DE202005008180U1 - Hardware encapsulation for protecting sensitive information, has safety cover contacting circuit board via conductive rubber - Google Patents

Abstract

A hardware capsule for protection of sensitive information and consists of a housing with tightly adjacent inner-lying safety conductor runs and a circuit board with electronic components The design of the housing is simplified and contacting of the safety cover with the circuit board follows via rubber conducting items, which are carried over a simple retention element and then fixed in place.

Description

The The invention relates to the field of hardware protection devices. Such safety devices have the task of hardware modules to protect against unauthorized access. This is a populated PCB by additional Facilities protected against access. These facilities are usually designed so that an attempt is recognized to attack, bypass or destroy this device. A Hardware circuit inside the fuse detects a such attack attempt and can respond appropriately. If secret inside the security device Information can be located deleted this information during an attack attempt and thus protected against unauthorized access.

State of technology

Of the Protection of hardware assemblies is usually done by having the one to protect Assembly is surrounded by a Leiterzuggeflecht. This conductor braid can e.g. be applied to a flexible circuit board, the wrapped around the hardware assembly. In addition, this construction becomes from hardware assembly and flexible circuit board usually with protected by a potting compound. The conductor tracks The flexible circuit board will come with a protection circuit inside the protected Assembly connected. This protection circuit has the task of attacks on the to be protected Detect hardware and delete sensitive information. One Attack could in an attempt to drill through the flexible circuit board. That's why the conductor tracks be placed so tight on the flexible circuit board that they destroyed in a piercing attempt become. Likewise, the potting compound is chosen such that in an attempt remove the potting compound, destroys the flexible circuit board and a Alarm triggered becomes.

When Alternative to a flexible printed circuit board are known plastic housing, in which fine conductor tracks are applied on the inside. such Plastic housing are called safety caps. These safety caps be on a circuit board, for example by gluing, screwing or soldering attached. In an attempt, a glued plastic cap of To remove the circuit board, glued conductor tracks are destroyed and thus an alarm is triggered. The fine conductor tracks on the cap inside also prevent a puncture, as in In this case, at least one of the conductor tracks is interrupted or shorted several conductor tracks become.

The Problem with plastic housings, which lead on the inside fine conductor tracks, there is usually in the contacting of the plastic housing with the hardware module. For this, e.g. on the edge area of the cap contact points attached with the help of conductive adhesive with the contact points on the hardware assembly. For security reasons are however, caps prefer to have their contacts inside the circuit board lie and not on the edge. Alternatively, recordings can be made in the housing be provided, fix the conductive rubber. Join this conductive rubber Contact points on the cap with contact points on the circuit board electric. Such plastic housing have the disadvantage that due to the complex geometries the manufacture of safety caps more complex than housings, the no cradle for Have conductive rubber.

Task of invention

The The invention is intended to include the advantages of existing protective devices and the problems of existing solutions bypass. The protective device should consist of a plastic cap, which are covered with a conductor braid on the inside is. The geometry of the plastic cap should be kept simple will be to facilitate the production of the cap. Furthermore the contacts should not lie on the edge area, but in the Inside of the cap. In previous designs are the different Contact points between the cap and circuit board usually spatially far apart. This complicates the production of the caps in that high demands on the accuracy of the position of the conductor tracks on the cap be put. The invention therefore also has the task of a greater deviation the position of the conductor tracks to tolerate on the cap. That means that deviations in the structuring and deviations in the dimensions of the injection molded parts in a certain Have no effect on the functionality of the protective device. The height These deviations should be maximized. Continue to the invention also placing the contacts in the middle of Allow cap.

One Part of the ladder trains should be conducted in such a way that these ladder trains be destroyed at a distance of the safety cap and thus over a Evaluation logic an attack on the system is detected. It is one favorable possibility to choose the mechanical attachment of the cap on the circuit board, the a destruction the conductor tracks assisted with removal of the cap.

Another requirement is that the installation of the protective device should be kept simple. The number of necessary for the establishment of the protection items should be kept low. At the same time but also a high reliability with temperature fluctuations or mechanical loads are ensured.

Not last is supposed to be a big one Protective function can be achieved, i. that the resolution of Ladder structure as possible finely executed shall be.

description the invention

The hardware encapsulation according to the invention consists of several components. On the one hand, a safety cap with applied conductor braid is used. This conductor braid can be applied with a high resolution, for example. In MID technology on the plastic cap. Furthermore, holding elements are used which are to receive the contacting elements between the safety cap and the printed circuit board. Overall, the holding elements together with the contacting elements form the so-called connecting elements. In order to obtain a closed system that completely encloses the hardware to be protected, the sixth side must be protected by a printed circuit board. The total protection device in 1 results from safety cap (No. 6 ), Connecting elements (No. 4 and no. 5 ) and printed circuit board (No. 1 ). The holding elements (No. 4 ) are in a preferred embodiment of the invention on the circuit board (no. 1 ), the safety cap (No. 6 ) is glued to the PCB.

safety cap

The safety cap in 2 shows an interior view and a side view. A flat inside of the cap (No. 1a and no. 1b ) allows easy production in MID technology. The contact points (No. 4a and no. 4b ) protrude over so-called contact ribs from the inside, so that a secure electrical contact can be made. The outer sides of the cap are defined by bevels (no. 3a and no. 3b ) educated. These bevels in turn facilitate the manufacture of the cap in MID technology. Furthermore, a socket (No. 2a and no. 2 B ), which opens up the possibility of adhesion to the peripheral edge of the cap.

The conductor runs over the entire inside of the cap (only partially shown in 3 ) as well as over the edges and on the base ( 3 No. 3 ). The guide on the base allows gluing of the conductor tracks, so that in an attempt to remove the cap, these conductor tracks are destroyed. In 3 (No. 2 ) shows a possible location of four contact points.

For contacting safety cap (No. 1 ) and printed circuit board (No. 4 ) in 4 lead rubber (no. 3 ) intended. These conductive rubbers are connected via special connecting elements (no. 2 ) held. The retaining element is made relatively high, so that the conductive rubber (no. 3 ) is conducted over as wide a range as possible. An advantageous embodiment of the invention is that the holding element is made conductive. In this embodiment, it is recommended that the conductive rubber receives an outer insulation, so that the conductive rubber with the retaining element receives no electrical contact. By this configuration, the conductive rubber and the contact areas receive additional protection against attacks from the side.

The conductive rubber contact at least four points on the safety cap. These contact points can be distributed over the safety cap. In the case of n contact points, n connecting elements and n conductive rubber would also be used in this case. If the contact points lie side by side, there are two different possibilities of arrangement. In 5 are the contact points (no. 1 to no. 4 ) arranged in a row. The conductive rubber (No. 5 ) is parallel to the contact points. The holding element (No. 6 ) lies around the conductive rubber. In 6 are the contact points (no. 1 to no. 4 ) parallel to four contact ribs (No. 5 to no. 8th ). Retaining elements (No. 9 ) and conductive rubber (No. 10 ) lie in this case transversely to the contact points.

An important safety aspect is the protection of the conductor tracks from tapping. Useful for this is the smallest possible width of the tracks and the smallest possible distances between the tracks. In 7 are with (No. 2 ) to (No. 5 ) four contact points. The contact points are connected by a conductor (no. 1 ), which is closely guided around the contact points, protected.

An alternative of protecting the contact points is in 8th shown. The conductor tracks (No. 1 to no. 4 ) of the contact points are here snail-like around the contacts pulled around.

Of the Advantage of a single contact area opposite to far apart Contacts lies in the fact that the accuracy in the production the safety cap especially respected only in this area Need to become. Deviations outside This contact area can be found in be tolerated to some extent without the safety cap loses its function.

An alternative to a single area with pads is to distribute multiple pads under the safety cap. 9 shows a printed circuit board (No. 1 ) and a safety cap (No. 6 ). On the circuit board (No. 1 ) are four holes (No. 2 ), with which the safety cap (no. 6 ) is centered on the circuit board. By doing Example in 9 four retaining elements (no. 4 ) and four conductive rubber (No. 5 ) used. The area under the safety cap (No. 3 ) is called a security area.

fasteners

The so-called connecting elements are used for electrical contact between the safety cap and circuit board and are composed of holding elements and conductive rubber. For this purpose, retaining elements are after 10 used, are inserted into the conductive rubber. Ideally, the retaining elements are soldered or glued to the circuit board in an automated process. To be able to solder the holding elements, an execution in a metallic material is recommended. The holding elements close to the circuit board and have only a small gap to the cap inside in the mounted state. This ensures that the conductive rubber are guided over a wide range and the conductive rubber can not tilt.

circuit board

The PCB forms the sixth side of the hardware enclosure. at the circuit board allowed safety-related contacts not on the unprotected back led the circuit board become. This can be realized by printed circuit boards in blind technique. Furthermore, the printed circuit board in an inner layer of a conductor braid contained, thereby detecting a puncture through the circuit board can be.

Total protection device

The entire hardware encapsulation, exemplary in 1 and 9 shown, thus consists of several parts. On the one hand printed circuit boards are used in blind technique, so that all signals to be protected are in the security area. The safety-relevant side of the PCB and its contacts ( 9 No. 3 ) are protected by a safety cap (No. 6 ) protected. This safety cap is glued in an advantageous embodiment of the invention with the circuit board. For electrical connection of the safety cap with the circuit board fasteners are used. These connecting elements consist of a holding element (no. 4 ) and a conductive rubber (No. 5 ). The electrical connection can be made with a connecting element with several contact points ( 1 ) or with several connecting elements ( 9 ) respectively.

description of the pictures

1 shows the components of a hardware encapsulation. A printed circuit board (No. 1 ) includes several holes (No. 2 ) with which the safety cap (No. 6 ) can be centered on the circuit board. Conductive rubber (No. 5 ) are used for electrical contact between the safety cap (No. 6 ) and the contacts (No. 3 ) on the circuit board (No. 1 ). The conductive rubbers are fixed via special holding elements (no. 4 ).

2 shows a safety cap with the elements cap inside (No. 1a and 1b ), Base (No. 2a and 2 B ), Side area (No. 3a and 3b ) and raised contact points (No. 4a and 4b ).

In 3 are shown the inside of the cap (No. 1 ), four contact points (No. 2 ) and exemplarily the conductor tracks on the side area and the base of the cap (no. 3 ).

In 4 is a printed circuit board (No. 4 ), the profile of the safety cap (No. 1 ), a holding element (No. 2 ) as well as a conductive rubber (No. 3 ).

5 shows an arrangement of four contact points (No. 1 to no. 4 ) in row. These contact points are covered by a conductive rubber (No. 5 ) covered in turn by a holding element (no. 6 ) is held.

In 6 are four contact points (No. 1 to no. 4 ) arranged in parallel. These four contact points lie on four contact ribs (No. 5 to no. 8th ). These contact points are in turn by a conductive rubber (no. 10 ) covered by a holding element (no. 9 ) is held.

7 shows the conductor tracks of four contact points (No. 2 to no. 5 ), which through a closely adjacent conductor train (No. 1 ) to be protected. Alternatively, in

8th four conductor tracks of the contact points (No. 1 to no. 4 ), which protect themselves by a helical ladder guide itself.

In 9 is a hardware encapsulation listed in which the contact points are spatially apart. The printed circuit board (No. 1 ) contains holes (No. 2 ), which is used to center the safety cap (No. 6 ) serve. The holding elements (No. 4 ) lead the conductive rubber (No. 5 ). PCB (No. 1 ) and safety cap (No. 6 ) form the safety area (no. 3 ) on the circuit board.

10 shows a holding element for guiding and holding the conductive rubber.

Claims (20)

Hardware encapsulation for the protection of sensitive In Formations consisting of a housing with closely juxtaposed internal safety conductor tracks and a printed circuit board with electronic components, characterized in that the construction of the housing is kept as simple as possible and the contacting of the safety cap with the circuit board via conductive rubber, which are guided and held on simple holding elements. A hardware encapsulation according to claim 1, characterized that several conductor tracks on the safety cap which lead to different potentials and thus the probability increase a short circuit in an attack attempt. A hardware encapsulation according to claim 1, characterized that the contact points of the conductor tracks on the safety cap can be arranged side by side in parallel or in series, whereby only one contact element consisting of holding element and conductive rubber must be used. A hardware encapsulation according to claim 1, characterized that the contact points on the Safety cap can be distributed, causing an attack on the hardware encapsulation of multiple pages is made difficult. A hardware encapsulation according to claim 1, characterized that the geometry of the safety cap is kept simple, thereby a simplified production of the cap is achieved. A hardware encapsulation according to claim 1, characterized that the contact between the safety cap and conductive rubber via contact ribs takes place, which is a spatial Separation between the contact points on the cap and the cap inside allow and thus short circuits prevent. A hardware encapsulation according to claim 1, characterized that the safety cap has a base, which is a bond the cap with the circuit board allowed. A hardware encapsulation according to claim 1, characterized that the safety cap glued, screwed or soldered can. A hardware encapsulation according to claim 1, characterized that on the base safety leader trains are led, which glued in the State in an attempted attack will be destroyed and thus a detection allow an attack. A hardware encapsulation according to claim 1, characterized that the holding elements guide the conductive rubber over a wide range, so that a tilting of the conductive rubber is excluded. A hardware encapsulation according to claim 1, characterized that the holding element are carried out in a metallic material can, whereby the contact points additionally secured by the side can be. A hardware encapsulation according to claim 1, characterized that the conductive rubber are laterally insulated, whereby a short circuit of the conductive rubber with the retaining element is prevented. A hardware encapsulation according to claim 1, characterized that the holding element in an automated process with the circuit board soldered or can be glued. A hardware encapsulation according to claim 1, characterized that the contacts of the conductor tracks on the safety cap can be arranged in series, thereby only a retaining element and a conductive rubber is required. A hardware encapsulation according to claim 1, characterized that the contacts of the conductor tracks on the safety cap can be arranged in parallel, thereby only a retaining element and a conductive rubber is required. A hardware encapsulation according to claim 1, characterized that to protect the contact points a conductor tight around the contact points around guided becomes. A hardware encapsulation according to claim 1, characterized that the conductor of the contact point closely around the contact point to be led and thus protects the contact point from attacks. A hardware encapsulation according to claim 1, characterized that for a hedge a circuit board in blind technique with a Leiterzuggeflecht used in an inner layer of the circuit board becomes. A hardware encapsulation according to claim 1, characterized that by using a single contact area with multiple Contact the tolerances in the structuring of the safety cap are relatively large. Hardware encapsulation according to claim 1, characterized in that the number of contact points and the number of conductor tracks on the safe cap is variable.