Liquid droplet micro-electromechanical system pyrotechnic device actuation device based on piezoelectric ceramic film

Abstract

A droplet micro-electromechanical system pyrotechnic device actuating device based on piezoelectric ceramic film comprises a lower substrate, an intermediate substrate and an upper substrate which are packaged as one body; the upper surface of the upper substrate is symmetrically provided with a first and a second piezoelectric ceramic film, and the lower surface is provided with a first and a second back cavity; a variable cross-section micro-channel is provided on the intermediate substrate, the variable cross-section micro-channel comprises a wide section and a narrow section, the wide section is located directly below the first and the second back cavities, a mercury droplet is contained in the wide section, a flameproof slider is provided in the narrow section, and first and second stop plates are provided in the first and second cavities on both sides of the flameproof slider; a pressure balancing groove is provided on the lower substrate; an upper detonation hole is provided on the upper substrate, and a lower detonation hole is provided on the lower substrate; the invention reduces the actuation time of the actuating device, reduces the impact acceleration after the pyrotechnic device is triggered, and increases the ability of the MEMS pyrotechnic device actuating device to resist interference from external acceleration signals; combined with the MEMS process, the volume and cost of the actuating device are reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-electromechanical system actuation devices, and in particular relates to a droplet micro-electromechanical system pyrotechnic device actuation device based on a piezoelectric ceramic film. Background Art

[0002] MEMS security devices are one of the key technologies that need to be solved in the research of intelligent MEMS pyrotechnics. They are key components to ensure the safety and reliability of MEMS pyrotechnics. It can be predicted that MEMS security devices will usher in large-scale development in the near future.

[0003] Micro-actuators refer to the actuators used in MEMS security devices, which mainly provide thrust or displacement for the partitions of the security devices. Micro-actuators are an important component of MEMS security devices, responsible for energy conversion, motion and force transmission within the security device, and responding to system information. For example, in 2017, Dakui Wang published an article in Micromachines, proposing a MEMS security device with two independent actuating mechanisms. In a safe state, the two actuating mechanisms lock the explosion-proof slider in a safe position, and the explosion transmission sequence is isolated; after receiving the launch command, under the action of centrifugal force, the centrifugal actuating mechanism releases the restriction on the explosion-proof slider, and then the electric thruster pushes the locking spring downward. Since the actuating mechanism in the MEMS security device often needs to work in extreme environments, this places high demands on the reliability of the actuating mechanism. The existing solid-state actuators have the disadvantages of excessive impact acceleration after initiation and long actuation time, which leads to a decrease in the reliability of pyrotechnic devices and components. Summary of the invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a droplet micro-electromechanical system pyrotechnic actuator device based on piezoelectric ceramic film, which utilizes piezoelectric ceramic film to drive the deformation of droplets to reduce the actuation time of the actuator; uses the deformation of metal droplets to promote the movement of the explosion-proof slider to reduce the impact acceleration after the pyrotechnic is triggered; limits the movement of droplets through variable-section microchannels to increase the ability of the MEMS pyrotechnic actuator to resist interference from external acceleration signals; and combines MEMS technology to reduce the size and cost of the actuator.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A droplet micro-electromechanical system pyrotechnic device actuating device based on a piezoelectric ceramic film comprises a lower substrate 1, an intermediate substrate 2, and an upper substrate 3 which are packaged as one body;

[0007] The upper surface of the upper substrate 3 is symmetrically provided with a first piezoelectric ceramic film 13 and a second piezoelectric ceramic film 14, the first piezoelectric ceramic film 13 is connected to a first pair of metal pads 15, and the second piezoelectric ceramic film 14 is connected to a second pair of metal pads 16; the lower surface of the upper substrate 3 is provided with a first back cavity 17 and a second back cavity 18 corresponding to the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14;

[0008] The intermediate substrate 2 is provided with a variable cross-section microchannel 7 corresponding to the first back cavity 17 and the second back cavity 18, the first wide section 71 and the second wide section 72 of the variable cross-section microchannel 7 are respectively located directly below the first back cavity 17 and the second back cavity 18, and the first wide section 71 and the second wide section 72 are respectively filled with a first mercury droplet 11 and a second mercury droplet 10; the narrow section 73 of the variable cross-section microchannel 7 is provided with a flameproof slider 4, and the first cavity 41 and the second cavity 42 on both sides of the flameproof slider 4 are provided with a first stopper 8 and a second stopper 9;

[0009] The lower substrate 1 is provided with a pressure balancing groove 5, and the two ends of the pressure balancing groove 5 are respectively located directly below the first wide section 71 and the second wide section 72;

[0010] The upper base plate 3 is provided with an upper detonation hole 12 , and the lower base plate 1 is provided with a lower detonation hole 6 . The upper detonation hole 12 corresponds to the lower detonation hole 6 in the vertical direction.

[0011] The first pair of metal pads 15 includes a first metal pad 151 and a third metal pad 152; the second pair of metal pads 16 includes a second metal pad 161 and a fourth metal pad 162; the first upper driving electrode 132 and the first lower driving electrode 131 are respectively deposited on the upper and lower surfaces of the first piezoelectric ceramic film 13; the second upper driving electrode 142 and the second lower driving electrode 141 are respectively deposited on the upper and lower surfaces of the second piezoelectric ceramic film 14; the first lower driving electrode 131 and the second lower driving electrode 141 are respectively connected to the first metal pad 151 and the second metal pad 161, and the first upper driving electrode 132 and the second upper driving electrode 142 are respectively connected to the third metal pad 152 and the fourth metal pad 162.

[0012] The planar dimensions of the first wide section 71 and the second wide section 72 are the same as those of the first back cavity 17 and the second back cavity 18 .

[0013] The flameproof slider 4 is slightly smaller than the narrow section 73 .

[0014] The lower substrate 1 , the middle substrate 2 , and the upper substrate 3 have the same plane size, and are aligned on all sides during packaging.

[0015] The upper explosion hole 12 and the lower explosion hole 6 are both vertical through holes.

[0016] When the actuating device is in the "safe" state, a small amount of the first mercury droplet 11 and the second mercury droplet 10 enter the narrow section 73, the second stopper 9 contacts the left edge of the second cavity 42 of the flameproof slider 4, the first stopper 8 contacts the left edge of the first cavity 41 of the flameproof slider 4, and the flameproof slider 4 blocks the upper explosion hole 12 and the lower explosion hole 6; when the actuating device is in the "released" state, the second mercury droplet 10 in the second back cavity 18 is squeezed and enters the narrow section 73 in large quantities, the first mercury droplet 11 in the first back cavity 17 shrinks, and a small amount returns to the first wide section 71, the second mercury droplet 10 pushes the flameproof slider 4 to move leftward, the second stopper 9 contacts the right edge of the second cavity 42 of the flameproof slider 4, the first stopper 8 contacts the right edge of the first cavity 41 of the flameproof slider 4, and the upper explosion hole 12 is connected to the lower explosion hole 6.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] 1. The present invention adopts a piezoelectric ceramic film to drive the movement of mercury droplets and utilizes a variable cross-section microchannel to reduce the deformation of the mercury droplets, thereby reducing the driving voltage and actuation time of the actuator.

[0019] 2. The present invention utilizes the liquid-solid contact mode between the mercury droplet and the flameproof slider, thereby improving the ability of the actuator to resist interference from external acceleration signals.

[0020] 3. The present invention uses mercury droplets, so they can quickly regroup from a dispersed state under a large impact. At the same time, the deformation of the mercury droplets is limited by using variable-section microchannels, thereby improving the impact resistance of the actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0022] Figure 2 It is a schematic diagram of the upper substrate structure of the present invention.

[0023] Figure 3 It is a schematic diagram of the lower substrate structure of the present invention.

[0024] Figure 4 It is a schematic diagram of the intermediate substrate and the flameproof slider of the present invention.

[0025] Figure 5 It is a schematic diagram of the present invention in a "safe" state.

[0026] Figure 6 It is a schematic diagram of the present invention in the "released" state. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0028] Reference Figure 1 , a droplet micro-electromechanical system pyrotechnic device actuating device based on a piezoelectric ceramic film, comprising a lower substrate 1, an intermediate substrate 2, and an upper substrate 3 which are packaged as one body;

[0029] The upper surface of the upper substrate 3 is symmetrically provided with a first piezoelectric ceramic film 13 and a second piezoelectric ceramic film 14, the first piezoelectric ceramic film 13 is connected to a first pair of metal pads 15, and the second piezoelectric ceramic film 14 is connected to a second pair of metal pads 16; the lower surface of the upper substrate 3 is provided with a first back cavity 17 and a second back cavity 18 corresponding to the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14;

[0030] The intermediate substrate 2 is provided with a variable cross-section microchannel 7 corresponding to the first back cavity 17 and the second back cavity 18, and the variable cross-section microchannel 7 contains a first mercury droplet 11, a second mercury droplet 10 and a flameproof slider 4, and a first stopper 8 and a second stopper 9 are provided on both sides of the flameproof slider 4;

[0031] The lower base plate 1 is provided with a pressure balancing groove 5;

[0032] The upper base plate 3 is provided with an upper detonation hole 12 , and the lower base plate 1 is provided with a lower detonation hole 6 . The upper detonation hole 12 corresponds to the lower detonation hole 6 in the vertical direction.

[0033] Reference Figure 1 , Figure 2 The upper substrate 3 is made of single crystal silicon material with a thickness of 200μm to 300μm. The first pair of metal pads 15 includes a first metal pad 151 and a third metal pad 152. The second pair of metal pads 16 includes a second metal pad 161 and a fourth metal pad 162. The first upper driving electrode 132 and the first lower driving electrode 131 are deposited on the upper and lower surfaces of the first piezoelectric ceramic film 13 respectively. The second upper driving electrode 142 and the second lower driving electrode 141 are deposited on the upper and lower surfaces of the second piezoelectric ceramic film 14 respectively. The first lower driving electrode 131 and the second lower driving electrode 141 are connected to the first metal pad 151 and the second metal pad 161 respectively, and the first upper driving electrode 132 and the second upper driving electrode 142 are connected to the third metal pad 152 and the fourth metal pad 162 respectively.

[0034] The preparation process of the upper substrate 3 and the structures thereon is as follows: a 1 μm thick layer of silicon dioxide is first deposited on the upper surface and the lower surface of the upper substrate 3 by using a plasma enhanced chemical vapor deposition (PECVD) process, and then a 30 nm to 50 nm thick titanium metal and a 200 nm to 250 nm thick platinum metal are sputtered on the upper surface of the silicon substrate after the silicon dioxide is deposited by using a magnetron sputtering apparatus to form a first lower layer driving electrode 131 and a second lower layer driving electrode 141;

[0035] Spin coating a piezoelectric ceramic PZT sol on a platinum-plated surface to prepare a PZT film with a thickness of 1 μm to 1.5 μm, spin coating a positive photoresist BP212 on the crystallized PZT film, and pre-bake it on a hot plate at 85° C. for 30 minutes to harden the film, then align and expose it with a photolithography machine, place the exposed sample in a 0.5% NaOH solution for development, and post-bake it at 85° C. for 30 minutes after the development is completed, sputter a titanium / platinum electrode layer with a thickness of 150 nm to 200 nm on the sample, soak the sputtered sample in an acetone solution, and peel off the titanium / platinum metal on the photoresist mask to obtain a patterned first upper driving electrode 132 and a second upper driving electrode 142;

[0036] The same photolithography process is used to spin-coat photoresist on the patterned platinum electrode layer, and a PZT masking layer is obtained after exposure and development. The sample is placed in a PZT etching solution to etch the film to obtain a first piezoelectric ceramic film 13 and a second piezoelectric ceramic film 14;

[0037] First, a photoresist pattern of a first metal pad 151, a second metal pad 161, a third metal pad 152 and a fourth metal pad 162 is prepared on the surface of the upper substrate by a photolithography process, and then a 150nm to 200nm thick gold is deposited on the upper surface of the upper substrate by a magnetron sputtering apparatus to obtain the first metal pad 151, the second metal pad 161, the third metal pad 152 and the fourth metal pad 162;

[0038] First, a photoresist masking layer of the first back cavity 17 and the second back cavity 18 is made on the back of the upper substrate 3 by using a photolithography process, and then a dry etching process DRIE is used to etch the silicon substrate to obtain the first back cavity 17 and the second back cavity 18;

[0039] The upper detonation hole 12 is etched on the upper substrate 3 by using a laser processing method.

[0040] Reference Figure 3 , Figure 4The first wide section 71 and the second wide section 72 of the variable-section microchannel 7 are respectively located directly below the first back cavity 17 and the second back cavity 18, and the first wide section 71 and the second wide section 72 are respectively filled with the first mercury droplet 11 and the second mercury droplet 10; a flameproof slider 4 is provided in the narrow section 73 of the variable-section microchannel 7, and a first stopper 8 and a second stopper 9 are provided in the first cavity 41 and the second cavity 42 on both sides of the flameproof slider 4; the lower substrate 1 is made of single crystal silicon material with a thickness of 300μm to 500μm, and the two ends of the pressure balance groove 5 are respectively located directly below the first wide section 71 and the second wide section 72.

[0041] The preparation process of the lower substrate 1 is as follows: a photoresist masking layer of the pressure balance groove 5 is made on the front of the lower substrate 1 by using a photolithography process, and then a dry etching process DRIE is used to etch the silicon substrate to obtain the pressure balance groove 5; a laser processing method is used to etch the lower explosion hole 6 on the lower substrate 1.

[0042] The preparation process of the intermediate substrate 2 and the flameproof slider 4 is as follows: a layer of SU-8 photoresist material with a thickness of 100μm to 200μm is coated on the lower substrate 1 by a uniform coating method, the photoresist is solidified and the stress inside the photoresist is removed by a step-by-step heating / cooling method, and a variable-section microchannel 7 and a first stopper 8 and a second stopper 9 are processed by exposure and development technology to form the intermediate substrate 2; first, a photoresist pattern of the first cavity 41 and the second cavity 42 is prepared on a single crystal silicon material with a thickness of 90μm to 190μm by a photolithography process, and then a dry etching process DRIE is used to etch the silicon substrate to obtain the flameproof slider 4.

[0043] The lower substrate 1 and the middle substrate 2 are packaged using the MEMS process, and the middle substrate 2 and the upper substrate 3 are packaged using ultraviolet adhesive. The plane dimensions of the lower substrate 1, the middle substrate 2, and the upper substrate 3 are the same, and the lower substrate 1, the middle substrate 2, and the upper substrate 3 are aligned on all sides during packaging.

[0044] The surface tension of the first mercury droplet 11 and the second mercury droplet 10 at room temperature is 0.485 N / m, which has a large surface tension. When no voltage is applied, the first mercury droplet 11 and the second mercury droplet 10 are not deformed, the flameproof slider 4 is stationary, and the actuating mechanism is in a "safe" state. When voltage is applied, the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14 are deformed, causing the first mercury droplet 11 and the second mercury droplet 10 to deform, pushing the flameproof slider 4 to move to the left, and the actuating mechanism is changed to a "released" state.

[0045] Reference Figure 5, the actuating device is in a "safe" state, the electric potential on the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14 is zero, the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14 are not deformed, the first mercury droplet 11 and the second mercury droplet 10 are not deformed, the second stopper 9 contacts the left edge of the second cavity 42 of the flameproof slider 4, the first stopper 8 contacts the left edge of the first cavity 41 of the flameproof slider 4, the flameproof slider 4 blocks the upper explosion-guiding hole 12 and the lower explosion-guiding hole 6, and the explosion signal is blocked and cannot be transmitted to subsequent devices;

[0046] Reference Figure 6 , the actuating device is in the "released" state, and there is an electric potential on the first piezoelectric ceramic film 13 and the second piezoelectric ceramic film 14. The first piezoelectric ceramic film 13 is deformed upward under the action of the electric potential, and the second piezoelectric ceramic film 14 is deformed downward under the action of the electric potential, squeezing the silicon film at the upper end of the second back cavity 18, and the second mercury droplet 10 in the second back cavity 18 is squeezed, and a large amount of it enters the narrow section 73, and the first mercury droplet 11 in the first back cavity 17 shrinks, and a small amount returns to the first wide section 71, and the second mercury droplet 10 pushes the explosion-proof slider 4 to move leftward, and the second stopper 9 contacts the right edge of the second cavity 42 of the explosion-proof slider 4, and the first stopper 8 contacts the right edge of the first cavity 41 of the explosion-proof slider 4, and the upper explosion-guiding hole 12 is connected with the lower explosion-guiding hole 6, and the explosion signal is transmitted to the subsequent devices through the upper explosion-guiding hole 12 and the lower explosion-guiding hole 6.

[0047] The above description is only a specific embodiment of the present invention and does not constitute any limitation to the present invention. It is obvious that for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A droplet micro-electromechanical system pyrotechnic device actuating device based on a piezoelectric ceramic film, comprising a lower substrate (1), an intermediate substrate (2), and an upper substrate (3) which are packaged as one body; The upper surface of the upper substrate (3) is symmetrically provided with a first piezoelectric ceramic film (13) and a second piezoelectric ceramic film (14); the first piezoelectric ceramic film (13) is connected to a first pair of metal pads (15), and the second piezoelectric ceramic film (14) is connected to a second pair of metal pads (16); the lower surface of the upper substrate (3) is provided with a first back cavity (17) and a second back cavity (18) corresponding to the first piezoelectric ceramic film (13) and the second piezoelectric ceramic film (14); The intermediate substrate (2) is provided with a variable cross-section microchannel (7) corresponding to the first back cavity (17) and the second back cavity (18); the first wide cross-section (71) and the second wide cross-section (72) of the variable cross-section microchannel (7) are respectively located directly below the first back cavity (17) and the second back cavity (18); the first wide cross-section (71) and the second wide cross-section (72) are respectively filled with a first mercury droplet (11) and a second mercury droplet (10); a flameproof slider (4) is provided in the narrow cross-section (73) of the variable cross-section microchannel (7); a first stopper (8) and a second stopper (9) are provided in the first cavity (41) and the second cavity (42) on both sides of the flameproof slider (4); The lower base plate (1) is provided with a pressure balancing groove (5), and two ends of the pressure balancing groove (5) are respectively located directly below the first wide section (71) and the second wide section (72); The upper base plate (3) is provided with an upper detonation hole (12), and the lower base plate (1) is provided with a lower detonation hole (6), and the upper detonation hole (12) and the lower detonation hole (6) correspond to each other in the vertical direction.

2. The device according to claim 1, characterized in that: The first pair of metal pads (15) comprises a first metal pad (151) and a third metal pad (152); the second pair of metal pads (16) comprises a second metal pad (161) and a fourth metal pad (162); a first upper driving electrode (132) and a first lower driving electrode (131) are deposited on the upper and lower surfaces of the first piezoelectric ceramic film (13) respectively; a second upper driving electrode (142) and a second lower driving electrode (141) are deposited on the upper and lower surfaces of the second piezoelectric ceramic film (14) respectively; the first lower driving electrode (131) and the second lower driving electrode (141) are connected to the first metal pad (151) and the second metal pad (161) respectively, and the first upper driving electrode (132) and the second upper driving electrode (142) are connected to the third metal pad (152) and the fourth metal pad (162) respectively.

3. The device according to claim 1, characterized in that: The planar dimensions of the first wide section (71) and the second wide section (72) are the same as those of the first back cavity (17) and the second back cavity (18).

4. The device according to claim 1, characterized in that: The size of the flameproof sliding block (4) is slightly smaller than the narrow section (73).

5. The device according to claim 1, characterized in that: The lower substrate (1), the middle substrate (2), and the upper substrate (3) have the same plane dimensions, and during packaging, the lower substrate (1), the middle substrate (2), and the upper substrate (3) are aligned on all sides.

6. The device according to claim 1, characterized in that: The upper detonation hole (12) and the lower detonation hole (6) are both upper and lower through holes.

7. The device according to claim 1, characterized in that: When the actuating device is in a "safe" state, a small amount of the first mercury droplet (11) and the second mercury droplet (10) enter the narrow cross section (73), the second stopper (9) contacts the left edge of the second cavity (42) of the flameproof slider (4), the first stopper (8) contacts the left edge of the first cavity (41) of the flameproof slider (4), and the flameproof slider (4) blocks the upper explosion-guiding hole (12) and the lower explosion-guiding hole (6); when the actuating device is in a "released" state, the second mercury droplet (11) and the second mercury droplet (10) in the second back cavity (18) are The silver droplet (10) is squeezed and enters the narrow section (73) in large quantities. The first mercury droplet (11) in the first back cavity (17) shrinks and returns in small quantities to the first wide section (71). The second mercury droplet (10) pushes the explosion-proof slider (4) to move leftward. The second stopper (9) contacts the right edge of the second cavity (42) of the explosion-proof slider (4). The first stopper (8) contacts the right edge of the first cavity (41) of the explosion-proof slider (4). The upper explosion-guiding hole (12) is connected to the lower explosion-guiding hole (6).

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