WO2013041288A1

WO2013041288A1 - Electrical control device with moulded housing

Info

Publication number: WO2013041288A1
Application number: PCT/EP2012/065285
Authority: WO
Inventors: Sven Lamers; Reinhard Rieger
Original assignee: Robert Bosch Gmbh
Priority date: 2011-09-20
Filing date: 2012-08-03
Publication date: 2013-03-28
Also published as: KR20140063713A; CN103814440A; DE102011083002A1

Abstract

An electrical control device (1) is proposed. The electrical control device (1) has a circuit carrier (3) with a first surface (5) and a second surface (7) facing the first surface (5). At least one electrical component (9) is arranged on the first surface (5) of the circuit carrier (3). The circuit carrier (3) is arranged in a moulded housing (11) made of a moulding material (13). Both the first surface (5) and the second surface (7) are in direct thermal contact with the moulding material (13).

Description

description

Electrical control unit with housing

State of the art

Electrical control devices are used in different areas for

used different applications. To protect the circuit elements located in the control unit from the environment, in particular against electrically conductive and aggressive media, the circuit elements are in a housing.

The housing may e.g. cupped a circuit carrier with the

Surrounded circuit elements. Furthermore, mold housing are known in which the circuit carrier can be cast. For example, EP 1 396 885 B1 discloses a circuit carrier with circuit elements. The circuit carrier is arranged on a base plate and surrounded by a mold housing. With such a construction, the stability and life of the controller may be limited because e.g. due to different

Thermal expansion coefficients of the materials of the circuit substrate, the base plate and the mold housing thermo-mechanical stresses can occur inside the controller.

Disclosure of the invention

There may therefore be a need for an improved electrical control device that has a simpler construction and better

Heat dissipation allows. This object can be achieved by the subject matter of the present invention according to the independent claims. Advantageous embodiments of the present invention are described in the dependent claims. The following are features, details and possible benefits of one

Device according to embodiments of the invention discussed in detail.

According to a first aspect of the invention, an electrical control unit is presented. The control unit has a circuit carrier having a first surface and a second surface opposite the first surface

Surface on. At least one electrical component is arranged on the first surface. The circuit carrier is in a mold housing of a

Mold compound arranged. In this case, both the first surface and the second surface are in direct thermal contact with the molding compound.

In other words, the idea of the present invention is based on surrounding the circuit carrier with the electrical components thereon with molding compound from all sides, so that the molding compound is distributed as symmetrically as possible on the first and second surfaces. The arrangement of the molding compound directly on both sides of the circuit substrate can be dispensed with further large-scale components and thus on further Materialein. In particular, a base plate used in the prior art can be omitted. This can reduce the number of components required. Further, in this way

reduced thermo-mechanical stresses inside the electrical control unit. A power loss of the electrical components can be due to the thermal contact of the molding compound to both surfaces of the

Circuit carrier over all surfaces of the housing housing by means of

Heat conduction or heat radiation will be. This can contribute to more effective cooling of the controller.

The electrical control unit can be used for example in motor vehicles for the regulation of vehicle-specific processes. In particular, the electrical control unit can be designed as a transmission control unit for motor vehicles. The circuit carrier, also referred to as a printed circuit substrate, can as

Be performed ceramic substrate. For example, the circuit carrier may include alumina Al ₂ O ₃ , high temperature cofired ceramic (HTCC), low temperature cofired ceramic (HTCC), or a conventional printed circuit board (PCB).

The circuit carrier may be in the form of a plate with a first side or

Surface and a second side or surface to be executed. On the first surface one and preferably a plurality of electrical components is arranged. Furthermore, electrical components, also referred to as circuit elements, may be arranged on the second surface. The

Circuit elements may e.g. be executed as "Central Processing Unit" (CPU), input and output circuits.

The mold housing consists of a molding compound, e.g. is made of resin-based plastic or thermosetting plastic. The specific thermal conductivity of the molding compound may be greater than 1 watt / Kelvin and meters (W / Km).

Preferably, the mold housing can enclose the complete circuit carrier with all electrical components. The molding compound is located directly on all surfaces of the circuit substrate and on the

electrical components while ensuring protection and optimum heat dissipation.

According to one embodiment of the invention, the electrical

Control unit further comprises a support element which is executed the

Connect circuit carrier through the mold housing with a support plate mechanically or to fix the circuit carrier during the molding process with respect to the support plate. During the molding process, the carrier plate has the task of holding the circuit carrier in its geometric target position.

The support element may be designed as a contact frame with at least three bearing surfaces. The contact frame, also referred to as Kontaktierungsleiste or lead frame, is provided with a recess in the middle through which the circuit carrier is in contact with the molding compound from both sides. The contact frame may comprise a conductive material. For example, there is the Contact frame made of copper. The bearing surfaces may be, for example, the edges of the frame. For example, the recess in the middle of the

Contact frame slightly smaller dimensions than the

Circuit carrier, so that the circuit carrier on the edges of

Contact frame rests. Alternatively or additionally, in quadrilateral

Execution of the contact frame at the corners of the contact frame

Support surfaces should be provided in the plane of the frame in the

Protrude recess. On the contact frame contact pins are further provided, which are connected in the embodiment shown here by means of bonding wires with the electrical components.

According to a further embodiment of the invention, at least three contact pins of the contact frame are designed as bearing surfaces. That the

Contact pins extend into the recess up to the circuit carrier and in particular up to the electrical components. In this way, the electrical components are contacted directly electrically and the bonding wires are at least partially dispensable. The contact pins offer both an electrical contact and a support surface.

According to a further embodiment of the invention that is

Support element as a spacer block, also referred to as equipped block executed. The spacer block is arranged on the carrier plate and replaces the contact frame. The circuit carrier can rest on at least three of the distance blocks. The spacer blocks have an electrically conductive material and / or are coated with an electrically conductive material. In this way, the electrical components are contacted directly electrically and both the contact frame with the contact pins and the bonding wires are unnecessary. Thus, the spacer blocks can be used both as a mechanical connection and as an electrical contact to the

Represent circuit board.

According to a further embodiment of the invention, the

Circuit carrier on a plane of symmetry. The molding compound is distributed symmetrically with respect to a plane of symmetry of the circuit carrier to the first and second surfaces. In the plane of symmetry lies the largest extent of the circuit carrier. In an embodiment of the circuit carrier as a plate, the plane of symmetry runs, for example, parallel to the first and to the second surface of the circuit carrier. The plane of symmetry is in particular a thermo-mechanical

Plane of symmetry. That the plane of symmetry runs through the

Circuit board, that also the extension of the circuit board disposed electrical components is taken into account.

In other words, the circuit carrier is arranged approximately in the thermo-mechanical axis of symmetry of the mold housing. A first

Volume of molding compound above the circuit substrate is in thermal contact with the first surface and substantially corresponds to a second volume below the circuit substrate, with the second

Surface is in thermal contact. Thermo-mechanical stresses due to different temperature-dependent coefficients of thermal expansion of the molding compound and the material of the circuit substrate act in this way symmetrically and bend, for example. Cracking before.

According to a further embodiment of the invention, the molding compound covers the electrical component by a maximum of 0.5 mm. By the symmetrical

Distribution of the molding compound around the circuit carrier and the electrical

Components can already satisfy a smaller Moldmasseschicht to protect the electrical components and for optimal heat dissipation. Thus, the total volume of the required molding compound can be reduced in comparison to known designs, thus saving material and costs.

According to a further embodiment of the invention, the material of the molding compound is chosen such that the coefficient of thermal expansion of the molding compound as possible the coefficient of thermal expansion of

Circuit carrier corresponds or as little as possible deviates from this.

The coefficient of thermal expansion, also referred to as the temperature coefficient, may e.g. be chosen so that the thermal expansion coefficient of the

Mold compound including its tolerances is greater than the

Thermal expansion coefficient of the circuit carrier including its Tolerances. The difference is as small as possible. For example, the thermal expansion coefficient of LTCC may be 5.5 ± 0.5 ppm / K. The thermal expansion coefficient of the molding compound can be 7 ± 1 ppm / K.

According to a second aspect of the invention, a method for producing an electrical control device described above is presented. The method comprises the following steps: providing a circuit carrier having a first surface and a second surface opposite the first surface; Arranging at least one electrical component on the first surface; Positioning the circuit carrier on a support element which connects the circuit carrier mechanically and preferably also electrically to a carrier plate; Potting the circuit substrate with molding compound, so that the first surface and the second surface are in direct thermal contact with the molding compound.

Other features and advantages of the present invention will become

Expert from the following description of exemplary

Embodiments, which should not be construed as limiting the invention, with reference to the accompanying drawings.

Fig. 1 shows a cross section through an electrical control unit with

corresponding heat dissipation according to an embodiment of the invention

Fig. 2 shows a plan view of a cross section through a control device according to an embodiment of the invention

Fig. 3 shows a running as a contact frame support element

Fig. 4 shows a cross section through an electrical control device according to another embodiment of the invention

Fig. 5 shows the arrangement of the electrical control device on a support plate

Fig. 6 shows different contacting variants of the electrical components All figures are merely schematic representations of devices according to the invention or of their components according to embodiments of the invention. In particular, distances and size relationships are not shown to scale in the figures. In the various figures, corresponding elements are provided with the same reference numbers.

In Fig. 1, the inventive electrical control unit 1 is shown. The electrical control unit 1 has a circuit carrier 3, which is surrounded by a mold housing 11. The circuit carrier 3 has a first

Surface 5 and one of the first surface 5 opposite second surface 7. On the first surface 5 are electrical components 9, e.g. a CPU arranged. About an electrical contact 37, the electrical components 9 can be connected to other electrical elements outside of the control unit.

The mold housing 11 consists of a molding compound 13, in which the

Circuit substrate 3 is cast with the electrical components 9 thereon. In this case, the first and the second surface 5, 7 are in direct thermal contact with the molding compound 13. D.h. the molding compound 13 surrounds the circuit carrier 3 from all sides and is distributed symmetrically about a thermomechanical plane of symmetry 27. Through this

Embodiment, the number of components of the electrical control unit 1 is kept minimal, in particular because of a base plate below the

Circuit carrier 3 can be dispensed with. Furthermore, by the

symmetrical design thermomechanical voltages between the circuit substrate 3 and molding compound 13 is reduced. Thanks to the direct thermal contact of the molding compound 13, a power loss of the electrical components 9 can be effectively delivered to all surfaces 5, 7 of the circuit substrate 3 by means of heat conduction or thermal radiation. This is in Fig. 1 by

Arrows indicated. In particular, a major portion of the electrical

Control unit 1 generated heat by the molding compound 13 by heat conduction directly into a heat sink, also referred to as "heatsink." The heat sink may be, for example, a support plate 19 and a valve plate (not shown in Fig. 1) 1 is shown by the arrows pointing upwards, and another part of the heat can be obtained by convection of a fluid the surfaces of the mold housing 11 are discharged via thermal radiation to the environment. Furthermore, another part of the heat can pass through

Heat conduction to the surrounding fluid, e.g. Air or gear oil to be delivered. Thus, a heat dissipation or heat dissipation over the entire surface of the circuit substrate 3 and the molding compound 13 is possible.

In Fig. 2, a cross section through the electrical control device is taken along a plane perpendicular to the plane shown in Fig. 1, i. parallel to

Symmetry plane 27 shown. The embodiment in Fig. 2 shows the

Arrangement of the circuit substrate 3 on a support element 15, which the

Circuit carrier 3 through the mold housing 11 passes through with a support plate 19 connects. The support element is designed in FIG. 2 as a contact frame 21. The electrical contact 37 is designed in the form of contact pins 23 on the contact frame 21. Alternatively, the support element 15 can be designed as a spacer block 25, as shown in FIG. 6C. The circuit carrier 3 may e.g. by means of

Contact aluminum bonding wires on the contact pins 23 of a contact frame 21 or alternatively on a flex foil (not shown in the figures) electrically. Alternatively, as shown in FIGS. 4 to 6, a direct contact can be made directly on the contact pins 23 or on the spacer block 25.

The contact frame 21 in Fig. 2 has at the corners bearing surfaces 17 (only one of which is shown) which serve to fix the circuit substrate 3 during the molding process. In the center of the contact frame 21 is a

Recess provided by the molding compound 13 from below with the

Circuit board 3 comes into contact.

3 shows an enlarged detail of the contact frame 21 with the contact pins 23 and the support surface 17. The contact pins are connected to one another by means of a support frame 39, also referred to as a dam bar. Of the

Support frame 39 may also serve to seal a tool during the molding process and is punched free after the molding process. The contour of the resting on the support surface 17 circuit substrate 3 is shown in dashed lines. The support surface 17 may alternatively be replaced by the fact that the contact pins 23 extend to the circuit substrate 3 and at the same time as direct electrical contact and serve as a support surface 17. This is shown for example in FIG. 4.

FIG. 4 further illustrates that the molding compound 13 completely surrounds the circuit carrier 3 with the electrical components 9. Further, the molding compound 13 is distributed so that the volume of molding compound 13 above and below the

Circuit substrate 3 and in particular above and below the thermo-mechanical plane of symmetry 27 is almost equal. As a result, any emerging thermo-mechanical stresses act symmetrically on the circuit substrate 3. In particular, the "highest" of the electrical components 9 is covered by molding compound 13 by a maximum of 0.5 mm.

The electrical contacting 37 of the circuit substrate 3 and the electrical components 9 takes place in the embodiments in FIGS. 4 to 6 directly. Thus assume the bearing surfaces 17 at the same time the functions of a

mechanical and electrical contact. The electric

Direct contacting can e.g. by gluing, in particular by means of a silver conductive adhesive or by soldering on the first surface 5 and / or on the second surface 7.

In a configuration as a gearbox control unit can be due to the direct thermal contact of the molding compound 13 on all sides or surfaces 5, 7 of the circuit substrate 3, both a heat radiation in the transmission (upper arrows in Fig. 4) and the heat conduction on a component side, e.g. on the side of a support plate 19 (lower arrow in Fig. 4) for cooling the electrical

Control unit 1 can be used.

5 shows the arrangement of the electrical control device 1 on a support plate 19. The support element 15 connects the circuit carrier 3 mechanically and preferably also electrically to a printed circuit board 29, also as a printed

Circuit board (PCB) designates. The circuit board 29 is on a

Support plate 19 is arranged. Between the electrical control unit 1 and the support plate 19 may be a fluid film, such as an oil film, of about 200 μηη. The fluid film is indicated by dots in FIG. 5. In Fig. 6 are different Direktkontaktierungsvarianten of

Circuit carrier 3 and the electrical components 9 shown. The

Support surfaces 17 thereby provide a mechanical and at the same time an electrical contacting of the circuit carrier 3 by the mold housing 11.

6A shows a so-called Gullwing IC concept (integrated circuit concept). In this case, contact pins 23 of a contact frame 21 are Z-shaped. These are applied to the circuit carrier 3 e.g. soldered to the solder 33. Outside the electrical control unit 1, the contact pins 21 are soldered to a circuit board 29 at the solder 33.

In Fig. 6B is a QFN principle (Quad Fiat No Leads- principle) of

Direct contact shown. In contrast to FIG. 6B, the housing housing 11 is designed with a gradation 31. The contact frame 21 is further bent under the mold housing 11 and directly to a circuit board 29 below the

Mold housing 11 soldered. In this embodiment space can be saved.

Fig. 6C shows a BGA (Ball Grid Array) principle of direct contacting. The mechanical and electrical contacting of the circuit substrate 3 is ensured here via spacer block 25. In this case, the mold housing 11 can have a gradation 31, as in FIG. 6B. The spacer blocks 25 can be soldered on one side to the printed circuit board 29. Furthermore, an epoxy underfill for sealing and fixing the electrical control unit 1 may be provided on the printed circuit board 29 and the spacer block 25. On the other hand, the

Distance blocks 25 to be glued to the circuit substrate 3 by means of a conductive adhesive. The spacer blocks 25 may be e.g. about lxlxl mm have dimensions.

Furthermore, at least three spacer blocks 25 are provided on the housing housing 11. In conclusion, it should be noted that terms such as "comprising" or the like are not intended to exclude that other elements or steps may be envisioned.Furthermore, it should be understood that "a" or "an" does not exclude a multitude It should further be noted that the reference signs in the claims should not be construed as limiting the scope of the claims.

Claims

claims

1 . Electric control unit (1), the electrical control unit (1) comprising a circuit carrier (3) having a first surface (5) and a second surface (7) opposite the first surface (5);

wherein at least one electrical component (9) is arranged on the first surface (5) of the circuit carrier (3);

wherein the circuit carrier (3) in a mold housing (1 1) of a molding compound (13) is arranged;

characterized in that

the first surface (5) and the second surface (7) are in direct thermal contact with the molding compound (13).

2. Electrical control unit (1) according to claim 1, further comprising

a support element (15) which is designed to mechanically connect the circuit carrier (3) through the mold housing (11) to a support plate (19);

wherein the support element (15) is designed as a contact frame (21) with at least three bearing surfaces (17);

wherein the circuit carrier (3) rests on the bearing surfaces (17) on the contact frame (21).

3. Electrical control device (1) according to claim 2,

the contact frame (21) having contact pins (23) for contacting the electrical component (9);

wherein at least three of these contact pins (23) form the bearing surfaces (17).

4. The electrical control device (1) according to claim 1, further comprising

a support element (15) which is designed to mechanically connect the circuit carrier (3) through the mold housing (1 1) with a support plate (19); wherein the support element (15) is designed as a spacer block (25) which is arranged on the support plate (19).

Electrical control unit (1) according to one of claims 2 to 4, wherein the support element (15) provides an electrical contact of the electrical component (9).

Electrical control unit (1) according to one of claims 1 to 5, wherein the molding compound (13) is distributed symmetrically with respect to a plane of symmetry (27) of the circuit carrier (3) on the first and second surfaces (5, 7).

Electrical control unit (1) according to one of claims 1 to 6, wherein the molding compound (13) covers the electrical component (9) by a maximum of 0.5 mm.

Electrical control device (1) according to one of claims 1 to 6, wherein a material of the molding compound (13) is selected such that a

Thermal expansion coefficient of the molding compound (13) substantially corresponds to a thermal expansion coefficient of the circuit substrate (3).

Method for producing an electrical control device (1) according to one of Claims 1 to 8, the method comprising the following steps: providing a circuit carrier (3) having a first surface (5) and a second surface (7) lying opposite the first surface (5) ); Arranging at least one electrical component (9) on the first

Surface (5);

Positioning the circuit carrier (3) on a support element (15) which connects the circuit carrier (3) to a carrier plate (19);

Potting the circuit carrier (3) with molding compound (13), so that the first surface (5) and the second surface (7) in direct thermal contact with the molding compound (13).