Pressure sensor module and pressure sensor with a pressure sensor module

Abstract

The invention relates to a pressure sensor module (1) with a base body (9), comprising a carrier substrate (2) with a first side (21) and a second side (22) facing away from the first side (21), a mold frame (3) made of molding compound and applied to the second side (22) of the carrier substrate (2), wherein the mold frame (3) has at least one depression (8), at the bottom of which a pressure sensor element (4) is arranged, which is in electrical contact with the carrier substrate (2), wherein the pressure sensor module (1) has at least one electronic component (5) arranged on the base body (9). It is proposed that the at least one electronic component (5) is applied to the first side (21) of the carrier substrate (2) facing away from the mold frame (3) and is provided with a gel cover (7) in a gel frame (6) applied to the first side (21).

Description

State of the art

[0001] Various types of pressure sensors for detecting the pressure of a measuring medium are known in the prior art. Some pressure sensors have a pressure sensor module comprising a compact base body with a carrier substrate and a mold frame made of molding compound applied to one side thereof. The mold frame is provided with at least one recess in which a pressure sensor element is received. In the known pressure sensor modules, an electronic control and evaluation circuit, which serves to condition the signal, is integrated into an application-specific integrated circuit (ASIC) that is encapsulated as an electronic component in the mold frame. Such pressure sensor modules can be provided with one or more pressure sensor elements and are known, for example, from DE 10 2016 201 847 A1 or DE 10 2019 205 154 A1.

[0002] The well-known pressure sensor modules, which are easy to manufacture, are flexible in use and can be installed in a pressure sensor housing in various ways, for example, by gluing them in. For sealing and media separation, a suitable adhesive can be used between the pressure sensor module and the inner wall of a pressure sensor housing. Silicone adhesives are preferred due to the different thermal expansion coefficients between the pressure sensor housing and the pressure sensor module. Disclosure of the invention

[0003] The invention proposes a pressure sensor module with a base body, which has a carrier substrate with a first side and a second side facing away from the first side and at least one contact surface arranged on the first side. A mold frame made of molding compound is applied to the second side of the carrier substrate, wherein the mold frame has at least one depression, at the bottom of which a pressure sensor element is arranged that is in electrical contact with the carrier substrate. The pressure sensor module also has at least one electronic component arranged on the base body. According to the invention, it is proposed that the at least one electronic component is applied to the first side of the carrier substrate facing away from the mold frame and is provided with a gel cover in a gel frame applied to the first side.

[0004] The pressure sensor modules can have a single pressure sensor element, two pressure sensor elements, or more than two pressure sensor elements. If multiple pressure sensor elements are provided, they can be used to record different pressure measurements.

[0005] The base body of the pressure sensor module can, for example, essentially be constructed as a land grid array / mold premold (LGA / MPM) or similar. The carrier substrate is provided with a connection grid configured as a grid array on one side and a mold frame and a semiconductor component as the actual pressure sensor element on the other side. The semiconductor component can be designed, for example, as an advanced porous silicon MEMS sensor element (MEMS = microelectromechanical systems) or as a conventional silicon chip.

[0006] In the context of this application, a fluid medium is understood to mean a liquid or gaseous medium, in particular a measuring medium whose pressure is to be measured. With more than one pressure sensor element, the pressure of different media can also be measured.

[0007] A carrier substrate is a plate-shaped substrate that can be used as a carrier for electrical contacts. The carrier substrate can have conductor tracks on one or more layers and can, in particular, be designed as a printed circuit board. The carrier substrate can, for example, have insulating layers made of epoxy resin (PCB, printed circuit board) or be designed as a ceramic circuit board or in another way.

[0008] The mold frame made of molding compound applied to the second side of the carrier substrate can, in particular, comprise an epoxy resin-based thermoset. The mold frame can preferably cover the entire second side of the carrier substrate except for contact openings of the at least one pressure sensor element. The base body of the pressure sensor module can have a compact, essentially cuboidal structure, with a pressure supply channel being formed by the at least one depression on one side of the base body.

[0009] The at least one pressure sensor element can be accommodated in the recess on a thin bottom wall of the mold frame and, in particular, can be glued there. The pressure sensor element can be electrically contacted with conductor tracks of the carrier substrate via suitable electrical contact means (e.g., bonding wire connections) through recesses in the mold frame. Advantages of the invention

[0010] If the pressure sensor modules known from the prior art are installed in pressure sensor housings used in applications with high humidity and / or aggressive media, in an unfavorable case, moisture and aggressive media can penetrate small gaps and air pockets and cause damage. Another problem is that the at least one electronic component encapsulated in the mold frame, in particular one designed as an ASIC, is sawn from a wafer during production and is therefore provided with sharp edges and contact surfaces on its upper surface for further contacting, for example, via bond wire connections.During alternating temperature loads, mechanical stresses occur at the edges of the ASIC due to the different thermal expansion coefficients of the ASIC and the molding compound of the mold frame surrounding it, which is, for example, an epoxy resin, which can cause cracks and shrinkage cavities over time.

[0011] In the solution according to the invention, the at least one electronic component, which can preferably be an ASIC, is not integrated into the mold frame facing the measuring medium, but instead is applied to the first side of the carrier substrate facing away from the mold frame and provided with a gel cover in a gel frame applied to the first side. This advantageously ensures that the electronic component, which is already well protected by the gel cover, is arranged on a side of the carrier substrate facing away from the pressure sensor element, which side can be easily inserted, for example, into a protected space within a pressure sensor housing. The arrangement in the gel cover also avoids the notch effect observed in the prior art and attributable to the sharp edges of an ASIC.In the mold frame, thermal stresses are advantageously reduced and the probability of penetration of moisture or aggressive substances is reduced.

[0012] Advantageous embodiments and further developments of the invention are made possible by the features contained in the dependent claims.

[0013] Since the arrangement of an additional passive electronic component in the mold frame can be associated with similar problems as the arrangement of the ASIC in the mold frame, it is advantageous to mount an additional passive electronic component on the first side of the carrier substrate outside or inside the gel frame in order to arrange it in a protected space and to prevent the formation of cracks or cavities in the molding compound of the mold frame.

[0014] The pressure sensor module according to the invention can be provided with one or more pressure sensor elements which are provided as absolute pressure sensor elements or as relative pressure sensor elements.

[0015] For example, in an advantageous embodiment, the mold frame of the pressure sensor module can have, on an outer side of the base body facing away from the carrier substrate, a first depression in which a first pressure sensor element is received, and a second depression in which a second pressure sensor element is received. These two pressure sensor elements can be provided, for example, for detecting the absolute pressure, wherein each of the pressure sensor elements can then be subjected to the pressure of a medium on one side.

[0016] In another embodiment, the pressure sensor module can have a base body that has at least one opening that extends from the first side of the carrier substrate through the carrier substrate and the molding compound of the mold frame to below the at least one pressure sensor element, so that the at least one pressure sensor element, as a relative pressure sensor element, can be subjected to a first pressure via the at least one depression and to a second pressure via the opening on an opposite side. This embodiment can also be implemented with two or more relative pressure sensor elements.

[0017] The use of the pressure sensor module according to the invention in a pressure sensor is particularly advantageous, wherein the pressure sensor has a housing with a housing lower part and a housing cover, wherein the housing lower part has at least one first pressure connection with a first supply channel and wherein a housing interior is provided between the housing lower part and the housing cover. The pressure sensor module can be arranged in a simple manner in the housing interior in a similar way to the known pressure sensor modules such that the at least one pressure sensor element can be subjected to the pressure of a fluid medium present in the supply channel. The electronic component arranged in the gel frame on the side of the carrier substrate facing away from the pressure sensor element can advantageously be introduced into a protected area of ​​the housing interior.

[0018] In this context, it is advantageous, for example, if the housing cover is provided with a partition wall projecting toward the housing interior, which rests on the carrier substrate at its end via a sealing element. The partition wall can, for example, completely surround at least one section on the first side of the carrier substrate occupied by the at least one electronic component and the gel frame. Moisture or aggressive substances are thus kept away from the gel frame and the electronic component protected beneath the gel cover. Short description of the drawings

[0019] Possible embodiments of the invention are explained below with reference to the accompanying figures. The drawings show: Fig. 1 a cross section through a first embodiment of a pressure sensor module according to the invention, Fig. 2 a cross section through a second embodiment of a pressure sensor module according to the invention, Fig. 3 a cross section through a third embodiment of a pressure sensor module according to the invention, Fig. 4 an embodiment of a pressure sensor according to the invention with a pressure sensor module installed therein. Embodiments of the invention

[0020] Fig. 1 shows a cross-section through a first embodiment of a pressure sensor module 1 according to the invention. The pressure sensor module 1 has a compact, for example, substantially cuboid-shaped base body 9 with a first outer side 11 and a second outer side 10 facing away from it. On the first outer side 11, the base body 9 has a carrier substrate 2, which is designed, for example, as a printed circuit board.

[0021] The carrier substrate 2 has a first side 21, which simultaneously represents the first outer side 11 of the base body 9, and a second side 22 facing away from the first side, to which a mold frame 3 made of molding compound, for example an epoxy resin, is applied. The mold frame 3 completely covers the second side 22 of the carrier substrate 2 except for contact openings (not shown) of a pressure sensor element 4 and forms the second outer side 10 of the base body 9. The carrier substrate 22 is provided on its first side 21 facing away from the mold frame 3 with electrical contact surfaces, which serve for further contacting and from which Fig. 1 only one contact surface 23 is shown.

[0022] The mold frame 3 has a depression 8, which extends from the second outer side 10 of the base body 9 into the interior of the mold frame 9. At the bottom of the depression, a pressure sensor element 4 is glued to the molding compound of the mold frame 9 in the bottom region of the depression. Electrical contacting means of the pressure sensor element 4 can be passed through recesses (not shown) in the molding compound of the mold frame 9 to the carrier substrate 2 and electrically connected to it.

[0023] On the first side 21 of the carrier substrate 2 facing away from the mold frame 9, at least one electronic component 5 is applied and electrically contacted with the carrier substrate 2. The at least one electronic component 5 is preferably designed as an ASIC. On the first side 21 of the carrier substrate 2, the electronic component 5 is surrounded by a circumferential gel frame 6, which is attached to the first side 21. This gel frame 76 is filled above the electronic component 5 with a gel 7, which completely covers the electronic component 5.

[0024] Fig. 2 shows a second exemplary embodiment of a pressure sensor module 1 according to the invention. In this exemplary embodiment, a first depression 8a and a second depression 8b extend inward from the second outer side 10 of the base body 9 towards the carrier substrate 2. A first pressure sensor element 4a is received in the first depression 8a. A second pressure sensor element 4b is received in the second depression 8b. Both pressure sensor elements 4a, 4b are electrically connected to the carrier substrate 2, wherein the carrier substrate 2 has, on its first side 21 facing away from the mold frame 9, a first electronic component 5a arranged in a first gel frame 6a and a second electronic component 5b arranged in a second gel frame 6b. The first electronic component 5a can be designed as an ASIC and, for example, have a sensor signal evaluation circuit assigned to the first pressure sensor element 4a.The second electronic component 5b can also be designed as an ASIC and, for example, have a sensor signal evaluation circuit associated with the second pressure sensor element 4b. Passive components 13, such as capacitors, can also be mounted outside the mold frame 9 on the first side 21 of the carrier substrate 2. However, the passive electronic components 13 can also be arranged in one of the two gel frames 6a, 6b or in a separate gel frame. In . Fig. 2, the two pressure sensor elements 4a, 4b are subjected to different pressure values ​​of a measuring medium or to pressure values ​​of different measuring media from the second outer side 10 of the base body 9 and therefore each record an absolute pressure.

[0025] Fig. 3 shows a third embodiment of a pressure sensor module 1 according to the invention. In this embodiment, in the base body 9 of the pressure sensor module 1 as in Fig. 2 a first pressure sensor element 4a and a second pressure sensor element 4b are accommodated. In contrast to Fig. 2, however, a first opening 12a extends beneath the first pressure sensor element 4a through the bottom of the first depression 8a and the carrier substrate 2 to the first outer side 11 of the base body 9. Beneath the second pressure sensor element 4b, a second opening 12b extends through the bottom of the second depression 8b and the carrier substrate 2 to the first outer side 11 of the base body 9. The first pressure sensor element 4a and the second pressure sensor element 4b can therefore be used as relative pressure sensors that can be subjected to pressure on both sides of the respective pressure sensor element. In this exemplary embodiment, only one electronic component 5 designed as an ASIC is arranged in a gel frame 6 on the first side of the carrier substrate 2 and covered with a gel 7.A sensor signal evaluation circuit arranged in the electronic component 5 can be assigned to the first pressure sensor element 4a and the second pressure sensor element 4b. In contrast to the embodiment of FIG. Fig. 2, for example, a passive electronic component 13 is embedded in the mold frame.

[0026] Fig. 4 shows an embodiment of a pressure sensor 100 with a pressure sensor module 1 installed therein. The pressure sensor 100 has a housing 110 with a housing base 111 and a housing cover 112, between which a housing interior 120 is formed. The housing base 111 is designed, for example, as an injection-molded part made of plastic and has a first pressure connection 113 with a first supply channel 115 and a second pressure connection 114 with a second supply channel 116. On one side of the housing base 111, it has an electrical plug connection 117 for external connection to, for example, a vehicle wiring harness. Electrical contact elements 118 of the plug connection 117 extend through the housing base 111 into the housing interior 120. A pressure sensor module 1, which is, for example, the pressure sensor module shown in Fig. 2, is inserted into a trough-shaped receiving space 127 of the lower housing part 111 and glued to the base of the receiving space 127 using a sealing adhesive (not shown), for example a silicone adhesive. The mold frame 9 faces the supply channels 115 and 116 with the second outer side 10 of the base body 9, so that the first supply channel 115 is connected to the first recess 8a and the second supply channel 116 is connected to the second recess 8b. Therefore, a pressure applied to the first pressure connection 113 acts on the first pressure sensor element 4a, while the pressure applied to the second pressure connection 116 acts on the second pressure sensor element 4b.

[0027] The pressure sensor module 1 is inserted into the trough-shaped receiving space 127 of the housing base 111 such that the carrier substrate 2, with the first electronic component 5a arranged in the first gel frame 6a and the second electronic component 5b arranged in the second gel frame 6a, faces the housing interior 120. The housing cover 112 completely covers the trough-shaped receiving space of the housing base 111, so that the housing interior 120 is closed off from the exterior. The housing cover 112 can be provided with a partition 121 projecting toward the housing interior 120, which rests on the carrier substrate 2 at its end via a sealing element 122. As shown in Fig. 4, it is also possible, for example, for the partition 121 to completely surround at least the section on the first side 21 of the carrier substrate 2 occupied by the electronic components 5a and 6b and the associated gel frames. The sealing element 122 can then be designed, for example, as a circumferential adhesive bead, into which the partition 121 engages like a sealing blade. Outside the area surrounded by the partition 121, contact surfaces of the carrier substrate 2 can be contacted via bonding wire connections 119 with the contact elements 118 of the plug connection 117 and covered with a passivation 125. As can be seen from Fig. 4, aggressive substances which penetrate into the housing interior 120 via the supply channels 115 or 116 through the gap between the pressure sensor module 1 and the housing base 111 cannot reach the electronic components 5a and 5b, since these are protected by the partition wall 121 and, in addition, by the two gel covers.

[0028] Of course, combinations and variations of the Fig. 1 to 4 shown structure of the pressure sensor modules and the housing 110 of the pressure sensor 100. For example, the housing 110 of the pressure sensor 100 can have only one pressure connection if the Fig. 1 is installed therein. Furthermore, it is possible, by appropriately designing pressure supply channels in the housing base 111 and / or the housing cover 112, to provide an additional supply of a medium pressure or different media pressures to the first outer side 11 of the base body 9 of the pressure sensor module 1, provided with the openings 12a and 12b. Fig. 3. By placing corresponding partition walls of the housing cover 112 on the first outer side 11 with the interposition of further sealing means, it is then easy, for example, to separate the two pressure supplies on this side of the pressure sensor module 1 as well.

[0029] Accordingly, for example, a pressure sensor module 1 with only one relative pressure sensor element and one opening 12 can also be installed in a housing 110 of a pressure sensor 100 with two pressure connections. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2016 201 847 A1

[0001] DE 10 2019 205 154 A1

[0001]

Claims

[1] Pressure sensor module (1) with a base body (9), comprising a carrier substrate (2) with a first side (21) and a second side (22) facing away from the first side (21), at least one mold frame (3) made of molding compound and applied to the second side (22) of the carrier substrate (2), wherein the mold frame (3) has at least one depression (8), at the bottom of which a pressure sensor element (4) is arranged that is in electrical contact with the carrier substrate (2), wherein the pressure sensor module (1) has at least one electronic component (5) arranged on the base body (9), characterized by that the at least one electronic component (5) is applied to the first side (21) of the carrier substrate (2) facing away from the mold frame (3) and is provided with a gel cover (7) in a gel frame (6) applied to the first side (21). [2] Pressure sensor module (1) according to claim 1, characterized bythat the at least one electronic component (5) is designed as an integrated circuit, in particular as an ASIC. [3] Pressure sensor module (1) according to claim 1 or 2, characterized by that on the first side (21) of the carrier substrate (2) outside or inside the gel frame (6) at least one passive electronic component (13) is fitted as an additional electronic component. [4] Pressure sensor module (1) according to one of the preceding claims, characterized by that the at least one pressure sensor element (8) is designed as an absolute pressure sensor element or as a relative pressure sensor element. [5] Pressure sensor module (1) according to one of the preceding claims, characterized bythat the mold frame (3) has, on an outer side (10) of the base body (9) facing away from the carrier substrate (2), a first depression (8a) in which a first pressure sensor element (4a) is received, and a second depression (8b) in which a second pressure sensor element (4b) is received. [6] Pressure sensor module (1) according to one of the preceding claims, characterized by in that the base body (9) has at least one opening (12) which extends from the first side (21) of the carrier substrate (2) through the carrier substrate (2) and the molding compound of the mold frame (3) to below the at least one pressure sensor element (4), so that the at least one pressure sensor element (4) as a relative pressure sensor element can be subjected to a first pressure via the at least one depression (8) and to a second pressure via the opening (12) on an opposite side. [7] Pressure sensor (100) with a pressure sensor module (1) according to one of claims 1 to 6, wherein the pressure sensor (100) has a housing (110) with a housing lower part (111) and a housing cover (112), wherein the housing lower part (111) has at least one first pressure connection (113) with a first supply channel (115), wherein a housing interior (120) is provided between the housing lower part (111) and the housing cover (112), wherein the pressure sensor module (1) is arranged in the housing interior (120) such that the at least one pressure sensor element (4) can be subjected to the pressure of a fluid medium present in the supply channel (115). [8] Pressure sensor (100) according to claim 7, characterized by that the housing cover (112) is provided with a partition wall (121) projecting towards the housing interior (120), which wall rests on the carrier substrate (2) at its end via a sealing element (122). [9] Pressure sensor (100) according to claim 8, characterized bythat the partition wall (121) completely surrounds at least one section on the first side (21) of the carrier substrate (2) which is covered with the at least one electronic component (5) and with the gel frame (6).

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