DE102011083419A1 - Electronic assembly, circuit board and process - Google Patents

Abstract

An electronic subassembly is described, comprising: a printed circuit board on or in which at least two printed conductors or a multiplicity of printed conductors are arranged, at least one electronic component or a multiplicity of electronic components which form an electronic circuit arranged on the printed circuit board, - A circuit covering or surrounding trace arrangement, - and a monitoring circuit whose inputs are electrically conductively connected to the track arrangement, - an electrically insulating insulating layer on side surfaces of the component or on side surfaces of the components, and wherein the conductor arrangement is arranged on the insulating layer.

Description

The invention relates to an electronic assembly, a printed circuit board and a method. The electronic module contains a printed circuit board on or in which at least two printed conductors or a plurality of printed conductors are arranged. At least one electronic component or typically a plurality of components form an electronic circuit arranged on the printed circuit board.

Electrical circuits may contain safety-relevant information and must therefore be protected against external manipulation. Attempts to electrically manipulate the circuit must be taken into account as well as chemical or mechanical manipulations, e.g. by drilling or laser ablation. Therefore, the circuit is combined with a control unit which results in irrevocably deleting security-relevant data in the event of an external manipulation. This protection must be as easy as possible to be integrated into the manufacturing process of the circuit and may not have a lot of space, especially in miniaturized circuits.

Electrical circuits could be protected by means of Bohrschutzfolien from external manipulation. After fabrication, the assembly would be packaged three-dimensionally in a drill protection film. The foil would carry electrical structures that are connected to the assembly and, if damaged, result in deletion of safety related data. Disadvantages would be the sensitivity of the metallic structures on the anti-drilling foil and therefore low mechanical stability, the packaging process, which deviates from standard electronic manufacturing processes, and the size of the package.

Alternatively, the protection against manipulation could be done via a housing of metallically structured circuit carriers, which are also connected to the module to be protected. This variant would be mechanically more stable and would also allow the use of standard manufacturing processes. The variant would not be suitable for miniaturized structures and would also be costly.

Thus, there is a need for a further assembly that is protected against unauthorized access. The assembly should be easy to manufacture.

This object is achieved by an assembly according to claim 1. Further developments are specified in the subclaims, the following description and the drawings.

The module may include a circuit arrangement surrounding or covering the circuit arrangement and a monitoring circuit whose inputs are electrically conductively connected to the conductor arrangement. The electrically insulating insulating layer can rest on side surfaces of the component or on side surfaces of the components. The conductor arrangement can be arranged on the insulating layer.

• – Höhenunterschiede größer als 50 Mikrometer, z.B. in Flip-Chip-Technik aufgebrachter integrierter Schaltkreis (Ball Grid Array o.ä.), oder
• – größer als 200 Mikrometer, oder
• – größer als 400 Mikrometer, z.B. SMD (Surface Mounted Device).

The components preferably generate on the circuit board:

• - Height differences greater than 50 microns, for example, in flip-chip technology applied integrated circuit (Ball Grid Array or similar), or
• - greater than 200 microns, or
• - greater than 400 microns, eg SMD (Surface Mounted Device).

A method for producing the assembly does not require any additional special foils, in particular without special foils which already contain conductor tracks. Many of the required processes are also common in printed circuit board manufacturing and thus no new machines need to be purchased in this regard.

The typical height differences prevent or complicate the use of prefabricated films, because then conductor breaks or conductor cracks may occur. However, the assembly can be made with high reliability, when the insulating layer and the wiring arrangement are applied separately, resulting in the abutment of the insulating layer on the side surfaces of the components, in particular on opposite side surfaces of a component or on the opposite side surfaces of the respective component , In particular, the insulating layer is also applied to all side surfaces of a component or all components. The differences in height produced by the components to the printed circuit board are preferably less than 1 millimeter, less than 2 millimeters or less than 3 millimeters.

In particular, the assembly contains no compensation films that would have to be punched out specifically for each type of assembly, and would be used separately. In the presence of a certain play, for example, a compensation film would always rest only on one side face of a component and not on other side faces of the component. Even more so, the spacer film would not be facing away from each other side surfaces of a component, as is the case with the invention.

The electrically insulating insulating layer can be arranged directly on the components. Preferably, the insulating layer contains only one layer. Alternatively, the insulating layer contains a plurality of insulating layers.

The conductor arrangement can be arranged directly on the insulating layer. The conductor arrangement expediently contains only one metal layer or only two metal layers of different material composition.

The insulating layer can also be arranged on the side facing away from the printed circuit board on the component or on the components. This structural feature is the result of a manufacturing process in which the insulating layer is applied separately from the printed conductor arrangement, in particular by casting, dipping or laminating.

The insulating layer may be arranged on the components such that height differences greater than 50 micrometers or greater than 200 micrometers or greater than 400 micrometers also occur on a side of the insulating layer facing away from the component. The interconnect arrangement may be arranged on the insulating layer, wherein height differences greater than 50 micrometers or greater than 200 micrometers or greater than 400 micrometers also occur at the interconnect arrangement.

Thus, the insulating layer compensates for the height differences in this variant, or only partially. On the other hand, an insulating layer with a constant thickness can be used, as is the case with films.

The insulating layer may be or contain a plastic film. A plastic film can be produced in a simple manner and also easily applied to a topography, for example by using negative pressure or overpressure and temperature. Because the plastic film contains no tracks, it is particularly adaptable to the topography. It is typical when using a foil that the insulating layer is not between the component and the printed circuit board.

The insulating layer may also be a cast onto the circuit board layer, which was then cured. It is then typical that the material of the insulating layer also flows between the component and the printed circuit board and is thus arranged there.

The height differences are compensated here by the use of applied in the flowable insulating layers, so that a surface of the insulating layer, for example, height differences that are smaller than 50 microns, or at least 50 percent smaller than one through the device or through the Components generated topography.

The reduced or leveled topography facilitates the application of the conductor track arrangement, in particular for small structural widths of the conductor tracks of less than 50 micrometers. By casting or dipping larger differences in height between the circuit board and components can be compensated, in particular height differences greater than 200 microns but less than 3 millimeters, less than 2 millimeters or even less than 1 millimeter.

In this embodiment, the insulating layer can be flattened towards its edge, for example by running a casting compound or immersion liquid or by using a specially designed mold. The flattening at the edge facilitates the application of the track arrangement, because there is no step.

The printed conductors of the printed conductor arrangement can preferably be arranged in an area which corresponds to the entire area of the printed circuit board or at least 90 percent of the printed circuit board or the area of the printed circuit board to be protected. In particular, the strip conductors of the strip conductor arrangement can be arranged in meandering fashion. Meandering here means that the conductors change their direction several times by, for example, 180 degrees. However, other meandering forms may be used instead of meanders, such as e.g. Spiral curves in which a center is circled with continuously increasing radius.

The area to be protected contains the meander or several meanders, including spaces that are the same width as the meanders or in the range of 0.5 to 2.0 of this width. The meandering or spiral tracks change their ohmic resistance particularly strong, so that an unauthorized engagement easier to detect.

The insulating layer may be a first insulating layer and the wiring arrangement may be a first wiring arrangement. In addition, there may be a second insulating layer on or even on the first trace arrangement. On or at the second insulating layer may be arranged a second interconnect arrangement which is connected to the monitoring circuit or to a further monitoring circuit.

The first insulating layer may be the same material as the second insulating layer included or another material. The layer thicknesses of both layers may be the same or different.

The first wiring arrangement may contain the same material as the second wiring arrangement or another material. The layer thicknesses of both interconnects may be the same or different.

If the conductor tracks of the two conductor track arrangements meander-shaped, a particularly high protection results, in particular if the meanders of both conductor track arrangements are arranged with lateral offset from one another, so that there is no area in plan view of the conductor track arrangement in which there are only intermediate spaces, so that there unauthorized access to the circuit would be facilitated.

The interconnects of the track array may have a width in the range of 1 micron to 100 microns, preferably a width in the range of 5 microns to 100 microns. The same dimensions apply to the distances between adjacent sections of printed conductors of the printed conductor arrangement.

The printed conductors of the printed conductor arrangement can be more than 1 micrometer thick. The layer thickness can be less than 100 microns. By a sufficient layer thickness of the conductor tracks is achieved that the resistance changes greatly in case of damage to the conductor arrangement.

In addition, a circuit board is concerned with a conductor layer, which contains in the area of the entire circuit board or in an area to be protected at least one conductor with a meandering or spiral course.

The bottom, i. one side of the PCB, which is not equipped, can be easily protected against unauthorized interference. The protective metal layer can be easily produced in the manufacture of the circuit board.

The interconnect layer may be a first layer, wherein the circuit board includes a second interconnect layer, which contains in the region of the entire circuit board at least one further interconnect with a meandering or spiral course. The protective effect can be increased in a simple way.

The conductor track of the first interconnect layer can be arranged with lateral offset to the second interconnect layer, so that the protective effect is further increased. The printed circuit board offers in particular with the conductor track arrangement of the module an all-round protection against interference from above and from below.

• – auf einer bestückten Leiterplatte wird eine Leiterbahnanordnung separat ohne gleichzeitiges Anordnen einer Isolierschicht angeordnet.

Also affected is a method of manufacturing an assembly:

• - On a populated circuit board, a wiring arrangement is arranged separately without simultaneous placement of an insulating layer.

Thus, the technical effects given above for the assembly also apply to the process. In particular, no special foils have to be used on which conductor tracks are already arranged. Furthermore, for example, a spacer film is not required.

On the circuit board, at least one component or a plurality of electronic components can be arranged, wherein an insulating layer is applied to the component or to the components. On the insulating layer, an electrically conductive layer is applied. The electrically conductive layer is structured after application to the insulating layer to the conductor track arrangement.

Also for this method, the technical effects given above for the assembly apply. The insulating layer can be applied over the entire surface. Likewise, the electrically conductive layer can first be applied over the entire surface and then patterned.

At least one printed conductor of the printed conductor arrangement can be connected to a monitoring circuit arranged on the printed circuit board, which protects the assembly against unauthorized access. The monitoring circuit preferably erases safety-relevant data in a memory of the module when an unauthorized intervention is detected. The deletion takes place in particular by overwriting with a given date.

The insulating layer can be applied as a film. This is a particularly simple process because no liquids need to be used. It can be used self-adhesive film. Alternatively, an additional adhesive may be used which is applied to the film and / or to the circuit board just prior to bonding, for example, less than 10 minutes before. Many films are already coated with an adhesive layer that cures only under pressure and temperature.

The film can be applied with overpressure or underpressure and / or with over-temperature. The pressure or the temperature are here based on the room pressure or the room temperature in a production room and are in particular 1 bar or 20 degrees Celsius. The application of the film can take place, for example, in a so-called autoclave, i. in a chamber whose internal pressure and temperature are adjustable.

The overpressure may, for example, be in the range of 2 bar to 30 bar. The temperature may be, for example, in the range of 80 degrees Celsius to 190 degrees Celsius, in particular in the range of 100 degrees Celsius to 150 degrees Celsius.

Alternatively, however, the insulating layer can also be cast, spin-coated or applied by immersion. These are also methods that are also easy to perform and that lead to an additional height compensation. The drying of the still liquid or viscous insulating layer can be effected by means of an additional temperature step, e.g. at a temperature in the range of 50 degrees Celsius to 200 degrees Celsius. Potting layers can be made harder than films, e.g. with a Shore hardness in the range of 40 to 90.

The insulating layer can be opened by laser in contact areas. The laser beam of the laser penetrates the insulating layer, e.g. only in two places or in more than two places, but preferably in less than 20 places. This makes lasing very fast. Alternatively, however, a photolithographic process may be used to penetrate the insulating layer.

The wiring arrangement can be easily applied by vapor deposition or sputtering, by electroplating or by both vapor deposition or sputtering and plating. By means of vapor deposition or sputtering, for example, a layer which improves the mechanical adhesion or a base layer which can be used for a galvanization process is applied. Typical materials here are titanium, tungsten and their nitrides. Typical layer thicknesses are in the range of 1 micrometer to 10 micrometers.

The sputtering can be carried out, for example, with a plasma, wherein the temperature on the circuit board can remain below 150 degrees Celsius or even below 100 degrees Celsius. In particular, copper is suitable for electroplating, which is applied with a mask which covers areas of a base layer which are not to be electroplated for current conduction during electroplating.

For the assembly, circuit board and method, an extremely small structure for protecting an electrical circuit from external manipulation can be realized with standard electronics manufacturing processes. A high integration density is thereby made possible. The circuit contains a control unit which, for example, leads to the erasure of safety-relevant data if an increase in the resistance of a printed conductor structure is detected.

Two cases can be distinguished. In the first case, the circuit board is one-sided, e.g. on the front, stocked. In this case, in the circuit board manufacturing, a meander-shaped structure with the smallest possible pitch can be produced on the back side, and a through-hole to the front side is realized. Multi-layer metallization with staggered meanders is possible to reduce the risk of external manipulation. After the assembly, a meander-shaped conductor track structure is produced on the front as follows. The circuit is insulated with a dielectric. This may be a laminated film, a lacquer or a potting material. The dielectric may vary in thickness depending on the surface topography, e.g. ranging from 1 micron to several hundred microns.

Contacts to the backside contact and to the control structure are e.g. opened by laser ablation. The following metallic interconnect structure with contact to the back metallization can be generated additive, semi-additive or subtractive. The surface of the dielectric is, e.g. by vapor deposition, metallised, e.g. with Cu, and can be galvanically reinforced to several micrometers if required. The metal layer is structured in a meandering pattern by means of photolithography and etching technology. The traces are so close together that they are damaged by drilling in the interstices and the total resistance increases.

To minimize the risk, a multilayer structure can also be selected on the front side. In this case, the first interconnect structure is covered with a dielectric. This may again be a laminated film, a lacquer or a potting material. Contact openings to the first metal level are redone, e.g. opened by laser ablation. The surface is metallized, e.g. by means of vapor deposition, and the metal layer is structured meandering offset to the first metal level. A final encapsulation for the mechanical and chemical protection of the overall structure is possible.

In the second case, the printed circuit board can be equipped on both sides. In this case, the metal structuring process is performed on both sides as described above.

• – elektrische Schaltungen können in einem kompakten Aufbau sicher geschützt werden, was eine hohe Integrationsdichte ermöglicht,
• – der Herstellungsprozess ist mit Standardherstellungsverfahren möglich,
• – der Verguss erzeugt zusätzlich mechanische Stabilität,
• – der Aufbau erlaubt Schutz gegen optische Prüfung und chemische oder mechanische Manipulation.

The following technical effects are achieved:

• - Electrical circuits can be safely protected in a compact design, which allows a high integration density,
• - the manufacturing process is possible with standard manufacturing processes,
• The encapsulation additionally produces mechanical stability,
• - The structure allows protection against optical inspection and chemical or mechanical manipulation.

• 1. Isolation der zu schützenden Schaltung mit einem Dielektrikum. Aufbringen des Dielektrikums z.B. mittels Vergießen, Tauchen oder Laminieren einer Folie. Die Folie kann auch photostrukturierbar sein.
• 2. Öffnung der Kontakte zur Schaltung und zum Controller mittels Fotolithographie und Ätztechnik oder mittels Laserablation.
• 3. Metallisierung der Oberfläche, z.B. mittels Gasphasenabscheidung.
• 4. Optional: metallische Verstärkung durch Galvanik für bessere mechanische Stabilität.
• 5. Mäanderförmige Strukturierung der Metallschicht, z.B. mittels Fotolithographie und Ätztechnik.
• 6. Optional: Verguss zum optischen Schutz und/oder Schutz vor chemischen oder mechanischen Einflüssen.

In summary, the procedure is as follows:

• 1. Isolation of the circuit to be protected with a dielectric. Applying the dielectric, for example by means of potting, dipping or laminating a film. The film can also be photostructurable.
• 2. Opening the contacts to the circuit and the controller by means of photolithography and etching or by laser ablation.
• 3. Metallization of the surface, eg by means of vapor deposition.
• 4. Optional: metallic reinforcement by electroplating for better mechanical stability.
• 5. Meander-shaped structuring of the metal layer, eg by means of photolithography and etching technology.
• 6. Optional: Potting for optical protection and / or protection against chemical or mechanical influences.

The monitoring circuit monitors, for example, the ohmic resistance, the capacitance or the inductance of the printed conductor arrangement. In case of deviations from a desired value, an electrical signal is generated and optionally output, for example. Also, depending on the electrical signal, a deletion of data can be automatically initiated or a destruction or change of components of the circuit, for example. With the help of so-called fuses or fuses.

The energy for the monitoring circuit is stored, for example, in a storage capacitor, in a rechargeable battery or in a battery, which is located within the protective conductor track arrangement. Should the voltage in one of these energy stores fall below a predetermined value, then an automatic deletion can be initiated.

In other embodiments, temperature and / or voltages are additionally monitored by the monitoring circuit. When the temperature rises or falls above or below a predetermined temperature value or the voltage above a predetermined voltage value, a deletion is also initiated.

The security-relevant data are, for example, encryption algorithms, electronic keys for electronic encryption or decryption methods, PIN codes (Personal Identification Number), important program data, important data records, etc.

At least two contacts of the circuitry may be routed outwardly through the protective track array as external terminals.

The circuit board is also referred to as a printed circuit and consists, for example, of FR4 (epoxy resin and glass fiber fabric) or FR5 material (epoxy resin and glass fiber fabric of higher heat resistance) or of other materials such as phenolic resin, ceramic, etc.

The printed circuit board can be single-layered or multi-layered apart from protective layers for monitoring and is usually provided with copper conductive tracks. Furthermore, the layers used for the circuit can be arranged only on one side of the circuit board or on both sides of the circuit board. Typical values for the layer thickness of the printed circuit board are in the range of 100 micrometers to 500 micrometers or even up to 2 millimeters.

The printed circuit board can be fixed or rigid and thus not bendable, or not below a bending radius of, for example, 10 centimeters. Alternatively, the circuit board may be flexible, i. bendable within certain limits of e.g. a radius of curvature smaller than 5 cm.

The devices are active devices, e.g. Transistors (BT (bipolar transistor), FET (field effect transistor), diodes), or passive devices such as resistors, capacitors, coils, etc.

The components are usually soldered, e.g. In SMD technology (Surface Mounted Device) or provided with connecting legs, which penetrate the holes in the circuit board.

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the embodiments. If the term "can" is used in this application, it is both the technical possibility and the actual technical implementation.

In the following, embodiments of the invention will be explained with reference to the accompanying drawings. Show:

1 a plan view of a single-layer protective metallization or protective track arrangement,

2 a cross section of the single-layer protective metallization in one-sided assembly,

3 a cross section through another embodiment with two-sided assembly and one-layer protective metallization,

4 a plan view of an embodiment with multi-layer protective metallization,

5 a cross section through the assembly with multi-layer protective metallization,

6 a first manufacturing step in the production of a protected assembly, wherein an insulating layer has already been applied,

7 a second manufacturing stage with contact openings in the insulating layer,

8th a third production stage with a first metallization layer,

9 a fourth production stage with a galvanically reinforced metallization layer,

10 a fifth production stage with a structured metallization layer, and

11 a sixth manufacturing stage with encapsulation of the assembly.

The 1 shows a plan view of an assembly 10 comprising a single-layer protective metallization or protective trace arrangement 12 contains.

• – eine Leiterplatte 14, die auch als Schaltungsträger bezeichnet werden kann,
• – eine elektrisch isolierende Isolierschicht 16,
• – zwei Kontaktabschnitte 18 und 20, welche die Isolierschicht 16 durchdringen und an den beiden Enden der Leiterbahnanordnung 12 ausgebildet sind.

The assembly 10 also contains:

• - a circuit board 14 , which can also be called a circuit carrier,
• - An electrically insulating insulating layer 16 .
• - two contact sections 18 and 20 which the insulating layer 16 penetrate and at the two ends of the track arrangement 12 are formed.

The track layout 12 contains a meandering track, which is a protected area of the circuit board 14 covered. Alternatively, the area of the entire circuit board 14 from the track layout 12 covered. In another embodiment, the wiring arrangement 12 for example, a spiral course.

The circuit board 14 has a rectangular plan in the embodiment. Alternatively, the circuit board has 14 a square floor plan or another floor plan.

The electrically insulating insulating layer 16 covered in the 1 not shown components of the module 10 , These components form a utility circuit assembly 10 and a monitoring circuit.

• – eine Schaltung zur Eingabe und optional Anzeige einer PIN,
• – eine Schaltung die einen Prozessor und einen elektronischen Speicher enthält mit Befehlen und Daten für den Prozessor, insbesondere eine Verschlüsselungsschaltung,
• – eine Sendeeinheit für ein Datenübertragungsverfahren bspw. ein Funkübertragungsverfahren, insbesondere für digitale Daten, oder
• – eine Empfangseinheit für ein Datenübertragungsverfahren bspw. ein Funkübertragungsverfahren, insbesondere für digitale Daten.

The useful circuit is for example:

• A circuit for input and optionally display of a PIN,
• A circuit containing a processor and an electronic memory with instructions and data for the processor, in particular an encryption circuit,
• A transmission unit for a data transmission method, for example a radio transmission method, in particular for digital data, or
• A receiving unit for a data transmission method, for example a radio transmission method, in particular for digital data.

In all cases, the purpose is to protect the circuit from unauthorized access, for example to prevent manipulation or to not disclose the structure of the circuit, for example software algorithms or hardware circuits.

• – eine Widerstandsüberwachung, deren Eingänge an die Leiterbahnanordnung 14 angeschlossen sind,
• – eine Steuerschaltung, die beim Überschreiten oder Unterschreiten eines oder mehrerer Sollwerte ein Ausgangssignal erzeugt, das bspw. zum Löschen von Daten, zum Beeinflussen der Schaltung oder zur Abgabe eines elektronischen Warnsignals verwendet wird, und
• – einen optionalen Energiespeicher.

The monitoring circuit contains, for example:

• - A resistance monitoring, whose inputs to the track arrangement 14 are connected,
• - A control circuit which generates an output signal when exceeding or falling below one or more setpoints, which is used, for example, for deleting data, for influencing the circuit or for delivering an electronic warning signal, and
• - an optional energy storage.

The control circuit is analog or digital, e.g. using a switching network or using a monitoring processor or a processor also used by the user circuit. In particular, the embodiments mentioned for the monitoring circuit in the introduction, e.g. additional temperature and voltage monitoring.

Without energy storage in the module 10 Tampering in the presence of an external voltage can be prevented. Optionally, the deletion of the data can be carried out in the event of loss of voltage, for example, if the monitoring has not been properly disabled before.

With energy storage in the module 10 it is also possible to protect the circuit arrangement without concerns an external voltage, for example. During transport or during a break in operation of a device.

The 2 shows a cross section through the assembly 10 , the one-layer protective metallization or protective track arrangement 12 contains. The circuit board 12 is on its bottom side over the entire surface with a meandering track arrangement 50 Mistake. vias 52 and 54 that the circuit board 12 penetrate, connect the trace arrangement 50 with the interconnect arrangement 12 or alternatively directly to the monitoring circuit 56 , eg a controller based on, for example, a microprocessor.

components 58 . 60 a circuit to be monitored 62 are in the left part of the 2 shown. The component 58 is, for example, a transistor or a diode. The component 60 is, for example, a resistance. Alternatively or additionally, the module to be protected contains 62 also an integrated circuit.

The monitoring circuit 56 can in another embodiment, which otherwise is similar to the embodiment shown, also below the protective trace assembly 12 be arranged, which further increases the protection, ie the track arrangement 12 then covers, for example, the entire circuit board 14 ,

A dummy component 64 serves to connect the second end of the track arrangement 12 to the monitoring circuit 56 , In place of the dummy device 64 In an otherwise similar embodiment, a direct contacting of the circuit board 12 used. The monitoring circuit is then on or in the circuit board 12 running conductor to the feedthrough 20 connected.

In the 2 In addition, a height H is shown to be the highest component 64 . 58 . 60 the assembly 10 over the circuit board 12 protrudes. This height H is, for example, in the range of 50 micrometers to 500 micrometers. Alternatively, the height H may be larger or smaller.

One in the assembly 10 containing potting compound 66 protects the assembly 10 additionally against unauthorized interventions.

The protective trace arrangement 50 does not attach to the protective trace assembly in another embodiment 12 connected but through the monitoring circuit 56 independent of the protection trace arrangement 12 supervised.

The 3 shows a cross section through an assembly 100 with two-sided assembly of a printed circuit board 114 and single-layer protective metallization or protective trace arrangement 112 ,

• – eine elektrisch isolierende Isolierschicht 116 auf der Oberseite,
• – zwei Kontaktabschnitte 118 und 120, welche die Isolierschicht 116 durchdringen und an den beiden Enden der Leiterbahnanordnung 112 ausgebildet sind,
• – eine Überwachungsschaltung 156, die in ihrem Aufbau und in ihrer Funktion der Überwachungsschaltung 56 entspricht,
• – Bauelemente 158 und 160, die den Bauelementen 58 und 60 entsprechen und die Bestandteil einer Nutzschaltung 162 sind,
• – ein optionales Dummybauelement 164, das dem Dummybauelement 64 entspricht,
• – eine der Vergussmasse 66 entsprechende Vergussmasse 166.

The assembly 100 also contains:

• - An electrically insulating insulating layer 116 on the top,
• - two contact sections 118 and 120 which the insulating layer 116 penetrate and at the two ends of the track arrangement 112 are trained
• A monitoring circuit 156 , in their construction and in their function of the monitoring circuit 56 corresponds,
• - Components 158 and 160 that the construction elements 58 and 60 correspond and are part of a utility circuit 162 are,
• - An optional dummy component 164 that the dummy device 64 corresponds,
• - one of the potting compound 66 corresponding potting compound 166 ,

A height H1 corresponds to the height H. At the bottom of the circuit board 114 If there is a two-sided assembly, there is now another use circuit 101 passing through another track layout 102 Covered with a meandering course and thereby protected. Alternatively, the payloads are 162 and 101 also parts of a common user circuit.

The utility circuit 101 contains components 104 . 106 and an optional dummy device 108 that the dummy device 164 equivalent. A potting compound 110 protects the assembly 100 additionally against interventions from below.

The 4 shows a plan view of an assembly 200 with multilayer protective metallization.

• – eine erste Schutz-Leiterbahnanordnung 212, die unter einer zweiten Schutz-Leiterbahnanordnung 224 liegt,
• – eine Isolierschicht 226, die zwischen den beiden Schutz-Leiterbahnanordnungen 212 und 222 angeordnet ist,
• – eine Leiterplatte 214, die auch als Schaltungsträger bezeichnet werden kann,
• – eine in 4 nicht dargestellte elektrisch isolierende Isolierschicht 216,
• – zwei Kontaktabschnitte 218 und 220, welche die Isolierschicht 216 durchdringen und an den beiden Enden der unteren Schutz-Leiterbahnanordnung 212 ausgebildet sind, und
• – zwei Kontaktabschnitte 221a und 221b an den Enden der oberen Schutz-Leiterbahnanordnung 222.

The assembly 200 includes:

• A first protection trace arrangement 212 that under a second protective track arrangement 224 lies,
• - an insulating layer 226 that exist between the two protective conductor tracks 212 and 222 is arranged
• - a circuit board 214 , which can also be called a circuit carrier,
• - one in 4 not shown electrically insulating insulating layer 216 .
• - two contact sections 218 and 220 which the insulating layer 216 penetrate and at the two ends of the lower protective trace assembly 212 are trained, and
• - two contact sections 221a and 221b at the ends of the upper protection trace assembly 222 ,

The protective conductor tracks 212 and 222 are like the protection track layout 12 built up. The circuit board 214 is like the circuit board 14 built up. The insulating layers 216 . 226 are like the insulating layer 16 built up. For the contact sections 218 and 220 that applies to the contact portions 18 . 20 Said. The contact sections 221a and 221b serve to connect the upper protective conductor arrangement 222 to the monitoring circuit of the module 200 ,

By in the 4 and 5 shown assembly 200 the protection is increased because at least two protection track assemblies 212 and 222 to penetrate are at interventions from above. The same applies to interventions from below, as on the basis of 5 will be explained in more detail.

Also the assembly 200 contains an in 4 not shown monitoring circuit, the resistance changes or the change of other characteristic electrical parameters of the protective conductor track assemblies 212 and 222 capture and take appropriate action when changes are detected, such as deleting relevant data.

• – eine Überwachungsschaltung 256, die der Überwachungsschaltung 56 entspricht,
• – Bauelemente 258 und 260, die den Bauelementen 58 und 56 entsprechen und die Bestandteil einer Nutzschaltung 262 sind,
• – ein optionales Dummybauelement 264, das dem Dummybauelement 64 entspricht,
• – eine Vergussmasse 270, die einen zusätzlichen Schutz gegen Eingriffe von oben bietet,
• – eine erste untere Schutz-Leiterbahnanordnung 250, die der Schutz-Leiterbahnanordnung 50 entspricht und insbesondere eine entlang eines Mäanders oder einer Spirale (kreisförmig, quadratisch oder rechteckförmig) verlaufende Leitbahn enthält,
• – eine zweite untere Schutz-Leiterbahnanordnung 255 an der Unterseite der Leiterplatte 214,
• – Durchkontaktierungen 252 und 254, die den Durchkontaktierungen 52 und 54 entsprechen und die aber zusätzlich auch die zweite Schutz-Leiterbahnanordnung 255 an die Überwachungsschaltung 256 anschließen.

The 5 shows a cross section through the assembly 200 with multilayer protective metallization or protective conductor track arrangements 212 and 222 , According to 5 contains the assembly 200 Farther:

• A monitoring circuit 256 that the monitoring circuit 56 corresponds,
• - Components 258 and 260 that the construction elements 58 and 56 correspond and are part of a utility circuit 262 are,
• - An optional dummy component 264 that the dummy device 64 corresponds,
• - a potting compound 270 which offers additional protection against interference from above,
• - A first lower protective conductor arrangement 250 that of the protective trace assembly 50 corresponds and in particular contains along along a meander or a spiral (circular, square or rectangular) running track,
• - A second lower protective conductor arrangement 255 at the bottom of the circuit board 214 .
• - vias 252 and 254 that the vias 52 and 54 correspond and but in addition also the second protective conductor arrangement 255 to the monitoring circuit 256 connect.

The contact sections 221a and 221b are not in the cross section that is in the 5 is shown, but are also on interconnects of the circuit board 214 with the monitoring circuit 256 connected.

A lateral offset V between the protective conductor tracks 212 and 222 prevents there being gaps in which, when viewed from above, the assembly 200 no protective conductor tracks are arranged. There is also one in 5 but not shown lateral offset between the protective track assemblies 250 and 255 , which considerably complicates an intervention from below.

The circuit boards 14 and 214 are also separately protected, that is, without assembly with components and without the upper protective conductor arrangement 12 or the protective conductor track arrangements 212 and 222 available.

In another embodiment, separate vias are also made for the connection of the protection trace assemblies 250 and 255 used. The protective trace arrangement 250 and 255 can also from the monitoring circuit 256 regardless of the protection track layouts 212 and 222 be monitored.

In other embodiments, both sides are populated and in each case two or more than two protective conductor arrangement are used above and below.

Also at the in 5 illustrated assembly or in the two-sided assembly mentioned in the previous paragraph, the monitoring circuit can be covered by the protective track assemblies to increase safety. For double-sided assembly, the monitoring circuit 156 also on both sides of the circuit board 114 to be ordered.

• – ein Leiterplattenhersteller hat die Leiterplatte 14 nach Kundenwunsch gefertigt, wobei auch schon die Schutz-Leiterbahnanordnung 50 sowie die Durchkontaktierungen 52 und 54 mit den üblichen Verfahren der Leiterplattentechnik hergestellt worden sind, bspw. unter Einsatz von fotolithografischen Verfahren und von Ätzprozessen,
• – die Leiterplatte 14 wurde bestückt mit den Bauelementen der Überwachungsschaltung 56 sowie mit den Bauelementen 58 und 60 der Nutzschaltung 62 sowie weiterhin ggf. mit dem optionalen Dummybauelement 64,
• – anschließend wurde die Isolierschicht 16 selektiv aufgebracht, bspw. mit einem Lift-Off-Verfahren. Alternativ wird die Isolierschicht 16 ganzflächig aufgebracht und mit einem fotolithografischen Verfahren strukturiert, bspw. gemeinsam mit der Ausbildung von Löchern für die Kontaktabschnitte 18 und 20.

The 6 shows a first manufacturing step in the manufacture of the protected assembly 10 already proceeding as follows:

• - A PCB manufacturer has the PCB 14 manufactured according to customer requirements, whereby even the protective track arrangement 50 as well as the vias 52 and 54 using the usual methods of printed circuit board technology, for example using photolithographic processes and etching processes,
• - the circuit board 14 was equipped with the components of the monitoring circuit 56 as well as with the components 58 and 60 the utility circuit 62 as well as possibly with the optional dummy component 64 .
• - then the insulating layer 16 selectively applied, for example. With a lift-off method. Alternatively, the insulating layer 16 Applied over the entire surface and structured with a photolithographic process, for example. Together with the formation of holes for the contact sections 18 and 20 ,

The insulating layer 16 was laminated, for example, using pressure and temperature, for example. In the range of 2 bar to 30 bar or in the range of 80 degrees Celsius to 190 degrees Celsius. As a material for the insulating layer is polyimide or Epoxy suitable. An optional additional adhesive layer or a self-adhesive film or a double-sided adhesive additional foil facilitates the application. It is possible to use the foils customary in printed circuit board technology. The thickness of the film is, for example, in the range of 20 micrometers to 100 micrometers or in the range of 40 micrometers to 60 micrometers.

Alternatively, the insulating layer 16 applied by potting, spin-coating or dipping processes, whereby at the edge of the insulating layer 16 does not form a stage. Again, suitable as a material for the insulating polyimide or epoxy. The still viscous insulating layer is dried in air or by additional temperature processes, for example. At a temperature in the range of 80 degrees Celsius to 150 degrees Celsius.

The 7 shows a second manufacturing stage, in which already contact openings 300 . 302 and 304 in the insulating layer 16 For example, by laser pulses or by using a photolithographic process followed by dry or wet etching. Alternatively, for the insulating layer 16 Also, a photosensitive sheet may be used, which is then selectively exposed and developed, and of the areas as an insulating layer 16 in the assembly 10 remain.

The contact opening 300 serves to accommodate the contact section 18 , Accordingly, the contact opening is used 304 for receiving the contact section 20 , The contact opening 302 takes part of the via 52 on.

The 8th shows a third manufacturing stage with a first metallization layer 310 the protective trace arrangement 12 , The metallization layer 310 is applied, for example, from the gas phase or sputtered (cathode sputtering) at temperatures at the insulating layer of, for example, only up to 80 degrees Celsius. The metallization layer 310 forms an adhesion-promoting layer and can serve as a base layer for the power supply in a galvanic process, possibly reinforced by a thin layer of copper vapor deposited or sputtered on. As a material of the metallization layer 310 For example, titanium, copper, tantalum, tungsten, chromium, a combination of these materials or their nitrides is suitable. Also a multilayer structure of the metallization layer 310 is possible. The layer thickness of the metallization layer 310 ranges from 5 microns to 15 microns. Typical values for a vapor deposition are 50 nanometers to 5 micrometers. The thicker the layer becomes, the more expensive it becomes. Theoretically, 15 micron thick layers can also be achieved by vapor deposition. If thicker layers (5 microns to 15 microns) are desired, the thin film process is typically combined with electrodeposition.

When applying the metallization layer 310 arise the contact sections 18 and 20 , as well as an upper part of the via 52 , The via 54 is at the edge of the insulating layer 16 also contacted by the first layer 310 for the production of the protective conductor track arrangement 12 ,

The 9 shows a fourth manufacturing stage with a galvanized metallization layer 320 which later the upper part of the protective track arrangement 12 forms and thus later the protective trace arrangement 12 reinforced, in terms of mechanical stability. The metallization layer 320 is, for example, a copper layer applied over the entire surface, which is subsequently patterned in a photolithographic process. Alternatively, a semi-additive method is used in which a photomask is applied to the metallization layer 310 is applied, whereupon subsequently the metallization layer 320 already applied in a structured manner, for example by electroplating.

The layer thickness of the metallization layer 320 is, for example, in the range of 20 microns to 50 microns. In addition to increasing the mechanical stability leads the metallization layer 320 also to a significant reduction of the ohmic resistance of the protective circuit arrangement 12 which accommodates the easier detection of interruptions.

Further electrically conductive protective layers can be applied. Purification steps between the process steps have not been discussed separately, especially back sputtering steps to achieve clean surfaces.

The 10 shows a fifth production step with structured metallization layer 310 . 320 causing the protective trace assembly 12 is produced. For structuring, for example, a photolithographic process using a photoresist or a photofoil is used. For structuring, a wet-chemical or dry-chemical etching process is then used. The width of the conductor track or the conductor tracks of the protective conductor arrangement 12 is, for example, in the range of 50 microns to 100 microns, so that the patterning of copper is not a problem. In particular, the methods used from the production of printed circuit boards are known and optimized.

The 11 shows a sixth production stage with already applied potting compound 66 the assembly 10 , The potting compound 66 contains, for example, an epoxide. Black or dark fillers make optical inspection of the assembly difficult 10 , When potting a wall can laterally run away the potting compound 66 prevent. Alternatively, a mold may be used in which the circuit board 14 is placed.

Instead of potting, a so-called mold process or injection molding process can be used in which the potting compound is applied under pressure and temperature with the aid of a mold.

The assemblies 100 and 200 become analogous to the module 10 manufactured, ie in particular using the explained methods, materials, layer thicknesses and manufacturing processes.

In other exemplary embodiments, three protective conductor track arrangements or more than three protective conductor track arrangements, in particular with a meandering or spiral course, are arranged one above the other in order to further complicate manipulation. In further embodiments, the protective measures are combined with other protective measures.

The embodiments are not to scale and are not restrictive. Modifications in the context of expert action are possible. Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (16)

Electronic assembly ( 10 . 100 . 200 ), with a printed circuit board ( 14 . 114 . 214 ), are arranged on or in the at least two interconnects or a plurality of interconnects, with at least one electronic component ( 58 ) or a plurality of components ( 58 . 60 ), the one on the circuit board ( 14 . 114 . 214 ) arranged electronic circuit ( 62 ), with one the circuit ( 62 ) covering conductor track arrangement ( 12 ), and with a monitoring circuit ( 56 ) whose inputs are connected to the track arrangement ( 12 ) are electrically conductively connected, wherein an electrically insulating insulating layer ( 16 ) on side surfaces of the component ( 58 ) or on side surfaces of the respective components ( 56 . 58 ), and wherein the track arrangement ( 12 ) on the insulating layer ( 16 ) is arranged. Assembly ( 10 . 100 . 200 ) according to claim 1, wherein the insulating layer also on the circuit board ( 14 . 114 . 214 ) facing away from the component ( 58 ) or on the components ( 58 . 60 ) is arranged. Assembly ( 10 . 100 . 200 ) according to claim 1 or 2, wherein the insulating layer ( 16 ) on the components ( 58 . 60 ) is arranged so that at one of the components ( 58 . 60 ) facing away from the insulating layer ( 16 ) Height differences (H) greater than 50 microns or greater than 200 microns or greater than 400 microns occur, wherein the track arrangement ( 12 ) is arranged on the insulating layer, and wherein on the interconnect arrangement ( 12 ) Height differences greater than 50 microns or greater than 200 microns or greater than 400 microns occur. Assembly ( 10 . 100 . 200 ) according to claim 3, wherein the insulating layer ( 16 ) is or contains a plastic film. Assembly ( 10 . 100 . 200 ) according to claim 1 or 2, wherein the insulating layer ( 16 ) one on the circuit board ( 14 . 114 . 214 ) is cast layer. Printed circuit board ( 14 . 114 . 214 ) with a conductor track position ( 12 ) in the area of the entire circuit board ( 14 . 114 . 214 ) or in an area to be protected at least one conductor track with a meandering or spiral course contains. Printed circuit board ( 14 . 114 . 214 ) according to claim 6, wherein the interconnect layer ( 250 ) is a first layer, and wherein the printed circuit board ( 214 ) a second interconnect layer ( 255 ) in the area of the entire circuit board ( 214 ) or in an area to be protected at least one further conductor track with a meandering or spiral course contains. Printed circuit board ( 14 . 114 . 214 ) according to claim 7, wherein the conductor track of the first interconnect layer ( 250 ) with lateral offset to the conductor track of the second interconnect layer ( 255 ) is arranged. Method for producing an assembly ( 10 . 100 . 200 ), wherein on a populated printed circuit board ( 14 . 114 . 214 ) a track arrangement ( 12 ) separately without simultaneous placement of an insulating layer ( 16 ) is arranged. Method according to claim 9, wherein on the printed circuit board ( 14 . 114 . 214 ) at least one component ( 58 ) or a plurality of electronic components ( 58 . 60 ) are arranged, wherein on the component ( 58 ) or on the components ( 58 . 60 ) an insulating layer ( 16 ) is applied, being on the insulating layer ( 16 ) an electrically conductive layer ( 310 . 320 ), and wherein the electrically conductive layer ( 310 . 320 ) after application to the insulating layer ( 16 ) is structured to the interconnect arrangement ( 12 ). Method according to claim 10, wherein at least one printed conductor of the printed conductor arrangement ( 12 ) with one on the printed circuit board ( 14 . 114 . 214 ) arranged monitoring circuit ( 56 ), which is the assembly ( 10 . 100 . 200 ) protects against unauthorized access. Method according to claim 10 or 11, wherein the insulating layer ( 16 ) is applied as a film. The method of claim 12, wherein the film ( 16 ) is applied with overpressure or underpressure and / or with excess temperature. Method according to claim 10 or 11, wherein the insulating layer ( 16 ) is poured on, spun on or applied by dipping. Method according to one of claims 10 to 14, wherein the insulating layer ( 16 ) is opened by laser in contact areas. Method according to one of claims 9 to 15, wherein the track arrangement ( 12 ) by vapor deposition or sputtering, by electroplating or by both vapor deposition or sputtering and plating.

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