DE102008039921A1 - Electronic device e.g. electronic guiding device, for use in vehicle, has free space formed between discrete element and component side of board, where openings of printed circuit board and free space are filled with adhesive mass - Google Patents

Abstract

The device (1) has a discrete component (3) with external connections (4-6), which stay in electrical and mechanical connection with a wiring side (9). A laminar heat conducting housing base (10) is aligned partially parallel to the side and stays in mechanical and thermal connection with the side over an adhesive mass (11). Openings (12) of a printed circuit board (7) and a free space (13) between the discrete component and a component side (8) of the board are filled with the adhesive mass of the wiring side of the board within an area of the openings, where the mass supports the component. The discrete component is selected from the group consisting of a coil (14), capacitor (15), resistor, ferrite element, potentiometer (15), variable capacitor or hybrid element. An independent claim is also included for a method for producing an electronic device.

Description

The The invention relates to an electronic device with at least a discrete component subjected to mechanical stress and a method for producing the same. The discrete component has external connections and is with these on fixed to a component side of a printed circuit board. The Printed circuit board has a wiring side, with which the external connections mechanically and electrically in communication. A flat heat-dissipating housing bottom is at least partially parallel aligned to the wiring side and stands over one Adhesive mass with the wiring side of the circuit board mechanically and thermally in contact.

such electronic devices with at least one discrete component are preferably used in vehicles, such electronic Devices are subject to increased vibration, some of the solder joints of the external connections the discrete components on the wiring side of the circuit board endangered to tearing off individual external connections of the discrete component of the body of the discrete Component. Such a tearing of an external connection can destroy the entire electronic device to lead.

In addition, a high heat loss performance is often developed in such electronic devices for motor vehicles, which is dissipated. This is from the document DE 10210041 A1 a heat dissipation device for dissipating heat generated by an electronic component is known. This heat dissipation device has at least one electrical component, a printed circuit board and a cooling element. Below a electronic component, which has a high heat loss, a cavity is arranged. This cavity is filled with a thermally highly conductive filler. In the areas of the printed circuit board at which waste heat is generated due to the power loss of the component, a connection with good thermal conductivity to the cooling element is provided.

at However, this known heat dissipation device is no solution for the occurrence of high vibrations revealed, so that there is still a risk that external connections the individual components of a risk of demolition on the circuit board are exposed.

task The invention is the vibration protection in particular of discrete Devices on a circuit board in an electronic device improve and specify a procedure with which discrete components better protected against vibration in the electronic device are.

These The object is achieved with the subject matter of the independent claims solved. Advantageous developments emerge from the dependent claims.

According to the invention an electronic device with at least one mechanical Strained discrete component and a method created for the production of the same. The discrete component has Outlets on and is with these on one Component side of a printed circuit board fixed. The circuit board has a wiring side, with which the external connections mechanically and electrically in communication. A flat heat-dissipating housing bottom is at least partially aligned parallel to the wiring side and stands over an adhesive mass with the wiring side of the circuit board mechanically and thermally in contact. Below the discrete component has the circuit board openings, the openings and a clearance between the discrete component and the component side the printed circuit board with the adhesive mass of the wiring side of the Printed circuit board filled in the area of the openings are, wherein the adhesive composition supports the discrete component.

This Electronic device has the advantage of being there for the discrete components located on the circuit board no requires separate support or support devices, to fix them on the PCB so that they are aware of the vibrations, which the electronic device is exposed to. In addition, it is possible this electronic Device inexpensive to manufacture, since previous Process steps are used and no extra support devices for discrete components on a vibration-prone Printed circuit board to protect the discrete components are applied.

The openings in the board underneath a vibration-prone discrete Component can be used simultaneously with the usual openings, which are required to external connections of loop through the component side to the wiring side, getting produced. When attaching the openings in shape of holes is their position, their diameter and their number each dependent on the component geometry of the discrete component. Also the later occurring mechanical loads in Shape of vibrations decide with over position, diameter and number of openings.

The amount of adhesive depends on the number of holes, the diameter of the holes and the passage depth of the holes, to ensure that when installing the circuit board genü Adhesive mass can penetrate through the openings to at least partially fill the space between discrete component and PCB top with adhesive mass. The discrete component is fixed next to the support by the adhesive composition with at least two wire connections as external connections on the printed circuit board. These external connections, which are endangered by vibrations, are protected against mechanical stresses by the supporting adhesive compound, so that the solder joints on the rear side of the circuit board are also subjected to a reduced load.

The electronic housing preferably has as discrete components Surface mountable components, with their external connections directly on the top side or the component side of the PCB are soldered on. These solder joints are not additionally supported by a through contact and are therefore at risk, especially under mechanical stress. With the measure according to the invention, namely the space between the top of the circuit board and bottom of the discrete semiconductor device can fill now vibrations from these sensitive surface mountable External terminals of a discrete component kept away become.

Preferably has the electronic device as a discrete component a component of the group coil, capacitor, resistor, ferrite component, Potentiometer, variable capacitor or hybrid component on.

Next the housing bottom has the electronic device also a housing cover, wherein the circuit board between Housing bottom and housing cover is fixed. By An additional measure can also the housing cover for fixing discrete components and for vibration protection contribute to the same by the free space between the housing cover and an upper side of a discrete component also at least partially filled with adhesive. Thus, the device is over the adhesive masses between housing cover and component As well as PCB top and component fixed in such a way that the discrete component practically between the housing cover and circuit board is clamped.

at the electronic device is preferably a guide device of a vehicle from the group Engine control device, transmission control device, antilock device (ABS) or electronic safety control device (ESP). Such guide devices are described in the above Housings from housing cover and housing bottom installed and can by the invention Support of individual components high reliability reach their functionality.

One Method for producing an electronic device with a discrete component on a circuit board in a housing has the following process steps. First becomes a housing with a flat heat dissipation area produced in the case back. This heat dissipation area may also have cooling fins to the outside. in the Inside, this heat dissipation area has a thermal conductive adhesive on which the circuit board with its wiring side can be stuck on.

In Another step is the printed circuit board with through-openings for touch contacts of at least one discrete component made, before loading the circuit board with the discrete component through holes through the Printed circuit board in the placement area of the discrete component getting produced. Subsequently, the assembly can the circuit board with integrated circuits and discrete components done. In preparation for the assembly of caseback with the PCB is the area heat dissipation area covered with an adhesive mass, the amount of adhesive mass is greater than it is for the a heat coupling in the heat dissipation area between PCB underside and caseback would be required.

Then becomes the printed circuit board equipped with the discrete component with its wiring side pressed into the adhesive mass and through the excess adhesive mass penetrates this adhesive mass through the passage openings in the region of the discrete component and fills a space between the discrete component and the component side of the circuit board with the adhesive mass of the wiring side of the circuit board in the area of the openings and can then be cured. The cured adhesive mass finally supports the discrete component and protects it from mechanical Loads, preferably against vibrations. Not just a mechanical one Fixation, but also good heat dissipation, is preferably a heat-conducting adhesive composition insulating adhesive material used.

In this case, the adhesive material can have incorporated thermally conductive particles. Thus, it is possible to use as adhesive material a two-component adhesive which has a gel with embedded thermally conductive particles of carbon. The thermally conductive particles in the insulating adhesive mass may well be metal particles whose outer dimensions are smaller than trace distances of the wiring side of the circuit board, so that when using this ther mixed with very good conductive adhesive no short circuits can occur. For this purpose, preferably spherical metal particles are used whose outer diameter is also smaller than the conductor track distances of the printed circuit board.

In a further preferred implementation of the method is at least before applying a housing cover partially adhesive mass on top of the discrete component applied, wherein the adhesive mass during assembly of the housing cover with the housing bottom to a housing a free space between the housing cover and top of the discrete component fills and hardens and thus another support for represents the discrete component.

The The invention will now be more apparent from the accompanying drawings explained.

1 shows a schematic cross section through an electronic device according to a first embodiment of the invention;

2 to 8th show schematic cross sections through portions of components for the production of an electronic device according to 1 ;

2 shows a schematic cross section through a portion of a housing cover of the electronic device according to 1 ;

3 shows a schematic cross section through a portion of a housing bottom of the electronic device;

4 shows a schematic cross section through a portion of a non-populated printed circuit board before the same;

5 shows a schematic cross section through the circuit board according to 4 after equipping them with a discrete component;

6 shows a schematic cross section through the housing bottom after application of an adhesive mass in a heat dissipation area;

7 shows a schematic cross section through the housing bottom according to 6 after applying the assembled printed circuit board according to 5 ;

8th shows a schematic cross section through the electronic device after application of the housing cover;

9 to 12 show schematic cross sections through an electronic device according to a second embodiment of the invention;

9 shows a schematic cross section through a housing bottom with applied adhesive mass and printed circuit board applied thereto;

10 shows a schematic cross section through a housing cover with applied adhesive mass;

11 shows a schematic cross section through a portion of an electronic device according to a second embodiment of the invention;

12 shows a schematic cross section through the electronic device according to the second embodiment of the invention;

13 shows a schematic cross section through an electronic device according to a third embodiment of the invention.

1 shows a schematic cross section through an electronic device 1 according to a first embodiment of the invention. The electronic device 1 has a housing 17 on with a housing cover 21 and a caseback 10 , In the border areas 26 is between the housing cover 21 and the caseback 10 a circuit board 7 fixed, which is a component side 8th and a wiring side 9 having. The wiring side 9 is with the case back 10 over a thin layer of electrically insulating and heat-conductive adhesive compound 11 connected. This adhesive mass 11 can when assembling the electronic device 1 over openings 12 through the circuit board 7 pressed through and a free space 13 between the bottom of discrete components 3 and the component side 8th the circuit board 7 fill up so that the discrete components 3 additionally be mechanically supported.

In this embodiment, in the electronic device, a coil 14 , a capacitor 15 and a potentiometer 16 with the help of such filled with plastic compound openings 12 and partially filled open spaces 13 under the components 3 protected against vibrations. In addition to the discrete components 3 has the electronic device 1 also integrated circuits, with their external connections to the wiring side 9 are electrically connected and because of their large number of external electrical connections and their discrete components 3 less mass endangered to the effect that vibrations solder joints and / or external connections of these integrated circuit components are damaged.

While the coil 14 only two external connections 4 and 5 like the capacitor device 15 has, is the potentiometer 16 with three external connections 4 . 5 and 6 via vias 18 through the circuit board 7 with the wiring side of the 9 the circuit board 7 electrically connected. This small number of external connections 4 to 6 the discrete components 3 is without the adhesive composition according to the invention, which has openings 12 in the circuit board 7 the space under the discrete components 3 refills, heavily loaded by vibration, resulting from the plastic mass 11 is mitigated.

2 to 8th show schematic cross sections through portions of components for the production of an electronic device 1 according to 1 , In addition shows 2 a schematic cross section through a portion of a housing cover 21 of the electrical device 1 on the right side of the 1 , This pot-shaped housing cover 21 points in its edge area 26 a flange 27 on and protects a cavity 28 against contamination. Such a housing cover 21 belongs to the three main components of the electronic device 1 and is prepared preparatory.

3 shows a schematic cross section through a portion of a housing bottom 10 of the electronic device 1 , This caseback 10 points in its edge area 26 also a flange 29 on, but with a recess 31 is provided so that between the housing cover 21 and the caseback 10 a field plate in the recess 31 can be fixed. Furthermore, the housing bottom 10 a depression 32 in a heat conduction area 19 on, which can be filled with an adhesive.

4 shows a schematic cross section through a portion of a non-populated circuit board 7 before equipping them. In the heat conduction area 19 has the circuit board next to the through hole 18 for attaching external connections further openings 12 in the form of holes which are arranged in the region of a discrete component.

5 shows a schematic cross section through the circuit board 7 according to 4 after equipping them with a discrete component 3 , This is an external connection 5 of the discrete component 3 in a passage opening 12 inserted and on the wiring side 9 soldered to the connecting lines located there.

Before the assembly of the housing becomes the recess 32 of the case bottom 10 , as 6 shows, with an adhesive mass 11 filled, with a larger amount of adhesive mass 11 is filled into the depression, as they are for pure bonding of the connection side 9 the circuit board 7 would be required. This additional adhesive mass 11 is used to how it is 7 shows adhesive mass through the openings 12 to squeeze when the circuit board 7 , as in 5 shown in the direction of arrow A, as is 6 shows on the adhesive mass 11 is pressed with simultaneous adjustment of the edge area 26 the circuit board 7 in the recess 31 of the flange 29 of the case bottom 10 ,

With this fitting, the adhesive mass penetrates 11 through the openings 12 on the component side 8th the circuit board 7 below the discrete component 3 and fills a section of the open space 13 between the discrete component 3 and the component side 8th the circuit board 7 on. After curing the plastic compound 11 is thus a support and a fixation for the discrete component 3 created.

At the conclusion is on the flange 29 of the case bottom 10 at the edge 26 the flange 27 of the housing cover 21 fixed and thus the housing 24 , like it 8th shows, gas- and liquid-tight finished. Finally, it will also be the circuit board 7 in its edge area 26 between housing cover 21 and caseback 10 trapped. Thus, in conventional electronic devices 1 by simply adding openings 12 in the circuit board 7 without additional process steps an improved form-fitting and cohesive fixation of discrete components 3 achieved and the vibration protection can be improved.

9 to 12 show schematic cross sections through an electronic device 2 according to a second embodiment of the invention. Components having the same functions as in the preceding figures are denoted by the same reference numerals in FIGS 9 to 12 marked and not discussed separately.

9 shows a schematic cross section through a housing bottom 10 with applied adhesive mass 11 and printed circuit board applied thereto 7 so that over the openings 12 in the form of holes adhesive mass 11 on the component side 8th the circuit board 7 penetrates and a free space 13 between the component 3 and the component side 8th the circuit board 7 with plastic compound 11 at least partially filled. This process step is the same as in 7 shown process stage for the production of the electronic device 1 according to the first embodiment of the invention.

10 shows a schematic cross section through a housing cover 21 with applied adhesive mass 11 in an adhesive area 20 , the positions of the discrete components equivalent.

11 shows a schematic cross section through a portion of the electronic device 2 according to a second embodiment of the invention. The housing cover 21 is now with its flange 27 at the edge 26 on the flange 29 of the case bottom 10 Pressed and fixed in a gas- and moisture-proof way. This is the adhesive mass 11 as they are in 10 on the housing cover 21 is shown on the top 23 of the discrete component 3 pressed, leaving the free space 22 between the top 23 and the housing cover is at least partially filled. The device is after curing of the adhesive mass 11 clamped between housing cover and PCB and protected against vibration.

12 shows a schematic cross section through the electronic device 2 according to the second embodiment of the invention. As can be seen in this cross section, now are the discrete components 3 like the coil 14 , the capacitor 15 and the potentiometer 16 not only fixed on its underside by an adhesive mass, but also on its tops 23 in appropriate adhesive masses 11 arranged. It is also possible, these plastic materials 11 first on the tops 23 the discrete components 14 . 15 and 16 apply and then the housing cover 21 on this plastic mass 11 to press, thus a cohesive connection with the housing cover 21 produce and the free space 22 between top of the discrete components 3 and the housing cover 21 fill.

13 shows a schematic cross section through an electronic device 30 according to a third embodiment of the invention. Components having the same functions as in the previous figures are identified by the same reference numerals and will not be discussed separately. The third embodiment of the invention according to 13 differs from the previous embodiments in that the housing bottom 25 a heat dissipation area 19 with cooling fins 35 has and another area 33 owns a cavity 34 between circuit board 7 and caseback 25 having.

In this area 33 are just integrated circuits 36 . 37 and 38 arranged with low heat loss before heating up by appropriate discrete components 3 or power semiconductor devices are protected by being on the wider area 33 at a distance from the heat conduction region, in which high temperatures can occur on the printed circuit board, are arranged remotely.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10210041 A1 [0003]

Claims (15)

Electronic device with at least one discrete component ( 3 ) comprising: - at least one component subjected to a discrete mechanical load ( 3 ) with external connections ( 4 . 5 . 6 ); At least one printed circuit board ( 7 ) with a component side ( 8th ) and a wiring side ( 9 ), wherein the discrete component ( 3 ) on the component side ( 8th ) and its external connections ( 4 . 5 . 6 ) with the wiring side ( 9 ) communicate mechanically and electrically; - a flat thermally conductive housing bottom ( 10 ) at least partially parallel to the wiring side ( 9 ) and via an adhesive composition ( 11 ) with the wiring side ( 9 ) is mechanically and thermally in communication; characterized in that below the discrete component ( 3 ) the printed circuit board ( 7 ) Openings ( 12 ), wherein the openings ( 12 ) and a free space ( 13 ) between the discrete component ( 3 ) and the component side ( 8th ) of the printed circuit board ( 7 ) with the adhesive mass ( 11 ) of the wiring side ( 9 ) of the printed circuit board ( 7 ) in the area of the openings ( 12 ) and the adhesive composition ( 11 ) the discrete component ( 3 ). Electronic device according to claim 1, characterized in that the discrete component ( 3 ) at least two wire connections as external connections ( 4 . 5 ) having. Electronic device according to one of the preceding claims, characterized in that the discrete component ( 3 ) a component ( 3 ) of the coil group ( 14 ), Capacitor ( 15 ), Resistor, ferrite component, potentiometer ( 16 ), Rotary capacitor or hybrid component. Electronic device according to one of the preceding claims, characterized in that the electronic device ( 1 ) a housing cover ( 21 ) whose free space ( 22 ) to a top ( 23 ) of a discrete component ( 3 ) at least partially with adhesive mass ( 11 ) is filled up. Electronic device according to one of the preceding claims, characterized in that the electronic device ( 1 ) comprises an electronic guidance device of a vehicle. Electronic device according to one of the preceding claims, characterized in that the electronic device ( 1 ) comprises a device of the group of engine control device, transmission control device, anti-lock brake device (ABS) or electronic safety control device (ESP). Method for producing an electronic device ( 1 ) with a discrete component ( 3 ) on a printed circuit board ( 7 ) in a housing ( 17 ), comprising the following method steps: - producing a housing ( 17 ) with areal heat dissipation area ( 19 ) in the housing bottom ( 10 ); - manufacture of a printed circuit board ( 7 ) with through-openings for Druchkontakte ( 18 ) at least one discrete component ( 3 ); - equipping the printed circuit board ( 7 ) with the discrete component ( 3 ); characterized in that - before loading the printed circuit board ( 7 ) with the discrete component ( 3 ) Passage openings ( 12 ) through the printed circuit board ( 7 ) are produced in the placement area of the discrete component; - the areal heat dissipation area ( 19 ) with an adhesive composition ( 11 ) is covered; - with the discrete component ( 3 ) equipped printed circuit board ( 7 ) with its wiring side ( 9 ) in the adhesive composition ( 11 ) is pressed and - the adhesive composition ( 11 ) through the passage openings ( 12 ) in the region of the discrete component ( 3 ) penetrates and a free space ( 13 ) between the discrete component ( 3 ) and the component side ( 8th ) of the printed circuit board ( 7 ) with the adhesive mass ( 11 ) of the wiring side ( 9 ) of the printed circuit board ( 7 ) in the area of the openings ( 12 ) and cures, and - the cured adhesive mass ( 11 ) the discrete component ( 3 ). A method according to claim 7, characterized in that as an adhesive composition ( 11 ) a thermally conductive insulating adhesive material is used. A method according to claim 7 or claim 8, characterized in that as an adhesive composition ( 11 ) a vibration-damping adhesive material is used. Method according to one of claims 7 to 9, characterized in that as an adhesive composition ( 11 ) an electrically insulating adhesive material with embedded thermally conductive particles is used. Method according to one of claims 7 to 10, characterized in that as an adhesive composition ( 11 ) a two-component adhesive is used. Method according to one of claims 7 to 11, characterized in that as an adhesive composition ( 11 ) a gel is used with embedded thermally conductive particles of carbon. Method according to one of claims 10 to 12, characterized in that as thermally conductive particles in the adhesive composition ( 11 ) Metal party whose outer dimensions are smaller than the conductor spacing of the wiring side of the printed circuit board ( 7 ) are. Method according to one of claims 10 to 13, characterized in that are used as thermally conductive particles spherical metal particles whose outer diameter is smaller than conductor spacing of the printed circuit board ( 7 ) are. Method according to one of claims 10 to 14, characterized in that prior to the application of a housing cover ( 21 ) at least partially adhesive mass ( 11 ) on a top side ( 23 ) of the discrete component ( 3 ) is applied, wherein the adhesive composition ( 23 ) during assembly of the housing cover ( 21 ) with the housing bottom ( 10 ) to a housing ( 24 ) a free space ( 22 ) between the housing cover ( 21 ) and top ( 23 ) of the discrete component ( 3 ).