Sensor system comprising at least one MEMS unit, at least one ASIC unit and a substrate

Abstract

Sensor system comprising at least one MEMS unit, at least one ASIC unit and a substrate having a main extension plane and a first and second main plane, where at least one ASIC unit is applied to the first main surface of the substrate, wherein at least one MEMS unit is applied to the side of at least one ASIC unit facing away from the substrate, wherein at least one ASIC unit and at least one MEMS unit are at least partially enclosed by an overmolded package.

Description

State of the art

[0001] The invention is based on a sensor system comprising at least one MEMS unit, at least one ASIC unit and a substrate according to the preamble of the main claim.

[0002] The requirements for sensor systems, particularly those consisting of at least one MEMS unit and at least one ASIC unit, are increasingly evolving towards a more compact and robust design (compared to conventional designs) (i.e., the aim is, in particular, to achieve the smallest and lightest possible design) on the one hand, and cost-effective production of these sensor systems (which is only partially compatible with a compact and robust design) on the other. The compact and robust design is particularly in demand for electronic devices that are becoming increasingly smaller and (electrotechnically) more complex, such as headphones (ear pods), fitness trackers, smartwatches, and smartphones.The prior art proposes two substrate types for the production of sensor systems that are intended to meet the above requirements: a ball grid array (BGA) and a land grid array (LGA). In both cases, this involves a substrate onto which at least one MEMS unit and / or at least one ASIC unit can be placed and secured (or plugged in), and thus electrically controlled via the contact elements. For special protection of the at least one MEMS unit and / or the at least one ASIC unit, they are at least partially (or completely) encapsulated in a housing. This encapsulated housing, usually made of a plastic or polymer material, protects the at least one MEMS unit and / or the at least one ASIC unit from external influences (water, dust, etc.).) and gives the construction stability and robustness.

[0003] However, the overmolded housing also causes mechanical stress (or mechanical stress effects) on the at least one MEMS unit and / or the at least one ASIC unit. In particular, temperature changes within the overmolded housing (or shrinkage processes) cause deformations and thus mechanical stresses within the overmolded housing and thus mechanical stresses on the at least one MEMS unit and / or the at least one ASIC unit. Disclosure of the invention

[0004] It is an object of the present invention to provide a sensor system comprising at least one MEMS unit, at least one ASIC unit and a substrate, which does not have the above-mentioned disadvantages.

[0005] The sensor system according to the invention, comprising at least one MEMS unit, at least one ASIC unit, and a substrate according to the main claim, has the advantage over the prior art that the at least one ASIC unit and the at least one MEMS unit are at least partially encased in a material with specific elastic properties such that they are mechanically decoupled from the overmolded housing. Due to the material with specific elastic properties, it is extremely advantageous that the mechanical stresses on the MEMS unit and / or the ASIC unit—in particular those arising due to temperature changes—can be effectively and efficiently reduced. This is preferably achieved using so-called "soft materials."Soft materials—used as an intermediate layer between the overmolded housing and the at least one MEMS unit and / or the at least one ASIC unit—allow for comparatively strong mechanical decoupling between the overmolded housing and the MEMS unit and / or ASIC unit. Furthermore, the invention provides for this intermediate layer of such a soft material to be structured and / or for its thickness or layer thickness to be varied, thereby advantageously enabling additional fine-tuning of this decoupling.In particular, the combination of at least partially encasing the at least one MEMS unit and / or the at least one ASIC unit with the soft material (with specific elastic properties) and the overmolded housing made of a special plastic is particularly preferred, since an overmolded housing consisting solely of a soft material would not have the necessary mechanical stability (particularly due to an unbalanced bimetallic effect). According to the invention, it is advantageously possible to use physical and / or chemical vapor deposition (CVD) and / or the use of water-based plastic materials and various coatings or coating methods to manufacture the sensor system according to the invention.

[0006] Advantageous embodiments and further developments of the invention can be found in the dependent claims and the description with reference to the drawings.

[0007] According to an advantageous embodiment of the invention, the material with the specific elastic properties extends between the at least one MEMS unit and the overmolded housing essentially parallel to the main extension plane. This makes it extremely advantageous to effectively reduce the mechanical stresses acting between the overmolded housing and in particular the MEMS unit (and possibly also the ASIC unit), thus decoupling the housing on the one hand and the MEMS unit or ASIC unit on the other.

[0008] According to an advantageous embodiment of the invention, the material with the specific elastic properties extends between the at least one MEMS unit and the overmolded housing, and between the at least one ASIC unit and the overmolded housing, essentially along a side surface of the ASIC unit and / or the MEMS unit. This makes it extremely advantageous to effectively reduce the mechanical stresses acting along the side surface of the ASIC unit and / or the MEMS unit, thus decoupling the housing on the one hand and the MEMS unit or ASIC unit on the other.

[0009] According to an advantageous embodiment of the invention, the at least one ASIC unit is at least partially encased in another material with further specific elastic properties. This makes it extremely advantageous to counteract further mechanical stress effects between the at least one MEMS unit and the at least one ASIC unit (and the overmolded housing) or to achieve a decoupling of the elastic modes from one another at this point as well.

[0010] According to an advantageous embodiment of the invention, the material with specific elastic properties consists of or comprises multiple layers, in particular with a thickness of 0.1 to 200 micrometers. This makes it extremely advantageous to achieve effective and efficient adaptation not only by structuring the material with specific elastic properties, but also to ensure desired properties or fine-tune the elastic properties by adjusting the thickness of these layers.

[0011] Embodiments of the present invention are illustrated in the drawings and explained in more detail in the following description. Short description of the drawings: Fig. 1 shows a schematic representation of a sensor system according to the state of the art. Fig. 2 shows a schematic representation of the sensor system according to an embodiment of the present invention. Fig. 3 shows a schematic representation of the sensor system according to another embodiment of the present invention. Fig. 4 shows a schematic representation of the sensor system according to another embodiment of the present invention. Embodiments of the invention:

[0012] Fig. Figure 1 shows a very schematic representation (to illustrate the principle) of a sensor system according to the prior art. It depicts a sensor system comprising at least one MEMS unit 101 and at least one ASIC unit 102, which are arranged on a substrate 110. Such a sensor system is conventionally surrounded by an overmolded housing 120, wherein Fig. 1 illustrates an arrangement in which the ASIC unit 102 is at least partially encased in a stress-decoupling material (hereinafter also referred to as additional material) with elastic properties 131. The stress-decoupling material (or the additional material) is in particular a soft material (soft DAF / material), so that mechanical stresses originating from the substrate 110 and / or between the ASIC unit 102 and the MEMS unit 101 are at least partially prevented or reduced. Although the overmolded housing protects the MEMS unit and the ASIC unit from external influences, such as water, dust, or the like, the mechanical stresses originating from the overmolded housing 120 act directly on the MEMS unit 101 and the ASIC unit 102.

[0013] Fig. Figure 2 shows a schematic representation of the sensor system according to an embodiment of the present invention. Shown is (as in the Fig. 3 and Fig. 4) a sensor system again comprising (at least) the MEMS unit 101 and (at least) the ASIC unit 102, which are arranged on the substrate 110. The sensor system is again surrounded by an overmolded housing 120. According to all embodiments of the invention, the substrate 110 has a main extension plane and a first and second main side; the ASIC unit 102 is applied to the first main side of the substrate 110 (on its top side in the illustration of all figures) and the MEMS unit 101 is applied (in the illustration of all figures) to the top side of the ASIC unit, i.e., on the side of the ASIC unit 102 facing away from the substrate 110.

[0014] Again, according to all embodiments of the invention, the sensor system comprises the substrate 110, which is designed in particular as a ball grid array (BGA) and / or land grid array (LGA); the sensor system can be controlled via electrical connections of the substrate 110. To protect it from external influences, such as water, dust, or the like, the sensor system is encased in the overmolded housing 120—in particular made of plastic. Deformations and mechanical stresses can occur within the overmolded housing 120—in particular due to (local) temperature changes. These mechanical stresses can have a detrimental effect on the sensor system.

[0015] According to the invention, according to all embodiments, it is provided that the sensor system is at least partially encased in a material with specific elastic properties 130 in order to minimize the effect of the mechanical stresses as much as possible, i.e. the ASIC unit 102 and the MEMS unit 101 are at least partially encased in the material with specific elastic properties 130 in such a way that they are mechanically decoupled from the over-molded housing 120. The material with specific elastic properties 130 preferably consists of so-called "soft materials". These materials have the option of achieving a decoupling of the mechanical stresses acting on them. By specifically structuring the material with specific elastic properties 130, it is advantageously possible to fine-tune these elastic properties.In addition, the thickness of the layer of material with specific elastic properties 130 can be varied to fine-tune the decoupling effect. Furthermore, according to all the requirements of the . Fig. 2, Fig. 3 and Fig. 4 also shows the further material with specific elastic properties 131, in particular between the substrate 110 and the ASIC unit 102 and / or between the ASIC unit 102 and the MEMS unit 101.

[0016] According to the Fig. 2, the material with the specific elastic properties 130 is between the MEMS unit 101 and the overmolded housing 120 (ie in the illustration of Fig. 2 above the MEMS unit 101) extending substantially parallel to the main extension plane.

[0017] Fig. 3 shows a schematic representation of the sensor system according to a further embodiment of the present invention, in which the material with the specific elastic properties 130 extends between the MEMS unit 101 and the overmolded housing 120 and between the ASIC unit 102 and the overmolded housing 120 substantially along a side surface (ie lateral) of the ASIC unit 102 and / or the MEMS unit 101. Fig. Fig. 4 shows a schematic representation of the sensor system according to a further embodiment of the present invention, in which - according to the embodiment according to Fig. 2 - the material with the specific elastic properties 130 between the MEMS unit 101 and the overmolded housing 120 (ie in the representation of Fig. 2 above the MEMS unit 101) is provided extending substantially parallel to the main extension plane and in which additionally - according to the embodiment according to Fig.3 - the material with the specific elastic properties 130 extends between the MEMS unit 101 and the overmolded housing 120 and between the ASIC unit 102 and the overmolded housing 120 substantially along a side surface (ie lateral) of the ASIC unit 102 and / or the MEMS unit 101.

[0018] In a further embodiment according to the present invention (not shown), it is conceivable that the material with specific elastic properties 130 consists of or comprises several layers of different thicknesses, in particular between 0.1 and 200 micrometers.

Claims

[1] Sensor system comprising at least one MEMS unit (101), at least one ASIC unit (102) and a substrate (110) having a main extension plane and a first and second main side, wherein the at least one ASIC unit (102) is applied to the first main side of the substrate (110), wherein the at least one MEMS unit (101) is applied to the side of the at least one ASIC unit (102) facing away from the substrate (110), wherein the at least one ASIC unit (102) and the at least one MEMS unit (101) are at least partially encased by an overmolded housing (120), characterized by that the at least one ASIC unit (102) and the at least one MEMS unit (101) are at least partially encased in a material with specific elastic properties (130) such that they are mechanically decoupled from the overmolded housing (120). [2] Sensor system according to claim 1, characterized bythat the material with the specific elastic properties (130) extends between the at least one MEMS unit (101) and the overmolded housing (120) substantially parallel to the main extension plane. [3] Sensor system according to one of the preceding claims, characterized by that the material with the specific elastic properties (130) extends between the at least one MEMS unit (101) and the overmolded housing (120) and between the at least one ASIC unit (102) and the overmolded housing (120) substantially along a side surface of the at least one ASIC unit (102) and / or the at least one MEMS unit (101). [4] Sensor system according to one of the preceding claims, characterized by that the at least one ASIC unit (102) is at least partially covered with a further material with further specific elastic properties (131). [5] Sensor system according to one of the preceding claims, characterized by that the material with specific elastic properties (130) consists of several layers, in particular with a thickness of 0.1 to 200 micrometers.

Images