CN112638059A

CN112638059A - Electronic module

Info

Publication number: CN112638059A
Application number: CN202011008446.0A
Authority: CN
Inventors: H.布劳恩; S.斯卡菲迪
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2019-09-24
Filing date: 2020-09-23
Publication date: 2021-04-09
Also published as: DE102019214606A1

Abstract

The invention relates to an electronic module 1 having a circuit board 10 with a loading side on which a first structural element 8 and a contact element 3 are arranged. The first structural element 8 is encased in a protective material 9 on the loading side. The contact element 3 is partially embedded in the protective material 9 in such a way that the second surface 32 of the contact element 3 projects from the protective material 9 in an exposed manner. The second component 4 is fixed to the contact element 3 and is electrically connected to the printed circuit board 10 via the contact element. The contact element 3 is inserted into the first recess 44 on the side 42 of the plastic sheathing 49 of the second component 4 facing the printed circuit board 10 in such a way that the second surface 32 of the contact element 3 rests against the connecting section 51 of the second component 4.

Description

Electronic module

Technical Field

The present invention relates to an electronic module.

Background

The known electronic module is provided with an electronic control circuit with an electrical component for processing signals and a power component, and with sensors and a plug. The electronic module can also be installed in a motor vehicle as a transmission control module and is exposed there to the hydraulic oil of the motor vehicle transmission and to temperatures between-40 ℃ and 150 ℃. Recently, electronic modules using a protective material that covers structural elements on a circuit board have been developed. Since the plugs and sensors are also in contact with components outside the electronic module, these plugs and sensors must be arranged outside the protective material or project from the protective material.

An electronic module is known from DE 102017210176 a1, which has a circuit board and a first component, which is arranged on a mounting side of the circuit board and which is in electrical contact with the circuit board. The contact element has a first surface and a second surface facing away from the first surface, is arranged with the first surface on the circuit board and is in electrical contact with the circuit board. The first structural element is encased in a protective material arranged on the loading side of the circuit board. The contact element is only partially embedded in the protective material, so that the lateral edges of the contact element are at least partially circumferentially covered by the protective material, while the second surface of the contact element protrudes exposed from the protective material. The second component is fixed to the contact element and is electrically connected to the circuit board via the contact element, wherein the second component has at least one electrical connection conductor which is embedded in the plastic sheathing and has a connection section which is oriented parallel to the second surface of the contact element and is electrically connected to the contact element.

For this purpose, the plastic encapsulation of the second structural element has a first recess on its side facing the circuit board. The contact element is inserted into the first recess in such a way that the second surface of the contact element bears against the connecting section.

Disclosure of Invention

The invention relates to an electronic module having the features of the preamble of claim 1. According to the invention, it is proposed that the printed circuit board has a through-opening on a second side facing away from the loading side, through which the side of the contact element facing the loading side can be accessed.

Furthermore, the invention relates to a method for producing an electronic module, having the following steps:

-providing a circuit board having: a first structural element arranged on the loading side of the circuit board and in electrical contact with the circuit board; a contact element having a first surface and a second surface facing away from the first surface and arranged with the first surface on and in electrical contact with a circuit board; a protective material which is arranged on a loading side of the circuit board and which encases the first structural element, wherein the contact element is partially embedded in the protective material in such a way that a lateral edge of the contact element is at least partially circumferentially covered by the protective material and a second surface of the contact element projects exposed from the protective material;

providing a second component, wherein the second component has at least one electrical connection conductor with a connection section, which is embedded in a plastic sheathing, wherein the plastic sheathing of the second component has a first recess on its side facing the circuit board, through which the connection section of the second component is accessible;

placing the second structural element on the contact element in such a way that the connecting section is oriented parallel to the second surface of the contact element, and inserting the contact element into the first recess until the second surface of the contact element rests on the connecting section;

-and welding the contact element with the connecting section. According to the invention, it is proposed that the circuit board has a through-opening on a second side facing away from the loading side, through which the surface of the contact element facing the loading side can be accessed, and that the contact element and the connecting section are soldered together by means of a soldering device inserted into the through-opening.

In the sense of the present invention, in addition to the at least one first component, a further first component, in addition to the at least one contact element, a further contact element and in addition to the at least one second component, a further second component can also be applied to the circuit board. In this case, a single contact element or also a plurality of contact elements can be assigned to the individual second components. Preferably, two contact elements are assigned to each second component. The contact elements can be configured of the same kind or of different kinds. The second component can, for example, have at least two electrical connection conductors, which are each electrically connected to an associated contact element.

In the case of the electronic module known from DE 102017210176 a1, a second component, which can be, for example, a rotational speed sensor or a position sensor, is formed and mounted from the mounting side of the printed circuit board. The second component is soldered to the contact element, wherein the soldering process is carried out on the mounting side through a second recess provided on the side of the plastic sheathing of the second component facing away from the circuit board. For this purpose, a free access for the soldering tool is required on the mounting side of the circuit board. However, since the free space above the printed circuit board is occupied by the second component and, if necessary, additional components of the same or different type, difficulties arise in the production of the soldered connections due to the small space.

The electronic module according to the invention advantageously makes possible an easy and cost-effective connection between the second component and the circuit board, wherein the mounting and fixing of the second component can be carried out not only via the mounting side of the circuit board but also via a second side of the circuit board facing away from the mounting side. For this purpose, the circuit board has a through-opening on a second side facing away from the loading side, through which the side of the contact element facing the loading side can be accessed. On this surface, a welding tool can be placed, for example, by means of a laser or a welding electrode, to which the energy required for welding is coupled.

The contact element can advantageously be soldered, for example, to a mounting side of a circuit board. This can be done, for example, inexpensively by the SMD process (Surface Mounting Device) by means of the Reflow soldering method (Reflow-Loetverfahren). This is preferably carried out in parallel with the loading of the first structural element on the loading side, for example by means of a common reflow soldering method. The protective material can be applied to the loading side of the circuit board immediately after the soldering process.

The second component can be formed in one piece and applied to the circuit board after the application and the curing of the protective material. The electronic module can be first of all configured to be substantially flat after the protective material has been applied and can be better processed in an automated production plant. The second component, which is designed, for example, as a sensor dome (Sensordom) and protrudes to a large extent from the finished electronic module, can be fixed to the electronic module after the application of the protective material. For this purpose, the soldering method can now also be advantageously used on the second side of the printed circuit board facing away from the loading side.

Advantageous embodiments and refinements of the invention can be achieved by the features contained in the dependent claims.

An embodiment is particularly advantageous in which the contact element has an internal recess on its first surface adjoining the through-opening. This internal recess can be configured, for example, as a blind hole. The inner recess terminates in a direction perpendicular to the loading side of the circuit board, starting from the first surface of the contact element, on an end face facing away from the second surface of the contact element. This end face can form the face of the contact element facing the loading side in a simple manner. During the welding, for example, a laser beam or a welding electrode can couple energy into the end face through the through-opening and the inner recess, as a result of which the end face is melted and can be welded to the connection section from the second side of the printed circuit board.

The plastic encapsulation of the second component can also optionally additionally have a second recess on its side facing away from the circuit board, through which the connecting section of the second component can be accessed. Such a second recess, which is known per se from DE 102017210176 a1, allows, in combination with the through-opening on the second side of the circuit board, which is described here, for example, the use of an inexpensive resistance welding method, in which a first welding electrode can be inserted into the second recess and a second electrode can be inserted into the through-opening for welding the contact element to the connection section.

The resistance welding method is particularly advantageous in combination with a welding projection arranged between the connecting section and the second surface. This solder projection can be formed, for example, on the connecting section or on the second surface of the contact element.

The contact element can preferably be formed from metal, so that a laser welding method or a resistance welding method can be carried out without problems.

Drawings

Wherein:

fig. 1 shows a cross section through a first exemplary embodiment of an electronic module according to the invention;

fig. 2 shows a partial cross section through a second exemplary embodiment of an electronic module according to the invention;

fig. 3 shows a cross section through a third exemplary embodiment of an electronic module according to the invention;

fig. 4 shows a partial cross section through a fourth exemplary embodiment of an electronic module according to the invention.

Detailed Description

Fig. 1 shows a cross section through an electronic module 1. The electronic module can, for example, be part of a transmission control of a motor vehicle and be exposed to hydraulic fluid of the transmission. However, it is also possible to use the electronic module as a control unit for controlling other assemblies. The electronic module 1 has a circuit board 10 which has a first side provided as a mounting side 11 and a second side 12 facing away from the first side. The printed circuit board 10 can be embodied, for example, as a glass-fiber-reinforced epoxy substrate, for example as an FR4 printed circuit board or a higher-value printed circuit board. Electrical components of the control lines, of which only one first component 8 is shown in fig. 1, are arranged on the mounting side 11 of the printed circuit board 10. The first component 8 can be electrically connected to the contact surface 5 arranged on the mounting side 11 of the printed circuit board 10 via conductor tracks, not shown.

A protective material 9 is arranged on a mounting side 11 of the printed circuit board 10, which material encloses the first component 8. The protective material can be a polymeric protective material, in particular a thermosetting plastic, and in particular comprise an epoxy resin, which adheres well to the circuit board 10. The protective material 9 can be applied to the printed circuit board, in particular, as a so-called hcd (hard cover release). This can be carried out by the Dam filling method (Dam Fill) in which a circumferential Dam made of, for example, a thixotropic adhesive is first applied to the printed circuit board and then a flowable filler is injected into the region surrounded by the Dam in order to cover the structural element with a protective material.

The contact element 3 is placed on the contact surface 5. The contact element 3 is made of metal and has a first surface 31 and a second surface 32 facing away from the first surface, and a lateral edge 34. The protective material 9 covers the side edges 34 of the contact elements 3 in a surrounding manner. However, the contact element 3 projects from the protective material 9 with the second surface 32 and with the part of the side edge 34 adjoining the second surface 32. The contact element 3 can be welded or soldered (for example by SMD technology) to the contact surface 5 with the first surface 31.

As can be seen in fig. 1, the printed circuit board 10 has through-openings 60 on the second side 12 below the contact elements 3. Each through-opening 60 can be configured, for example, as a simple perforation in the printed circuit board 1, having a preferably circular cross section. The through-opening 60 is provided with a contact surface 5 on the loading side 11 in a circumferential manner. The contact element 3 is soldered or welded to this contact surface 5 with the first surface 31. The contact element 3 can, for example, be provided with a cylindrical outer surface in a substantially thick-walled manner, like the contact element 3b in the left part of fig. 1, or with a wall that is thinner than the contact element 3b and with a flange that is connected to the contact surface 5, like the contact element 3a in the right part of fig. 1. The contact element 3a can be produced, for example, as a deep-drawn part from a metal sheet. In fig. 1 two contact elements 3 are shown loaded onto a circuit board 10. It is however also possible to load only a single contact element or three or more contact elements 3 onto the circuit board.

In the embodiment shown in fig. 1, each of the shown contact elements 3a, 3b has an inner space 61 on its first surface 31 adjoining the assigned through hole 60 of the circuit board 1. The interior recess 61 is configured, for example, as a blind hole. The inner recess 61 runs in a direction perpendicular to the loading side 11 of the circuit board 10 and ends from the first surface 31 on an end face 62 facing away from the second surface 32 of the contact element. Said end surface 62 forms a surface 63 of the contact element 3 facing the loading side 11. This face 63 preferably runs parallel to the second surface 32 with a spacing of, for example, 1 or 2 mm.

The second component 4 can be, for example, a sensor, in particular a rotational speed sensor or an electrical connection or another electrical component. The second component 4 has at least one electrical connection conductor 50, which is inserted into the plastic sheath 49. The plastic sheath can be an injection molded part, for example. In fig. 1, the second structural element 4 has two connecting conductors 50. The plastic sheath 49 of the second component 4 can have a base 40 from which the projections 43 on the side 41 facing away from the printed circuit board 10 project. The base plate 40 has a first side 42 facing the circuit board 10 and a second side 41 facing away from the circuit board 10. Only a portion of the projection 43 is visible in fig. 1. At the end section of the projection 43, for example, a sensor element or a plug-in part encapsulated in a plastic sheath can be provided. The electrical connection conductor 50 is arranged in the projection 43 perpendicularly to the circuit board 10. The connection sections 51 of the connection conductors 50 are each bent at right angles so that they run parallel to the circuit board 10. The two connecting sections 51 are bent away from each other and are embedded in the base plate 40 of the plastic sheath 49.

The plastic sheath 49 of the second component 4 has a first recess 44 on the first side 42, through which the connecting section 51 of the second component 4 is accessible. The recess 44 can, for example, be blind. A respective connecting section 51 is situated on the bottom of each recess 44, or the connecting section 51 is exposed there.

The second surface 32 of the contact element 3 is inserted into the recess 44 in such a way that the second surface 32 lies flat against the side of the connecting section 51 facing the circuit board. In the exemplary embodiment of fig. 1, the plastic sheath 49 additionally has a second recess 45 on the opposite side 41 of the connecting section 51. The edge of the second recess 45 can be surrounded by a flange 46. The second recess 45 is used for producing the electronic module and can be filled with a protective material after production of the electronic module in order to prevent swarf of transmission oil from penetrating into the second recess 45 during operation of the electronic module 1.

A second embodiment is shown in fig. 2. The exemplary embodiment in fig. 2 differs from the exemplary embodiment in fig. 1 only in that the plastic sheathing 49 does not have a second recess 45 on the side 41 of the connecting section 51 opposite the contact element 3 and is designed as a closed structure.

For fastening the second component 4 to the contact element 3, the second component 4 is placed on the contact element 3 in such a way that each of the connecting sections 51 is oriented parallel to the second surface 32 of the assigned contact element 3. In this case, each contact element 3 is inserted into the assigned first recess 44 until the second surface 32 of the contact element 3 comes to bear against the connecting section 51. Subsequently, the contact element 3 and the connecting section 51 are welded together by means of a laser beam 100 entering the through-opening 60. In this case, the laser beam impinges on the second side 12 of the printed circuit board into the through-opening 60 and the inner recess 61 and illuminates the end face 62, which is thereby melted and connected to the connecting section 51. The second recess 45 is provided in the embodiment of fig. 1 to prevent melting of the plastic above the connecting section 51.

However, slight melting of the plastic can also be tolerated. In this case, the second recess 45 can be dispensed with, as in fig. 2.

Fig. 3 shows a third exemplary embodiment of an electronic module 1 according to the invention. In fig. 3, the contact element 3 is designed as a solid socket part 3c made of metal. In this exemplary embodiment, the first surface 31 of the contact element 3 is exposed at the through-opening 60 and thus forms a surface 63 of the contact element 3 facing the loading side 11, on which surface 63 a welding tool can be placed. On the opposite side of the contact element 3, the connecting section 51 bears flat against the second surface 32 of the contact element 3. In this embodiment, a second recess 45 is provided on the side of the connecting section 51 opposite the contact element 3, through which the connecting section 51 of the second component 4 is accessible. In this embodiment, the electrical contact between the connection section 51 and the contact element 3 is made by means of a resistance welding method. For this purpose, the first electrode 102 of the resistance welding device is inserted into the second recess 45 and the second electrode 101 into the through-hole 60. Said first electrode 102 is placed directly on the first surface 31 of the contact element 3. The current flowing from the first electrode 101 to the second electrode 102 melts the joint, thereby welding the connecting section 51 and the respectively assigned contact element 3 together.

An embodiment of this embodiment is shown in fig. 4. In contrast to fig. 3, in fig. 4, a welding projection 64 is additionally provided between the connecting section 51 and the second surface 32 of the contact element 3. This welding projection has an increased electrical resistance in the resistance welding process due to its small wire cross section and therefore melts more quickly. The welding projection 64 can be formed on the connecting section 51 or on the second surface 32. In fig. 4, the welding projection in the left part is configured as a stub shaft (Noppen) on the surface 32 of the contact element 3. In the right-hand part of fig. 4, the welding projection 64 is formed on the connecting section 51 by deep drawing.

It goes without saying that the embodiments of fig. 1 to 4 are not mutually exclusive and can also be used in a mixed manner in the electronic module 1.

Claims

1. An electronic module (1) having

A circuit board (10) having a plurality of conductive layers,

a first structural element (8) which is arranged on a loading side (11) of the circuit board (10) and is in electrical contact with the circuit board,

a contact element (3) which has a first surface (31) and a second surface (32) facing away from the first surface (31) and is arranged with the first surface (31) on the circuit board (10) and is in electrical contact with the circuit board,

a protective material (9) which is arranged on a loading side (11) of the circuit board (10) and which encloses the first structural element (8), wherein the contact element (3) is partially embedded in the protective material (9) in such a way that a lateral edge (34) of the contact element (3) is at least partially circumferentially covered by the protective material (9) and a second surface (32) of the contact element (3) protrudes in an exposed manner from the protective material (9),

a second component (4) which is fastened to the contact element (3) and via which it is electrically connected to the circuit board (10), wherein the second component (4) has at least one electrical connection conductor (50) which is embedded in a plastic sheathing (49) and has a connection section (51) which is oriented parallel to a second surface (32) of the contact element (3) and is electrically connected to the contact element (3),

wherein the plastic sheath (49) of the second component (4) has a first recess (44) on its side (42) facing the circuit board (10), and the contact element (3) is inserted into the first recess (44) in such a way that the second surface (32) of the contact element (3) rests on the connecting section (51),

characterized in that the circuit board (10) has a through-opening (60) on a second side (12) facing away from the loading side (11), through which a surface (63) of the contact element (3) facing the loading side (11) can be accessed.

2. Electronic module according to claim 1, characterized in that the contact element (3) has an internal void (61) on its first surface (31) adjoining the through hole (60).

3. The electronic module according to claim 2, characterized in that the inner void (61) is configured as a blind hole.

4. An electronic module according to claim 2 or 3, characterized in that the inner void (61) ends from the first surface (31) on an end face (62) facing away from the second surface (32) of the contact element in a direction perpendicular to the loading side (11) of the circuit board (10), which end face (62) at least partially forms a face (63) of the contact element (3) facing the loading side (11).

5. The electronic module according to claim 1, characterized in that the plastic sheathing (49) of the second component (4) has a second recess (45) on its side (41) facing away from the circuit board (10), by means of which the connection section (51) of the second component (4) is accessible.

6. An electronic module as claimed in claim 1, characterized in that a soldering projection (64) configured on the connecting section (51) or on the second surface (32) is provided between the connecting section (51) and the second surface (32).

7. The electronic module according to any of the preceding claims, characterized in that the contact element (3) is constructed from metal.

8. The electronic module according to any of the preceding claims, characterized in that the electronic module (1) is part of a transmission control mechanism of a motor vehicle.

9. Method for manufacturing an electronic module, having the following steps:

-providing a circuit board (10), the circuit board (10) having: a first structural element (8) which is arranged on a loading side (11) of the circuit board (10) and is in electrical contact with the circuit board; a contact element (3) which has a first surface (31) and a second surface (32) facing away from the first surface (31) and which is arranged with the first surface (31) on the circuit board (10) and is in electrical contact therewith; a protective material (9) which is arranged on a loading side (11) of the circuit board (10) and which encloses the first structural element (8), wherein the contact element (3) is partially embedded in the protective material (9) in such a way that a lateral edge (34) of the contact element (3) is at least partially circumferentially covered by the protective material (9) and a second surface (32) of the contact element (3) projects in an exposed manner from the protective material (9);

-providing a second component (4), wherein the second component (4) has at least one electrical connection conductor (50) with a connection section (51) embedded in a plastic sheathing (49), wherein the plastic sheathing (49) of the second component (4) has a first recess (44) on its side (42) facing the circuit board (10), through which the connection section (51) of the second component (4) is accessible;

-placing the second structural element (4) on the contact element (3) in such a way that the connecting section (51) is oriented parallel to the second surface (32) of the contact element (3), and inserting the contact element (3) into the first recess (44) until the second surface (32) of the contact element (3) abuts against the connecting section (51);

and welding the contact element (3) and the connecting section (51) together,

characterized in that the circuit board (10) has a through-opening (60) on a second side (12) facing away from the loading side (11), through which a face (63) of the contact element (3) facing the loading side (11) can be accessed, and in that the contact element (3) and the connecting section (51) are soldered together by means of a soldering device (100) inserted into the through-opening.

10. The method of claim 9, wherein a laser welding method is used in the step of welding.

11. Method according to claim 9, characterized in that the plastic sheathing (49) of the second component (4) has, on its side (41) facing away from the printed circuit board (10), a second recess (45) through which the connecting section (51) of the second component (4) is accessible, and in that in the step of welding a resistance welding method is used in which a first electrode (102) is inserted into the second recess (45) and a second electrode (101) is inserted into the through-opening (60).