CN116573605A

CN116573605A - Packaging method and packaging structure of MEMS pressure sensor

Info

Publication number: CN116573605A
Application number: CN202310656870.3A
Authority: CN
Inventors: 倪藻; 王文涛; 李伟; 黄宏宇
Original assignee: Shanghai Maze Technology Co ltd
Current assignee: Shanghai Maze Technology Co ltd
Priority date: 2023-06-05
Filing date: 2023-06-05
Publication date: 2023-08-11

Abstract

The application provides a packaging method and a packaging structure of an MEMS pressure sensor, wherein the packaging method comprises the following steps: the substrate and the stress sensitive chip are internally provided with blind holes, the bonding medium layer is integrally filled in the blind holes and gaps between the substrate and the stress sensitive chip, the projection of the pressure sensing part of the stress sensitive chip on the substrate is positioned in the blind holes, the lower part of the pressure sensing part is provided with crystal-fixing soft glue with enough thickness to meet the requirement of reducing the influence of packaging stress, meanwhile, the bonding medium layer formed between the stress sensitive chip and the substrate is thinner, the substrate can effectively support the stress sensitive chip during wire bonding, the height between the MEMS chip and the substrate is reduced, and the height of the packaged whole device is reduced. According to the application, the die bonding soft rubber is filled in the blind hole, and the die bonding soft rubber with enough thickness is arranged below the pressure sensing part of the stress sensitive chip, so that the influence of packaging stress or stress in the process of mounting the chip can be avoided.

Description

Packaging method and packaging structure of MEMS pressure sensor

Technical Field

The application belongs to the technical field of silicon micro-mechanical sensors, and particularly relates to a packaging structure for a small-size MEMS pressure sensor and a manufacturing method thereof.

Background

MEMS pressure sensors have evolved rapidly over the last decade and are widely used, such as in consumer, medical, automotive, industrial fields, and the like. The pressure sensing element used in most MEMS pressure sensors is a silicon diaphragm, and the pressure sensor can be divided into three types according to the measurement method when the thin film element is deformed by pressure: piezoresistive pressure sensors, capacitive pressure sensors, and resonant pressure sensors. Currently, the most widely used piezoresistive pressure sensor has a specific principle that silicon piezoresistors are diffused on a silicon diaphragm to form a wheatstone bridge circuit, when the diaphragm is subjected to deformation/stress caused by pressure, the resistance value of the silicon piezoresistors can be changed to cause unbalance of the bridge, the unbalance is proportional to the measured pressure, the pressure is converted through an output voltage signal, the pressure is represented through the conversion of the output voltage signal, and therefore external stress is one of key factors interfering the performance of the pressure sensor. In addition, with the development trend of miniaturization and multifunction of electronic products in the market, the smaller the size, the better the size of the sensing device attached inside the electronic product is.

Fig. 1 is a schematic top view of a MEMS pressure sensor package structure in the prior art, and fig. 2 is a schematic cross-sectional view of the package structure shown in fig. 1 along a section line A-A', where in the conventional packaging process of the MEMS pressure sensor, the thickness of a Die Bond (DB) is generally selected to be thicker so as to avoid the influence of packaging stress or stress during the process of mounting chips by downstream clients. However, for MEMS with smaller size, during the wire bonding process of bonding with the package substrate through metal leads, the thicker die bond colloid often causes inclination or rollover of MEMS, resulting in wire bonding failure, and as shown in fig. 2, the thicker die bond colloid raises the height of the whole device, so that the requirement of small-size package cannot be met; on the contrary, if the die attach encapsulant is thinned to a certain thickness to normally perform the wire bonding process of the wire bonding process, the influence of stress on the MEMS cannot be avoided.

Therefore, the design of the packaging method and the packaging structure of the MEMS pressure sensor is necessary, not only can the bonding wires be realized, but also the influence of packaging stress on the performance of the pressure sensing chip can be reduced, thereby meeting the packaging requirement of the MEMS chip with small size.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present application is to provide a packaging structure of a MEMS pressure sensor chip and a manufacturing method thereof, which are used for solving the problem that in the packaging process of the MEMS pressure sensor in the prior art, the wire bonding process of the small-sized chip is difficult to achieve and causes a slipping phenomenon when receiving a high impact, thereby causing the device to fail.

To achieve the above and other related objects, the present application provides a package structure of a MEMS pressure sensor, comprising:

the packaging structure comprises a substrate, wherein a mounting area and a bonding pad at the periphery of the mounting area are arranged on the substrate, and blind holes are formed in the mounting area of the substrate;

the stress sensitive chip is provided with a pressure sensing part and welding spots at the periphery of the pressure sensing part, the stress sensitive chip is attached to the substrate through an adhesive medium layer in a pressure sensing surface direction, the adhesive medium layer is integrally filled in the blind hole and gaps between the substrate and the stress sensitive chip, the projection of the pressure sensing part of the stress sensitive chip on the substrate is positioned in the blind hole, and the welding spots of the stress sensitive chip are electrically connected with the welding pads of the substrate.

Further, a blind hole is formed in the substrate, the blind hole is arranged so that the projection of the pressure sensing part of the stress sensitive chip on the substrate is located inside the blind hole, and the non-blind hole area of the substrate and the area outside the pressure sensing part of the stress sensitive chip are overlapped in the vertical projection direction to provide support for the stress sensitive chip.

Further, the adhesive medium layer is further arranged to cover the side surface of the stress sensitive chip to a set height along the lower surface of the stress sensitive chip and is formed integrally.

Further, a spacing between the lower surface of the stress sensitive chip and the upper surface of the substrate is between 15 μm and 35 μm.

The application also provides a packaging method of the MEMS pressure sensor, which comprises the following steps:

1) Providing a substrate, wherein a mounting area and a bonding pad positioned at the periphery of the mounting area are defined on the substrate, and blind holes are formed in the mounting area of the substrate;

2) Injecting a die-bonding soft rubber into the blind hole to preform the die-bonding soft rubber into a soft rubber die body, wherein the soft rubber die body is formed to protrude out of the surface of the substrate;

3) Providing a stress sensitive chip, wherein the stress sensitive chip is provided with a pressure sensing part and welding spots arranged on the periphery of the pressure sensing part, the stress sensitive chip is attached to the substrate with the pressure sensing surface facing upwards, so that the projection of the pressure sensing part on the substrate is positioned in the blind hole and is attached to the die bonding soft adhesive, and the die bonding soft adhesive filled in the blind hole and gaps between the substrate and the stress sensitive chip are formed into an integrated adhesive medium layer;

4) Baking and solidifying the bonding medium layer;

5) And electrically connecting the bonding pad of the substrate with the welding spot of the stress sensitive chip.

Optionally, the substrate includes a PCB board, a blind hole is provided on the substrate, and the packaging method further includes:

3) And mounting the stress sensitive chip with the pressure sensitive surface facing the substrate so that the projection of the pressure sensitive part on the substrate is positioned in the blind hole, wherein a non-blind hole area of the substrate is overlapped with an area outside the pressure sensitive part of the stress sensitive chip in a vertical projection direction so as to provide support for the stress sensitive chip.

Optionally, the depth of the blind holes is in the range of 20-80 μm

Optionally, step 2) further comprises:

2-1) injecting the die-bonding soft adhesive into the blind holes by adopting a vacuum adhesive injection method or a heating adhesive injection method after pre-cleaning the substrate, wherein the die-bonding soft adhesive comprises silicon resin soft adhesive;

2-2) exhausting bubbles from the die-bonding soft rubber through vacuumizing treatment, and simultaneously preforming the die-bonding soft rubber into a soft rubber mold body, wherein the preformed soft rubber mold body protrudes from the surface of the substrate by 50-80 mu m.

Optionally, in step 3), a pressure is applied to attach the stress sensitive chip to the substrate, so that the die bond soft adhesive overflows from the soft adhesive die body obtained in step 2), and meanwhile, the die bond soft adhesive is redistributed to fill a gap between the lower surface of the stress sensitive chip and the upper surface of the substrate and is coated up to a set height along the side surface of the stress sensitive chip.

As described above, the packaging structure of the MEMS pressure sensor utilizes the substrate with the blind hole to form the integrated bonding medium layer in the gap between the stress sensitive chip and the substrate and in the blind hole, the projection of the pressure sensing part of the stress sensitive chip on the substrate is positioned in the blind hole, the die bonding soft glue with enough thickness is arranged below the pressure sensing part to meet the requirement of reducing the stress influence, meanwhile, the bonding medium layer formed between the stress sensitive chip and the substrate is thinner, and the substrate can form effective support for the stress sensitive chip during wire bonding, so that the height between the MEMS chip and the substrate is reduced, and the requirement of a terminal customer can be better met.

According to the packaging method of the MEMS pressure sensor, the blind holes in the substrate mounting area are utilized, the die bonding soft adhesive is filled in the blind holes, so that the die bonding soft adhesive filled in the blind holes and in gaps between the pressure sensing chip and the substrate is formed into an integrated adhesive medium layer, the viscous force is greatly improved, and the stress sensitive chip is prevented from being turned over and inclined due to uneven stress during wire bonding; in addition, the side surface of the overflowed colloid viscous sensor can not slip to cause the failure of the device when being subjected to high impact. The die bonding soft glue is filled in the blind hole, and the die bonding soft glue with enough thickness is arranged below the pressure sensing part of the stress sensitive chip, so that the influence of packaging stress or stress in the process of mounting the chip can be avoided; the thinner die bonding colloid between the chip and the substrate can avoid the problem of rollover when the chip is subjected to wire bonding, meanwhile, the height between the MEMS chip and the substrate is reduced, the height of the packaged whole device is reduced, and the requirements of terminal customers can be better met.

Drawings

FIG. 1 shows a schematic top view of a package structure of a MEMS pressure sensor of the prior art.

Fig. 2 is a schematic cross-sectional view of the package structure shown in fig. 1 along a section line A-A'.

Fig. 3 shows a schematic perspective view of a package structure of the MEMS pressure sensor of the present application.

FIG. 4 is a schematic perspective view of the package structure of the MEMS pressure sensor of the present application, wherein the cut line B-B' is the process cut line of FIGS. 6A-9B.

FIG. 5 is a process flow diagram showing the steps of a packaging method of a MEMS pressure sensor according to the present application.

Fig. 6A to 9B are schematic views showing respective steps of a packaging method of a MEMS pressure sensor according to the present application, which are longitudinal sectional views along a sectional line B-B' shown by an arrow in fig. 4.

Description of element numbers: a substrate-10; a stress sensitive chip-20; crystal-fixing soft rubber-30; metal lead-40; blind holes-110; a first blind hole-110 a; a second blind hole-110 b; a pad-130; a pressure sensing part-210; welding spot-220; soft rubber mold body-310; an adhesive dielectric layer-320; distance-D; height-H1, H2.

Detailed Description

Other advantages and effects of the present application will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present application with reference to specific examples. The application may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present application.

As described in detail in the embodiments of the present application, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present application. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.

For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Furthermore, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may also be present.

In the context of the present application, unless otherwise specified and defined, the structural terminology "above" a first feature described is to be understood in a broad sense, and may include, for example, embodiments in which the first and second features are formed in direct contact, as well as embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

Please refer to fig. 3 to fig. 9B. It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present application by way of illustration, and only the components related to the present application are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.

Example 1

Referring to fig. 5 to 9B, the present application provides a packaging method of a MEMS pressure sensor, comprising the following steps:

referring to fig. 5 and 6A, step 1) is first performed to provide a substrate 10, on which a mounting area and a bonding pad 130 located at the periphery of the mounting area are defined, and blind holes 110 are formed in the mounting area of the substrate.

As an example, the substrate 10 is selected as a PCB board, wherein the material of the PCB board may be bismaleimide modified triazine (BT) resin, or a ceramic-based material.

Specifically, as shown in fig. 6B, a first blind hole 110a and a plurality of second blind holes 110B surrounding the first blind hole are formed in the mounting region of the substrate 10.

As an example, the center of the first blind hole 110a is disposed to be aligned with the center of the stress sensitive chip to be bonded. Preferably, a plurality of second blind holes 110b are arranged around the first blind hole 110a, and each second blind hole 110b is spaced apart from the first blind hole 110a or overlaps therewith. It should be noted that, although the specific details of step 1) are described in this embodiment taking the arrangement of the plurality of second blind holes around the first blind hole as an example, the size, number and arrangement of the first blind holes 110a and the second blind holes 120 may be flexibly designed according to the needs in the implementation process.

As an example, the shape of the first blind hole 110a and the second blind hole 110b may include a circle, an ellipse, an oblong arc, a semicircle, or the like. The depth of the first blind hole 110a and the second blind hole 110b can be adjusted according to design requirements and the thickness of the substrate, and the depth ranges from 20 μm to 80 μm, wherein the first blind hole 110a can have the same depth as the second blind hole 110b, as shown in fig. 6A; alternatively, the first blind hole 110a may have a different depth than the second blind hole 110B, for example, a depth greater than the second blind hole 110B, as shown in fig. 6B. In some examples, the first blind via 110a and the second blind via 110b may be formed sequentially using laser drilling, mechanical drilling, or in a manner similar to making non-copper-precipitating vias (NPTH).

As an example, the second blind holes 110b are arranged in an array that is symmetrical about the center of the first blind holes 110 a.

As an example, as shown in fig. 4, the first blind holes 110a may be circular in shape, the number of the second blind holes 110b may be 4, and the second blind holes 110b may be arranged at equal angular intervals centering on the center of the first blind holes 110 a.

It should be noted that the present application provides a substrate for mounting a MEMS sensor chip with 4 second blind holes as one non-limiting example, and in other embodiments, a substrate with 4 or more, 6 or more, 8 or more or other numbers of second blind holes may be used.

As an example, referring to fig. 4, the second blind hole 110b may be provided in a circular shape.

Next, referring to fig. 6, step 2) is performed, the die-bonding soft rubber 30 is injected into the blind hole 110, so that the die-bonding soft rubber 30 is preformed into a soft rubber mold 310, and the soft rubber mold 310 is formed to protrude from the surface of the substrate 10.

Specifically, as shown in fig. 7, step 2) includes: 2-1) injecting the die-bonding soft adhesive 30 into the blind holes 110 by using an adhesive injection mechanism; 2-2) removing bubbles from the die-bonding soft rubber 30 by vacuum-pumping treatment, and simultaneously preforming the die-bonding soft rubber 30 into a soft rubber mold body 310. In step 2), if there are bubbles in the blind hole 110 during the injection, the appearance and performance of the adhesive will be affected to some extent; if there are more bubbles, the package may also fail.

In some examples, step 2) includes passing at least one of:

before step 2-1), pre-cleaning the substrate 10, and then injecting glue, wherein a proper solvent can be selected to clean the plate, so that the inner surface of the hole of the substrate is clean and no residue is left when the hole is dug;

in the step 2-1), an automatic vacuum glue injection or a heating glue injection method is adopted to execute the glue injection step, wherein the heating glue injection method comprises the steps of adopting a heating platform and a heating needle tube to slowly inject glue;

in the step 2-2), the silicone soft rubber with moderate viscosity can be selected, so that the adhesive can be ensured to have certain elasticity and the flowing performance required in the process of filling the blind holes can be ensured, and the generation of bubbles during glue injection can be reduced or eliminated. Preferably, the viscosity of the silicone soft gel ranges from 800 mPas to 2000 mPas. The type and the proportion of the cleaning solution can be determined according to the type of the substrate and the pore-forming process, and the selection of the cleaning solution is well known to those skilled in the art, and will not be described herein.

As an example, the height of the soft mold 310 protruding from the surface of the substrate is denoted by H1 (labeled in fig. 7), where the range of H1 is between 50 μm and 80 μm, and the overflow of the die bond soft adhesive 30 may cause contamination to the bonding location and affect the electrical performance of the device, or even may not implement wire bonding, so that the die bond soft adhesive is ensured to have a sufficient thickness, and at the same time, it is also required to prevent the overflow die bond soft adhesive from being scattered on the bonding pad of the substrate too much, so as to avoid the influence on the subsequent wire bonding step.

Next, referring to fig. 5 and 8, step 3) is performed: the stress sensitive chip 20 is provided, the stress sensitive chip 20 has a pressure sensing portion 210 and a welding spot 220 disposed at the periphery of the pressure sensing portion, the stress sensitive chip 20 is attached to the substrate 10 with the pressure sensing surface of the pressure sensing portion 210, so that the projection of the pressure sensing portion 210 on the substrate is located in the blind hole 110 and is attached to the die bonding soft adhesive 30, and the die bonding soft adhesive filled in the blind hole 110 and the gap between the substrate 10 and the stress sensitive chip 20 is formed into an integrated adhesive medium layer 320, thereby greatly improving the viscous force.

As an example, as shown in fig. 9A, the stress sensitive chip 20 is placed over the die bond paste 30, and the pressure sensitive portion 210 is disposed with its center aligned with the center of the blind hole 110. Since the stress sensitive chip 20 is mounted on the mounting area of the substrate so that the projection of the pressure sensing portion 210 of the stress sensitive chip on the substrate is located in the blind hole 110, the die bonding soft adhesive with sufficient thickness is arranged below the pressure sensing portion 210 of the stress sensitive chip, thereby reducing the influence of stress on the measurement accuracy of the stress sensitive chip 20.

As an example, the stress sensitive chip 20 is mounted on the substrate 10 such that the projection of the pressure sensing portion 210 on the substrate is located inside the blind hole 110, and the non-blind hole area of the substrate 10 overlaps the area outside the pressure sensing portion of the stress sensitive chip in the vertical projection direction to provide support for the stress sensitive chip, so as to ensure that the chip is not inclined or even falls into the blind hole 110 during mounting.

As an example, as shown in fig. 9B, a first blind hole 110a and a plurality of second blind holes 110B are disposed on the substrate 10, and a die bond soft adhesive is filled in the first blind holes 110a and the second blind holes 110B, and a gap between the substrate 10 and the stress sensitive chip 20, as shown in fig. 8, is a gap with a distance D to form an integrated adhesive medium layer 320.

As an example, in step 3), the MEMS wafer may be automatically die-bonded, and tuned to a suitable mounting pressure, and when the MEMS wafer is bonded to the mounting area of the substrate, the soft plastic mold body 310 in the blind hole is pressed and deformed, and the die-bonded soft plastic overflows outwards, so that a relatively flat adhesive medium layer 320 is formed between the stress sensitive chip 20 and the substrate 10, thereby meeting the requirement of flatness during packaging. The appropriate mounting pressure may be set according to the bonding requirement of the chip mounting, and may be, for example, about 10g, but it is not meant to limit the mounting pressure to this range.

As an example, a pressure is applied to attach the stress sensitive chip 20 to the substrate 10, so that the die bond paste 30 overflows from the die body 310 obtained in step 2), and at the same time, the die bond paste is redistributed to fill the gap between the lower surface of the stress sensitive chip 20 and the upper surface of the substrate 10 and is coated up to a set height H2 (indicated in fig. 8) along the side surface of the stress sensitive chip, so as to form the adhesive medium layer 320. The combination of the first blind holes 110a and the second blind holes 110b facilitates the overflow of the excess flexible glue mold 310 through the second blind holes 110b, so that a relatively thin and flat adhesive medium layer is formed between the stress sensitive chip 20 and the substrate 10. Through making solid brilliant soft gum and the inseparable laminating of stress sensitive chip, the soft gum that overflows simultaneously is stuck to the sensor side, has increased the area of contact of chip and solid brilliant soft gum, and viscous force improves by a wide margin for MEMS chip can not produce side turn, slope because of the atress is uneven when the wire bonding, when receiving high impact moreover, can not take place the phenomenon of sliding and lead to the device to become invalid.

As an example, the die bond paste 30 cannot contact the bonding pad 130 of the substrate when overflowing, so as to avoid contamination of the bonding location, which affects the electrical performance of the device, or even makes wire bonding impossible.

As an example, the space D between the lower surface of the pressure sensitive chip 20 and the upper surface of the substrate 10 after mounting is between 15 μm and 35 μm, so that the stress influence of the die attach encapsulant 30 on the pressure sensitive chip 20 in the subsequent step is relatively minimal, and the required viscous force requirement can be satisfied.

Next, as shown in fig. 5, step 4) is performed: and baking and curing the adhesive medium layer 320.

As an example, in step 4), the die bond paste is baked and cured at a curing temperature of 120 to 150 ℃ for more than 30 minutes to cure the adhesive medium layer 320.

Next, referring to fig. 5 and 9A to 9B, step 5) is performed: the bonding pads 130 of the substrate are electrically connected to the pads 220 of the stress sensitive die by wire bonding.

As an example, at step 5), the metal leads 40 are electrically connected to the bonding pads 130 of the substrate and the pads 220 of the stress sensitive die by wire bonding.

In this embodiment, the substrate 10 and the stress-sensitive chip 20 are electrically connected by wire bonding using gold wires, and the gold wires have a gauge between 0.8mil and 1 mil.

The packaging method further comprises the following steps: 6) A dicing process is performed on the substrate 10. The width of the scribing glue can be adjusted according to design requirements. Preferably, the width of the scribing glue is in the range of 130-250 μm.

In step 6), the material of the glue is epoxy glue or conductive silver paste.

The packaging method further comprises the following steps: 7) A surface assembly process is performed to adhere the package to the substrate 10 by means of the glue applied in step 7).

In this embodiment, step 7) includes: and executing an automatic shell pasting process, wherein the push-pull force after shell pasting is kept above 3KG, and the shell of the packaging shell is a plastic shell or a metal shell.

Example two

Referring to fig. 3 to 4, the present application further provides a packaging structure of a MEMS pressure sensor, which can be manufactured according to the foregoing packaging method of a MEMS pressure sensor.

The packaging structure of the MEMS pressure sensor comprises: the substrate 10, the stress sensitive chip 20, and the bonding medium layer 320 disposed between the substrate 10 and the stress sensitive chip 20, wherein a mounting area and a bonding pad 130 at the periphery of the mounting area are disposed on the substrate 10, a blind hole 110 is formed in the mounting area of the substrate 10, the stress sensitive chip 20 has a pressure sensing portion 210 and a bonding pad 220 disposed at the periphery of the pressure sensing portion, the stress sensitive chip 20 is attached to the substrate 10 with the pressure sensing surface facing up through the bonding medium layer 320, the stress sensitive chip 20 is disposed such that the projection of the pressure sensing portion 210 on the substrate 10 is located within the blind hole 110, and the bonding pad 220 of the stress sensitive chip is electrically connected with the bonding pad 130 of the substrate.

As an example, as shown in fig. 3, a single blind hole 110 is provided on the substrate 10, and the blind hole 110 is configured such that a projection of the pressure sensing portion 210 of the stress sensitive chip on the substrate 10 is located inside the blind hole 110.

As an example, as shown in fig. 4, the substrate 10 is provided with a first blind hole 110a and a plurality of second blind holes 110b, and the first blind hole 110a is configured such that a projection of the pressure sensing portion 210 of the stress sensitive chip on the substrate 10 is located inside the first blind hole 110 a. The second blind hole 110b is beneficial to the outward overflow of the soft plastic mold body 310 in the blind hole during mounting, so that a thinner and flatter adhesive medium is formed between the stress sensitive chip 20 and the substrate 10. It should be noted that, although the present embodiment is described taking the case that the plurality of second blind holes are disposed around the first blind hole as an example, in the specific implementation process, the size, number and arrangement of the first blind holes 110a and the second blind holes 110b may be flexibly designed according to the needs.

As an example, the spacing D between the lower surface of the stress sensitive die 20 and the upper surface of the substrate 10 is between 15 μm and 35 μm, so that the adhesive dielectric layer 320 filled in the gap between the lower surface of the stress sensitive die 20 and the upper surface of the substrate 10 has a sufficient thickness to relatively minimize the stress influence on the stress sensitive die 20 during packaging, and also to provide a desired viscous force.

As an example, the adhesion medium layer 320 is further disposed to cover the side surface of the stress sensitive chip 20 up to the set height H2 along the lower surface of the stress sensitive chip 20 and is formed as an integral unit, which increases the contact area between the chip and the adhesion medium layer, and is beneficial to improving the firmness of the whole packaging structure.

As an example, the MEMS pressure sensor includes a piezoresistive pressure sensor.

The utility model provides a packaging structure of MEMS pressure sensor utilizes the base plate of taking the blind hole, in stress sensitive chip with the clearance between the base plate and form the bonding medium layer of integration in the blind hole, stress sensitive chip's pressure sensitive part below has enough thick solid brilliant soft gum in order to satisfy the requirement that reduces stress influence, forms bonding medium layer thinner between stress sensitive chip and the base plate simultaneously, and the base plate can form effective support to stress sensitive chip, has still reduced the height between MEMS chip and the base plate to can better satisfy terminal customer's demand.

In summary, the application provides a packaging structure of an MEMS pressure sensor, which utilizes a substrate with a blind hole to form an integrated bonding medium layer in the blind hole and in a gap between a stress sensitive chip and the substrate, wherein a die bonding soft adhesive with sufficient thickness is arranged below a pressure sensitive part of the stress sensitive chip to meet the requirement of reducing stress influence, and meanwhile, the bonding medium layer formed between the stress sensitive chip and the substrate is thinner, so that the substrate can effectively support the stress sensitive chip, and the height between the MEMS chip and the substrate is reduced.

According to the packaging method of the MEMS pressure sensor, the blind holes are formed in the area of the substrate, and the die bonding soft glue is filled in the blind holes, so that the die bonding soft glue filled in the blind holes and gaps between the pressure sensing chip and the substrate is formed into an integrated adhesive medium layer, and the viscosity is greatly improved.

Therefore, the application effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present application and its effectiveness, and are not intended to limit the application. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the application. Accordingly, it is intended that all equivalent modifications and variations of the application be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A package structure of a MEMS pressure sensor, comprising:

2. The package structure of claim 1, wherein: the substrate is provided with a blind hole, the blind hole is arranged in such a way that the projection of the pressure sensing part of the stress sensitive chip on the substrate is positioned in the blind hole, and the non-blind hole area of the substrate and the area outside the pressure sensing part of the stress sensitive chip are overlapped in the vertical projection direction so as to provide support for the stress sensitive chip.

3. The package structure of claim 2, wherein: the bonding medium layer is further arranged to be coated on the side surface of the stress sensitive chip along the lower surface of the stress sensitive chip to a set height and is formed into a whole.

4. The package structure of claim 1, wherein: the spacing between the lower surface of the stress sensitive chip and the upper surface of the substrate is between 15 and 35 mu m.

5. A method of packaging a MEMS pressure sensor, comprising the steps of:

4) Baking and solidifying the bonding medium layer;

6. The packaging method of claim 5, wherein: the substrate comprises a PCB board, a blind hole is formed in the substrate, and the packaging method further comprises the following steps:

7. The packaging method of claim 6, wherein: the depth of the blind holes is 20-80 μm.

8. The packaging method of claim 5, wherein step 2) further comprises:

9. The packaging method of claim 5, wherein: in step 3), a pressure is applied to attach the stress sensitive chip and the substrate, so that the die bond soft rubber overflows from the soft rubber die body obtained in step 2), and meanwhile, the die bond soft rubber is redistributed to fill a gap between the lower surface of the stress sensitive chip and the upper surface of the substrate and is coated to a set height along the side surface of the stress sensitive chip.