Patent Publication Number: US-2023143773-A1

Title: Soldering apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application relates and claims priority to German Patent Application No. 10 2021 129 122.4, filed Nov. 9, 2021, the entirety of which is hereby incorporated by reference. 
     BACKGROUND 
     The invention relates to a soldering apparatus, in particular a reflow soldering apparatus, for the continuous soldering of printed circuit boards along a transport direction, comprising a process channel comprising a preheating zone, a soldering zone and/or a cooling zone, having a main body and a cover hood, wherein the cover hood is displaceable between a closed position in which the process channel is closed and an open position in which the cover hood is open and the process channel is accessible. The cover hood encloses a hood compartment which is located above the process channel and in which in particular fan motors are provided. 
     By means of reflow soldering apparatuses, so-called SMD components (surface-mounted devices) are soldered onto the surface of printed circuit boards by means of solder paste. The solder paste, which is in particular a mixture of solder metal granules, flux and pasty components, is applied to or printed onto the surface of the printed circuit boards for reflow soldering. The components to be soldered are then set into the solder paste. In the reflow soldering process, the material for soldering, i.e. the assembly consisting of printed circuit board, solder paste and the components to be soldered, is preheated in a preheating zone along the process channel and in a soldering zone heated to a temperature above the melting point of the solder paste. As a result, the solder paste melts and the solder joints are formed. In a cooling zone, if one is present, the material for soldering is cooled until the melted solder solidifies before said material is removed from the reflow soldering apparatus. 
     DE 10 2019 128 780 A1, DE 10 2019 125 981 A1 and DE 10 2005 055 283 A1 describe soldering apparatuses for the continuous soldering of printed circuit boards. 
     In the case of reflow soldering apparatuses, the process channel is generally formed by two channel halves: an upper and a lower channel half. The lower channel half is provided in or on the main body and the upper channel half is provided in or on the cover hood. Further components, such as, for example, nozzle plates, fan units, air channels conducting the process gas, filter elements and/or cooling elements, are generally provided in or on the process channel or in or on the main body and in or on the cover hood. Overall, a desired temperature profile is thus provided in the process channel along the transport direction, wherein the process gas is blown into the process channel, suctioned from said channel, in particular cooled in the cooling zone, cleaned and fed back to the process channel. 
     In particular when a change of the material for soldering is imminent, it will be necessary to adapt the target temperature profile desired in the soldering apparatus to the changed components to be soldered. It may be necessary here to reduce the temperature within the soldering apparatus and, in particular, within the soldering zone as quickly as possible. To do so, it is known to open the cover hood so that the components forming and surrounding the process channel, in particular the channel halves, the nozzle plates, the transport system, the heating elements and fan motors and/or air channels cool down in the ambient temperature. However, it is disadvantageous that hot process gas here flows out of the soldering apparatus, whereby a high heat input into the space surrounding the soldering apparatus, in particular a production hall, takes place. In addition, cooling also takes a considerable time and is associated with a high noise level. In addition, harmful process gas can pass into the space surrounding the soldering apparatus, in particular into the production hall. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a soldering apparatus in which a change of the temperature profile can be effected in a simple manner without the above-mentioned disadvantages occurring. 
     This object is achieved by means of a soldering apparatus. Consequently, it is provided in particular that a central suction channel is provided in the hood compartment, in which first suction elements connected in the hood compartment to the suction channel are provided in the region of the fan motors for the suction of hood compartment air, that second suction elements connected in the hood compartment to the suction channel are provided for the suction of process gas from the process channel, and that a switching device is provided and designed for switching between an operating mode in which hood compartment air is suctioned via the first suction elements and a cooling mode in which process gas is suctioned via the second suction elements. 
     By switching between the operating mode and the cooling mode and by providing the first and second suction elements, when the cover hood is closed the soldering apparatus for soldering material for soldering can be operated in the operating mode. In this case, the first suction elements suction from the hood compartment hood compartment air heated by the electric motors. If the soldering apparatus is to be cooled rapidly after completion of a production cycle, it can be switched into cooling mode by hot process gas being suctioned from the process channel via the second suction elements in order to cool the process channel. 
     Here the central suction channel has a dual function: On the one hand, in the operating mode, the hood compartment in which the fan motors are provided is vented and thus cooled. On the other hand, in the cooling mode, the hot process gas is discharged from the process channel via said mode, whereby rapid cooling of the process channel can be achieved. Due to the fact that the soldering apparatus is not open in the cooling mode, the suctioned hot gas can be discharged via a corresponding exhaust air apparatus or can also be conditioned in such a way that it can be discharged into the ambient air at an appropriate temperature and correspondingly cleaned. The provision of the central suction channel also has the advantage that, in particular in the cooling mode, hot process gas can be suctioned at a high rate from the soldering apparatus, in particular over the entire longitudinal extent of the soldering apparatus. The suction channel is in particular dimensioned such that sufficient gas can be suctioned from the soldering apparatus to achieve a correspondingly rapid cooling. 
     It is further advantageous if third suction elements are provided and if the switching device is configured such that, in the operating mode, process gas is suctioned from the region of the entry and/or of the exit via the third suction elements and that in the cooling mode no process gas is suctioned via the third suction elements. The switching device consequently not only causes the first and second suction elements to switch on or over or to switch off, but also the third suction elements. In the operating mode, the third suction elements are opened together with the first suction elements and in the cooling mode closed together with the first suction elements. 
     Advantageously, the suction channel extends substantially parallel to the transport direction and is configured to stiffen the cover hood. The central suction channel consequently has a further function; in the operating mode and in the cooling mode, the hood compartment air or process gas can be suctioned centrally from the soldering apparatus and in addition said central suction channel serves to stabilize and stiffen the cover hood. 
     It is further advantageous if the first suction elements are designed as suction tubes with suction openings, wherein the suction openings are provided in the region of the underside of the cover hood and in the region of the fan motors. 
     It is further advantageous if the second suction elements are designed as suction tubes with suction openings, wherein in the closed position of the cover hood the suction openings are located in the region of the process channel. 
     The suction tubes can each have a tube mouth which opens into the central suction channel. Furthermore, the suction tubes can each have at least one suction opening located within the hood compartment. By the provision of suction tubes, the suction opening can consequently be located where suction is efficient. 
     It is conceivable here for the first suction elements in the closed position of the cover hood to have a portion extending substantially horizontally and/or transversely to the transport direction and having a plurality of suction openings over its longitudinal extent. This enables a large-area suction in the hood compartment. 
     Furthermore, it is advantageous if a plurality of second suction elements are provided, the suction openings of which, in the closed position of the cover hood, lie in the region of the process channel or open into the latter. The suction openings can consequently intervene in or adjoin the process channel in order to suction the hot process gas from the process channel. In particular, it is conceivable that the suction openings of the second suction elements are coupled into the respective zone and/or open out between two nozzle plates located in the process channel in order to effect an efficient and non-disruptive suction. 
     In the closed position of the cover hood, the second suction elements can preferably have a substantially vertically extending end portion with an open free end which is provided in the process channel or adjacent to the process channel. This design has the advantage that the vertical portion can be arranged such that the function of the individual zone is not impaired. 
     Furthermore, it is advantageous if tube mouths of the first suction elements and tube mouths of the second suction elements in each case open out adjacently into the suction channel, and if the switching device comprises and/or operates closure elements in such a way that in the operating mode the latter close the tube mouths of the second suction elements and in the cooling mode close the tube mouths of the first suction elements. The central suction channel here can have a triangular or polygonal cross-section with adjacent channel walls. Advantageously, a quadrangular cross-section with four channel walls is to be provided. Furthermore, it is advantageous if the tube mouths of at least two suction tubes are provided on adjacent walls. The planes of the respective tube mouths then enclose an angle which is a right angle in the case of a rectangular cross-section of the suction channel. Furthermore, it is advantageous if closure elements are provided in the suction channel which, in a first position, close the one tube mouth, and in a second position the other tube mouth. 
     The closure elements are preferably designed as pivoting flaps which are pivotable between the respective positions about a pivot axis, which preferably runs parallel to the transport direction. 
     In this case, it is advantageous if the switching device comprises or operates a controllable actuator and an adjustment mechanism via which several closure elements can be adjusted together. It is conceivable for the actuator to be driven pneumatically or electrically and for a lifting gear and/or a drive shaft to be provided as an adjustment mechanism, by means of which a plurality of pivoting flaps can be pivoted into the respective position. For example, all flaps which lie within a zone of the soldering apparatus can be moved synchronously. 
     The third suction elements are provided in particular at the entry  12  and at the exit  14  of the soldering apparatus and are in particular designed as suction chambers. 
     It is further advantageous if suction elements are provided which can be switched between an open position and a closed position and which can be switched or controlled by the switching device such that in the operating mode the suction elements are closed and in the cooling mode the suction elements are open, whereby in the cooling mode ambient air can flow into the soldering apparatus. In this way, in the cooling mode sufficient fresh air can flow from the environment into the machine in order to cool the process channel or the associated components. 
     As mentioned at the outset, it is advantageous if a suction device connected to the suction channel is provided and is configured to suction process gas in the operating mode and in the cooling mode. The suction device can be integrated into the soldering apparatus or can be realized as a device to be provided separately therefrom. It is further advantageous if a cooling and/or cleaning device is provided for cooling and/or cleaning the process gas suctioned via the suction channel. Cooled and cleaned process gas can then be discharged into the environment of the soldering apparatus. 
     In order to form the hood compartment, it is particularly advantageous if the cover comprises a frame structure with portal-like frame legs extending transversely to the transport direction, wherein the frame legs each have a first support portion directed toward a hood axis about which the cover hood is pivotable and a second support portion directed vertically downwards and a central portion provided between the support portions, and wherein the suction channel is arranged on the frame legs. Overall, this results in an advantageous stiffening of the cover hood. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details of the invention can be found in the following description, on the basis of which an exemplary embodiment of the invention is described and explained in more detail. 
       The drawings show: 
         FIG.  1    a reflow soldering apparatus in a side view obliquely from the front with closed cover hood and closed hood flaps; 
         FIG.  2    the reflow soldering apparatus according to  FIG.  1    in a front view with open cover hood and opened hood flaps; 
         FIG.  3    the reflow soldering apparatus according to  FIG.  1    from obliquely to the front with open cover hood and opened hood flaps; 
         FIG.  4    the reflow soldering apparatus according to  FIG.  1    from obliquely to the rear with open cover hood and opened hood flaps; 
         FIG.  5    the reflow soldering apparatus according to  FIG.  1    from obliquely to the front without machine panels; 
         FIG.  6    the cover hood with central suction channel without panels; 
         FIG.  7    a section through the central suction channel transverse to the transport direction; 
         FIG.  8    a section through a third suction element transverse to the transport direction; and 
         FIG.  9    a closable suction element as an individual part. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    shows a reflow soldering apparatus  10  for the continuous soldering of material for soldering. The reflow soldering apparatus  10  has an entry  12  and an exit  14 , wherein the material for soldering reaches the reflow soldering apparatus  10  via the entry  12  and is discharged from the reflow soldering apparatus  10  via the exit  14 . The material for soldering is transported here along a transport direction  18  through a process channel  16  indicated in  FIG.  1   . 
     A preheating zone  20 , a soldering zone  22  and a cooling zone  24  are provided in the process channel  16 . In the reflow soldering apparatus  10  shown in  FIG.  1   , a cover hood  25  with two hood flaps  26 ,  28  is provided for covering the hood compartment  30  enclosed by the cover hood  25 , in which compartment the upper channel half of the process channel  16  is located. 
     As is clear from  FIGS.  1  and  2   , a communications unit  36  having a screen and an input device is provided, by means of which it is possible to communicate with a machine controller of the reflow soldering apparatus  10 . 
     The material for soldering, that is to say the printed circuit board provided with solder paste and populated with electronic components, is first heated in the preheating zone  20   to a temperature which is below the melting temperature of the solder paste. In the soldering zone  22 , the printed circuit board is heated for a certain time to a process temperature which lies above the melting point of the solder paste, so that this melts in the soldering zone in order to solder the electronic components to the printed circuit board. In the cooling zone  24 , the material for soldering is cooled so that the liquid solder solidifies before the material for soldering is removed at the exit  14  of the reflow soldering apparatus  10 . 
     A transport system  34  is provided within the reflow soldering apparatus  10  for transporting the printed circuit boards along the transport direction  18 . 
     As is clear from  FIG.  2   , the cover hood  25  can be pivoted open about a hood axis  32  extending parallel to the transport direction  18 . By the cover hood  25  pivoting open, the interior of the process channel  16  and the transport system  34  become accessible so that they can be checked visually, maintained, cleaned, set up, replaced, and, if necessary, repaired. 
     As is further apparent from  FIG.  2   , the hood flaps  26  can be pivoted open about a flap axis  38  running parallel to the hood axis  32 . By the hood flaps  26 ,  28  pivoting open, the hood compartment  30  above the process channel and thus the hood compartment  30  lying above the upper channel half become accessible in which, as shown further below, in particular fan modules  50 , heating elements and air channels are provided. As is also clear from  FIG.  2   , the flap axis  38  is arranged vertically above the hood axis  32 , namely not only when the cover hood  25  is open but also when the cover hood  25  is closed. 
     The soldering apparatus  10  has two longitudinal sides  42  and  44  and two narrow sides  46  and  48 . As can be clearly seen in  FIG.  2   , the hood axis  32  is located in the region of the one rear longitudinal side  44 . In contrast, the flap axis  38  is located in the region of the front longitudinal side  42  or is closer to the front longitudinal side  42  than to the rear longitudinal side  44 . 
     In  FIG.  3   , in which on the one hand the cover hood  25  and on the other hand the hood flaps  26 ,  28  are open, the open process channel  16  can be seen in particular. The process channel  16  is formed by two channel halves: an upper channel half and a lower channel half. The lower channel half with the lower nozzle plates  40  is provided in or on a main body  60  and the upper channel half with the upper nozzle plates  40  is provided in or on the cover hood  25 . The upper channel half, the upper nozzle plates  40  and further components located in the hood compartment  30  are arranged on the cover hood  25  such that they also pivot open as the cover hood  25  is opened and the process channel  16  is uncovered. 
     Such an arrangement ensures that, as is clear from  FIGS.  2  to  4   , when the cover hood  25  is open the process channel  16  is accessible from the front longitudinal side  42 , and that the upper hood compartment  30  covered by the hood flaps  26 ,  28  is accessible from the other rear longitudinal side  44 . 
     Among other things, this has the advantage that, when the cover hood  25  is being opened, and thus when the process channel  16  is being uncovered, gas flowing out of the process channel  16  does not flow into the upper hood compartment  30  covered by the cover flaps  26 ,  28 . Furthermore, a plurality of operators can monitor or maintain the process channel  16  at the same time and independently thereof the hood compartment  30  covered by the cover flaps  26 ,  28 . 
     As is clear from  FIGS.  4  and  5   , a plurality of fan modules  50  with fan motors  51  are located above the upper channel half in the hood compartment  30  covered by the hood flaps  26 ,  28 , said fan motors being provided for generating a provided air flow in the process channel  16 . The fan modules  50  can additionally have heating elements in order to provide a predefined temperature in particular in the preheating zone  20  and in the process zone  22 . By means of the fan modules  50  or their fan motors  51 , correspondingly heated process gas is introduced through the nozzle plates  40  towards the material for soldering. 
     If the cover hood  25  is opened, in particular the process channel  16  and the transport system provided therein will therefore be accessible. If the hood flaps  26 ,  28  are opened up, in particular the fan motors  51  provided therein will be accessible together with their heating elements and also air channels provided there. 
     In their closed position, which is shown in  FIG.  1   , the two hood flaps  26 ,  28  have a horizontal portion  52  which is located close to the flap axis  38  and extends substantially in the horizontal direction. This horizontal portion is adjoined by a sloping portion  56  which is remote from the flap axis  38  and which with the horizontal portion  50  encloses an obtuse angle  54 . As is clear in particular from  FIG.  4   , handles  58  for opening the two hood flaps  26 ,  28  are provided on the sloping portion. The obtuse angle  54  can be clearly seen in  FIG.  2   . 
     The main body  60  stands on a substrate by means of feet  62 . The feet  62  are provided on a lower frame  64 . Furthermore, drive units  66  are provided for the motorized opening and closing of the cover hood  25  and are braced at one end on the lower frame  64  and at the other end on the cover hood  25 . As is also clear from  FIG.  5   , which shows the cover hood  25  without its panels, the cover hood  25  comprises portal-like frame arms  68 , each of which has a first support portion  70  directed towards the hood axis  32  and a second support portion  72  directed toward the respective drive unit  66 . A central portion  74  is provided between the two support portions. 
     As is clear from  FIG.  6   , a central suction channel  100  is provided over the longitudinal extent of the soldering apparatus  10  in the cover hood  25 . The suction channel  100 , which has a rectangular cross-section, is fastened to the frame arms  68  or connects the frame arms  68  to one another. Here the arrangement of the suction channel  100  is in the region of the support portions  72  which are remote from the hood axis  32 . The suction channel  100  extending substantially parallel to the transport direction  18  stiffens the cover hood  25 . 
     The suction channel  100  has a plurality of first suction elements  104 , a plurality of second suction elements  106  and two third suction elements  108 . The first and second suction elements  104  and  106  are designed as suction tubes. The two third suction elements  108  are each provided at the entry  12  and at the exit  14  of the soldering apparatus  10  and are designed as suction chambers. 
     A switching device  109  for switching between an operating mode and a cooling mode can be operated via the communications unit  36 . In the operating mode, material for soldering is soldered in the soldering apparatus  10 . In the cooling mode, in which no soldering of material for soldering takes place, in particular the preheating zone  20  and the soldering zone  22  are cooled. Here the switching device  109  can operate or comprise an actuator and also an adjustment mechanism. 
     In the operating mode, the heated hood compartment air  114  which is enclosed by the cover hood  25  is suctioned from the hood compartment  30  via the suction elements  104 . On the other hand, process gas  113  is suctioned via the suction elements  108  in the region of the entry  12  and the exit  14 , as a result of which an undesired escape of process gas  113  from the entry  12  or the exit  14  is prevented. 
     In the cooling mode on the other hand, process gas  115 , as can be seen from  FIG.  7   , is suctioned from the process channel  16  exclusively via the suction elements  106 . In the cooling mode, no air is suctioned from the hood compartment  30  via the suction elements  104 . 
       FIG.  6    schematically indicates two suction devices  110 , for example in the form of fans or vacuum pumps, which can be connected to suction nozzles  111  of the soldering apparatus  110 . Instead of two suction devices  110 , it is also conceivable to provide only one suction device  110 , which then suctions air or process gas from the two suction nozzles  111 . In each case a cooling and cleaning unit  112 , in which the suctioned process gas is cooled and cleaned, is connected downstream of the respective suction device  110 . 
     The air  117  having passed through the suction device  110  and the cleaning unit  112  can be discharged into the environment. The suction devices  110  or the cleaning units  112  can be arranged outside the soldering apparatus  10 . 
     In order to enable subsequent flow of ambient air into the soldering apparatus  110  in the cooling mode, closable suction elements  116  indicated in  FIG.  6    are provided on the underside of the soldering apparatus  100 . One of these suction elements  116  is shown enlarged in  FIG.  9   . Consequently, in cooling mode when process gas  115  is being suctioned from the process channel  16  via the suction device  110 , the suction elements  116  will be activated and opened. 
     In the section according to  FIG.  7   , it can be seen that the suction channel  100  has a rectangular cross-section. Furthermore, a suction element  104  of the first type and a suction element  106  of the second type are shown. The suction elements  104  are provided in such a way that in the closed position of the cover hood  25  they run substantially horizontally and transversely to the transport direction  18 . The suction elements  104  provide a plurality of suction openings  118  distributed over their longitudinal extent. Hood compartment air  114  in the region directly below the cover hood  25  or in the region of the motors  51  is finally suctioned via the suction openings  118 . 
     The suction elements  106  of the second type are designed as curved tubes or hoses and each have a suction opening  118  which, when the cover hood  25  is closed, is located in the region of the process channel  16  and in the cooling mode suctions process gas  115  from the process channel  16 . The suction elements  106  have an end portion  120  which extends in the vertical direction so that the suction opening  118  adjoins or extends into the process channel. 
     As is clear from  FIG.  7   , the suction elements  104  and  106  each have a tube mouth  122  which opens out into the central suction channel  100 . The tube mouths  122  of the two suction elements  104  and  106  are also in each case located on adjacent channel walls  124 ,  126 . The tube mouths  122  of the different suction tubes  104  and  106  are in each case located, as is also clear from  FIG.  7   , within a sectional plane running perpendicular to the longitudinal axis of the suction channel  100 . 
     Furthermore, closure elements  128  in the form of pivoting flaps  130  are provided in the suction channel  100 . The pivoting flaps  130  can be pivoted between different positions about a pivot axis  132  running parallel to the axis of the suction channel  100  or to the transport direction  18 . In the first pivot position shown in  FIG.  7   , which is assumed in the operating mode, the pivoting flap  130  closes the tube mouth  122  of the suction element  106  and the tube mouth  122  of the suction element  104  is open. Hood compartment air  114  can consequently be suctioned. 
     In a second position, in the cooling mode, the pivoting flap  130  is pivoted in the direction of the arrow  136  until it closes the tube mouth  122  of the suction tube  104 . In this position, process gas  115  can be suctioned from the process channel  16  solely via the respective suction element  106 . 
     As is clear from  FIG.  6   , a total of six first suction elements  104  and four second suction elements  106  are provided. Six closure elements  128 , with which the individual tube mouths  122  are closed, are then preferably provided within the suction channel  100 . Furthermore, it is advantageous if a common control of the closure elements  128  or pivoting flaps  130  is effected via the switching device  109 . It is conceivable that a control shaft  133  which can be operated by the switching device  109  is provided, on which control shaft the individual pivoting flaps  130  are provided in a rotationally fixed manner. 
       FIG.  8   , which shows a section transverse to the transport direction  18  and through a third suction element  108  at the exit  14 , clearly shows that the suction elements  108  are passed through by the suctioned hood compartment air  114  or by the suctioned process gas  115  and have an inflow opening  150  that can be closed with a closure element  128 . The closure element  128  is motion-coupled to the drive shaft  133  by means of a mechanism  152  in such a way that in the operating mode the inflow opening  150  is open and in the cooling mode the inflow opening  150  is closed. Here the closure element  128  is displaceable along the arrow  154  towards the inflow opening  150 . Consequently, the suction elements  104  and  108  can be simultaneously closed or opened via the switching device  109  or the control shaft  133  connected thereto. 
     Suction elements  116 , as shown in  FIG.  9   , are preferably installed in the lower region of the soldering apparatus  10  that is close to the base. The individual suction elements  116  provide a flap  136  which can be adjusted between an open position and a closed position via an adjusting element  138 . A suction tube  142 , which preferably opens out into the process channel  16 , is connected to the flap  136 . 
     In  FIG.  9   , which shows the suction elements  116  in the operating mode, the flap  136  and thus the suction tube  142  are closed. In the operating mode, no fresh air is suctioned through the suction elements  116  in order to obtain a predefined temperature profile within the soldering apparatus. It is rather the case that, in the operating mode, gas, in particular nitrogen, is specifically introduced into the soldering apparatus  10  in order to prevent in particular oxidation at solder joints during the soldering process. In the cooling mode, the respective suction element  116  is in the open position in which the respective flap  136  is open, so that fresh air for cooling can flow into the process channel  16  via the free end  140  of the respective suction tube  142 . 
     When switching into the cooling mode, the adjusting elements  138  are thus controlled such that the flaps  136  are opened. When switching into the operating mode, the adjusting elements of  138  are controlled such that the flaps  136  are closed. 
     With the soldering apparatus  10  described, in particular when a profile change is imminent, process gas  115  can be suctioned via the central suction channel  100  from the process channel  16  or the preheating zone  20  and/or the process zone  22 . As a result, a rapid and reliable cooling in particular of the preheating zone  20  and the process zone  22  can be effected.