Disclosure of Invention
Based on this, the invention aims to provide a sensor and a preparation method thereof, aiming at solving the problem that the accuracy of the sensor is poor due to the influence of external stress on a sensitive element in the prior art.
According to an embodiment of the present invention, a sensor includes a glass substrate, a stress isolation layer extending outward from the glass substrate, and a sensing element extending from the stress isolation layer in a direction away from the glass substrate, wherein a stiffness of the stress isolation layer is lower than a stiffness of the glass substrate and the sensing element.
Preferably, the material of the stress isolation layer is polydimethylsiloxane.
Preferably, the thickness of the stress isolation layer is 10 to 2000 μm.
According to an embodiment of the present invention, a method for manufacturing a sensor is provided, the method including:
preparing a sensitive element and a stress isolation layer with a preset thickness;
aligning and placing the sensitive element, the stress isolation layer and the glass substrate side by side in sequence, and placing the sensitive element, the stress isolation layer and the glass substrate into plasma excitation equipment for pretreatment, wherein the sensitive element, the stress isolation layer and the glass substrate are placed at a preset spacing distance;
and bonding the pretreated sensitive element, the pretreated stress isolation layer and the glass substrate within preset time to complete bonding connection.
Preferably, the step of preparing the sensitive element and the stress isolation layer with a preset thickness comprises the following steps:
and punching the stress isolation layer and the glass substrate to form a first through hole and a second through hole on the stress isolation layer and the glass substrate respectively.
Preferably, in the step of preparing the stress isolation layer with the preset thickness, polydimethylsiloxane and a curing agent are uniformly mixed according to a preset ratio, and then the mixture is poured into a mold to form the stress isolation layer with the preset thickness.
Preferably, in the step of pretreatment, oxygen is introduced into the plasma excitation equipment, and the oxygen pressure, the radio frequency source power for exciting the plasma and the treatment time are controlled.
Preferably, the oxygen pressure is 10 to 300Pa, the radio frequency source power is 10 to 100W, and the processing time is 10 to 100s.
Preferably, the preset time is 0 to 30min.
Preferably, the preset spacing distance is 1 to 10mm.
Compared with the prior art: by arranging the glass substrate, the stress isolation layer extending outwards from the glass substrate and the sensitive element extending towards the direction far away from the glass substrate from the stress isolation layer, the rigidity of the stress isolation layer is lower than that of the glass substrate and the sensitive element, so that the stress on one side of the glass substrate, whether thermal stress or mechanical stress, is almost completely blocked by the stress isolation layer and cannot be transferred to the sensitive element, and the sensitive area of the sensitive element cannot be sufficiently influenced, so that the measurement accuracy of the sensor is improved.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Several embodiments of the invention are presented in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for purposes of illustration only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Example one
Referring to fig. 1, a sensor according to an embodiment of the invention is shown, which includes a glass substrate 1, a stress isolation layer 2 extending outward from the glass substrate 1, and a sensing element extending from the stress isolation layer 2 in a direction away from the glass substrate 1.
In particular, the stress isolation layer 2 has a lower stiffness than the glass substrate 1 and the sensitive component, and in some alternative embodiments, the glass substrate 1 may be the one commonly used for the glass substrate 1 and the sensitive componentThe silicon-anodized borosilicate glass, such as Pyrex7740 glass, the sensitive element can be made of silicon material, the stress isolation layer 2 can be made of polydimethylsiloxane, namely silicon rubber, specifically Sylgard184 silicon rubber, and it should be noted that the application temperature of the stress isolation layer 2 is-40 to 150 ℃, and the thermal expansion coefficient is less than 300 × 10 -6 The elastic modulus is less than 1GPa per degree, in addition, the thickness of the stress isolation layer 2 is 10-2000 μm, preferably 50-200 μm, and it can be understood that the thickness of the stress isolation layer 2 can be several micrometers to several millimeters according to the requirements of a specific sensing principle.
In this embodiment, taking a pressure sensor as an example, the sensing element includes a sensing portion 31 and a connecting portion 32 extending from the sensing portion 31 toward the glass substrate 1 and surrounding the sensing portion 31, so that the sensing element forms a concave structure, the connecting portion 32 is used for connecting with the stress isolation layer 2, and both the stress isolation layer 2 and the glass substrate 1 are adapted to the connecting portion 32, specifically, when a groove region for sensing pressure exists in the sensing element, matching holes are formed at corresponding positions on the stress isolation layer 2 and the glass substrate 1, it can be understood that when a circular groove exists in the sensing element, matching circular holes are formed on the stress isolation layer 2 and the glass substrate 1, when a rectangular groove exists in the sensing element, matching circular holes can also be formed on the stress isolation layer 2 and the glass substrate 1, in addition, the sensing portion 31 and the connecting portion 32 are both of a symmetrical structure, and symmetry axes of the two coincide, so that the stability of the structure is better, when the glass substrate 1 is affected by an external stress, the external stress isolation layer can be uniformly distributed on the stress isolation layer 2 and the sensing element connected to the glass substrate 1, a specific working mode can be considered as an isolation layer, when the glass substrate 1 is affected by the external stress, the external pressure can be sensed by the external pressure, the external pressure isolation layer, the sensing medium can be accurately contacted with the sensing portion, and the pressure medium can be accurately sensed, and the pressure sensing portion 31, and the sensing medium can be accurately measured, and the pressure sensing portion, and the sensing medium can be accurately, and the pressure sensing portion can be accurately measured by the pressure sensing portion, and the pressure sensing portion.
In this embodiment, the sensor may be fixed to the substrate of the sensor by some common methods, for example, the glass substrate 1 of the sensor and the substrate of the sensor are bonded by common high-strength glue, at this time, stress caused by thermal expansion and contraction is blocked by the stress isolation layer 2 and cannot be transmitted to the sensing element, for example, the glass substrate 1 of the sensor and the substrate of the sensor are welded by metal, at this time, external acting force caused by installation is transmitted to the glass substrate 1 of the sensor through the substrate of the sensor and the metal, but cannot be transmitted to the sensing element continuously.
Example two
Referring to fig. 2 and fig. 3, fig. 2 is a schematic diagram illustrating a method for manufacturing a sensor according to a second embodiment of the present invention, which is used to manufacture the sensor according to the first embodiment, and fig. 3 is a schematic diagram illustrating a process for manufacturing the sensor, where the method specifically includes steps S201 to S203, where:
step S201, a sensitive element and a stress isolation layer with a preset thickness are prepared.
In the embodiment, the polydimethylsiloxane prepolymer can be Sylgard184 silicone rubber, and specifically, the polydimethylsiloxane monomer and the curing agent are mixed according to a mass ratio of 10.
Step S202, aligning and placing the sensitive element, the stress isolation layer and the glass substrate side by side in sequence, and placing the sensitive element, the stress isolation layer and the glass substrate into plasma excitation equipment for pretreatment, wherein the sensitive element, the stress isolation layer and the glass substrate are placed at a preset spacing distance.
It should be noted that samples aligned side by side are placed in a plasma excitation device for pretreatment, specifically, rapid placement of the sensitive element 3, the stress isolation layer 2 and the glass substrate 1 can be achieved through a tool, wherein a gap between the sensitive element 3, the stress isolation layer 2 and the glass substrate 1 can be controlled within 1 to 10mm, that is, the sensitive element 3, the stress isolation layer 2 and the glass substrate 1 are not in contact with each other.
Step S203, the pretreated sensitive element, the stress isolation layer and the glass substrate are bonded within a preset time to complete bonding connection.
The sensitive element 3, the stress isolation layer 2 and the glass substrate 1 are bonded and maintained within a preset time of 0-30min to form automatic bonding, and it should be noted that the bonding effect is better within a preset time of 4 min.
EXAMPLE III
A manufacturing method of a sensor according to a third embodiment of the present invention is used for manufacturing a sensor according to the first embodiment, and is different from the manufacturing method according to the second embodiment in that the manufacturing method according to the third embodiment is used for manufacturing sensors in batch, please refer to fig. 4, where fig. 4 is a schematic flow chart of manufacturing sensors in batch, where:
the method comprises the following steps of pouring polydimethylsiloxane prepolymer into a mold for batch preparation of the sensor, wherein the mold for batch preparation of the sensor can enable the polydimethylsiloxane prepolymer to be poured into the mold to be cured, and then forming a stress isolation layer 2 containing array holes, specifically, after the stress isolation layer 2 is cured, pouring a thicker transfer layer (not shown) on the basis, and curing, wherein the material and the proportion of the transfer layer are consistent with those of the stress isolation layer 2, in the embodiment, the thickness of the transfer layer can be 1-0 1mm, and after the transfer layer is cured, the stress isolation layer 2 can be taken out of the mold through the transfer layer and is flattened on a flexible substrate.
Further, aligning the stress isolation layer 2 with the matched glass substrate 1, keeping a certain gap, putting the stress isolation layer and the matched glass substrate into plasma excitation equipment together for pretreatment, attaching the stress isolation layer and the matched glass substrate after the treatment is finished, realizing automatic bonding, peeling the bendable substrate after the bonding is finished, aligning and bonding the bendable substrate with the sensitive element 3, scribing from the side of the sensitive element 3 and the side of the glass substrate 1 respectively after the bonding, controlling the scribing depth not to touch the stress isolation layer 2, and finally cutting the stress isolation layer 2 at the joint of each sensor by using a blade to obtain a discrete sensor.
Example four
The fourth embodiment of the present invention provides a sensor, which can be prepared by the method for preparing a sensor in the second embodiment.
Referring to fig. 5 and 6, fig. 5 is a schematic diagram of a thermal stress simulation model of a non-stressed isolation layer, and fig. 6 is a schematic diagram of a thermal stress simulation model of a stressed isolation layer, which is an example of a conventional piezoresistive MEMS pressure sensor in the present embodiment, showing the influence of thermal stress on the sensor before and after adding the stressed isolation layer, it should be noted that the size of the thermal stress simulation model used is only 1/4 of that of the sensor, because the sensor in practice is a symmetric structure, and therefore, in view of reducing the calculation amount, it is reasonable to use the 1/4 model.
Specifically, the thermal stress simulation model of the unstressed isolation layer comprises a silicon-based induction layer 6 and a glass base 5, wherein the silicon-based induction layer 6 is bonded with the glass base 5, and the glass base 5 is bonded with the stainless steel substrate through high-strength glue. The critical dimensions are typical values, for example, the sensing area diaphragm is square, the thickness is 50um, the side length is 1mm, the thickness of the silicon-based sensing layer 6 is 500um, the thickness of the glass substrate 5 is 500um, and the thickness of the stainless steel layer 4 is 2mm. According to the method of the invention, a second stress isolation layer 7 is added between a silicon-based induction layer 6 and a glass substrate 5, the thickness of the added second stress isolation layer 7 is 100 micrometers, the thermal stress under the condition of 100 ℃ temperature change is simulated and calculated in the embodiment, it is noted that in the piezoresistive MEMS pressure sensor, the radial stress at the midpoint of the side length of a square diaphragm is important, therefore, the embodiment only focuses on the thermal stress in the direction, and the simulation result is that in the thermal stress simulation model of the stress-free isolation layer, the thermal stress applied to the silicon-based induction layer 6 is 3.02x10 7 Pa, thermal stress simulation model of stress isolation layerIn the medium, the thermal stress of the silicon-based induction layer 6 is 1.18x10 4 Pa, i.e. the second stress isolation layer 7, reduces the thermal stress by 3 orders of magnitude.
In summary, according to the invention, the glass substrate, the stress isolation layer extending outwards from the glass substrate, and the sensing element extending from the stress isolation layer towards the direction away from the glass substrate are provided, and the rigidity of the stress isolation layer is lower than that of the glass substrate and the sensing element, so that the stress on one side of the glass substrate, whether thermal stress or mechanical stress, is almost completely blocked by the stress isolation layer and cannot be transferred to the sensing element, and the sensitive area of the sensing element cannot be sufficiently affected, thereby improving the measurement accuracy of the sensor.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.