CN115211239A

CN115211239A - Method for manufacturing an electrical device

Info

Publication number: CN115211239A
Application number: CN202180016588.8A
Authority: CN
Inventors: M.布雷塞克; H.克鲁格; D.温格茨曼
Original assignee: Siemens Mobility GmbH
Current assignee: Siemens Mobility GmbH
Priority date: 2020-02-28
Filing date: 2021-02-10
Publication date: 2022-10-18
Also published as: WO2021170407A1; EP4074148A1; DE102020202598A1

Abstract

The invention relates to a method for producing an electrical device on the basis of a printed circuit board, which has a first conductor circuit structure with a conductor circuit on one side of the printed circuit board, which is referred to below as the primary side; a second conductor circuit structure having a conductor circuit, which is arranged on the other side of the circuit board, which is referred to below as the secondary side, and/or as an internally located conductor circuit structure in an intermediate layer of the circuit board; a plurality of metallized through holes through which the conductor circuits of the first conductor circuit structure can be electrically connected with the conductor circuits of the second conductor circuit structure, respectively. At least one first electrical element is arranged on the primary side, which is soldered to the first conductor circuit structure by means of a first soldering step. According to the invention, at least one of the metallized through-holes is closed by means of a protective layer only on the primary side before at least one first electrical element is arranged on the primary side and soldered by means of the first soldering step.

Description

Method for manufacturing an electrical device

The present invention relates to a method of manufacturing an electrical device and to such an electrical device.

Furthermore, the invention relates to a method for producing an electrical device on the basis of a circuit board, wherein the circuit board has: a first conductor circuit structure with a conductor circuit on one side of the circuit board, hereinafter referred to as primary side; a second conductor circuit structure with a conductor circuit, which is arranged on the other side of the circuit board, which is referred to below as the secondary side, and/or as an internally located conductor circuit structure in an intermediate layer of the circuit board; and a plurality of metallized through holes, by means of which the conductor circuits of the first conductor circuit arrangement can be electrically connected in each case to the conductor circuits of the second conductor circuit arrangement, wherein at least one first electrical element is arranged on the primary side, which is soldered to the first conductor circuit arrangement by means of a first soldering step.

Circuit boards of this type are generally known in the art of circuit boards. It is also known to mount at least one electrical component, for example in the form of a Surface-Mounted component (also called SMD, surface Mounted Device), or a plug-in component (also called THD component), on the primary side and to solder the first or second conductor circuit arrangement.

The object of the present invention is to provide a method which provides better results with regard to the protection of metallized through-holes against corrosion than the known methods.

The object is achieved according to the invention by a method having the features of claim 1. Advantageous embodiments of the method according to the invention are given in the dependent claims.

According to the invention, it is provided that, before the at least one first electrical component is arranged on the primary side and is soldered by the first soldering step, at least one of these metallized through-holes is closed only on the primary side by means of a protective layer.

A major advantage of the method according to the invention is that reliable corrosion protection is ensured also for the primary side by the sealing of the not yet assembled metallization channel by means of the protective layer. If, for example, the metallization channels that have not yet been assembled are blocked by components that are to be mounted on the circuit board or are subsequently mounted on the circuit board, it is not possible to ensure reliable corrosion protection later on in the course of the subsequent steps. By coating the primary side with a protective layer before fixing the component on the primary side according to the invention, it is ensured that no shaded metallization channels remain, which are not protected on the primary side by a suitable protective layer.

According to a further development of the method according to the invention, any corrosion-resistant material that can withstand the subsequent processing steps, for example welding steps, can be used for the protective layer. It is considered particularly advantageous, however, if the protective layer is formed by a welding protective layer, which serves as a welding protection, in particular in the first welding step. In order to protect the conductor tracks, which should not be in contact with the soldering material, from wetting by the soldering material, it is known to apply a so-called solder protective varnish to the conductor tracks before the first soldering step. The welding protective lacquer application step can be used in an advantageous manner with synergistic effects, in order to close off the not yet assembled metallization channels also on the primary side. In other words, the welding protection paint performs a dual function in this case: on the one hand, the solder resist coats and protects the conductor path from solder material, which may wet the conductor path in a subsequent soldering step, and on the other hand, as a closed structure above the metallization channel or on the primary side, which has not yet been assembled; both protective functions can be achieved by this coating step.

Epoxy resins are preferably used as the solder resist.

According to a further embodiment, after the circuit board has been provided with electrical components, the primary side of the circuit board is coated with a coating, in particular made of acrylic or a lacquer containing acrylic, at least in the region with the metallized through-holes. The resulting arrangement can be coated with such a coating, in particular on both sides of the printed circuit board, over the entire surface or at least in a partial region.

Any material which is suitable for the electrical operation of the device and which offers good corrosion protection, for example silicon or a silicon-containing lacquer, can be used as material for the cover layer. However, with regard to particularly good protective properties, in particular particularly good protection against corrosion, it is considered to be advantageous, after the assembly of the circuit board with the electrical components, to coat the resulting assembly with a coating in the form of an acrylic resin or a lacquer containing an acrylic resin on both sides of the circuit board over the entire surface or at least in the region provided with the metallization channels. Acrylic or lacquer containing acrylic is strong and not strong in gas permeability, at least stronger than silicon and less gas permeable.

According to a further development, after the assembly of the printed circuit board, the secondary side is coated over the entire surface or at least in the region with the metallized through-holes with a coating, which is made of an acrylic resin or a lacquer containing an acrylic resin.

It is considered to be advantageous here if, before the first electrical component is fixed on the primary side and soldered in the first soldering step, all of the non-mounted metallization channels which are located below the first electrical component after the mounting of the components and which are obscured by the components after the fixing and soldering of the components are closed off on the primary side by means of a protective layer.

In a first soldering step, the first electrical component is soldered to one or more conductor circuits of the conductor circuit arrangement.

According to a further development, after the first soldering step, at least one second electrical element is arranged on the primary side and soldered to, in particular, one or more conductor tracks of the second conductor track structure by means of a second soldering step.

According to a further development, the protective layer is used to exclude the metallized through-holes for the arrangement of the at least one second electrical component from the coating and to leave them unclosed.

In particular, all inner-wall-side electrically conductive metallization channels for mounting one or more second electrical components on the primary side after mounting and soldering the one or more first electrical components and for soldering the one or more second electrical components to at least one second conductor circuit of the second conductor circuit arrangement remain excluded from the coating and remain unclosed by means of the protective layer.

According to a further development, before the at least one first electrical component is mounted on the primary side and soldered by the first soldering step, the metallized through-hole which is located below the at least one second electrical component after the arrangement thereof is closed on the primary side by means of the protective layer.

If the second conductor track structure is an inner conductor track structure arranged in an intermediate layer of the circuit board, it is advantageous if the electrically conductive metallization channels on the inner wall side or at least some of them extend to the intermediate layer and electrically interconnect the primary side and the intermediate layer.

If a second conductor circuit structure with a second conductor circuit is located on the secondary side, the or at least some of the metallized vias may extend through the circuit board and electrically connect the primary side with the secondary side.

According to a further development, the at least one second electrical component has a plurality of connection contacts which are introduced into the metallized through-holes which are excluded from the coating by the protective layer when the second component is arranged, and the connection contacts are soldered to the second conductor track structure by means of the second soldering step.

According to a further development, the diameter of the metallized through-hole is designed such that, as a result of the second soldering step, the soldering material is drawn by capillary action from the secondary side in the direction of the primary side and the metallized through-hole is completely or at least partially filled with the soldering material.

According to a further development, a reflow soldering method is preferably carried out in the first soldering step and/or wave soldering is preferably carried out in the second soldering step.

The first component is preferably a surface mount component and/or the second component is preferably a plug-in component.

The invention further relates to an electrical device having a circuit board, wherein the circuit board has: a first conductor circuit structure with a conductor circuit on one side of the circuit board, hereinafter referred to as primary side; a second conductor circuit structure having a conductor circuit, which is arranged on the other side of the circuit board, which is referred to below as the secondary side, and/or as an internally located conductor circuit structure in an intermediate layer of the circuit board; and a plurality of metallized through holes, by means of which the conductor circuits of the first conductor circuit arrangement can be electrically connected with the conductor circuits of the second conductor circuit arrangement, respectively, and wherein at least one electrical element is arranged on the primary side and soldered with the first and/or the second conductor circuit arrangement.

According to the invention, at least one of the metallized vias arranged below the at least one electrical element is closed only on the primary side by means of a protective layer.

With regard to the advantages of the device according to the invention and the advantageous embodiments of the device according to the invention, reference is made to the above-described embodiments in conjunction with the method according to the invention.

According to a further development of the device, the protective layer is a solder protective layer.

According to a further development of the device, the primary side of the printed circuit board is coated with a coating, in particular made of acrylic or a lacquer containing acrylic, in the region with the metallized through-holes, and/or the secondary side of the printed circuit board is coated over the entire surface or at least in the region with the metallized through-holes with a coating, in particular made of acrylic or a lacquer containing acrylic.

The invention further relates to a rail vehicle, in particular a rail vehicle having a traction converter. According to the invention, the rail vehicle, in particular a traction converter of a rail vehicle or one of the traction converters of a rail vehicle, has the electrical device and/or the electrical device produced according to the method.

The present invention is illustrated in detail below with reference to examples; is illustrated by way of example in the accompanying drawings

Figure 1 shows an embodiment of a circuit board that can be used for manufacturing an embodiment of the device according to the invention,

fig. 2 shows an embodiment of a device according to the invention, which can be manufactured on the basis of the circuit board shown in fig. 1,

FIG. 3 shows, in the form of a flow chart, method steps of an embodiment of the method according to the invention for producing the device shown in FIG. 2, and

fig. 4 shows an embodiment of the rail vehicle according to the invention.

In the drawings, the same reference numerals are used throughout for the same or similar components.

Fig. 1 is a schematic sectional view of a section of a circuit board 10 that can be further processed to manufacture an electrical device. The circuit board 10 has a first conductor circuit structure 11a, which comprises a plurality of conductor circuits, on its side which is referred to below as the primary side 11. A second conductor circuit structure 12a, which likewise comprises a plurality of conductor circuits, is located on the opposite side, which is referred to below as secondary side 12.

Furthermore, in the illustration according to fig. 1, the inner wall side is coated with a conductive material B and thus electrically conductive metallization channels are present as metallization vias on the inner wall side, wherein the metallization channels 21 to 25 serve to electrically connect the conductor paths of the first conductor circuit structure 11a to the conductor paths of the second conductor circuit structure 12a. The metallization channels 21 to 25 are thus not yet fitted and are not connection contacts for receiving components to be mounted on the circuit board 10.

The

metallization channels

26 and 27 serve to enable the connection contacts of a so-called plug-in element to pass through. Such a plug-in element can be mounted on the primary side 11 of the circuit board 10 and the connection contacts of the plug-in element are guided through the

metallization channels

26 and 27 in order to connect the connection contacts to the second conductor circuit structure 12a.

The

conductor circuit structures

11a and 12a, which are usually relatively thin, are not shown to scale in fig. 1, but rather are shown much thicker than they actually are, in order to show the interaction with the metallization channels.

Fig. 2 shows an exemplary embodiment of an electrical device 50 produced on the basis of the circuit board 10 according to fig. 1, which electrical device comprises the circuit board 10 according to fig. 1 and a first element 100 and a second element 200. The first component 100 is preferably a Surface Mounted component, also called SMD component (Surface Mounted Device); the second component 200 is preferably an insert component, also referred to as a THD component (Through-Hole Device).

The circuit board 10 may naturally also have more surface mount components and more plug-in components than those shown here, fig. 2 being limited to the

components

100 and 200 only for reasons of clarity of illustration. The two

conductor circuit arrangements

11a and 12a, which are shown in fig. 1 and whose thickness is very small, are likewise omitted from the illustration in fig. 2 for reasons of clarity only.

The production of the device according to fig. 2 is preferably carried out by the method steps which are executed in the form of a flow chart in fig. 3. Reference is therefore made below to fig. 2 and 3 jointly.

In order to produce the device according to fig. 2, in a first method step 1000,

conductor circuit structures

11a and 12a according to fig. 1 are first defined on circuit board 10, as is generally known, for example, by etching. The printed circuit board 10 provided with the conductor circuit structure is therefore used as a base material for the following embodiments, which is still to be further processed.

In a next method step 1100, a protective layer in the form of a solder protective layer 30 is first applied to the primary side 11 provided with the

conductor track structures

11a and 12a. The solder resist 30 preferably covers the entire section of the first conductor circuit structure 11a which should not be covered by solder in the subsequent first soldering step. In addition, in the context of coating the printed circuit board 10, all the production of the device according to fig. 2 on the primary side 11 by means of the solder resist 30 should not be closed by the assembly or the provision of plug-in component metallization channels. This closes the metallization channels 21 to 25, which are not to be assembled, in the illustration according to fig. 2.

Only the

metallization channels

26 and 27 remain free of the solder resist 30, since these metallization channels should be used for the connection contacts 210 and 220 of the plug-in element 200 to be inserted.

In a next method step 1200, the printed circuit board 10 is mounted with the first component 100 or all surface-mounted components on the primary side 11. The component assembly according to method step 1200 preferably comprises the application of solder paste to the conductor path sections of the first conductor path structure 11a that are to be soldered to the

connection contacts

110 and 120 of the first component 100.

The first component 100 is then "reflow" soldered to the first conductor circuit structure 11a of the circuit board 10, preferably in a reflow oven, in the context of the first soldering step 1300.

In a next component assembly step 1400, the second element 200 is placed with its connection contacts 210 and 220 on the primary side 11 of the circuit board 10, wherein the connection contacts 210 and 220 are inserted into and preferably pass through the

metallization channels

26 and 27. Advantageously, the connection contacts 210 and 220 extend to the second conductor circuit structure 12a on the secondary side 12.

In a following second soldering step 1500, by means of which the second element 200 is soldered with the second conductor circuit structure 12a (see fig. 1) on the secondary side 12 of the circuit board 10 by means of its connection contacts 210 and 220, said second soldering step preferably being wave soldering or wave soldering. The solder 35 can here enter the channel contact means 26 and 27 from below or from the secondary side wetted by the solder 35 upwards by capillary effect; this also applies to open-bottomed metallization channels 21 to 25, even if this is not explicitly shown in fig. 1, if the dimensions in cross section are sufficiently large.

After the second welding step 1500 is finished, the resulting assembly is preferably cleaned bilaterally in the context of a cleaning step. The assembly is dried in a subsequent drying step 1700.

After the drying has ended, the entire assembly is provided with a covering layer 40 in the form of a protective lacquer, which may be a silicone lacquer or a silicon-containing lacquer, over the entire surface of both the primary side 11 and the secondary side 12 of the printed circuit board 10 in the context of a painting step 1800. It is considered particularly advantageous, however, for the cover layer 40 to be acrylic or to contain at least acrylic, i.e. to form an acrylic lacquer.

By the painting in the painting step 1800, the closing of the unmounted metallization channels 21 to 25 is also formed on the secondary side 12, so that all the unmounted metallization channels 21 to 25 of the printed circuit board 10 are covered or closed on both sides, i.e. on the primary side 11, by the solder resist 30 and the cover layer 40 located thereon and on the secondary side 12 individually by the cover layer 40.

After painting, the resulting device 50 according to fig. 2 is dried in a drying step 1900.

Overall, the method steps described in conjunction with fig. 2 and 3 ensure that the non-assembled metallization channels, i.e. metallization channels 21 to 25, are closed on both sides and thus reliably prevent corrosion of the metallization structure on the inner wall side.

Fig. 4 shows an exemplary embodiment of a rail vehicle 500 according to the invention, which has one or more traction converters 510. The traction converter 510 has one or more of the devices 50 described above in connection with fig. 1 to 3, respectively.

List of reference numerals

10. Circuit board

11. Primary side

11a first conductor circuit structure

12. Secondary side

12a second conductor circuit structure

21-27 metallized vias

30. Welding protective layer/protective layer

35. Solder

40. Covering layer

50. Electrical device

100. First component/surface mount component

110. Connecting contact

120. Connecting contact

200. Second component/plug-in component

210. Connecting contact

220. Connecting contact

500. Rail vehicle

510. Traction converter

1000. Method step

1100. Method step

1200. Method step

1300. First welding step

1400. Component assembly procedure

1500. Second welding step

1600. Cleaning step

1700. Drying step

1800. Step of painting

1900. Drying step

B conductive material

Claims

1. A method of manufacturing an electrical device (50) on the basis of a circuit board (10), wherein the circuit board has:

a first conductor circuit structure (11 a) with a conductor circuit on a side of the circuit board (10) which is referred to below as primary side (11),

-a second conductor circuit structure (12 a) with a conductor circuit, which is arranged on the other side of the circuit board (10), hereinafter referred to as secondary side (12), and/or as an internally located conductor circuit structure in an intermediate layer of the circuit board (10), and

-a plurality of metallized vias (21-25) through which conductor circuits of the first conductor circuit structure (11 a) can be electrically connected with conductor circuits of the second conductor circuit structure (12 a), respectively,

wherein at least one first electrical element (100) is arranged on the primary side (11), said at least one first electrical element being soldered to the first conductor circuit structure (11 a, 12 a) by means of a first soldering step (1300),

characterized in that at least one of the metallized through-holes (21-25) is closed by means of a protective layer (30) only on the primary side (11) before the at least one first electrical element (100) is arranged on the primary side (11) and soldered by means of the first soldering step (1300).

2. Method according to claim 1, characterized in that the protective layer (30) is a welding protective layer (30), which in particular plays a role as welding protection in the first welding step (1300).

3. Method according to one of the preceding claims, characterized in that after the circuit board (10) has been fitted with electrical components (100), the primary side (11) of the circuit board (10) is coated with a cover layer (40), in particular consisting of an acrylic resin or a lacquer containing an acrylic resin, at least in the region with metallized through holes.

4. Method according to one of the preceding claims, characterized in that, after the assembly of the circuit board (10), the secondary side (12) is coated over the entire surface or at least in the region with the metallized through-holes with a coating (40), in particular consisting of an acrylic resin or a lacquer containing an acrylic resin.

5. Method according to one of the preceding claims, characterized in that after the first soldering step (1300), at least one second electrical element (200) is arranged on the primary side (11) and soldered with the second conductor circuit structure (12 a) by means of a second soldering step (1500).

6. Method according to claim 5, characterized in that metallized through holes (26, 27) for arranging the at least one second electrical element (200) are excluded from the coating and remain unsealed by means of the protective layer (30).

7. Method according to one of claims 5 or 6, characterized in that before arranging the at least one first electrical element (100) on the primary side (11) and soldering by the first soldering step (1300), a metallized through-hole (25) located below at least one second electrical element (200) after arrangement of the second element (200) is closed on the primary side (11) by means of the protective layer (30).

8. Method according to claim 6, characterized in that the at least one second electrical component (200) has a plurality of connection contacts (210, 220) which are introduced into the metallized through-holes (26-27) excluded from the coating by the protective layer (30) when arranging the second component (200), and in that the connection contacts (210, 220) are soldered to the second conductor circuit structure (12 a) by means of the second soldering step (1500).

9. Method according to one of claims 5 to 8, characterized in that the diameter of the metallized through-holes (21-27) is designed such that, by means of the second soldering step (1500), the soldering material is drawn by capillary effect from the secondary side (12) in the direction of the primary side (11) and the metallized through-holes (21-27) are completely or at least partially filled with soldering material.

10. Method according to one of the preceding claims,

-performing a reflow soldering method in said first soldering step (1300), and/or

-performing wave soldering or wave soldering in the second soldering step (1500).

11. Method according to one of the preceding claims,

-the first component (100) is a surface mounted component (100), and/or

-the second component (200) is a plug-in component.

12. An electrical device (50) having a circuit board (10), wherein the circuit board (10) has:

and wherein at least one electrical element (100) is arranged and soldered on the primary side (11),

characterized in that at least one of the metallized vias (21) arranged below the at least one electrical element (100) is closed only on the primary side (11) by means of a protective layer (30).

13. The device (50) according to claim 12, wherein the protective layer (30) is a welding protective layer.

14. Device according to claim 13, characterized in that the primary side (11) of the circuit board (10) is coated with a covering layer (40), in particular made of acrylic resin or lacquer containing acrylic resin, in the region with the metallized through holes, and/or the secondary side (12) of the circuit board (10) is coated with a covering layer (40), in particular made of acrylic resin or lacquer containing acrylic resin, over the whole or at least in the region with the metallized through holes.

15. A rail vehicle (500), in particular a rail vehicle having a traction converter (510), characterized in that the rail vehicle (500), in particular the traction converter (510) of a rail vehicle, or one of the traction converters (510) of a rail vehicle, has an electrical device (50) according to one of claims 12 to 14 and/or an electrical device (50) produced according to claims 1 to 11.