DE102017208076A1 - Component with EMC protection for electronic board - Google Patents

Abstract

It is proposed a component at least consisting of electronic and / or electrical components, which are mounted on one or more boards or connected thereto, wherein the components are molded with the board having a first and a second plastic layer, and wherein at least one shield against electromagnetic Radiation is present, wherein the shield is a stamped grid, which is embedded between the first plastic layer and the second plastic layer.

Description

The invention relates to a component at least consisting of electronic and / or electrical components which are mounted on or connected to one or more circuit boards, wherein the components are encapsulated with the circuit board having a first and a second plastic layer, and wherein at least one shield against electromagnetic Radiation is present.

Furthermore, the invention relates to a method for producing such a component.

State of the art

Electronics, especially power electronics cause electromagnetic radiation in different frequency ranges, which can cause interference with other devices. In order to reduce these disturbances and to keep them below the standardized limits, shielding measures should generally be provided.

As far as possible, an attempt is made to reduce emissions through a correspondingly optimized board layout. Often this is only partially sufficient and further shielding measures must be taken.

One measure consists of applying EMC protective coatings directly to the electronic components of the board. However, these protective coatings have the disadvantage that they are not temperature resistant when the board is encapsulated for protection with a thermoplastic.

Furthermore, it is known to install shielding plates and contacting metallic housing parts, but this requires additional components and an additional installation effort.

This shows the US20090091907A1 Metallic layers that surround a unit or groups of components. These layers are made by coating or printing on a first plastic layer. However, the coating of plastic with metal is not without problems.

It is therefore an object of the invention to produce a component with a circuit board in which the EMC protection is optimized and the production of the encapsulation is simplified.

The object is solved with the features of claim 1 and 5.

In detail, the object is achieved with a component at least consisting of electronic and / or electrical components, which are mounted on one or more boards or connected thereto, wherein the components are molded with the board having a first and a second plastic layer, and wherein at least a shield against electromagnetic radiation is present, wherein the shield is at least one stamped grid, which is embedded between the first plastic layer and the second plastic layer.

It is advantageous that the stamped grid has at least one contact strip to the board, so as to establish the connection to the ground of the board. The stamped grid can also be constructed in several parts.

It is advantageous if the stamped grid has at least one device for mechanical fixation and stabilization of the components. Thus, the punched grid not only serves the electromagnetic shielding, but also to stabilize the components on the board.

It is advantageous that the stamped grid has at least one area for thermal contacting of components. As a result, waste heat is dissipated from the board, without the first plastic layer must have special thermal properties. Thus, a wider range of plastics for the production of the first plastic layer can be used.

To meet the task, it is advantageous that the stamped grid covers at least the largest part of the surface of the board. It does not have to cover the entire surface of the board, but only the surface that covers the particular shielded components.

• Vormontieren der Platine und des Stanzgitters zu einem Modul Umspritzen des Moduls mit einem ersten Kunststoffmaterial,
• Überspritzen des Moduls mit der ersten Kunststoffschicht mit einer zweiten Kunststoffschicht.

The method according to the invention comprises the following steps:

• Preassembling the board and the punched grid to form a module overmolding the module with a first plastic material,
• Overmolding the module with the first plastic layer with a second plastic layer.

It is particularly advantageous that the module is held by punch of the injection molding tool during encapsulation with the first plastic material.

list of figures

• 1 und 2 zeigen eine schematische Darstellung einer ersten beispielhaften Ausführungsform.
• 2 zeigt einen Längsschnitt, 2a eine Aufsicht und 2b einen Querschnitt.

The invention will now be described by way of example with reference to the accompanying drawings.

• 1 and 2 show a schematic representation of a first exemplary embodiment.
• 2 shows a longitudinal section, 2a a supervision and 2 B a cross section.

1 and 2 show an embodiment of a component, in which the electronics used 4 So all the electrical and electronic components on the board 3 is encapsulated with two plastic layers. About a plug 1 the board is electrically connected.

At the edge of the board 3 In this embodiment, surfaces with grounding connections 2 kept free, which are connected to the shield.

The ground connection of the board can be created anywhere. The ground connection 2 can be a through-contacting by pressfit. The punched grid can also be clamped or soldered. Important is sufficient electrical contact and mechanical fixation.

The first plastic layer 11 protects the components and the board 3 and should offer the best possible thermal connection in order to be able to derive the resulting waste heat supportive.

The second plastic layer 12 For example, it consists of a cheaper plastic that offers a defined strength and media tightness and can already be used as a housing of the entire component. Alternatively, the second plastic layer is made of the same material as the first plastic layer.

The 1 and 2 show an embodiment in which the shield is brought about by a metallic material in the form of a stamped grid. A punched grid is a predominantly flat structure made of a sheet metal produced by punching. The punched grid 8th is over a ground 2 with the board 3 simply or multiply connected. The punched grid 8th has a shape that is optimized for the particular board. To protect the board can also be mounted several punched grid, for example, above and below the board.

The punched grid must 8th an electrical connection to the board in the form of a contact 23 own, which is punched out of the material of the stamped grid and bent in the direction of the board.

Alternatively, also a contact strip 23 be soldered. The punched grid 8th has areas 9 for thermal contacting of components 4 with high dissipative waste heat, in order to achieve a distribution of the waste heat via the thermal conductivity of the metal. The areas 9 can be made by stamping and / or bending and / or deep drawing of the stamped grid. There are all shaping methods possible, which are familiar to the expert.

Furthermore, the stamped grid has devices 10 for the mechanical fixation and stabilization of components, so that the first encapsulation process can take place more securely. Especially capacitors and chokes should be stably supported during encapsulation.

The stamped grid also has support areas 22 in which punches of an injection molding tool can attack to hold the lead frame during the first Umspritzungsvorgangs with the first plastic layer.

The encapsulation of the board 3 with the punched grid 8th as a module 24 done with little pressure with a thin material as possible, which can flow through the different cavities between the board and punched grid optimally and fill.

The first plastic layer thus produced is overmolded with the second plastic layer, so that the stamped grid is securely integrated between the layers. The design of the stamped grid arise areas 5 in which the first plastic layer is directly connected to the second plastic layer. In these areas there is no punched grid between the two plastic layers.

Depending on what binds better second plastic on punched grid or first plastic on second plastic, the punched grid can be perforated more or less. Small holes affect the EMC protection behavior only slightly.

The production process according to the invention takes place in several steps.

The first step involves mounting the board with all components 4 on and with the punched grid. The devices 10 for mechanical fixation of components are with the components 4 to a module 24 connected. This module is inserted into a first injection-molded tool where it is held by punches, and in a second manufacturing step, the board is overmolded 3 with the electronics 4 and the punched grid 8th with a first plastic material. During the injection process, the punches are slowly withdrawn in the injection mold and the cavities are filled up by the inflowing plastic material.

For a double-sided punched grid, the board could be at the plug 1 and the punched bars 8th being held. The use of stamps would not be necessary, which represents a more favorable solution.

The stamp of the plastic injection tool prevents the prefabricated module from shifting. The stamps lie on contact areas 22 of the module so on both the board and the lead frame.

The injection-molded inputs must be placed so that the plastic material quickly reaches and fills the cavities and forms no trapped air bubbles.

In a third step, the shield 13 , the punched grid 8th encapsulated by a second plastic layer.

An important advantage is that the stamped grid is designed so that it obstructs the encapsulation process as little as possible, ie the deep-drawn areas 9 in which the board or a component is contacted offer only a small face in the injection direction, which affects the injection behavior only slightly.

Furthermore, the board can be held on the punched grid in the tool. This has the advantage that the board is molded around cleanly. Without punched grid, the board must be held in the tool by means of holding pins, which are pulled out during the extrusion process, which makes the tool complex and expensive. If the outside of the punched grid remains free during the first coating, this is not a problem.

LIST OF REFERENCE NUMBERS

1

plug

2

grounding

3

circuit board

4

electronics

5th

contact areas

8th

lead frame

9

areas

10

devices

11

First plastic layer

12

Second plastic layer

13

shielding

22

support area

23

Contact strips

24

module

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 20090091907 A1 [0007]

Claims (7)

Component at least consisting of electronic and / or electrical components (4) which are mounted on or connected to one or more circuit boards (3), the components being overmolded by the circuit board with a first and a second plastic layer (11, 12), and wherein there is at least one shield (13) against electromagnetic radiation, characterized in that the shield (13) is at least one stamped grid (8) embedded between the first plastic layer (11) and the second plastic layer (12). Component after Claim 1 , characterized in that the stamped grid (8) has at least one contact (23) to the board (3). Component after Claim 1 or 2 , characterized in that the stamped grid (8) has at least one device (10) for mechanically fixing and stabilizing the components (4). Component according to one of the preceding claims, characterized in that the stamped grid (8) has at least one area (9) for thermal contacting of components. Component according to one of the preceding claims, characterized in that the stamped grid (8) covers at least the largest part of the surface of the board (3). Method for producing a component according to the preceding claims, characterized by the following steps: Pre-assembly of the printed circuit board (3) and the stamped grid (8) to form a module (24). Overmolding the module (24) with a first plastic material (11), overmolding the module with the first plastic layer (11) with a second plastic layer (12). Method according to Claim 6 in which, during the encapsulation with the first plastic material, the module (24) is held by punches of the injection molding tool.

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