WO2010031864A1 - Reflow soldering device with a process chamber comprising a separating wall method for reflow soldering using such a reflow soldering device - Google Patents

Abstract

The invention relates to a reflow soldering device comprising - a process chamber with a feed apparatus for feeding assemblies to be subjected to a heat treatment, - fan devices (28) for feeding an air stream to the circuit boards, - heating devices (35) for heating the air stream. The reflow soldering device further comprises a separating wall (10) disposed in the process chamber, said wall dividing the process chamber in the lateral direction into two process chamber sections (11, 12), wherein the fan devices (28) and the heating devices (35) of the two process chamber sections (11, 12) can be controlled independently of one another so that different temperatures can be established in the process chamber sections (11, 12).

Description

 REFLOW LOT DEVICE WITH A PROCESS CHAMBER HAVING A SEPARATION WALL METHOD FOR REFLOW-SOLDERING USING SUCH A REFLOW SOLDERING DEVICE

The present invention relates to a reflow soldering apparatus and a reflow soldering method.

From EP 1 525 067 B1 a process chamber for a reflow soldering device is known. In this process chamber, a conveyor for conveying assemblies is provided. The assemblies are printed circuit boards with electronic components, wherein the electronic components are soldered to the circuit board. For this purpose, a heated air flow is generated by means of fan rollers, which is supplied to the modules. Above and below the conveyor track of the assemblies, two sets of fan rollers are arranged. The fan rollers extend over the entire width of the conveyor track, whereby a homogeneous, band-shaped air flow is achieved. As a result, a uniform over the entire width of the conveyor track temperature distribution is achieved, which is very precisely adjustable.

This known reflow soldering apparatus has proven very successful in practice, since it can reliably and very accurately predetermined temperature profiles are applied to the modules with her. From DE 100 31 071 C2 discloses a system for the thermal treatment of workpieces, in particular for soldering, in which in each process or heating level in each case at least two transport devices are arranged side by side. The transport devices can be designed in the manner of a chain conveyor and arranged side by side.

EP 1 116 147 A1 discloses a further device for heating printed circuit boards, in which two heating lines are arranged side by side and parallel to one another in a horizontal transport plane. It is also possible to arrange several heating streets above each other.

DE 102 26 593 A1 is your patent application, which relates to a reflow device with a fan roller, which is open at its two end faces, wherein the fan roller is arranged with its axis of rotation transversely to the transport direction of the printed circuit boards to be soldered. The air is drawn in via the end faces of the fan roller and discharged radially from the roller to the printed circuit boards to be soldered.

In US 36,941 E, a cooking oven is described, which has two conveyors and a circulating air blower to act on the object to be heated with hot air.

The invention has the object of providing such a reflow soldering device and a method for reflow soldering educate so that a temperature profile can be generated with essentially the same quality and reliability, with a more cost effective design of the reflow soldering a higher throughput of processing assemblies to be achieved.

The object is achieved by a reflow soldering device having the features of claim 1 and by a method having the features of claim 12. Advantageous embodiments are specified in the respective subclaims.

The reflow soldering device comprises

a process chamber with a conveyor for conveying a heat treated circuit boards,

a blower device for supplying an air flow to the printed circuit boards,

- A heater for heating the air flow.

The reflow soldering device according to the invention is characterized in that a partition wall is arranged in the process chamber, which subdivides the process chamber in the transverse direction into two process sub-chambers, whereby blower devices and heating devices are provided in each process sub-chamber. The blower devices and heating devices of the two process subchambers can be controlled independently of one another by means of a control device, so that different temperatures can be set in the process subchambers.

Thus, different products or different assemblies with different temperature profiles can be processed in the two process sub-chambers. By integrating two process chambers with a different temperature profile in a reflow soldering a twice as high throughput is achieved as with a conventional reflow soldering. By providing two process subchambers, it is not necessary that all components of the soldering device be duplicated. Thus, the two process sub-chambers are arranged in a common housing. The control device for controlling the individual components of the soldering device comprises a hardware module (processor unit, keyboard, screen, etc.), which essentially corresponds to the hardware module of the reflow soldering device mentioned above. Only the control software used here for the independent control of the two Prozessteilkam- trained.

Preferably, in each case a conveyor is arranged in the Prozessteilkammern, which are controlled differently, so that the temperature profiles can be traversed at different speeds.

The reflow soldering device has a housing in which the two process sub-chambers are formed, and it is preferably a single electrical control unit for driving both Prozessteilkammern provided. The reflow soldering device is preferably formed with a single cooling device for cooling the printed circuit boards in both Prozessteilkammern.

The reflow soldering device has as fan devices preferably radial fans, which are arranged laterally from a conveyor track for the printed circuit boards.

By using a centrifugal fan arranged laterally of the conveyor track, a radial fan replaces two fan rollers of the reflow soldering device explained in the introduction. This allows despite the provision of two process chambers, the number of fans or blowers compared to the above-mentioned reflow soldering device to keep approximately constant.

The partition wall between the two insulation part chambers is preferably provided with a thermal insulation layer.

The advantages achieved with the reflow soldering device according to the invention over two conventional soldering devices, with which the same throughput is achieved, are: - Lower footprint

- Less need for media (electricity, nitrogen, etc.)

- Less wear

- Reduced maintenance

- Higher flexibility - Lower staff costs

- Higher economic efficiency

The invention is explained below by way of example with reference to an embodiment shown in the drawings. The drawings show:

1 shows a reflow soldering device according to the invention with the lid open in a perspective view, FIG. 2 shows the soldering device according to FIG. 1 in cross section, FIG.

Fig. 3 shows the cross-sectional view of FIG. 2 in a schematically simplified

Representation, wherein in one half of the soldering device, the flow directions of the air flow are shown, and

Fig. 4 shows one half of the soldering device with a section in the longitudinal direction and in

Transverse direction schematically simplified, the flow directions are shown by arrows.

The reflow soldering device 1 according to the invention has a housing 2, which consists of a lower housing pan 3 and a cover 4 which is pivotably arranged on the housing pan. The housing pan has two end walls 5, two side walls 6 and a bottom wall 7. In the end walls 5 horizontal slots 5a are formed through which electronic assemblies can be added or removed. Between the slots 5a conveyors (not shown) for transporting the assemblies 8 are provided. These conveyors are conventionally formed by, for example, narrow conveyor belts on which the assemblies are placed. The conveying speed is individually adjustable. The modules are conveyed in the conveying direction 9 along a conveyor track through the housing. The horizontal plane in which the conveyor track lies forms a plane of symmetry for the essential components of the reflow soldering device 1.

According to the invention, the housing 2 is subdivided by a partition wall 10 which extends in the longitudinal direction, so that two process part chambers 11, 12 are formed. The Prozessteilkammern 1 1, 12 are arranged symmetrically to the partition wall 10 and formed substantially symmetrically to the partition wall 10.

The partition wall 10 is formed in the present embodiment of a metal sheet. In the context of the invention, it can also be unilaterally or bilaterally with an insulating layer for thermal insulation of the two process sub-chambers 11, 12 be provided. It can also be formed of a different material than metal.

Above and below the conveyor lanes 13 are formed. The air guide 13 have a base wall 14 which is rectangular in plan view and arranged parallel to the plane of the conveyor track. The base wall 14 is provided at its edge with a peripheral peripheral wall 15 which extends away from the base wall 14 away from the plane of the conveyor track.

In the base wall 14, nozzle slots 16 are formed. The nozzle slots 16 may have a flanged edge in the direction of the conveyor track. The nozzle slots 16 are formed running transversely to the conveying direction 9 in the present embodiment.

In the transverse direction to the conveying direction 9 return tubes 17 extend, which extend between two opposite sides of the peripheral wall 15 and open at this in each case with an opening 18. In Figure 4, the peripheral walls 15 are shown at the level of the openings 18 with a dashed line.

At the opposite side of the partition 10 of the aerobar 13, a longitudinally extending vacuum or suction channel 20 is formed. This vacuum channel 20 is bounded by a lower and upper Unterdruckkanalleitblech 21, which is attached with an edge to the edges of the remote from the partition 10 portion of the peripheral wall 15 of the airway corner 14, extending from there vertically away from the guide elements 13, in an arc 22 passes over and on the other side of the arc in a vertical outer boundary wall 25, which extends to approximately the height of the conveyor track. From there, the vacuum duct baffle 21 is once again guided a distance in the direction of the partition wall 10 to form a bottom wall 23. From the bottom wall 23, a vertical inner boundary wall 24, to which the remote from the partition wall 10 side of the air guide 13 extends. In the adjacent area to the base wall 14 of the air duct 13, openings 19 are formed on the inner boundary wall, so that the area between the conveyor track and the base wall siswandung 14 communicating with the vacuum channel 20 is connected. The vacuum channel 20 is further communicatively connected to the return tubes 17 via the openings 18 in the peripheral wall 15.

At the outer boundary walls 25, the vacuum channels 20 each have a semicircular opening 26, wherein in each case one above and below the conveyor track arranged vacuum channel 2 complement each other with its semicircular opening 26 so that they form a circular opening.

The outer boundary wall 25 of the vacuum channel 20 is a piece spaced from the adjacent side wall 6 of the housing 2 of the reflow soldering device 1 is arranged. The sheets 22 of the vacuum channels 20 are spaced a distance from the bottom wall 7 and the lid 4 of the housing 2. The intermediate region between the vacuum duct baffle 21 and the air baffle 13 on the one side and the side wall 5, the bottom wall 7 and the cover 4 of the housing 2 on the other side delimit an overpressure channel 27. A radial ventilator 28 is arranged in this overpressure duct 27. The radial fan 28 has a radial rotor 29, which is a rotor disk 30 and formed with rotor blades 30 radially aligned at the periphery of the rotor disk 31. The rotor blades 31 form a rotor rim, whose inner diameter corresponds approximately to the diameter of the limited by the semi-circular openings 26 opening, wherein the rotor ring is arranged in alignment with this opening. The rotor disk 30 has centrally a hub 32, which sits on a guided through the side wall 6 of the housing 2 shaft 33. The shaft 33 is driven outside of the housing 2 by a motor 34.

The radial rotor 29 is configured such that, in operation, when the rotor is rotated, air is accelerated radially outward from the center of the radial rotor 29 through the rotor blades 31 into the overpressure passage 27. The radial rotor 29 is surrounded by a radial heater 35, which heats the air conveyed by the radial fan 28 to the outside. In the longitudinal direction of the housing 2 of the reflow soldering device 1, a plurality of heating segments 36 are formed, each having a radial fan 28 with a radial heater 35, an upper and a lower vacuum duct 20 and an upper and lower spoiler 13. The heating segments 36 are separated from each other by transverse to the conveying direction 9 extending segment dividing walls 37 from each other (Fig. 4). This makes it possible to set 36 different temperatures in the individual heating segments, since the individual radial fans 28 and radiator 35 by means of a control device (not shown) are independently controllable.

The air delivered by the radial fans 28 into the overpressure channel 27 is first heated by the radial heater 35. The heated air flows along the bends 22 to the baffles 13. The air from the overpressure channel 27 passes through the nozzle slots 16. The heated air exits the nozzle slots 16 and impinges on the assemblies 8 conveyed along the conveyor. The assemblies 8 are heated by the heated air heated to a predetermined temperature. The conveyor is supplied with heated air both from below and from above. The air streams are deflected in the region of the conveyor track to the base wall 14. The base wall 14 and the air exiting the nozzle slots 16 urge the air reflected from the assemblies to the side, i. transversely to the conveying direction 9. As a result, the air flow is diverted transversely to the conveying direction 9 partly in the direction of the partition wall 10 and the other part in the direction of the vacuum channel 20. The part of the air flow derived from the vacuum duct flows directly via the openings 19 into the vacuum duct 20 (FIG. 4). The other part flows in the direction of the dividing wall 10, into the region between the dividing wall 10 and the peripheral wall 15 of the air guide basin 13 and from there through the return tubes 17 into the vacuum passage 20.

In the vacuum channel 20, the used or cooled air is collected and fed through the openings 26 to the centrifugal fan 28 again. The air is thus circulated in the individual heating segments in the circuit. The circulation speed can be adjusted by the rotational speed of the centrifugal fan 28. The supplied heat can be adjusted individually to the radiators 35. Furthermore, in the process sub-chambers 11, 12, the conveying speed can be set independently. Thus, completely independent temperature profiles can be generated in the two process chambers.

When using a metal plate as a partition 10 can be in adjacent sections of the two process chambers 11, 12 temperature differences of about 40 ⁰ C set. If the partition is provided with a thermal insulation layer, much higher temperature differences can be set, for example, 80 ^° C. or more.

The reflow soldering device has a cooling device (not shown) at its rear end region in the conveying direction 9 in order to cool the assemblies 8. There is a single cooling device for both Prozessteilkammern 11, 12 is provided. In the context of the invention, two cooling devices for one of the two process sub-chambers 11, 12 may be provided.

Below are two groups of applications, each requiring a different soldering profile. These different soldering profiles can be performed simultaneously in the reflow soldering device according to the invention. The conveyor paths in the two process sub-chambers 11, 12 are referred to as spuri or track 2:

TRACK 1:

Soldering profile with low peak temperature of about 200 ⁰ C - 220 ° C> Peak, for easy assembly

- Thermally sensitive assemblies

- Thin circuit boards

- Simple Cu layers

- Low assembly density with homogeneous structure - Low mass components

- Thermally low demanding

- Leaded alloy (SN63 Pb37, melting point 183 ⁰ C)

- Delta temp. > / = 0

TRACK 2:

Soldering profile with increased peak temperature of approx. 290 ⁰ C - 300 ° C-> peak, for complex assemblies.

- Thermally demanding assemblies - Thick PCBs

- Strong Cu layers

- Dense assembly with inhomogeneous structure

- Many high-mass and large-area components

- Thermally very demanding - Lead-free alloy (SnAg3.8CuO, 7, melting point 217 ° C)

- Delta temp. > 0

The reflow soldering device according to the invention is also suitable for the automatic performance of a bonding process. Here, in parallel, two different adhesive profiles can be driven.

With the soldering device according to the invention, a very wide variety of thermal processes can be carried out, with fundamentally other products than printed circuit boards can be edited herewith. However, the reflow soldering device according to the invention is designed primarily for the processing of printed circuit boards or printed circuit boards containing assemblies.

The invention has been explained above with reference to an embodiment in which a baffle is used. In the context of the invention, another suitable air guiding device may be provided instead of a spoiler, as long as it allows the air flow from the overpressure channel 27 to the assemblies 8 and from there the discharge to the vacuum channel 20. Preferably, the return air flow is split and a part passed back by means of the return tubes 17. In the context of the invention, it is also possible to form the nozzles for supplying the heated air to the modules directly to the return tubes by, for example. The side walls are slightly extended in the direction of the conveyor track in each case by a projection. These projections then limit the nozzles.

LIST OF REFERENCE NUMBERS

1 reflow soldering device 19 opening

2 housing 20 vacuum or suction channel

3 housing pan 21 vacuum channel baffle

Cover 25 22 sheets

5 end wall 23 bottom wall

5a slot 24 inner boundary wall

6 side wall 25 outer boundary wall

7 bottom wall 26 semicircular opening

8 Module 30 27 Overpressure channel

9 Direction of delivery 28 Radial fan

10 Partition 29 Radial rotor

11 Process Chamber 30 Rotor ...

12 process chamber 31 rotor blades

13 air guide 35 32 hub

14 base wall 33 shaft

15 peripheral wall 34 engine

16 nozzle slot 35 radial radiator

17 return pipe 36 heating segment

18 Opening 40 37 Segment partition

Claims

protection claims 1. Reflow soldering comprising a process chamber having a conveyor for conveying assemblies to be heat treated, fan means (28) for supplying an air flow to the circuit boards, Heating means (35) for heating the air flow, characterized in that in the process chamber a dividing wall (10) is arranged, which divides the process chamber in the transverse direction into two process chambers (11, 12), the fan means (28) and heating means (35 ) of the two Prozessteilkammern (11, 12) are independently controllable, so that in the Prozessteilkammern (1 1, 12) different temperatures are adjustable. 2. reflow soldering apparatus according to claim 1, characterized in that in the process part chambers (11, 12) each have a conveyor is arranged, which are controlled differently. 3. reflow soldering apparatus according to claim 1 or 2, characterized in that the reflow soldering a housing (2) in which the two process part chambers (11, 12) are formed, and an electrical control unit for driving in the two process sub-chambers ( 11, 12) contained components. 4. reflow soldering device according to one of claims 1 to 3, characterized in that a single cooling device for cooling the modules in both process part of chambers (11, 12) is provided. 5. reflow soldering apparatus according to one of claims 1 to 4, characterized in that the fan means (28) each have at least one radial rotor (29) sen, which is arranged laterally from a conveyor track for the assemblies (8). 6. reflow soldering apparatus according to claim 5, characterized in that the radial rotor (29) has a blade ring on the peripheral region, which is designed such that air from the center of the radial rotor (29) is blown radially outward. 7. reflow soldering apparatus according to claim 5 or 6, characterized in that adjacent to the conveying path of the modules (8) transversely to the conveying direction (9) extending nozzle slots (16) are provided which are formed in a base wall (14). 8. reflow soldering apparatus according to claim 7, characterized in that on the. With respect to the conveying path of the base wall (14) side facing away return tubes (17) are arranged, extending from the region adjacent to the partition wall (10) via the base wall (14 ) to direct air from the dividing wall to the fan means (28). 9. reflow soldering apparatus according to one of claims 1 to 8, characterized in that the partition wall (10) is provided with a thermal insulation layer. 10. reflow soldering device according to one of claims 1 to 9, characterized in that a control unit is provided which is formed to control a soldering process. 11. reflow soldering apparatus according to one of claims 1 to 10, characterized in that a control unit is provided, which is designed to control a bonding process. 12. A method for reflow soldering of assemblies, wherein a reflow soldering apparatus, in particular according to one of claims 1 to 11, comprising - a process chamber with a conveyor for conveying one Heat treatment to be subjected to assemblies, Blower means (28) for supplying an air flow to the printed circuit boards, - Heating means (35) for heating the air flow, wherein in the process chamber, a partition wall (10) is arranged, which divides the process chamber in the transverse direction into two process sub-chambers (11, 12), wherein the blower means (28) and heating means (35) of the two Process sub-chambers (11, 12) are independently controllable, so that in the Prozessteilkammern (11, 12) different temperatures are adjustable, is used, and Assemblies are soldered simultaneously with different temperature profiles in the process sub-chambers (11, 12). 13. The method according to claim 12, characterized in that the assemblies in the Prozessteilkammern (11, 12) are each conveyed by means of a separate conveyor at different speeds.