Protection For Circuit Boards
A system has a circuit board, an integrated circuit being mounted on the circuit board by external contacts, and a cover irreversibly connected to the circuit board. The cover covers the external contacts so that external access to the external contacts is prohibited by the cover.
The present invention relates to a protection for circuit boards against tampering.
BACKGROUNDIn some applications, it would be favourable to be able to prevent circuit boards from abuse. For example, there is a need to protect the information in ICs in any business model where a IC containing device is given to the consumer at a reduced price with the obligation to use that device only with services from a certain provider. One already existing example for this kind of business model is the Simlock Cellphone® where the device is programmed to be only functioning using the Simcard from a specific provider. Similar need for protection exists for pay-per-use business models or receiving content over mass distributed channels, e.g. Cable and Satellite Pay TV.
Referring to the figures, embodiments are described in more detail below. In particular
In the following description, same elements or elements corresponding to each other in terms of functionality are given the same reference numbers, and a repetitive description of same is avoided.
Integrated circuits 14a, 14b are mounted onto a mounting surface 12a of the circuit board 12. A surface 12b of the circuit board 12 being opposed to the mounting surface 12a may, or may not serve as a mounting surface for further integrated circuits (not shown) as well.
Exemplarily, merely two integrated circuits 14a, 14b are shown in
In
In particular, the integrated circuits 14a, 14b are mounted to the circuit board such that the external electrodes 20 thereof are electrically connected to contact pads 22 disposed on the mounting surface 12a of the circuit board 12. For example, the external contacts 20 are soldered to the contact pads 22. Alternatively, an electrically conductive adhesive may be used to achieve mechanical and electrical connection between the external contacts 20 and the contact pads 22.
The circuit board 12 comprises conductor lines interconnecting contact pads 22 and electrodes 18 so as to form an electrical circuit for performing a certain functionality. In
Among the integrated circuits 14a, 14b, integrated circuit 14b is, for example, a processor being able of executing computer programs running thereon. The integrated circuit 14a may comprise an encryption unit that participates in the cooperation of the integrated circuits 14a, 14b in connection with, for example, a functionality of interest of the circuit board 12, such that the functionality is not activatable or is defective, when the integrated circuit 14a has been removed. In this regard, the integrated circuit 14a should be protected as it is described in the following. Alternatively or additionally, the integrated circuit 14a could participate in the desired functionality of the circuit board 12 such that the data being transmitted via the external contacts 20 of the integrated circuit 14a should be protected from a spy out or a manipulation from outside. Such data could, for example, relate to the duration of usage of the desired functionality of the circuit board 12 or other pay per use data. In this regard, the integrated circuit 14a could also be an integrated circuit that should be protected from outside. In the following, embodiments for providing this protection will be described. It should be noted that the encryption unit for the integrated circuit 14a may comprise an asymmetric or a symmetric encryption unit. For example, the integrated circuit 14a may implement a RSA or an elliptic curve algorithm. Alternatively, the integrated circuit 14a may implement an AES, DES, or Triple-DES algorithm.
As a protection means, the system 10 of
As will be described in more detail below, the cover 24 will not necessarily have to be implemented as a protective cap 26 having anchoring pins 28. However, preferably, the cover 24 is affixed to the circuit board 12 in an irreversible fashion, i.e. such that it is not possible to remove the cover 24, without destroying the circuitry of the circuit board 12, including the integrated circuits 14a, 14b, and the conductor lines interconnecting the contact pads 22. Even more preferably, the relationship between the labour necessary to remove the cover 24 from the circuit board 12 and the damage to the circuitry of the circuit board 12 resulting therefrom should be such, that the costs for the removal and the repair exceed a prospective gain associated with the removal due to, for example, the manipulation of the pay per use data communicated to the integrated circuit 14a.
In
As shown in
As shown in
Preferably, the adhesive 34 is selected such that same results in a stable mechanical connection between anchoring pin 28 and circuit board 12, so as to guarantee an irreversible anchoring of pin 28 in hole 30. Moreover, adhesive 34 is preferably selected such that same, in its hardened state, is substantially chemical inert. That is, adhesive 34 should withstand chemical substances, such as etch solutions and the like, at least to the extent that removing the adhesive 34 to release anchoring pin 28 from hole 30 unavoidably leads to a destruction of the circuitry implemented on circuit board 12 by, for example, interrupting conductor lines of the circuit board 12 connecting some of the contact pads 22.
As shown in
As shown in
As shown in
As shown in
It should be noted that the material of the protective cap 26 could be chosen from, for example, metal, ceramic, glass or plastic. In any case, it is preferred that the protective cap shows a high resistance against sawing, rasping, mechanical shocks and the like. Thus, it should be stable, and rigid without being brittle. Moreover, the material should be chemically inert so that a chemical attack on the protective cap 26 is likely to result in a destruction of the circuitry of the circuit board 12. For example, in order to achieve access to manipulate data on external contacts 20 of integrated circuit 14a, a potential attacker has to remove the protective cap 26. However, since the sidewall 26b of the protective cap is anchored in circuit board 12, this removal will unavoidably or will likely lead to a destruction of the circuit board 12 such that same is rendered useless. For example, in case of the material of the protective cap 26 being steel or an Al203 ceramic or a highly-filled epoxy resin, a removal of the protective cap 26 by means of chemical substances such as solvents, acids and bases is not possible without concurrently etching away the conductor lines of the circuit board 12, rendering the circuit board 12 useless. An attempt to mechanically achieve access to the external contacts 20 for manipulation such as, for example, by means of a polishing or milling attack, leads to tension and shearing stresses on the anchoring surface of the protective cap 26 within the circuit board material what, in turn, damages the conductor lines of the circuit board 12a such that, again, the board 12 becomes useless.
Reference is now made to
In the embodiment of
In
As illustrated by the left hand anchoring pin 28 in
It should be noted that the sensitivity of the anchoring surface against mechanical stress is adjustable via the geometric parameter of the pin diameter, the distance of the anchoring pin to a respective conductor line as well as material selected. In this regard, a diameter of the anchoring pin is preferably greater than 0.1 times the thickness of the circuit board. A possible arrangement of the holes relative to the conductor lines will be exemplarily discussed in more detail with regard to
However, prior thereto,
In connection with
In accordance with
In the above embodiments, the protective cap had anchoring pins extending into the circuit board for irreversible affixation to the circuit board. In the following, with regard to
In order to prohibit any external access to, for example, the bond wires 48 a cover 24 covers the whole chip module 42, as well as the contact pads (not shown), to which connections 46 are connected. As in the foregoing examples, cover 24 comprises a protective cap 26. However, no anchoring pin protrudes from the seat area 60 of cap 26 at the distal end of the sidewalls 26b facing circuit board 12. Rather, the seat area 60 of protective cap 26 abuts to the mounting surface 12a within a closed band thereof surrounding a mounting area of the chip module 42.
The protective cap 26 is affixed to the circuit board 121 by means of adhesive 62. As mentioned above with respect to adhesive 34 of
As described with respect to
In the embodiment of
In accordance with the embodiment of
In accordance with the embodiment of
In the embodiments described above, cover 24 comprised a protective cap made up of, for example, metal, ceramics, glass, or plastic. Differing therefrom, in the embodiments of
Differing from
Of course it is possible to combine the embodiments according to
The above-described embodiments may be modified in various ways. With respect to the embodiment of
Moreover, with regard to
In the description of the above embodiments, the description mostly related to the already assembled state. However, according to another embodiment, the aforementioned protective cap comprising the anchoring pin or portion, respectively, has not yet been inserted into the respective hole. Accordingly, the protective cap and circuit board form a kit. During a fabrication or a protection step, the already mounted integrated circuit may be protected by means of the protective cap with eventually, as described above, using adhesive or soldering. Moreover, various ways in order to dispose the aforementioned resin on top of the external contacts and/or the integrated circuit to be protected are possible.
In any case, the above embodiments prevent the portions where a manipulator may access the signals of interest to/from the integrated circuit, on the circuit board against being exposed by means of simple chemical or physical preparation. In particular, the above embodiments protect an integrated circuit or a chip module to the extent that a respective preparative attack for exposing the terminals of the integrated circuit either involves overheads or costs in an unattractive amount that exceeds the value of the computer system, or that such a preparative attack unavoidably leads to the destruction of the board surface, rendering the board useless. Thus, the above embodiments may be used to protect integrated circuit from removal from the circuit board without destroying the board. Thus, a device containing the integrated circuits may be given to a consumer at, for example, a reduced price with the obligation to use that device only with services from a certain provider. For example, the device including one of the above circuit boards could be programmed to be only functional using circuitry from a specific provider residing inside the integrated circuit 14a.
While the foregoing has been particularly described with reference to particular embodiments thereof, it will be understood by those skilled in the art that various other changes in the forms and details may be made without departing from the broader spirit and scope thereof. It is to be understood that various changes may be made in adapting to different embodiments without departing from the broad concept disclosed herein, and comprehended by the claims that follow.
REFERENCE SIGNS
Claims
1. A system comprising
- a circuit board;
- an integrated circuit having an encrypting unit and being mounted on the circuit board by means of external contacts; and
- a cover connected to the circuit board, the cover covering the external contacts.
2. The system according to claim 1, wherein the cover also covers the integrated circuit.
3. The system according to claim 1, wherein the cover comprises a protective cap being affixed to the circuit board so that the integrated circuit is enclosed by the protective cap
4. The system according to claim 3, wherein the protective cap is affixed to the circuit board by at least one of at least one anchoring portion extending into the circuit board, and adhesive.
5. The system according to claim 1, wherein the cover comprises a resin being disposed on the integrated circuit and/or the external contacts such that external access to the external contacts is prohibited by the resin.
6. The system according to claim 3, wherein the circuit board comprises conductor lines connected to the external contacts, the conductor lines extending internally to the circuit board.
7. A system comprising
- a circuit board;
- an integrated circuit being mounted on the circuit board by means of external contacts; and
- a protective cap being affixed to the circuit board so that the integrated circuit is enclosed by the protective cap and the circuit board and external access to the external contacts is prohibited by the protective cap, wherein the protective cap is affixed to the circuit board by at least one of at least one anchoring portion extending into the circuit board, and an irreversibly hardening adhesive.
8. The system according to claim 7, wherein the circuit board comprises conductor lines connected to the external contacts, the conductor lines extending internally to the circuit board.
9. The system according to claim 7, wherein the at least one anchoring portion protrudes from and is integrally part of the protective cap.
10. The system according to claim 7, wherein the at least one anchoring portion extends into the circuit board so that the anchoring portion touches or extends at a distance to a conductor line of the circuit board, the distance between the at least one anchoring portion and the conductor line being less than 1 mm.
11. The system according to claim 10, wherein the conductor line of the circuit board is connected to the integrated circuit.
12. The system according to claim 10, wherein the conductor line of the circuit board is buried into the circuit board.
13. The system according to claim 7, wherein the anchoring portion is an anchoring pin, and a diameter of the anchoring pin is greater than 0.1 times the thickness of the circuit board.
14. The system according to claim 7, wherein the anchoring portion is an anchoring pin, and the anchoring pin comprises a smaller diameter portion and a larger diameter portion, a diameter of the anchoring pin in the smaller diameter portion being less than a diameter of the anchoring pin in the larger diameter portion, and the larger diameter portion being located at a distal location relative to the smaller diameter portion.
15. The system according to claim 7, wherein the at least one anchoring portion comprises a hook portion engaging with the circuit board so as to counteract a movement of the anchoring portion out of the circuit board.
16. The system according to claim 7, wherein the circuit board comprises at least one hole into which the anchoring portion is inserted.
17. The system according to claim 16, wherein the at least one hole is a through hole extending from a first surface of the circuit board onto which the integrated circuit is mounted to a second surface of the circuit board being opposite to the first surface.
18. The system according to claim 7, wherein the at least one anchoring portion is affixed to the circuit board by means of solder.
19. The system according to claim 7, wherein the at least one anchoring portion is affixed to the circuit board by means of adhesive.
20. The system according to claim 7, further comprising a resin being disposed on the integrated circuit and/or the external contacts such that external access to the external contacts is prohibited by the resin
21. The system according to claim 20, wherein the integrated circuit and the resin are enclosed by the protective cap and the circuit board.
22. The system according to claim 21, wherein the resin covers an area of a surface of the circuit board surrounding the integrated circuit, wherein the circuit board comprises at least one recess or protrusion in the area of the surface of the circuit board surrounding the integrated circuit.
23. The system according to claim 22, wherein the resin takes up more than 50% of the space enclosed by the protective cap and circuit board and surrounding the integrated circuit such that the resin contacts the protective cap from inside.
24. The system according to claim 7, wherein the protective cap is affixed to the circuit board by means of the adhesive, with a recess being formed in a portion of the circuit board facing a seat area of the protective cap or an edge of the protective cap formed between an inner wall of the protective cap and the seat area, and with the resin being at least partially disposed in the recess.
25. The system according to claim 20, wherein the resin is non-conductive.
26. The system according to claim 7, wherein the protective cap is affixed to the circuit board such that the protective cap is electrically isolated from any conductive part of the circuit board.
27. The system according to claim 7, wherein the irreversibly hardening adhesive is a resin.
28. A system comprising
- a circuit board;
- an integrated circuit being mounted on the circuit board by means of external contacts; and
- a resin being disposed on the integrated circuit and the external contacts such that external access to the integrated circuit and the external contacts is prohibited by the resin.
29. The system according to claim 28, wherein the circuit board comprises conductor lines connected to the external contacts, the conductor lines extending internally to the circuit board.
30. The system according to claim 28, wherein the circuit board comprises at least one recess or protrusion in an area of a surface of the circuit board surrounding the integrated circuit and being covered by the resin so as to increase a degree of affixation between the resin and the circuit board.
31. The system according to claim 28, wherein the resin is non-conductive.
32. The system according to claim 28, wherein the resin is an irreversibly hardening adhesive.
33. A system comprising
- a circuit board;
- an integrated circuit being mounted on the circuit board by means of external contacts;
- a resin being disposed on the integrated circuit and/or the external contacts such that external access to the external contacts is prohibited by the resin; and
- a protective cap being affixed to the circuit board so that the integrated circuit and the resin are enclosed by the protective cap and the circuit board, wherein the protective cap is affixed to the circuit board by at least one anchoring portion extending into the circuit board and/or an irreversibly hardening adhesive.
34. A kit comprising
- a circuit board comprising holes in an area surrounding a chip mounting area; and
- a protective cap comprising anchoring pins such that the anchoring pins can be inserted into the holes to enable an affixation of the protective cap to the circuit board.
35. The kit according to claim 34, wherein at least one of the holes extends into the circuit board so that same abuts to or extends at a distance to a conductor line of the circuit board, the distance between the at least one hole and the conductor line being less than 1 mm.
36. The kit according to claim 35, wherein the conductor line of the circuit board is connected to an integrated circuit mounting pad in the chip mounting area.
37. A method for protecting an integrated circuit, comprising affixing a protective cap to a circuit board onto which the circuit board is mounted such that the integrated circuit is enclosed by the protective cap and the circuit board, such that external access to the external contacts is prohibited by the protective cap, and such that the protective cap is affixed to the circuit board by at least one anchoring portion extending into the circuit board and/or an irreversibly hardening adhesive.
38. A method for protecting an integrated circuit, comprising disposing a resin onto the integrated circuit and the external contacts such that external access to the integrated circuit and the external contacts is prohibited by the resin.
39. A system comprising
- a circuit board;
- an integrated circuit being mounted on the circuit board by means of external contacts; and
- a cover irreversibly connected to the circuit board, the cover covering the external contacts so that external access to the external contacts is prohibited by the cover.
40. The system according to claim 39, wherein the cover also covers the integrated circuit.
Type: Application
Filed: Feb 9, 2007
Publication Date: Aug 14, 2008
Inventors: Johannes Hankofer (Aiterhofen), Manfred Mengel (Bad Abbach), Stephan Schaecher (Muenchen)
Application Number: 11/673,253
International Classification: H05K 5/04 (20060101);