Technical Field

[0001] The present application relates to a reflow oven, and in particular to a reflow oven including a conveying device.

Background

[0002] In the production of printed circuit boards, electronic elements are typically mounted to circuit boards using a process called “reflow soldering.” In a typical reflow soldering process, a solder paste (e.g., tin paste) is deposited into a selected area on a circuit board and a wire of one or more electronic elements is inserted into the deposited soldering paste. A conveying device then conveys the circuit board through the oven chamber of the reflow oven. In the oven chamber of the reflow oven, the solder paste refluxes (i.e., is heated to a melting or reflux temperature) in a heating area and then cools in a cooling area to electrically and mechanically connect the wires of the electronic elements to the circuit board. As used herein, the term “circuit board” includes a substrate assembly of any type of electronic element, such as including a wafer substrate.

Summary

[0003] At least one object of the present application is to provide a reflow oven, including: a oven chamber having a length direction and a width direction; a conveying belt for carry i ng a circuit board; a drive device configured to drive the conveying belt to travel along a conveying direction to convey the circuit board through the oven chamber; and at least two support rods arranged side by side below the conveying belt in the width direction and in contact with the conveying belt to support the conveying belt; wherein each of the support rods extends obliquely in the conveying direction.

[0004] In accordance with the foregoing, each of the support rods includes an inner core and an electroplated layer.

[0005] In accordance with the foregoing, the electroplated layer is a chrome electroplated layer, and the inner core and the conveying belt are made of a stainless steel material. [0006] In accordance with the foregoing, the at least two support rods include at least one set of support rods, each set of the support rods including at least two support rods, each set of the support rods being arranged along the length direction of the oven chamber, and each set of the support rods including two pairs of support rods, each pair of the support rods including at least one of the support rods; wherein the two pairs of support rods in each set of the support rods are arranged symmetrically in the width direction of the oven chamber.

[0007] In accordance with the foregoing, each pair of the support rods includes two of the support rods, wherein in the length direction of the oven chamber, in each set of the support rods, two support rods in each pair of support rods extend in parallel to each other, and the two pairs of support rods extend obliquely oppositely or at a distance from each other.

[0008] In accordance with the foregoing, the reflow oven further includes at least one mounting bracket, the mounting brackets being disposed at intervals in the length direction of the oven chamber, wherein at least one end of each of the support rods is connected to the mounting bracket in an extension direction, thereby connecting each of the support rods to the oven chamber.

[0009] In accordance with the foregoing, each of the mounting brackets includes a plurality of long strip holes and a plurality of round holes, each of the support rods including a lever portion and a pair of bends connected to both ends of the lever portion, wherein one of the bends of each of the support rods is inserted into the long strip hole of one of the mounting brackets or cantilevered, and the other of the bends is inserted into the round hole of another one of the mounting brackets.

[0010] In accordance with the foregoing, the reflow oven further includes at least one support bracket, the at least one support bracket being disposed spaced in the length direction of the oven chamber, and the at least one support bracket being configured to support the support rod from below the support rod.

[0011] In accordance with the foregoing, the oven chamber includes an upper oven chamber and a lower oven chamber; the mounting bracket and the support bracket are connected in the lower oven chamber.

[0012] In accordance with the foregoing, the conveying belt includes a plurality of metal strips woven together along the length direction and the width direction of the oven chamber to form the conveying belt; an inclined distance of each of the support rods in the width direction satisfies: DI < D2 - D3 * 2; wherein D2 represents the width of the metal strip and D3 represents an allowable deviation distance of the conveying belt.

[0013] Other objects and advantages of the present application will be apparent from the description of the present application hereinafter with reference to the accompanying drawings, and may help with a full understanding of the present application.

Brief Description of the Drawings

[0014] Fig. 1 is a schematic view of the principle of a reflow oven of the present application; [0015] Fig. 2A is a perspective view of one embodiment of the reflow oven shown in Fig. 1;

[0016] Fig. 2B is a perspective view of a conveying device in the reflow oven shown in Fig. 2A;

[0017] Fig. 2C is a right view of a conveying belt and a support rod of Fig. 2B;

[0018] Fig. 2D is a partial top view of Fig. 2B;

[0019] Fig. 3A is a perspective view of the conveying device of Fig. 2B with the conveying belt removed;

[0020] Fig. 3B is a top view of the support rod of Fig. 3 A;

[0021] Fig. 4A is a perspective view of a support rod set in Fig. 2A;

[0022] Fig. 4B is an exploded view of Fig. 4A;

[0023] Fig. 4C is a perspective view of a mounting bracket of Fig. 4A;

[0024] Fig. 5 is a cross-sectional view of the support rod of Fig. 4A.

Detailed Description

[0025] Various specific embodiments of the present application will be described below with reference to the attached drawings that form a part of the present specification. It should be understood that while terms denoting orientation, such as “front,” “rear,” “upper,” “lower,” “left,” “right,” “top,” “bottom,” “inside,” “outside,” etc., are used in the present application to describe various exemplary structural parts and elements of the present application, these terms are used herein for convenience of illustration only and are determined based on the exemplary orientations shown in the attached drawings. Since the examples disclosed in the present application may be disposed in different orientations, these terms denoting orientation are for illustrative purposes only and should not be considered as limiting.

[0026] Fig. 1 is a schematic view of the principle of a reflow oven 100 of the present application. As shown in Fig. 1, the reflow oven 100 includes a oven chamber 110 and a conveying device 118. The oven chamber 110 has a length direction L, a width direction W, and a height direction FL Fig. 1 shows a structure of the reflow oven 100 in the length direction L and the height direction H. In the length direction L of the oven chamber 110, the oven chamber 112 includes a heating region 102 and a cooling region 105, and the heating region 102 is disposed upstream of the cooling region 105. A heating device (not shown) is provided in the heating region 102 for heating a circuit board 108 and a cooling device (not shown) is provided in the cooling region 105 for cooling the circuit board 108. The heating region 102 includes a preheating region 101 and a peak region 103. The preheating region 101 is disposed upstream of the peak region 103, and the heating temperature in the preheating region 101 is lower than the heating temperature in the peak region 103. In the present example, the heating region 102 and the cooling region 105 further include a plurality of sub-areas, the temperatures in the various sub-areas of the heating region 102 gradually increasing, and the temperatures in the various sub-areas of the cooling region 105 gradually decreasing, depending on the processing needs.

[0027] In the height direction H of the oven chamber 112, the oven chamber 110 includes an upper oven chamber 111 and a lower oven chamber 112, and a conveying space 106 is formed between the upper oven chamber 111 and the lower oven chamber 112. The conveying device 118 is at least partially disposed in the conveying space 106 for conveying the circuit board 108 through the heating region 102 and the cooling region 105 of the oven chamber 110 in the conveying direction x. In the present example, the conveying direction x is the same as the length direction L of the oven chamber 110, i.e., the circuit board 108 is capable of passing through the various regions of the oven chamber 110 in the length direction L of the oven chamber 110.

[0028] As such, as the circuit board 108 is conveyed through the oven chamber 110 by the conveying device 118, upon entry into the oven chamber 110 from an inlet end 145 (i.e. the left end) of the oven chamber 110, the circuit board 108 is able to be heated passing through the preheating region 101 and the peak region 103 in the heating region 102 in this order. In the preheating region 101, a portion of the solder flux in the solder paste dispensed on the circuit board 108 for soldering an electronic element is vaporized. In the peak region 103, the solder flux in the solder paste dispensed on the circuit board 108 is completely vaporized and the solder paste is fully melted. After the circuit board 108 enters the cooling region 105, the circuit board 108 can be cooled and the melted solder paste on the circuit board 108 is cooled and cured, thereby electrically and mechanically connecting the electronic element to the circuit board 108. Finally the circuit board 108 is conveyed out of the oven chamber 110 from an outlet end 146 (i.e., the right end) of the oven chamber 110 to complete the soldering process.

[0029] Figs. 2A to 2D show a specific structure of one example of the reflow oven 100 shown in Fig. 1, wherein Fig. 2A shows a perspective view of the reflow oven 100; Fig. 2B shows a partial internal structure of the reflow oven 100 including the conveying device 118 and the lower oven chamber 112 shown in Fig. 2A, with a housing 202 removed and a partial magnified view show n by a dashed box; Fig. 2C shows a right view of a conveying belt 217 and a support rod 219 in the conveying device 118 of Fig. 2B, with a partial magnified view shown by a dashed box; and Fig. 2D is a partial top view of Fig. 2B. As shown in Figs. 2Ato 2D, the reflow oven 100 includes a housing 202 within which the oven chamber 110 and the conveying device 118 are disposed. The conveying device 118 includes a drive device 216 and a conveying belt 217. The drive device 216 includes a motor (not shown) and a drive assembly, such as a drive roller 215, and the drive device 216 drives the conveying belt 217 to advance through the rotation of the drive roller 215 driven by the motor.

[0030] The conveying device 118 also includes a plurality of support rods 219 that are arranged in groups in the length direction L of the oven chamber 110 and side by side in the width direction W of the oven chamber 110. Each support rod 219 is disposed below the conveying belt 217 and is stationary relative to the oven chamber 110. The top of each support rod 219 is in contact with the lower surface of the conveying belt 217 to support the conveying belt 217 from below. The support rod 219 is used to prevent the conveying belt 217 from becoming partially recessed or the like when the circuit board 108 carried on the conveying belt 217 is overweight during the conveying of the circuit board 108 in the conveying direction x by the conveying belt 217. [0031] In the present application, each of the support rods 219 extends obliquely in the conveying direction x. That is, while each of the support rods 219 extends generally from the inlet end 145 towards the outlet end 146, the length direction of the support rod 219 is not parallel to the conveying direction x and the length direction L of the oven chamber 110 but rather forms a pinch angle with the conveying direction x that is not 0°. Such a setting can enable the conveying belt 217 to have a larger contact area with the support rod 219 as the conveying belt 217 advances. As one example, the conveying belt 217 has a contact site 230 that is generally rectangular in shape, such the contact site 230 that is rectangular in shape shown by a dashed box in Fig. 2D. For each of the support rods 219, the contact site 230 of the conveying belt 217 in contact with the support rod 219 is a rectangular shape that is collectively defined by the inclined distance DI of the support rod 219 in the width direction W and the length of the support rod 219 in the length direction L.

[0032] Since the support rod 219 and the conveying belt 217 need to pass through the heating region 102 having a higher temperature in the oven chamber 110 of the reflow oven 100, the support rod 219 and the conveying belt 217 are typically made of metal materials. Moreover, since the support rod 219 is stationary relative to the oven chamber 110 and the conveying belt 217 travels in the conveying direction x relative to the oven chamber 110, wear may occur at the site where the support rod 219 is in contact with the conveying belt 217 when the conveying belt 217 advances. To generally reduce the friction between the support rod 219 and the conveying belt 217, the support rod 219 is set to be cylindrical. However, after the support rod 219 and the conveying belt 217 are worn, the line contact between the top of the support rod 219 and the conveying belt 217 becomes surface contact, increasing the friction between the support rod 219 and the conveying belt 217 on the one hand, and on the other hand, possibly causing the conveying belt 217 to jitter up and down to be unable to convey the circuit board stably in the case of non-uniform wear on the other hand. As a result, the service life of the support rod 219 and the conveying belt 217 will be affected, and the support rod 219 and the conveying belt 217 need to be replaced regularly.

[0033] If the support rod extends in the conveying direction x, the support rod is only in contact with the conveying belt 217 within a linear range in its extension direction. However, by setting the support rod 219 to extend obliquely in the conveying direction x, the support rod 219 can contact the conveying belt 217 within the rectangular range of the contact site 230. Such a seting increases the area of the site where the conveying belt 217 can contact the support rod 219, thereby extending the service life of the conveying belt 217.

[0034] It will be appreciated by one skilled in the art that the support rod 219 can play the role of guiding the conveying belt 217 to travel along the conveying direction x to some extent. In order to prevent the conveying belt 217 from deviating from the conveying direction x, the tilt angle of the support rod 219 needs to be controlled within a certain range. In the present example, the conveying belt 217 includes a plurality of metal strips 229, and the plurality of metal strips 229 are woven in rows and in columns along the length direction L and the width direction W to form a meshed conveying belt 217. The corresponding inclined distance DI in the width direction W of the tilt angle of the support rod 219 satisfies DI < D2 - D3 * 2. Here, the inclined distance DI represents the distance between the two ends of the support rod 219 in the width direction W, D2 represents the width of each metal strip 229 of the conveying belt 217, and D3 represents an allowable deviation distance of the conveying belt 217. As one example, the tilt angle between the support rod 219 and the conveying direction x is 1.1°.

[0035] A plurality of mounting brackets 223 and a plurality of support brackets 224, 225 are provided in the lower oven chamber 112, and the plurality of mounting brackets 223 and the plurality of support brackets 224, 225 are disposed spaced apart from each other in the length direction L of the oven chamber 110 and extending in the width direction W. The mounting bracket 223 is used to secure an end of the support rod 219 to enable the support rod 219 to be secured relative to the oven chamber 110. The support brackets 224 and 225 are used to support the support rod 219 from below to prevent the support rod 219 from bending. The support bracket 225 includes a support bracket 225a disposed at the inlet end 145 and a support bracket 225b disposed at the outlet end 146. A plurality of mounting brackets 223 are disposed generally parallel to each other at the ends of the various support rods 219 between the support brackets 225a and the support brackets 225b (shown in Fig. 2B and Fig. 3A in combination). The number of mounting brackets 223 is determined by the number of the support rods 219 in the length direction L of the oven chamber 110. A plurality of support brackets 224 are disposed between adjacent mounting brackets 223 or between the support brackets 225 at the end and adjacent mounting brackets 223. In the present example, the mounting brackets 223 and the support brackets 224 are disposed adjacent to various subareas in the oven chamber 110. It will be appreciated by one skilled in the art that at the inlet end 145 and the outlet end 146, the support rod 219 is supported by the support bracket 225 a and the support bracket 225b and no additional mounting bracket 223 is provided to secure the ends of the support bracket 219.

[0036] The specific arrangement structure of the support rod 219 and the mounting brackets and support brackets will be described in detail in conjunction with Figs. 3A to 3B. The specific structure of the mounting bracket 223 will be described in detail in connection with Figs. 4Ato 4C.

[0037] Figs. 3 A to 3B show the specific structure of the support rod 219, the mounting bracket, and the support bracket, with Fig. 3 A showing the support rod 219 and the lower oven chamber 112 with the conveying belt 217 omitted in Fig. 2B, and Fig. 3B showing the arrangement of the support rods 219. As shown in the example of Figs. 3A and 3B, the plurality of support rods 219 include three sets of support rods 331, 332, and 333, which are disposed sequentially in the length direction L of the oven chamber 110. In particular, in the conveying direction x, the support rod set 331 is disposed upstream of the support rod set 332 and the support rod set 332 is disposed upstream of the support rod set 333.

[0038] In the present example, each set of support rods includes two pairs of support rods 341 and 342, and each pair of support rods 341 and 342 includes two support rods 219, i.e., each set of support rods includes four support rods 219. These four support rods 219 are provided side by side in the width direction W of the oven chamber, and the two pairs of support rods 341 and 342 are arranged symmetrically in the width direction W relative to a midline i. The symmetrically arranged support rod pairs 341 and 342 can substantially balance the support force received by the conveying belt 217 to prevent the conveying belt 217 from deviating from the conveying direction x as much as possible. It will be understood by those skilled in the art that more or less support rods may also be provided in each set of support rods to meet the width needs of the oven chamber 110 and more or less support rod sets may be provided to meet the length needs of the oven chamber 110.

[0039] Specifically, in the length direction L, in the first set of support rods 331, the two support rods 219 of the pair of support rods 341 are parallel to each other and the two support rods 219 of the pair of support rods 342 are also parallel to each other. Moreover, the two support rods 219 in each pair of support rods are each tilted outwardly in the conveying direction x, i.e., extending obliquely away from each other. In the second set of support rods 332, the two support rods 219 in each pair of support rods are also parallel to each other. In the conveying direction x, the two support rods 219 of each pair of support rods are each tilted inwardly, i.e., extending obliquely towards each other. In the third set of support rods 333, the two support rods 219 in each pair of support rods are also parallel to each other. In the conveying direction x, the two support rods 219 in each pair of support rods are each tilted outwardly in the conveying direction x, i.e., extending obliquely away from each other.

[0040] In the width direction W, the support rod pairs of each set of support rods are arranged in a staggered manner. In the present example, the two support rods 219 in the support rod pairs of the first set of support rods 331 and the third set of support rods 333 are respectively disposed outside of the two support rods 219 in the corresponding support rod pairs of the second set of support rods 332.

[0041] As the present example includes three sets of support rods, the number of the mounting bracket 223 is accordingly set to two. The first set of support rods 331 are connected between the support bracket 225 a disposed at the inlet end 145 and the first mounting bracket 223a, the second set of support rods 332 are connected between the first mounting bracket 223a and the second mounting bracket 223b, and the third set of support rods 333 are connected between the second mounting bracket 223b and the support bracket 225b disposed at the outlet end 146.

[0042] In the present example, the arrangement of the support rods 219 in sets in the length direction L can meet the requirements of various lengths of the oven chamber, and prevent the inconvenience of the processing of the support rods caused by the excessive length of the oven chamber. Further, the arrangement of the support rods 219 in pairs in the width direction W can meet the processing needs of circuit boards of various sizes, and prevent the conveying belt 217 from becoming partially recessed when the circuit board is too small in size. It will be appreciated by one skilled in the art that when the length of the oven chamber 110 is within a certain range, it is also fine to provide only one set of support rods as long as the support rod 219 extends directly from the inlet end 145 to the outlet end 146. Moreover, when the width of the oven chamber 110 is within a certain range, or when the circuit board is of a single size, it is also fine to provide only two support rods that are symmetrically disposed in the width direction. [0043] Figs. 4Ato 4C show the connection relationship of the mounting bracket 223 and the support rod 219. To facilitate illustrating the structure of the mounting bracket 223, the support rod 219 shown in Figs. 4A to 4C is a support rod in the second set of support rods 332. Fig. 4A shows a perspective view of the mounting bracket 223 and the support rod 219, Fig. 4B shows an exploded view of Fig. 4A, and Fig. 4C shows a perspective view of the mounting bracket 223. As shown in Figs. 4A to 4C, the support rod 219 is generally barshaped, including a lever portion 435 and a pair of bends 436 formed by bending downward from both ends of the lever portion 435, respectively.

[0044] The mounting bracket 223 is generally in the form of a hollow, rectangular body, and the mounting bracket 223 is oriented in a length direction that is consistent with the width direction W of the oven chamber 110 and is connected between two sidewalls of the oven chamber 110 in the width direction W. The top of the mounting bracket 223 is provided with a plurality of long strip holes 426 and a plurality of round holes 427, and the long strip holes 426 and the round holes 427 are disposed spaced along the length direction of the mounting bracket 223. Each long strip hole 426 extends in a direction generally perpendicular to the length direction of the mounting bracket 223, i.e., the extension direction of each long strip hole 426 is the same as the length direction L of the oven chamber 110. The number of the plurality of long strip holes 426 and the number of the plurality of round holes 427 are equal to or greater than the number of support rods 219 in the width direction W. In the present example, the number of long strip holes 426 and the number of round holes 427 are equal to or greater than 4, for example, the number of long strip holes 426 is 4, and the number of round holes 426 is 9.

[0045] The bend 436 of one end of each support rod 219 is inserted into the round hole 427 of one mounting bracket 223 and the bend 436 of the other end is inserted into the long strip hole 426 of another mounting bracket 223 or cantilevered. As such, the mounting bracket 223 is capable of securing the support rod 219 in the length direction while allowing the support rod 219 to have a certain deformation space. In the example shown in Figs. 4A and 4B, the bends 436 at both ends of the support rod 219 in the second set of support rods 332 are connected to the mounting bracket 223. A bend 436a of the support rod 219 is inserted into the round hole 427 and another bend 436b is inserted into the long strip hole 426. As the support rod 219 is heated, the support rod 219 may deform, causing the lever portion 435 to stretch a distance. The bend 436b can move a distance in the long strip hole 426 to allow the lever portion 435 to stretch and deform, thereby avoiding a bend deformation of the support rod 219.

[0046] Fig. 5 shows a cross-sectional view of the support rod 219 at the lever portion 435 in accordance with the present example. The specific structure of the support rod 219 is illustrated. As shown in Fig. 5, the support rod 219 includes an electroplated layer 521 and an inner core 520, and the electroplated layer 521 is disposed outside the inner core 520 surrounding the inner core 520 by an electroplating process. That is, the electroplated layer 521 is used to contact the conveying belt 217 to support the conveying belt 217. In the present example, both the inner core 520 and the conveying belt 217 are made of stainless steel materials and the electroplated layer 521 is a chrome electroplated layer. By disposing the electroplated layer 521 on the periphery of the inner core 520, it is possible to increase the rigidity of the support rod 219 and reduce the wear of the support rod 219, thereby maintaining a line contact between the support rod 219 and the conveying belt 217, thus increasing the service life of the support rod 219. The applicant has found that when the electroplated layer 521 is a chrome electroplated layer, the rigidity of the support rod 219 increases significantly, thereby being able to reduce wear of the support rod 219 to a greater extent and increase the service life of the support rod 219.

[0047]

[0048] In a reflow oven, a conveying device generally includes a conveying belt for carry ing a circuit board and a drive device for driving the conveying belt along a conveying direction. Due to the weight of the circuit board, the conveying belt is prone to deformation when carrying the circuit board. A support rod is typically provided below the conveying belt to prevent the conveying belt from deforming during travel.

[0049] In the reflow oven of the present application, by setting the support rod to extend obliquely in the conveying direction rather than extending along the conveying direction, it is possible to increase the area of the contact site of the conveying belt with the support rod, thereby reducing partial wear of the conveying belt and extending the service life of the conveying belt. [0050] Moreover, by providing an electroplated layer on the periphery of the inner core of the support rods in the reflow oven of the present application, it is possible to reduce wear of the support rods and increase the service life of the support rods.

[0051] Further, by symmetrically arranging the support rods of the reflow oven of the present application in the width direction and in groups in the length direction, it is possible to reduce the deviation of the conveying belt in the travel process under the premise that the support rods are disposed inclined in the conveying direction.

[0052] Although the present disclosure has been described in connection with examples of the examples outlined above, various alternatives, modifications, variations, improvements, and/or substantial equivalents, whether known or foreseeable now or in the near future, may be apparent to those having at least ordinary skill in the art. In addition, the technical effects and/or technical problems described in the present specification are exemplary and not limiting; therefore, the disclosure in the present specification may be used to solve other technical problems and have other technical effects and/or may solve other technical problems. Therefore, examples of the present disclosure as set forth above are intended to be illustrative and not limiting. Various changes may be made without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is intended to include all known or earlier developed alternatives, modifications, variations, improvements and/or substantial equivalents.