Soldering Device Minimizing Voids When Soldering Printed Circuit Boards

Abstract

A soldering device for soldering a printed circuit board includes at least one heating appliance melting solder situated between electrical or electronic components being soldered onto a printed circuit board and the printed circuit board. At least one actuator mechanically oscillates the printed circuit board at a variable frequency of oscillation in a direction of a plane defioned by the printed circuit board. A second lateral edge of the printed circuit board, the second lateral edge being opposite to the first lateral edge of the printed circuit board, rests against iand supported by a fixed stop.

Claims

1. A soldering device for soldering a printed circuit board, said device comprising: at least one heating appliance heating molten solder situated between electrical or electronic components being soldered onto a printed circuit board and the printed circuit board; at least one actuator mechanically oscillating the printed circuit board at a frequency of oscillation, wherein the actuator, in an area of a first lateral edge of the printed circuit board, indirectly or directly comes to rest against said printed circuit board in such a manner that an oscillation is introduced into the printed circuit board substantially parallel to a plane defined by the printed circuit board, said frequency of oscillation changing between a start frequency and an end frequency; and a fixed stop acting in a manner of a thrust bearing rests against and supports a second lateral edge of the printed circuit board, the second lateral edge being opposite to the first lateral edge of the printed circuit board.

2. The soldering device according to claim 1, in which the actuator includes a piezoelectric transducer.

3. The soldering device according to claim 1, in which the actuator includes a magnetostrictive transducer, a transducer being made from a magnetic shape memory alloy and/or an electromagnetic oscillation coil.

4. The soldering device according to claim 1, in which the soldering device is a rest soldering device or a rework soldering station.

5. The soldering device according to claim 1, including a transport device transporting the printed circuit board into a soldering area of the soldering device, through the soldering area, and out of the soldering area, wherein the actuator and the dead stop can be moved in the transport direction together with the printed circuit board or at the very least synchronously with the same.

6. The soldering device according to claim 5, including a transport frame or a printed circuit board frame receiving the printed circuit board.

7. The soldering device according to claim 6, in which the actuator is indirectly coupled to the printed circuit board via the transport device, via the transport frame or the printed circuit board frame.

8. The soldering deice according to claim 6, in which the printed circuit board is indirectly supported at the dead stop via the transport device, via the transport frame or the printed circuit board frame, or wherein the dead stop is formed by the transport frame or the printed circuit board frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The following description explains the invention in greater detail with the help of drawings only showing examples, in the figures:

[0031] FIG. 1 shows a first exempla embodiment of an arrangement of a printed circuit board being equipped with components with an oscillation generator in cross-section;

[0032] FIG. 2 shows a second exemplary embodiment of an arrangement of a printed circuit board being equipped with components with an oscillation generator in cross-section along sectional line

A-A in FIG. 3;

[0033] FIG. 3 shows the exemplary embodiment according to FIG. 2 in a view from above;

[0034] FIG. 4 shows a third exemplary embodiment of an arrangement of a printed circuit board being equipped with components with an oscillation generator in as view from above that corresponds to FIG. 3;

[0035] FIG. 5 shows, in a schematic illustration in cross-section, the soldering connection between a component and the printed circuit board with voids being present;

[0036] FIG. 6 shows, in a section along sectional line B-B in FIG. 5, a typical distribution of voids in the soldering connection:

[0037] FIG. 7 shows, in an illustration that corresponds to FIG. 5, the soldering connection between a component and the printed circuit board with voids that have been reduced in accordance with the invention; and

[0038] FIG. 8 shows, in an illustration that corresponds to FIG. 6, along sectional line C-C in FIG. 7, the soldering connection with voids that have been reduced in accordance with the invention.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENT

[0039] In FIG. 1, in a first exemplary embodiment, the arrangement of an oscillation generator or actuator 10 for exciting oscillations in as printed circuit board 01 is schematically illustrated. For reasons of a simpler and clearer illustration, the soldering installation in which the arrangement of the printed circuit board and of the actuator is arranged is not illustrated.

[0040] The printed circuit board 01 being equipped with electronic components 02 rests on a pair of carriers 11 and 12. In this respect, the carrier 12 is embodied as an angle that is L-shaped in cross-section, against the vertical leg of which a longitudinal edge 03 of the printed circuit board comes to rest. The carrier 12 is substantially rigidly fixed to a machine rack or to a housing of the soldering installation in a manner that is not illustrated and in this way forms a dead stop for the printed circuit board 01. The carrier 11 that is opposite to the carrier 12 only forms a rest for the lateral edge 04 of the printed circuit board 01 that is opposite to the lateral edge 03, so that said lateral edge 04 is arranged on the carrier 11 in the type of a floating bearing.

[0041] With its oscillator 13, the actuator 10 is directly coupled to the longitudinal edge 04 of the printed circuit board 01, that is to say it has come to rest against the same. In this respect, said resting can he effected under a low prestress at the very least.

[0042] If the actuator 10 is now excited to oscillate via a control appliance that is not illustrated, the oscillator 13 compresses and decompresses the printed circuit board 01 in quick succession between the actuator 10 and the carrier 12 acting as a dead stop.

[0043] In the exemplary embodiment of the invention that is illustrated in FIGS. 2 and 3, the two carriers 11 and 12 form a part of a transport device for transporting into or through the soldering chamber or into or through the sol den 11 area of a soldering installation that is not illustrated. The carrier 12, in turn, forms a dead stop for the longitudinal edge 03 of the printed circuit board 01 with its vertical leg. In contrast to the exemplary embodiment that is illustrated in FIG. 1, the carrier 11 is also embodied as an angle that is L-shaped in cross-section, against the vertical leg of which the longitudinal edge 04 of the printed circuit board that is opposite to the longitudinal edge 03 comes to rest. In this respect, the printed circuit board can he held between the vertical legs of the carriers 11 and 12 under a low prestress at the very least.

[0044] The oscillator 13 of the actuator 10 rests, possibly under a prestress, against the vertical leg of the carrier 12 and thus indirectly against the longitudinal edge 04 of the printed circuit board 01. If the actuator is now excited to oscillate by means of the control appliance, the oscillation is indirectly transmitted onto the printed circuit board, either due to an elastic deformability of the carrier 11, or due to an at least marginal movabililty of the carrier 11 relative to the carrier 12, resulting in the printed circuit board in turn being compressed and decompressed in quick succession.

[0045] The exemplary embodiment that is illustrated in FIG. 4 corresponds, in its basic structure, to the exemplary embodiment according to FIGS. 2 and 3. In contrast to the previous exemplary embodiment, in which the printed circuit board 01 directly rests on the carriers 11 and 12 of the transport device, in the exemplary embodiment according to FIG. 4, the printed circuit board 01 is arranged in a soldering frame 14. In said soldering frame, the printed circuit board, while being transported through the soldering device or through the soldering installation, is held or supported at the carriers 11 and 12. In this respect, the soldering frame features two transverse struts 15 and 16 as well as two longitudinal struts 17 and 18. In this respect, the soldering frame 14 has to be designed and dimensioned so that, when indirectly introducing oscillations into the printed circuit board 01 via the carrier 11 and via the transverse struts 15 by means of the actuator 10, a deformability that is in particular elastic, at the very least of the longitudinal struts 17 and 18, can be effected by means of compression and/or bending, so that the printed circuit board, in accordance with the invention, can be compressed and decompressed in quick succession.

[0046] At the beginning of the oscillation excitation, a plurality of voids 06 in the form of gaseous inclusions is situatedas FIG. 5 outlines by way of examplein the solder 05 between the component 02 and the printed circuit board 01, the voids accounting for a substantial part of the surfacesee the soldering connection in FIG. 6 that is outlined by way of example concerning the printed circuit board plane.

[0047] Due to the oscillation excitation of the printed circuit board 01, as is explained hereinbefore, a movement of the voids 06 in the liquid solder 05 is caused, said voids being driven out of the molten solder 05 when the edge of the connection between the component 02 and the printed circuit board 01 is reached. This results in the number of voids 06 in the solder 05 being significantly reduced after the oscillation excitation has been carried outas FIGS. 7 and 8 outline by of example. Hereby, a considerably improved quality of the soldering connection between the components 02 and the printed circuit board 01 is ensured.