DE10048527A1 - Elements of HF screening of plastics casings, using metallised fabric or felt materials - Google Patents

Abstract

The screening material is stamped-out with such geometric shape blank (1) that, on application to the plastics casing (2) walls, an enclosed surface is formed of the HF screen or fully, or partly enclosed manner. The screening surface of the stamped blank is pref. located at the plastics casing sides, in fitted state, where the screening is required. Typically metallised felt material is used for screening, contg. e.g. Cu, CuNi, Al, etc. Metallised glass fabric may be used. Independent claims are included for fitting stamped screening blanks.

Description

The invention relates to the reliable high-frequency shielding of non-metallic Housings.

So far, such housings have been used to protect them against high-frequency radiation provided with a metal layer. For this, the metal was sprayed onto the housing. However, in order to obtain an adequate shielding solution, the housing had to be included several layers of metal. Adequate cushioning is usually can only be reached from the 4th to 6th shift. However, the more metal layers on that Housing is applied, the more brittle the shield covering becomes. Through the Many layers of metal on the inside of the case, it can be light Vibrations (fine vibrations) but also in normal use The metal coating layer will come off.

The requirement for a thick metal layer also results from the requirement for Broadband RF shielding.

There are already a number about the brittleness of such metal coatings competent publications and reports in the specialist media.

In order to maintain the flexibility of the plastic housing, has been done in the past tries to insert a textile shield into the plastic housing. In this process an electrically conductive textile was pressed into the injection mold. This method requires large production technology expenses, has high material losses and as a result has a high error rate. When pressing in the textile part the homogeneous regular shape and distribution of the textile composite becomes the shape deformed indefinitely. That means that it can also happen that the textile is on  certain critical points tears, or is stretched so extreme that the expected homogeneous shielding no longer exists. So everyone becomes metrological determined shielding attenuation value as the basis for further processing incalculable.

Especially in the marginal zones and corners, as well as on structurally determined bumps the textile structures are damaged or even destroyed. All of these procedures require an individual inspection of each individual housing for product liability reasons. This is technologically and economically extremely complex and takes place therefore no application in practice.

Derived from this prior art, the object of the invention is a textile Introduce shielding in the plastic housing, which have the disadvantages of the prior art avoids.

An inventive solution to this problem is in claim 1 and 6 to 8 specified. Further developments of the invention are in the associated subclaims characterized.

According to the concept of the invention, the shielding means or Shielding material no longer as a closed electrically conductive fabric or Fleece composite introduced into the shielding plastic housing, but that Shielding material is die-cut in a suitable geometry.

The die-cut shielding material is referred to below as die-cut blank. It has such a geometry that after the introduction of the respective Punch cut into the shielding plastic housing and thereby converting the planes Shape (initial state) in a spatial form (installation state) a closed or largely closed surface or only a partially closed surface Surface results. The shielding areas of the die cuts are in the Installed condition preferably at the points of the housing where there is an HF shield is desired.  

A metallized non-woven material is used as the material for the die cuts chemical solidification used. Through the chemical consolidation of the fleece In contrast to thermal consolidation, the fibrillation of (conductive) Parts excluded, creating an uncontrolled and non-reproducible Contacting is no longer necessary and system triggering or short circuits are eliminated.

The application of the coating to carry out the metallization of the Non-woven material is made using an electron beam process using an arc. Here, the metallization does not take place via the enrichment of metal on the Fiber like in electroplating, but the metal parts diffuse through the high particle speed also in the fibers. The result is one in comparison for galvanizing thinner skin, which has a positive connection with the particles enters the fiber. This can result in a higher metal content on the nonwoven material be applied without the material becoming brittle. The higher metal content of the Fleece in turn leads to better conductivity and higher current carrying capacity. Metals such as Cu, CuNi, Alu can be used for the metallization. On the other hand, as materials for the die cuts, glass fiber, glass fleece or Glass carbon can be used, which are coated by the same method.

The punch cuts can be used to support their fixation when installed have one-sided adhesive layer.

The following are used to insert the punch cuts into the housing to be shielded Proposed procedure.

On the one hand, the one that can be inserted into the plastic housing and thereby shielded Electronic component during the insertion process the punch blank in front of it slide and position in the end position. On the other hand, the die cut preferably if he has an adhesive layer to carry out the adhesive label Principle, by means of a separate positioning tool in the plastic housing brought in.  

Another way to insert and position the die cuts in the or in the plastic housing (s) is that the die cuts have an adhesive layer to carry out the heat seal principle and after the action of one Hot air jet to melt the adhesive using a positioning tool with the The die cut is immersed in the housing and the die cut in the end position suppressed.

Further details, features and advantages of the invention result from the following description of an embodiment with reference to the associated drawing.

Show it

Fig. 1, various punching blanks,

Fig. 2 is a schematic representation of the assembly of a punched blank with the introduced into the plastic shell electronic component,

Fig. 3 is a schematic representation of the placement and positioning of a punched blank in the plastic housing using the heat-sealing principle,

Fig. 1 shows four exemplary embodiments or geometries of punching blanks 1.

The punch cut shown at the top right leads to a closed surface of the shielding material, the one shown at the bottom right Die-cut only results in a partially closed surface.

Fig. 2 illustrates a method for introducing a solution punching blank 1 in a plastic housing 2.

The stamped blank 1 is introduced together with the assembly, the insertion of an electronic component 4 into the plastic housing 2 , in one process cut.

Fig. 2 shows two states moment shows the assembly procedure.

State I identifies the initial state with the flat punch blank 1 positioned in front of the electronic component 4 ; the punch blank 1 extends perpendicular to the assembly direction 7 .

The state II (left-hand illustration) describes the insertion process of the electronic component 4 that has started with the upstream punch blank 1 into the plastic housing 2 . The stamped blank 1 lies against the walls of the housing 2 as the insert progresses.

Fig. 3 contains the schematic representation of the insertion process of a punch blank 1 in the housing 2 using the heat seal principle. For this purpose, the punch blank 1 has an adhesive layer 3 on the side facing the wall of the housing 2 . This adhesive layer is first melted by means of a hot air jet 6 and subsequently the punch blank 1 is introduced into the housing 2 using a positioning tool 5 . The positioning tool S plunges into the housing 2 and presses the punch blank into the end position.

LIST OF REFERENCES

1

punched blank

1.1

screening surfaces

2

Plastic case, plastic case

3

adhesive layer

4

Electronic component

5

Positioning

6

Hot air jet

7

mounting direction

Claims (8)

1. Means for HF shielding of plastic housings using metallized woven or non-woven materials, characterized in that the shielding material is stamped with such a geometry to form a stamped blank ( 1 ) that after the stamped blank ( 1 ) has been introduced into the plastic housing ( 2 ) by applying the punch blank ( 1 ) to the walls of the plastic housing ( 2 ) and thereby assuming a spatial shape, a closed, largely closed or partially closed surface of the spatial RF shielding formed in its end position results. 2. Means according to claim 1, characterized in that the shielding surfaces ( 1.1 ) of the blank ( 1 ) are preferably in the installed state at the locations of the plastic housing ( 2 ) where shielding is desired. 3. Means according to claim 1 or 2, characterized in that a metallized non-woven material is provided as the shielding material for the die cuts ( 1 ), metals such as Cu, CuNi, aluminum being used for the metallization. 4. Means according to claim 1 or 2, characterized in that metallized glass silk, glass fleece or glass carbon is provided as materials for the die cuts ( 1 ). 5. Means according to one or more of claims 1 to 4, characterized in that the die cuts ( 1 ) have an adhesive layer ( 3 ) facing the plastic housing ( 2 ). 6. The method for introducing the punched blanks according to claim 1 to 5, characterized in that the electronic component ( 4 ) to be introduced into the plastic housing ( 2 ) and thereby to be shielded pushes the punched blank ( 1 ) in front of it during its insertion process and positions it in the end position , 7. The method for introducing the die cuts according to claim 1 to 5, characterized in that the die cut ( 1 ) has an adhesive layer ( 3 ) and for performing the adhesive label principle of the die cut ( 1 ) by means of a separate positioning tool (S) in the plastic housing ( 2 ) is introduced and positioned. 8. The method for introducing the punch blanks according to claim 1 to 5, characterized in that punch blank ( 1 ) has an adhesive layer ( 3 ) for executing the heat seal principle and after exposure to a hot air jet ( 6 ) for melting the adhesive ( 3 ) Immerse the positioning tool ( 5 ) with the punch blank ( 1 ) in the housing ( 2 ) and press the blank ( 1 ) into the end position.