 can be designed as a positive pressure chamber 24 or as a vacuum chamber 26. A positive pressure valve 30 is arranged on the soft cooling module 22. Furthermore, the soft cooling module 22 is connected to a backing pump 38 via an evacuation valve 36. For purging the electronic assemblies, a gas collection container 32 connected via an inlet valve 28 to the soft cooling module 22 is provided in this embodiment. The gas collection container can collect for example the gas, in particular nitrogen, using which the electronic assemblies in the soft cooling module 22 are purged. Advantageously, the gas is cleaned before, after or inside the gas collection container 2 in order to then be fed back to the soft cooling module 22 via a supply line. The gas can thus be re-used. Furthermore, the soft cooling module 22 comprises a quick bleed valve 34. With the structure as described, a positive pressure, a negative pressure or a vacuum inside the soft cooling module 22 can be controlled.
[0106] FIG. 4 shows an embodiment of a cold trap 46. The cold trap 46 can be arranged inside the process chamber of the soft cooling module 22. The cold trap 46 has in this embodiment fins 48 for enlarging a cooling surface and to permit condensate to run off. Furthermore, the cold trap 46 can have a drip tray (not shown) configured to collect the condensate. The cold trap 46 can also act as a gas cooler to protect the downstream valves and the downstream pump system.
[0107] FIG. 5 shows a circuit diagram of a further embodiment of a system 10 in accordance with the invention. Unlike in the embodiment according to FIG. 3, a further pressure control valve 42 is arranged on the soft cooling module 22. This can, like the positive pressure relief valve 30, have a connection to the waste air.
[0108] In all the embodiments shown, a positive pressure can be generated in the soft cooling module 22, wherein the positive pressure can for example be less than 0.5 bar to avoid the need for certification in accordance with the pressure equipment directive. The soft cooling module 22 too can be designed in accordance with the pressure equipment directive and have a positive pressure of for example 3 bar or more. A controlled temperature adjustment to just below the solder solidification temperature can be made using a heating and/or cooling device in the soft cooling module 22. This allows impurities in the solder to be prevented, since they already remain behind in the soft cooling module 22 before complete cooling down to room temperature in the downstream cooling module 20 and so cannot collect on the electronic assemblies. Advantageously, therefore, a purging gas is used in the soft cooling module 22 with which the impurities are removed or purged directly out of the soft cooling module 22.
[0109] FIG. 6 shows a plan view onto a process chamber 52. The process chamber 52 is preferably designed as a gas-tightly sealable process chamber 52 and arranged inside a module 16 designed as a soldering module 18. In the process chamber 52, a plurality of electronic assemblies are arranged on a workpiece carrier 56. Furthermore, a heat source 50 (shown in FIG. 7) and a cold trap 46 are arranged in the process chamber 52. This allows a cold area 72 and a hot area 74 to be formed. The process chamber 52 is preferably a vacuum process chamber. With the heat source 50 and the cold trap 46, a specific process atmosphere can be provided in the process chamber 52. Due to the arrangement of the cold trap 46 and of the heat source 50 relative to one another, currents in the process atmosphere thus arise solely due to convection, which is generated by a temperature difference between the cold trap 46 and the heat source 50.
[0110] FIG. 7 shows a sectional view of the process chamber 52 of FIG. 6. In this view the heat source 50 is shown on the underside of the process chamber 52. The heat source 50 is therefore preferably underneath the workpiece carrier 56. An additional heat source (not shown) can be arranged for additional heating of the process chamber 52. To achieve an optimum effect, it is advantageous for the cold area 72 to project as far as possible into the process chamber 52. Less fouling of the modules 16 results during the soldering process thanks to the cold trap 46. This is achieved in that the condensate from the solder paste is collected and deliberately passed out of the system. Preferably, a pressure of less than or equal to 950 bar prevails here in the process chamber 52. This can be achieved for example by N2, N2H2 or HCOOH or by gas mixtures. In particular, a quiescent gas without forced guidance is present. This results in evaporation of the organic constituents, with the hot gas rising upwards with the organic constituents in the process chamber 52. The temperature gradient between the hot and the cold surfaces leads however to convection of the gas inside the process chamber 52, in particular inside the vacuum process chamber. Volatile constituents therefore condense on the cold surfaces and are thus passed into the cold trap 46 and collected there. Further advantages result for example in that residues of the condensate evaporate on surfaces at approx. 100° C. and can finally be deliberately disposed of by evacuation of the vacuum process chamber, for example by an extraction vacuum pump 66 and/or a liquid separator 68.
[0111] FIG. 8 shows a further view of the process chamber 52 of FIG. 6. The surfaces on which the residues of the condensate evaporate are shown by the temperature adjustment zones 76. In an embodiment of this type, a deliberate use of the vapor pressure of solvents can be exploited in particular. Some solvents condense on the temperature adjustment zones 76, since the vapor pressure is higher than at 100° C. with a pressure of 950 bar. By the deliberate evacuation of the process chamber 52, in particular of the vacuum process chamber, the residues of the solvents evaporate and also condense on the cold surfaces, i.e. in the cold areas 72, of the cold trap 46 and are therefore deliberately collected. In the area of the cold trap 46, a temperature range of 2° C. to 30° C., preferably 16° C. to 25° C., can therefore prevail. In the temperature adjustment zone 76, the temperatures can be 100° C. In the area of the heat source 50 and on the upper side of the process chamber 52, the temperatures can be 150° C. to 300° C., for example due to an additional heat source 54.
[0112] FIG. 9 shows a cold trap 46 with cooling fins 48. The cooling fins 48 can be arranged on the inner wall of the process chamber 52 and serve to enlarge the cooling surface. Furthermore, running off of the condensate can be improved by the cooling fins 48. The representation shows a view from the interior of the process chamber 52, with a workpiece carrier 56 being arranged on the floor of the process chamber 52.
[0113] FIG. 10 shows a further embodiment of a cold trap 46 with cooling fins 48. Underneath the cooling fins 48 a collection device 64 is discernible which is designed for collection of the condensate generated at the cold trap 46.
[0114] FIG. 11 shows a side view of a further cold trap 46. The arrow directions show the running off direction or flow direction of the condensate. The condensate runs downwards inside the cooling fins 48 in the cold trap 46 and lands on the collection device 64. The collection device 64 can for example be designed as a drip tray. The collected condensate flows in the direction of a collection container 82 via the collection device 64. A continuous evacuation can be assisted by a vacuum pump line. The condensate contains in particular solvents, unwanted deposits and/or impurities.
[0115] FIG. 12 shows a possible cooling circuit of a cold trap 46, shown by the arrow direction. FIG. 13 shows a receiving element 69 for the cold trap 46 of FIG. 12. In an embodiment of this type, the cold trap 46 can therefore be mountable in exchangeable manner. The cold trap 46 is inserted from the rear into the receiving element 69, in particular over guides 84 arranged on two opposite sides of the receiving element 69. Thermal insulation is also arranged in particular on the guides 84. The receiving element 69 is mounted directly on the process chamber 52 (not shown). The receiving element 69 can also itself form the process chamber 52, wherein the cold trap 46 can be mounted directly on the process chamber 52.
[0116] FIG. 14 shows a collection device 64 of a cold trap 46. As in FIG. 11, in this representation the collection device 64 is designed as a drip tray, wherein the collected condensate is drained via an opening 65, in this embodiment designed as a slot, rearwards into the receiving element 69.
[0117] FIG. 15 shows a plan view onto a module 16 of the soldering system 10a with robot. The shown module 16 can represent in particular the module 16 shown right on the left-hand side in FIG. 1, and can in particular be designed as a loading station. In the loading station, in particular the workpiece carriers 56 are loaded with electronic assemblies 12, wherein this can be done using a robot arm 78 in this embodiment.
[0118] FIG. 16 shows an embodiment of a workpiece carrier 56. This is designed for six electronic assemblies 12. A workpiece carrier 56 of this type is used in particular in a process chamber 52 as shown in FIGS. 6 to 9.
[0119] FIG. 17 shows a further embodiment of a cold trap 46. In this embodiment too, the cold trap 46 has a collection device 64 extending as an inclined plane on the underside of the cold trap 46. In contrast to the representation according to FIG. 14, the collection device 64 has no slot, but individual openings 65 out of which the condensate is drained from the cold trap 46 and into the receiving element 69 (not shown).
[0120] FIG. 18 shows an embodiment of a receiving element 69 for the cold trap 46 of FIG. 17. On the underside of the receiving element 69, a plurality of inclined surfaces 86 are arranged via which the condensate can be passed out of the openings 65 of the cold trap 46. The condensate runs over the inclined surfaces 86 to an opening 88 and is drained via the opening 88 out of the receiving element 69. In the embodiment shown, the receiving element 69 has two openings 88 of this type, to each of which two inclined surfaces 86 lead. The receiving element 69 forms in other words a kind of receiving box for the cold trap.
[0121] FIG. 19 shows a side view of the receiving element 69 with cold trap 46 of FIGS. 17 and 18. It can be seen that a pipeline 60 which deliberately drains the condensate is connected to the opening 88. In other words, the process chamber 52 is connected via the pipeline 60. An outlet of the pipeline 60 connected to the opening 88 is provided immediately adjacent to the cold trap 46. A heating sleeve 90 can be arranged around the pipeline 60.
[0122] A structure of this type with a receiving element 69 can also be referred to as an evacuation device 62. The evacuation device 62 can of course be designed differently to that shown in FIG. 19.
[0123] FIG. 20 shows a further view of the embodiment of FIG. 19. It can be seen that the receiving element 69 has two openings 88 on the underside which are each connected via a pipeline 60.
[0124] FIG. 21 shows a sectional view of the embodiment of FIG. 19. In this embodiment it can be seen how the cold trap 46 with the collection device 64, in particular in the form of a drip tray, is inserted from one side into the receiving element 69. The cold trap 46 can be held in guided manner in the receiving element 69 by guides 84.
[0125] FIG. 22 shows a detailed view of the embodiment of FIG. 20. Two connections 47 for the cold trap 46 are provided on the right-hand side. A heating element 92, whose connection 94 is likewise on the right-hand side of the receiving element 69, is arranged on the underside of the receiving element 69. This heating element 92 can for example form an additional heat source 54.
[0126] FIG. 23 shows an isometric representation of the receiving element 69 with opening element 69a. The opening element 69a is swivelably mounted on the receiving element 69.
[0127] FIG. 24 shows a sectional representation through a process chamber 52. A heating plate 96 provided with a heating conductor 98 is provided on the underside of the process chamber 52. To close the process chamber 52, it can have a swiveling cover (not shown) that can be bolted to the process chamber 52. This allows the process chamber 52 to be designed gas-tight.
[0128] FIG. 25 shows a further embodiment of a workpiece carrier 56. FIG. 26 shows a further view of the embodiment of FIG. 25. The heating plate 96 is discernible directly underneath the receiving elements for the electronic assemblies 12 (not shown). The heating plate 96 can be designed as a contact plate with a sandwich structure. A cooling operation can be performed using thermal oil and/or a heating cable. A sandwich plate of this type can form a controllable and heatable contact plate and also be referred to as a soft cooling plate. For soft cooling, heating conductors 98 inserted in meandering form are comprised in the heating plate 92. Furthermore, a thermocouple, in particular a substrate thermocouple, can be comprised, which is for example arranged in the center and/or flexibly designed.
LIST OF REFERENCE SIGNS
[0129] 10 System [0130] 10a Soldering system [0131] 12 Electronic assemblies [0132] 14 Preheating module [0133] 16 Module [0134] 18 Soldering or sintering module [0135] 20 Cooling module [0136] 22 Soft cooling module [0137] 24 Positive pressure chamber [0138] 26 Vacuum chamber [0139] 28 Inlet valve [0140] 30 Positive pressure valve [0141] 32 Gas collection container [0142] 34 Quick bleed valve [0143] 36 Evacuation valve [0144] 38 Backing pump [0145] 40 Pressure monitoring chamber [0146] 42 Pressure control valve [0147] 44 Vacuum insertable gate valve [0148] 46 Cold trap [0149] 47 Connection of cold trap [0150] 48 Fins/cooling fins [0151] 50 Heat source [0152] 52 Process chamber [0153] 54 Additional heat source [0154] 56 Workpiece carrier [0155] 58 Transport device [0156] 60 Pipeline [0157] 62 Evacuation device [0158] 64 Collection device [0159] 65 Opening [0160] 66 Extraction vacuum pump [0161] 68 Liquid separator [0162] 69 Receiving element [0163] 69a Opening element for receiving element [0164] 72 Cold area [0165] 74 Hot area [0166] 76 Temperature adjustment zone [0167] 78 Robot arm [0168] 80 Cooling element [0169] 82 Collection container [0170] 84 Guides [0171] 86 Inclined surface [0172] 88 Opening [0173] 90 Heating sleeve [0174] 92 Heating element for receiving element [0175] 94 Connection for heating element [0176] 96 Heating plate [0177] 98 Heating conductor
