Sensor device and method for producing a sensor device

Abstract

A sensor device (1) is described, comprising: - a ceramic base substrate (2); - at least one sensor chip (3) directly connected to the substrate (2) in horizontal position by means of a bonding material (5); - a first contact element (8a) and a second contact element (8b) adapted and arranged to function as external electrodes (6) of the sensor device (1), wherein the first contact element (8a) comprises a contact member (11) adapted and arranged to electrically contact the sensor chip (3) by means of the bonding material (5); and - an insulator (7) enclosing at least some parts of the contact elements (8a, 8b) and the sensor chip (3), wherein the substrate (2) is mostly free of material of the insulator (7). Furthermore, a method for producing a sensor device is described.

Description

[0001] The present invention relates to a sensor device, for example for measuring temperature. Furthermore, the present invention relates to a method for producing a sensor device, for example for measuring temperature.

[0002] The temperature surface sensitivity in NTC (negative temperature coefficient) sensor designs cannot be obtained in an optimal way due to the position constraints of the sensing element, mainly at the vertical position. This is exacerbated by the fact that, in order to meet the high voltage resistance and moisture resistance performance requirements, a reinforced packaging is required.

[0003] Furthermore, achieving high operating temperatures up to 200°C is challenging due to the very limited choice of available materials. Known sensor designs do not solve all the described challenges in terms of small size, cost- comprehensive design and packaging solutions suitable for mass production.

[0004] Document US 2018 / 122537 A describes a temperature sensor comprising a carrier substrate, an NTC element, a pair of electrodes, and a metal block electrically contacting the NTC element and forming an external electrode on the surface of an insulating housing.

[0005] Document WO 96 / 04536 A1 describes a temperature sensor having a housing made of an insulating material, a thermally conductive element, a thermosensitive sensor chip arranged in the region of the thermally conductive element and / or pressed against the thermally conductive element, and at least two connecting elements. At least one electrically conductive pin is provided. One end of the electrically conductive pin exerts a pressure on the sensor chip directed against the thermally conductive element, and the other end of the electrically conductive pin is supported on the end of one of the two connecting elements located inside the housing or on the end of a separate fixing portion of a spring.

[0006] Document US 2008 / 308886 A describes a semiconductor sensor comprising a carrier having an electrically conductive structure with pads and leads protruding from a resin package, a wire.

[0007] Document US 2017 / 352603 A describes a sensor chip package with a ceramic carrier, an electrically conductive structure with pads and leads, and a resin package.

[0008] Document KR 2005 / 0112719 A describes an arrangement of a chip thermistor soldered to a bent lead frame.

[0009] Document US 2018 / 0306646 AA describes a sensor device comprising a sensor chip having at least one electrode and at least one contact element shaped as a metal bracket. The contact element is arranged and configured for wireless contact of the sensor chip.

[0010] It is an object of the present disclosure to solve the above-mentioned problems. This object is solved by the sensor device and the method according to the independent claims.

[0011] According to a first aspect of the present disclosure, a sensor device is provided. The sensor device can be adapted to measure temperature. The sensor device can be a temperature sensor device. The sensor device can be adapted to operate at high temperatures of up to 200°C.

[0012] The sensor device comprises a substrate. The substrate can be ceramic-based. In other words, the substrate can comprise a ceramic material. The substrate can be a high-performance ceramic substrate which is excellent in terms of electrical insulation and moisture resistance properties and has a high thermal conductivity. The substrate can further be adapted and arranged to mechanically stabilize further components of the sensor device and to electrically insulate said further components.

[0013] For example, the ceramic material can comprise AI2O3. AI2O3 (alumina) ceramics are commonly used due to their well-known properties, i.e. high thermal conductivity, high electrical insulation, low thermal expansion. However, alternative materials of both oxide and non-oxide ceramics can also be used. Silicate ceramics or even ZTA (zirconia toughened alumina) which is of higher mechanical strength are examples of oxide ceramics. Alternatively, non-oxide ceramics such as AI N (aluminum nitride) ceramics or Si3N4 (silicon nitride) ceramics can be used.

[0014] The sensor device further comprises at least one sensor chip. The sensor chip can be an NTC sensor chip. Alternatively, the sensor chip can be a PTC (positive temperature coefficient) sensor chip. The sensor device can comprise more than one sensor chip. For example, the sensor device can comprise a combination of NTC sensor chips and PTC sensor chips.

[0015] The sensor chip is particularly an electrode arranged on a surface, e.g. a lower surface, of the sensor chip, which is directly connected to the substrate in horizontal position. By "horizontal" it is meant that the surface of the sensor chip having the largest extension is connected to the substrate. This increases the surface sensitivity of the sensor chip. Although the sensor chip 3 is directly bonded, the sensor chip 3 is still completely isolated due to the excellent electrical insulation and moisture resistance properties of the ceramic substrate.

[0016] The sensor chip is connected to the substrate by means of a bonding material. In other words, the sensor chip is bonded to the substrate, particularly to a metallized pad of the substrate. The bonding material can be a high melting point solder having an operating temperature of more than 200°C. The bonding material can be lead-containing or lead-free. For example, a suitable material can be Pb 97.5 SnAg 1.5 , SnAg 0.3 Cu0.7 or Sn 90 Sb 10 .

[0017] The sensor device further comprises a first contact element and a second contact element. The contact elements comprise, for example, copper, brass or phosphor bronze. The contact elements are adapted and arranged to function as external electrodes of the sensor device. This means that the contact elements enable an electrical connection of the sensor device from the outside of the sensor device.

[0018] The contact elements are electrically and mechanically connected to the substrate, in particular to the metallized pads of the substrate. The contact elements are connected to the substrate by means of the aforementioned bonding material.

[0019] The first contact element further comprises a contact member. The first contact element and the contact member can be integrally formed. The contact member is adapted and arranged to electrically contact the sensor chip by means of the bonding material. In other words, the contact member is bonded to the sensor chip, in particular to an electrode arranged on a surface, for example the upper surface, of the sensor chip, by means of the aforementioned bonding material.

[0020] The sensor device further comprises an insulator. The insulator is designed to electrically insulate the sensor device and to protect the sensor device from the environment. The insulator completely encloses the sensor chip. The insulator encloses at least some portions of the contact elements. For example, the insulator completely covers the contact member. However, the substrate is mostly free of material of the insulator.

[0021] Due to the specific design and composition of the sensor device, the sensor device provides a high performance thermal coupling for excellent surface sensitivity. In other words, the sensor device is a fast responding sensor. Furthermore, the sensor device comprises a high voltage resistance and is able to operate at temperatures up to 200°C. Moreover, the sensor device comprises a compact and small size and is suitable for mass production. In summary, a very robust, fast and cost-effective sensor device is provided which is very flexible in use.

[0022] According to one embodiment, the material of the insulator is adapted and arranged to increase the electrical resistance and the moisture resistance of the sensor device. The insulating material of the insulator comprises a thermoset epoxy material having a glass transition temperature close to 200°C.

[0023] The combination between the ceramic substrate and the insulating material meets the requirements of a high voltage resistance, a moisture resistance and a high operating temperature (up to 200°C). Furthermore, the combination provides a specific design for a compact and small sensor device. In addition, the sensor device is very cost-effective with the specific selection of materials and well-known production processes. The materials are selected to achieve a green product which complies with the ROHS, lead-free and halogen-free requirements.

[0024] The material of the insulator is arranged directly on the upper surface of the substrate. In particular, the material of the insulator covers at least some portions of the surface of the substrate, i.e. the upper surface of the substrate, which are connected with the sensor chip and the contact elements.

[0025] The connection between the sensor chip and the substrate and the connection between the contact elements and the substrate are encapsulated by the material of the insulator. The side surface and the lower surface of the substrate are free of the material of the insulator. This free area of the substrate serves as a sensing portion of the sensor device. Also, likewise, a circumferential edge area of the upper surface of the substrate can be free of the material of the insulator.

[0026] According to one embodiment, the respective contact element is U-shaped. In particular, the contact element comprises a U-shaped bracket or spring member. In other words, the respective contact element can comprise two legs connected by a stem or bridge. The legs and the stem are integrally formed. This means that the first leg is incorporated into the stem and the stem is incorporated into the second leg of the respective contact element. In other words, the legs and the stem can be made in one piece.

[0027] The specific shape of the contact elements provides a good solderability, a small mass density and a small mechanical stress to the sensor chip during the bonding process.

[0028] According to one embodiment, the individual contact elements comprise a first contact area. The first contact area can be formed / provided by one of the two legs of the respective U-shaped spring member. The first contact area is free of the insulating material of the body. In other words, the first contact area protrudes from the insulating material of the body. The first contact area serves as an external electrode of the sensor device. In this way, an efficient further processing of the sensor device is enabled.

[0029] According to one embodiment, the individual contact elements comprise a second contact area. The second contact area is formed by the other of the two legs of the respective U-shaped spring member. The second contact area is completely enclosed by the insulating material of the body. In other words, the second contact area is arranged within the insulator of the sensor device.

[0030] The second contact area is bonded to the metallized pads of the substrate to establish an electrical contact between the contact elements and the substrate. In this way, an efficient electrical connection between the substrate and the contact elements is enabled. Furthermore, the specific shape of the contact elements accumulates less heat, for example, compared to a metal block. This will result in more precise measurement results due to a fast dissipation.

[0031] According to one embodiment, the contact member is designed to reduce mechanical stress between the first contact element and the sensor chip. The contact member can comprise a flat shape or an arcuate shape. The contact member can comprise an additional spring arranged at the free end of the second contact area of the first contact element. The contact member is arranged within the insulating material of the body. The specific shape of the contact member allows the sensor chip to be used as a sensing element without wire bonding, to achieve a more robust connection and a very economic solution.

[0032] According to another aspect, a method for producing a sensor device is described. The sensor device can be the aforementioned sensor device. All features described in connection with the sensor device apply to the method, and the method applies to all features described in connection with the sensor device.

[0033] The method comprises the following steps:

[0034] A) Providing a ceramic base substrate and arranging a plurality of metallized pads on a surface, in particular on an upper surface, of the substrate. The substrate can be a high-performance ceramic which is excellent in terms of electrical insulation and moisture resistance properties and has a high thermal conductivity. The substrate can comprise AI2O3, ZTA, silicate, AIN or Si3N4ceramics.

[0035] B) Providing a joining material. The joining material can comprise a solder paste. The joining material can be a high-melting solder having an operating temperature of more than 200°C. The joining material can be lead-containing or lead-free. An example of a high-melting solder but lead-containing material can be Pb 97.5 SnAg 1.5 . Alternatively, SnAg 0.3 Cu 0.7 or Sn 90 Sb 10 can be an option for lead-free materials and high-temperature soldering materials for applications above 200°C.

[0036] The joining material can be applied in a dot-like manner. In particular, one respective dot of the joining material can be applied to a portion of the metallized pads. The joining material can be dispensed or screen-printed onto the metallized pads.

[0037] C) Providing a plurality of sensor chips. Each sensor chip can comprise electrodes arranged on an upper side and on a lower side (upper and lower electrodes) of the sensor chip. The sensor chips can comprise NTC sensor chips and / or PTC sensor chips.

[0038] The sensor chips can be placed on the substrate and, in particular, on the joining material applied on the metallized pads of the substrate. In particular, the tip of each sensor chip is placed on the dot-like joining material. The sensor chips are placed such that each sensor chip is arranged in a horizontal position on the substrate.

[0039] D) performing reflow soldering to electrically connect one of the electrodes of the respective sensor chip (i.e. the lower electrode) with the substrate such that the respective sensor chip is arranged in a horizontal position on the substrate.

[0040] E) providing the bonding material again. The bonding material can be the same bonding material as applied in step B).

[0041] The bonding material can be applied in dots. In particular, one respective dot of the bonding material can be applied onto the upper electrode of the respective sensor chip. Further dots of the bonding material can be applied onto at least some portions of the metallized pads. In particular, two dots of the bonding material can be applied to two of the metallized pads to realize one final sensor device. The bonding material can be dispensed or screen printed onto the metallized pads and the sensor chip.

[0042] F) providing a plurality of first and second contact elements. Each contact element comprises a first contact area and a second contact area. The first contact area is adapted to serve as an external electrode of the sensor device. The second contact area is adapted to electrically connect the substrate to the respective contact element. Each first contact element comprises a contact member. The contact member is adapted and arranged to establish an electrical connection between the sensor chip and the first contact element.

[0043] The contact elements are placed on the substrate such that one respective second contact area is arranged on one respective dot of the bonding material arranged on the metallized pads. Further, the contact elements are placed such that the respective contact member is arranged on the dot-like bonding material provided on the upper electrode of the sensor chip.

[0044] G) performing reflow soldering to electrically connect the second contact areas with the metallized pads and to electrically connect the contact members with the other one of the electrodes of the sensor chip (i.e. the upper electrode).

[0045] H) performing encapsulation. This step comprises providing an insulating material and molding an insulator from the insulating material. The insulating material is molded such that it only covers some portions of the surface of the substrate, i.e. the upper surface of the substrate, to which the sensor chips and the second contact areas are connected.

[0046] The insulating material is arranged to completely encapsulate the connections between the contact elements and the substrate and the connections between the sensor chips and the substrate. The insulating material is further arranged to completely cover the sensor chips, the second contact areas and the contact members. The first contact areas as well as the lateral and lower surfaces of the substrate remain free of the insulating material. Further, some portions of the upper surface of the substrate, e.g. the circumferential edge region, can also remain free of the insulating material.

[0047] The insulating material comprises a thermoset epoxy material having a glass transition temperature close to 200°C.

[0048] I) singulation. This step comprises cutting the substrate into individual parts to provide a plurality of sensor devices.

[0049] By means of the described method, a fast and cost-effective process for producing a plurality of sensor devices having a high surface sensitivity, small size, high voltage resistance, moisture resistance and high operating temperatures up to 200°C is provided. The sensor devices with two robust electrodes (contact elements) enable easy further processing and provide optimal system integration.

[0050] Further features, improvements and aptitudes become apparent from the following description of exemplary embodiments in connection with the attached drawings.

[0051] Figure 1 A cross-sectional side view of a sensor device according to a first embodiment is schematically shown,

[0052] Figure 2 A cross-sectional side view of a sensor device according to a second embodiment is schematically shown,

[0053] Figure 3 A cross-sectional side view of a sensor device according to another embodiment is schematically shown,

[0054] Figure 4 A top view of a multi-sensor device package is schematically shown;

[0055] Figure 5 A top view of a multi-sensor device package according to another embodiment is schematically shown.

[0056] In the drawings, elements of identical structure and / or function can be denoted by identical reference signs. It is understood that the embodiments shown in the drawings are representational and not necessarily drawn to scale.

[0057] Figure 1 A sensor device 1 for temperature measurement according to a first embodiment is shown. The sensor device 1 is adapted to provide a high surface sensitivity, a high voltage resistance and an operating temperature up to 200°C. The sensor device has a small and compact design.

[0058] The sensor device 1 comprises a ceramic-based substrate 2. For example, the ceramic material of the substrate 2 comprises AI2O3, ZTA, silicate, AIN or Si3N4. The substrate 2 is electrically insulating and comprises a high moisture resistance.

[0059] The substrate 2 comprises an upper surface 2a, a lower surface 2c and side surfaces 2b. The substrate 2 comprises metallized pads 4 enabling electrical connections of the substrate 2. The metallized pads 4 are arranged directly on the upper surface 2a of the substrate 2.

[0060] The sensor device 1 further comprises a sensor chip 3. In this embodiment, the sensor chip 3 is an NTC temperature sensor chip. However, in alternative embodiments, the sensor device 1 can further comprise a PTC sensor or a combination of an NTC sensor and a PTC sensor.

[0061] The sensor chip 3 comprises electrodes 3a arranged on an upper surface of the sensor chip 3 (upper electrodes) and electrodes 3a arranged on a lower surface of the sensor chip 3 (lower electrodes).

[0062] The sensor chip 3 and in particular the lower electrodes 3a are joined to the metallized pads 4 of the substrate 2 in a horizontal position to obtain a good surface sensitivity. In this context, the term "horizontal position" will mean that the lower surface of the sensor chip 3 joined to the substrate 2 has a greater extension than the side surface of the sensor chip 3 extending perpendicularly to the upper surface 2a of the substrate 2.

[0063] The sensor chip 3 is joined to the substrate 2 by means of a joining material 5. The joining material 5 is a high melting point solder having an operating temperature greater than 200°C. For example, the joining material 5 comprises a high melting solder but leaded material such as Pb 97.5 SnAg 1.5 . Alternatively, for example, the joining material 5 comprises a lead-free SnAg 0.3 Cu 0.7 or Sn 90 Sb 10 .

[0064] The sensor device 1 further comprises a first contact element 8a and a second contact element 8b. The contact elements 8a, 8b are U-shaped. In particular, the first contact element 8a and the second contact element 8b comprise two legs connected by means of a bar or web 9. Said legs and the bar 9 are integrally formed, i.e. they are made in one piece.

[0065] The contact elements 8a, 8b are at least to some extent elastically deformable. This helps to reduce mechanical stresses generated when the components of the sensor device 1 are connected to each other. The contact elements 8a, 8b are U-shaped spring members. The contact elements 8a, 8b comprise a metal. Suitable materials for the contact elements 8a, 8b can be copper, brass or phosphor bronze.

[0066] The contact elements 8a, 8b each comprise a first contact area 12 and a second contact area 13. In this embodiment, the first contact area 12 and the second contact area 13 are oppositely arranged. The first contact area 12 is located in an upper region of the sensor device 1. The second contact area 13 is arranged in a lower region of the sensor device 1. The first contact area 12 is provided by one of the two legs of the respective U-shaped spring member, in particular the upper leg. The second contact area 13 is provided by the other of the two legs of the respective U-shaped spring member, in particular the lower leg.

[0067] The first contact area 12 protrudes from the insulator 7 of the sensor device 1. The insulator 7 is described in detail later. However, as can be gathered from the Figure 1 contact area 12 does not protrude from the upper surface of the insulator 7 / sensor device 1. Rather, the upper surface of the insulator 7 / sensor device 1 is flat. The contact area 12 is integrated into this upper surface and forms part of the upper surface of the insulator 7 / sensor device 1.

[0068] As mentioned above, in this embodiment, the first contact area 12 is formed on the upper surface of the sensor device 1. In other words, the first contact area 12 is accessible from the upper side of the sensor device 1 to enable further processing. The first contact area 12 serves as an external electrode 6 of the sensor device 1. The free end 14 of the upper leg of each contact element 8a, 8b is bent with respect to the first contact surface 12. In particular, the free end 14 is bent towards the substrate 2. This can contribute to further reducing mechanical stress.

[0069] The second contact area 13 is connected to the metallized pad 4 by means of the aforementioned bonding material 5.

[0070] The first contact element 8a further comprises a contact member 11 which is bonded to the upper electrode 3a of the sensor chip 3 by means of the aforementioned bonding material 5.

[0071] The contact member 11 is part of the first contact element 8a. In particular, the contact member 11 is integrally formed with the first contact element 8a. The contact member 11 is formed by the free end of the second contact area 13 of the first contact element 8a. In an intermediate region 15, the second contact area 13 passes over and into the contact member 11. The intermediate region 15 is curved.

[0072] The contact member 11 is designed to reduce mechanical stress between the first contact element 8a and the sensor chip 3. The contact member 11 comprises an additional spring arranged at the free end of the second contact area 13. In this embodiment, the contact member 11 comprises a flat shape. The contact member 11 lies completely on the upper electrode 3a of the sensor chip 3.

[0073] The sensor device 1 further comprises the above mentioned insulation 7. The insulation 7 increases the electrical resistance and the moisture resistance of the sensor device 1. The insulation 7 comprises a thermoset epoxy material having a glass transition temperature of approximately 200°C.

[0074] The material of the insulation 7 (insulating material) completely covers the sensor chip 3, the contact member 11 and the second contact area 13. Likewise, the free end 14 of the first contact area 12 is also completely arranged within the insulation 7.

[0075] However, the first contact area 12, in particular the upper side of the first contact area 12, is not covered by the insulating material of the body 7. In other words, the first contact area 12 protrudes from the body 7 and thus serves as an external electrode 6 of the sensor device 1.

[0076] Furthermore, the insulation 7 only covers some portions of the substrate 2. The material of the body 7 is at least partially arranged on the upper surface 2a of the substrate 2. In particular, the insulating material covers some portions of the surface of the substrate 2 which is connected with the sensor chip 3 and the contact elements 8a, 8b. Thus, the connection between the contact elements 8a, 8b and the substrate 2 as well as the connection between the sensor chip 3 and the substrate 2 are completely encapsulated by the material of the insulation 7.

[0077] However, as can be derived from Figure 1 the material of the insulation 7 does not protrude onto the upper surface 2a of the substrate 2. The side surface 2b and the lower surface 2c of the substrate 2 are free of the material of the insulation 7. This portion without insulating material serves as a sensing portion of the sensor device 1.

[0078] The above described design and materials of the sensor device 1 result in a high surface sensitivity, a high voltage resistance, a high moisture resistance and a high operating temperature (up to 200°C) of the sensor device 1.

[0079] Figure 2 A sensor device 1 for temperature measurement according to a second embodiment is shown. The sensor device 1 comprises the same components as the above described sensor device 1, i.e. a substrate 2, a sensor chip 3, contact elements 8a, 8b having a first contact area 12 and a second contact area 13 and an insulation 7. With regard to these components, reference is made to the above description in Figure 1 .

[0080] In comparison to the sensor device described in connection with Figure 1 the contact member 11 of the first contact element 8a is not flat but has an arcuate shape. Thus, the contact member 11 does not lie completely on the upper electrode 3a of the sensor chip 3, i.e. over the entire extension of the upper electrode 3a. Rather, the contact member 11 is joined to the upper electrode 3 only in a small area, namely in the middle area 16. The side areas 17 of the middle area 16 surrounding the contact member 11 are curved upwards towards the upper surface of the sensor device 1.

[0081] This design helps to further reduce the mechanical stress between the sensor chip 3 and the first contact element 8a. Furthermore, thickness variations of the sensor chip 3 can be compensated in a better way with the arcuate shape of the contact member 11.

[0082] Figure 3 A sensor device 1 for temperature measurement according to a third embodiment is shown. The sensor device 1 comprises the same components as the above-described sensor device 1, i.e. a substrate 2, a sensor chip 3, contact elements 8a, 8b with a first contact area 12 and a second contact area 13, an insulator 7 and a contact member 11. With regard to these components, reference is made to the above description. Figure 1

[0083] In contrast to the above-described embodiments, the first contact area 12 is not formed on the upper surface of the insulator 7 / sensor device 1. In this embodiment, the first contact area 12 is formed on a side surface of the body 7 / sensor device 1. Thus, the first contact surface 12 serving as an external electrode 6 can be accessed from the side surface of the sensor device 1 to enable further processing.

[0084] Furthermore, in this embodiment, the free end 14 of the upper leg of each contact element 8a, 8b is not bent with respect to the first contact surface 12. Rather, the free end extends along the side surface of the body 7 and can be accessed from the outside of the body 7.

[0085] As already described in connection with Figure 1 , the contact area 12 does not protrude from the side surface, but is integrated into the side surface and forms a part of the side surface.

[0086] Figure 4 and Figure 5 A top view of a multi-chip package 10 is schematically shown. The multi-chip package 10 comprises a plurality of sensor chips 3, e.g. two sensor chips 3 (see Figure 4 ) or three sensor chips 3 (see Figure 5 ). Of course, the multi-chip package 10 can comprise more than three sensor chips 3, e.g. five or ten sensor chips 3.

[0087] The multi-chip package 10 can be electrically connected by means of external electrodes 6 formed by the first contact areas 12 of the contact elements 8a, 8b as described above. The contact elements 8a, 8b and the sensor chips 3 are bonded to a substrate 2 (not explicitly shown, see Figures 1 to 3 ) and embedded in an insulator 7.

[0088] ​In the following, a method for producing the sensor device 1 and / or the multi-chip package 10 is described. In particular, by means of the method, the aforementioned sensor device 1 / multi-chip package 10 is produced.

[0089] The method comprises the following steps:

[0090] A) In a first step, a ceramic-based substrate 2 is provided. The substrate 2 is a high-performance ceramic substrate which is excellent in terms of electrical insulation and moisture resistance properties and has a high thermal conductivity. The substrate 2 comprises AI2O3, ZTA, silicate, AIN or Si3N4ceramics. Thereafter, a plurality of metallized pads 4 is arranged on the substrate 2. The metallized pads 4 are arranged on the upper surface 2a of the substrate 2.

[0091] B) In a second step, a bonding material 5 is provided. The bonding material 5 is a high-melting solder having an operating temperature of more than 200°C. For example, the bonding material 5 can comprise Pb 97.5 SnAg 1.5 , SnAg 0.3 Cu 0.7 or Sn 90 Sb 10 .

[0092] A respective dot of the bonding material 5 is applied to a partial amount of the metallized pads 4. In particular, a specific dot of the bonding material 5 is applied to one metallized pad 4 to achieve an electrical connection of one of the sensor chips 3. The bonding material 5 is dispensed or screen-printed onto the partial amount of the metallized pads 4.

[0093] C) In a further step, a plurality of sensor chips 3 is provided. The sensor chips 3 can be NTC chips or PTC chips or a combination thereof. A combination of NTC chips and PTC chips is used for applications in which the temperature measurement is equipped with safety function requirements. Each sensor chip 3 comprises electrodes 3a arranged on the upper side and on the lower side of the sensor chip 3.

[0094] The sensor chips 3 are placed on the substrate 2 and, in particular, on the dot-like bonding material 5. The sensor chips 3 are placed in such a way that each sensor chip 3 is arranged in a horizontal position on the substrate 2.

[0095] D) In a next step, reflow soldering is performed. In this way, the lower electrodes 3a of each sensor chip 3 are electrically connected to the substrate 2. The lower electrodes 3a are connected to the metallized pads 4 by means of the bonding material 5, so that each sensor chip 3 is arranged in a horizontal position on the substrate 2. In this way, the surface sensitivity of the sensor device 1 / multi-chip package 10 is increased.

[0096] E) In a next step, the bonding material 5 is provided again, for example by screen printing or dispensing. The bonding material 5 is applied in dots onto the upper electrodes 3a of the individual sensor chips 3.

[0097] Further dots of the bonding material 5 are applied to the remaining amount of the metallized pads 4. In particular, two dots of the bonding material 5 are applied to two of the metallized pads 4 to realize one final sensor device 1. Thus, in this method step, a total of three dots of the bonding material 5 are applied to obtain one final sensor device 1.

[0098] F) In a further step, a plurality of first and second contact elements 8a, 8b is provided. Thereby, one pair of contact elements 8a, 8b is provided for one sensor chip 3. The individual contact elements 8a, 8b comprise a first contact area 12 and a second contact area 13.

[0099] The first contact area 12 serves as an external electrode 6 of the sensor device 1 / the multi-chip package 10 and thus can be accessed from the outside of the sensor device 1 / the multi-chip package 10.

[0100] The second contact area 13 serves for electrically connecting the substrate 2 to the individual contact elements 8a, 8b. The individual first contact elements 8a comprise a contact member 11 for electrically connecting the sensor chip 3 with the first contact element 8a.

[0101] One respective contact element 8a, 8b is placed on one dot of the bonding material 5 arranged on the metallized pads 4. Further, the contact elements 8a, 8b are placed such that the respective contact member 11 is arranged on the dot of the bonding material 5 provided on the upper electrode 3a of the sensor chip 3. In other words, three dots of the bonding material 5 are required to electrically connect one pair of contact elements 8a, 8b to the substrate 2 and further to electrically connect the first contact element 8a, in particular the contact member 11, to the sensor chip 3.

[0102] G) In a next step, reflow soldering is performed to electrically connect the contact elements 8a, 8b, in particular the second contact areas 13, with the metallized pads 4 and to electrically connect the contact members 11 with the upper electrodes 3a of the individual sensor chips 3.

[0103] H) In a next step, encapsulation is performed. Thereby, an insulating material is provided and an insulator 7 is molded from the insulating material. The insulating material comprises a thermoset epoxy material having a glass transition temperature of approximately 200°C.

[0104] The body 7 is formed such that the insulating material covers at least some portions of the upper surface 2a of the substrate 2. For example, the circumferential edge region of the upper surface 2 can remain free of insulating material. However, the insulating material completely covers the connections between the contact elements 8a, 8b and the substrate 2 as well as the connections between the sensor chip 3 and the substrate 2.

[0105] The insulating material also completely covers the sensor chip 3, the second contact region 13 and the contact member 11. The first contact region 12 remains free of insulating material. Furthermore, the side surface 2a and the lower surface 2c of the substrate 2 also remain free of insulating material.

[0106] I) In the last step, singulation is carried out. Thereby, the substrate 2 is cut into individual parts to provide a plurality of sensor devices 1. The cutting pattern can vary to obtain a multi-chip package 10.

[0107] Reference signs

[0108] 1 sensor device

[0109] 2 substrate

[0110] 2a upper surface

[0111] 2b side surface

[0112] 2c lower surface

[0113] 3 sensor chip

[0114] 3a electrode of the sensor chip

[0115] 4 metallized pad

[0116] 5 bonding material

[0117] 6 external electrode

[0118] 7 insulating / body

[0119] 8a first contact element

[0120] 8b second contact element

[0121] 9 stem

[0122] 10 multi-chip package

[0123] 11 contact member

[0124] 12 first contact region

[0125] 13 second contact region

[0126] 14 free end

[0127] 15 intermediate region

[0128] 16 central region

[0129] 17 side region

Claims

1. A sensor device (1) for temperature measurement, comprising: - a ceramic base substrate (2); - at least one sensor chip (3) directly connected to the substrate (2) in a horizontal position by means of a bonding material (5); - at least one first contact element (8a) and at least one second contact element (8b) adapted and arranged to function as external electrodes (6) of the sensor device (1), wherein the first contact element (8a) comprises a contact member (11) adapted and arranged to electrically contact the sensor chip (3) by means of the bonding material (5); and - an insulator (7) enclosing at least some parts of the contact elements (8a, 8b) and the sensor chip (3), wherein the substrate (2) is mostly free of material of the insulator (7), wherein material of the insulator (7) is directly arranged on at least some parts of an upper surface (2a) of the substrate (2), wherein side surfaces (2b) and a lower surface (2c) of the substrate (2) are free of material of the insulator (7), and the contact member (11) is designed to reduce mechanical stress between the first contact element (8a) and the sensor chip (3).

2. The sensor device (1) according to claim 1, wherein the material of the insulator (7) is adapted and arranged to increase the electrical resistance and moisture resistance of the sensor device (1).

3. The sensor device (1) according to claim 1 or claim 2, wherein, the material of the insulator (7) comprises a thermosetting epoxy material having a glass transition temperature of 200°C.

4. The sensor device (1) according to claim 1 or 2, wherein each contact element (8a, 8b) comprises a U-shaped spring member.

5. The sensor device (1) according to claim 1 or 2, wherein each contact element (8a, 8b) comprises a first contact area (12) free of insulating material of the insulator (7), wherein the first contact area (12) functions as an external electrode (6) of the sensor device (1).

6. The sensor device (1) according to claim 5, wherein the first contact area (12) is formed by one of two legs of the respective U-shaped spring member comprised in each contact element (8a, 8b).

7. The sensor device (1) according to claim 1 or 2, wherein each contact element (8a, 8b) comprises a second contact area (13) completely arranged within the insulator (7), wherein the second contact area (13) is bonded to a metallized pad (4) of the substrate (2) to establish electrical contact between the contact element (8a, 8b) and the substrate (2).

8. The sensor device (1) according to claim 7, wherein, The second contact area (13) is formed by the other of the two legs of the respective U-shaped spring member comprised in each contact element (8a, 8b).

9. The sensor device (1) according to claim 7, wherein The contact member (11) comprises an additional spring arranged at the free end of the second contact area (13) of the first contact element (8a).

10. The sensor device (1) according to claim 1 or 2, wherein The contact elements (8a, 8b) comprise copper, brass or phosphor bronze.

11. The sensor device (1) according to claim 1 or 2, wherein, The substrate (2) comprises an Al2O3, ZTA, silicate, AlN or Si3N4 ceramic.

12. The sensor device (1) according to claim 1 or 2, wherein The sensor device (1) comprises at least one NTC sensor chip (3) and / or at least one PTC sensor chip (3).

13. The sensor device (1) according to claim 1 or 2, wherein, The bonding material (5) comprises a high melting point solder having an operating temperature of more than 200°C.

14. The sensor device (1) according to claim 1 or 2, wherein, The sensor device (1) is adapted to be operated at high temperatures of up to 200°C.

15. A method for producing a sensor device (1) for measuring temperature, the method comprising the following steps: A) providing a ceramic-based substrate (2) and arranging a plurality of metallized pads (4) on the upper surface (2a) of the substrate; B) providing a bonding material (5); C) providing a plurality of sensor chips (3), wherein each sensor chip (3) comprises electrodes (3a) arranged on the upper side and on the lower side of the sensor chip (3); D) performing reflow soldering to electrically connect one of the electrodes (3a) of each sensor chip (3) with the substrate (2) such that each sensor chip (3) is arranged in a horizontal position on the substrate (2); E) providing the bonding material (5); F) providing a plurality of first and second contact elements (8a, 8b), wherein each contact element (8a, 8b) comprises a first contact area (12) and a second contact area (13), and wherein each first contact element (8a) comprises a contact member (11); G) performing reflow soldering to electrically connect the second contact area (13) with the metallized pads (4) and to electrically connect the contact member (11) with the other of the electrodes (3a) of the sensor chip (3); H) performing encapsulation; I) performing singulation, wherein step H) comprises providing an insulating material and molding an insulator (7) such that the insulating material covers at least some parts of the surface of the substrate (2) connected with the sensor chip (3) and the second contact area (13).

16. The method according to claim 15, wherein The insulating material completely covers the sensor chip (3), the second contact area (13) and the contact member (11), and wherein the first contact area (12) is free of insulating material.

17. The method according to claim 15 or claim 16, wherein The insulator (7) comprises a thermoset epoxy material having a glass transition temperature of 200°C.

18. The method according to claim 15 or 16, wherein The substrate (2) comprises an Al2O3, ZTA, silicate, AlN or Si3N4 ceramic.

19. The method according to claim 15 or 16, wherein, The sensor chip (3) comprises a plurality of NTC sensor chips (3) and / or PTC sensor chips (3).

20. The method according to claim 15 or 16, wherein, The bonding material (5) comprises a high melting point solder having an operating temperature of greater than 200°C.

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