KR20020089526A - Shielding compartment - Google Patents

Abstract

The present invention relates to a shielding chamber for shielding a circuit on a printed circuit board, in which case the shielding chamber, which is open in the direction of the printed circuit board, covers the circuit disposed on the printed circuit board in an assembled state. do. The shielding chamber has a plastic shielding frame disposed on the printed circuit board, which extends around the circuit to be shielded in an assembled state, and a shielding lid fixed to the shielding frame.

Description

Shielded Room {SHIELDING COMPARTMENT}

In practice, shielding techniques are known in which separate shield rooms are formed by metal covers in the form of separate boxes or hoods. The shield is soldered directly to the shield protrusion on the printed circuit board. The shielding chamber is relatively inexpensive and is generally placed over the circuit with the parts immediately after the printed circuit board is installed and at the same time soldered with the remaining parts, for example with a reflow-oven. However, since the components of the circuit are covered by the shielding chamber, in this case, the automatic optical inspection (AOI) of the individual components is no longer possible in the correct position direction. In addition, there is a disadvantage that the linear expansion coefficient of the shielded chamber made of metal is different from the linear expansion coefficient of the printed circuit board, which may cause distortion of the printed circuit board after soldering.

The present invention relates to a shielding chamber for shielding a circuit on a printed circuit board, in which case the shielding chamber, which is open in the direction of the printed circuit board, covers the circuit disposed on the printed circuit board in an assembled state. do.

In many cases circuits on a printed circuit board must be electrically and magnetically shielded for high frequencies. This is especially true for logic and radio circuits, for example in mobile radio equipment, which are inevitably placed in close proximity to the transmitting and receiving devices and should not be disturbed by the transmitted or received high frequency signals. Circuit). In this case, different quantities of shielded rooms are required depending on the configuration of the apparatus. Thus, for example, the next generation mobile radio standard UMTS requires more shield rooms, in which case up to seven different layout-areas must be separated and shielded from each other.

1 is a plan view of a printed circuit board, on which the shielding frame with two partial shield rooms is arranged and there is a common shielding cover with no engagement;

2 is a plan view according to FIG. 1 with the shield lid closed;

3 is an enlarged plan view of a corner section of a shielded room with a recessed shielding frame intermittently disposed on the base surface and a non-engaged shielding cover disposed thereon;

4 is a plan view according to FIG. 3 with the shield lid closed;

It is an object of the present invention to provide an alternative to the prior art.

The object is achieved by having a plastic shielding frame fixed on the printed circuit board and a shielding cover fixed to the shielding frame, which extends around the circuit to be shielded with the shielding chamber assembled. .

The shielding frame and the shielding cover disposed and fixed thereon form a high frequency sealing chamber (HF-dichte Kammer) in this case, the high frequency sealing chamber covering a layout-surface in which parts are fitted. Shield on the substrate. In other words, the shielding chamber is in this case two parts, in which case the plastic shielding frame is used for shielding on the side and the shielding lid covers the circuit upwards. In order to achieve the shielding effect, the shielding frame may be made of, for example, a metalized thermoplastic. Conductive plastics can also be handled.

The use of a plastic shield frame has the advantage that the linear expansion coefficient is within the size of the printed circuit board, so that a smaller printed circuit board distortion can be expected after soldering.

By metallizing the outer wall of the frame, the frame can be soldered on a printed circuit board to a shielding protrusion, generally to a Goldspur, as in a conventional metal shield room. The soldering can be performed by various processes, for example by reflow-soldering or similar processes.

The two-part shielding chamber form makes it possible to fix only the shielding frame on the printed circuit board first, in which case the shielding cover is not yet installed. Thus, automatic optical inspection of the circuit is possible even after the soldering process.

The shielding frame has a separating strip (Trennsteg) that divides the shielding chamber into a partial shielding chamber. The separating strip is part of the shielding frame and is preferably made integral with the outer frame. In this way, several layout-areas can be separated and shielded by one shielding frame. Obviously the shielding frame can be placed and arbitrarily extended in any quantity such separation strips to create any number of partial shielded rooms.

In this case, a single shield cover can be used that can cover multiple partial shield rooms at once. Instead, a plurality of separate shield covers can be used which individually cover the partial shield room, the plurality of separate shield covers adjoining one another in a separating strip. Obviously, all the various temporary disassembly is possible, such that a number of interfacing adjacent partial shielding rooms may have a common shielding cover, and some special partial shielding rooms may have individual shielding covers.

The advantage of the above structure having the separating strips dividing the shield into multiple partial shields is that only one on the printed circuit board to which the shield projections are soldered thereon in delimiting two shielded areas separated from one another. It only requires a shielding protrusion of. In the conventional method having a plurality of shield rooms arranged next to each other, on the contrary, two shield protrusions extending in parallel to each other are required. The shield according to the invention thus improves the space utilization of the printed circuit board.

In a particularly preferred embodiment, the shield cover is secured to a demountable center shield frame. This has the advantage that the shield room can be opened for repair or adjustment at any time, without the entire shield room being separated from the printed circuit board. In the early stages of the shielding technique described above, repairs, on the other hand, are very difficult or impossible, and very expensive to make them economically useful. This causes an increase in defective products. The use of individually degradable shield covers for the various partial shield rooms has the further advantage that in this case only the shield rooms to be repaired are opened.

The demountable fixation is preferably implemented by jointly providing a clamp member and / or a locking member (Klemmund / Oder Rastelemente) in which the shielding lid and the shielding frame interact.

The shielding cover itself is made of steel, for example from metal, preferably as a punched bending part (Stanzbiegeteil) with the required clamping and / or locking members.

In the case of the clamp member and / or the locking member, for example, there is a molding in which a shield, which is installed on the frame, into a slot, a recess or the inside thereof in the frame is engaged or fixed.

By metallization of the shielding frame or by using a conductive plastic for the shielding frame, an excellent electrical contact between the shielding cover and the shielding frame is automatically ensured.

In another preferred embodiment, the shielding frame has one or in some cases a plurality of through-holes at the corners facing the printed circuit board. In particular, in the present case, a plurality of uniform through holes arranged in each other within a predetermined interval correspond. In other words, the frame is formed intermittently in this case, that is to say partly excluded from the base surface. Correspondingly, an intermittent gold protrusion is coated on the printed circuit board and soldered on the printed circuit board only at that position of the shielding frame. This measure includes layout technical advantages because various conductions from or between the shield rooms can be lead through on the printed circuit board surface or on the top layer. Correspondingly, not only the outer frame of the shielding frame, but also a separation strip are thus formed intermittently.

Since the shielding frame is plastic, in principle almost any shape is possible on a printed circuit board. A substantially flat shielding cover is formed in this case to fit any shape. This makes it possible to form much more freely than the conventional shielding method in the layout of the printed circuit board, and for this reason, space utilization can be further improved, and overall, the overall apparatus performs better in terms of placement and shielding effect. Will have the ability. In particular, it is possible to manufacture smaller and more compact devices, whereby better integration is achieved.

The invention is explained in more detail with reference to the accompanying drawings in accordance with an embodiment. The features shown in the figures and the features described above may be essential to the invention in the given combinations as well as individually or in any other combination.

In order to manufacture the shielding chamber 1 according to the invention shown in the drawings, firstly a shielding frame 3 is made of plastic, for example thermoplastic material, suitably for the circuit layout. As can be seen in particular in the enlarged view according to FIG. 3, the upper edges 9 of the shielding frame 3 are provided with moldings in the form of suitable recesses 11 or slots or recesses at intermittent intervals. Fabrication can, for example, be made in a single injection molding process at low cost, in which case the recesses 11 can also be molded together.

Corresponding to the shape of the shielding frame 3, the shielding cover 4 having a projection 8 bent in the direction of the shielding frame 3 at its outer edge 7 is produced by punching and bending a steel sheet. The protrusions 8 are arranged to engage precisely into the recesses 11 in the upper edge 9 of the shielding frame 3.

A molded surface 11 is formed on the protrusion 8 of the shielding cover 4 by the molding 11 at the upper edge 9 of the shielding frame 3, and the shielding cover is formed by the mating surface. (4) can be reliably snapped to or engaged with the shielding frame (3). Since the shielding frame 3 is entirely metallized after manufacture, the contact between the shielding cover 4 and the shielding frame 3 is also automatically ensured. In other words, the shielding lid 4 is contacted and fixed in the outer size of the shielding frame 3 in the case of this embodiment, thereby reducing the space required, as opposed to the solution in which the lid is fixed on the outer surface of the shielding frame. .

1 and 2 respectively show a shielding frame 3 with an uninterrupted base surface or lower edge 10. On the contrary, in the case of the shielding frame 3 according to FIGS. 3 and 4, recesses 13 are disposed on the lower edges 10 at intermittent intervals, and printed circuit tracks are formed through the recesses 13. This can be lead through from the shield chamber 1.

1 shows a shielding chamber 1 according to the invention with two partial shielding chambers 5, 6. The two partial shielding chambers 5, 6 are here formed by a separating strip extending inside the shielding frame portion which surrounds the outside. Since the separation strip is covered by the shield cover 1, the separation strip is not visible in FIGS. 1 and 2. However, the separation strips in principle look the same as the shielding frame portion surrounding the outside, in particular with the same kind of recess as the recess 11. In order to form the projection 12 for the recess in the separation strip, a U-shaped cutout (Ausstanzung) is made in the shielding cover 1 at the top along the separation strip, and the free end thus formed is Bent into Thus, a stable locking or clamping connection is made between the shielding cover 4 and the separation strip.

Alternatively, the two partial shielding rooms 5, 6 may each be covered by separate shielding covers. In this case a wider recess is preferably provided in the separation strip, in which the protrusions of adjacent shield covers are each situated side by side. Alternatively, recesses that are displaced and facing each other may be used, and corresponding projections in the two partial shields into the recesses may engage the separating strips.

The illustrated shielding frame 3 and shielding lid 4 can be arbitrarily adapted to the layout of the circuit.

Claims (14)

Shielding of the circuit on the printed circuit board 2 which covers the circuit disposed on the printed circuit board 2 in the state where the shielding chamber 1 opened in the printed circuit board 2 direction is assembled. In the shielded room (1) for In the assembled state, the shielding chamber 1 is fixed to the shielding frame 3 and the shielding frame 3 made of plastic disposed on the printed circuit board 2 while extending around the circuit to be shielded. Shielded room characterized in that it comprises a shielding cover (4). The method of claim 1, Shielding room, characterized in that the shielding frame (3) has a separating strip which divides the shielding room (1) into partial shielding rooms (5, 6). The method of claim 2, Shielding room, characterized in that a single shielding cover (4) covers a plurality of partial shielding rooms (5, 6) at one time. The method of claim 2 or 3, A shielded room, characterized in that a plurality of separate shielded covers individually cover the partial shielded room. The method according to any one of claims 1 to 4, Shielding room, characterized in that the shielding cover (4) is removably fixed to the shielding frame (3). The method of claim 5, And a clamp member and / or a locking member (8, 11) for coupling the shielding cover (4) and the shielding frame (3) to each other. The method of claim 6, The shielding frame 3 has a recess 11 in and / or on an upper edge 9 facing the printed circuit board 2, and into the recess 11. Shielding chamber, characterized in that the projection (8) arranged in 4) is engaged for fixing the shielding cover (4). The method according to any one of claims 1 to 7, Shielding room, characterized in that the shielding frame (3) is metallized. The method according to any one of claims 1 to 8, Shielding room, characterized in that the shielding frame is made of a conductive plastic. The method according to any one of claims 1 to 9, Shielding room, characterized in that the shielding cover (4) is made of a steel sheet. The method according to any one of claims 1 to 10, Shielding room, characterized in that the through hole (13) is provided in the corner (10) of the shielding frame (3) facing the printed circuit board (2). Printed circuit board (2) with a shielding chamber (1) according to any of the preceding claims. The method of claim 12, Shielding room, characterized in that the edge of the shielding frame (3) facing the printed circuit board (2) is soldered at least partially on a shielding protrusion (14) disposed on the printed circuit board (2). Communication terminal with a printed circuit board (2) according to claim 12 or 13.