Miniaturized exploding foil exploder

Abstract

The invention discloses a miniaturized exploding foil exploder, which comprises a plastic package block used for plastic package of the exploding foil exploder; the substrate is used as a carrier of the exploding foil exploder; the metal bridge foil is arranged on the substrate and comprises a bridge area and a bridge wing; the second guide columns are arranged in the base, correspond to bridge wing parts of the metal bridge foil respectively and are connected with the bridge wings; the metal bonding pads are arranged below the substrate and correspond to the bridge wings of the metal bridge foil respectively, and the upper surfaces of the metal bonding pads are connected with the second guide columns; the first guide post is arranged below the metal bonding pad and is connected with the lower surface of the metal bonding pad; the flyer layer is positioned on the metal bridge foil; and the acceleration chamber is located on the flyer layer, and a chamber hole of the acceleration chamber corresponds to the bridge area of the metal bridge foil. A trigger current is connected to the first guide column, under the action of the trigger current, electric explosion occurs at the bridge area of the metal bridge foil, the flyer is driven, and the flyer impacts the insensitive explosive after being accelerated by the acceleration chamber. The exploding foil exploder is low in cost and small in size.

Description

Technical Field

[0001] This invention belongs to the technical field of micro-power conversion devices, and in particular relates to a miniaturized explosive foil initiator. Background Technology

[0002] An Exploding Foil Initiator (EFI) system consists of a pulse power module and an explosive foil initiator, and is a type of inline pyrotechnic device. Its basic structure includes a substrate, a metal bridge foil, a flyer layer, an acceleration chamber, and insensitive explosive. Its working principle is as follows: under appropriate triggering signals, the pulse discharge circuit containing the metal bridge foil is energized and rapidly discharged, applying high voltage and strong current to both ends of the bridge foil at extremely high speed. This causes the bridge region of the metal bridge foil to rapidly heat up, undergoing a rapid and continuous phase transition from solid metal to vapor and expansion. During this process, due to the rigid constraints of the substrate and the acceleration chamber, the gaseous metal is forced to expand upwards, compressing the flyer layer and "cutting" flyers out at the edge of the acceleration chamber. The expanded metal vapor undergoes breakdown under subsequent energy, forming plasma. The high-temperature, high-pressure plasma continuously accelerates the flyers within the acceleration chamber bore. Finally, the flyers reach maximum velocity at the exit and collide with the insensitive explosive. The shock wave generated by the impact directly detonates the insensitive explosive, thereby igniting the main charge.

[0003] The biggest difference between explosive foil initiators and traditional initiators is that the detonation of insensitive explosives is directly triggered by the impact of the flying disc, rather than using a more sensitive initiator. Furthermore, early explosive foil initiators used a single MEMS process, often with a silicon-based substrate, which could cause the metal foil, flying disc, and accelerator to detach during operation. This could lead to accidental or premature detonation of the fuse. Using explosive foil initiators can effectively avoid accidental and premature detonation of the fuse.

[0004] Due to their high safety, reliability, and detectability, explosive foil initiators are widely used not only in nuclear weapon detonation systems but also in modern weapon systems. However, existing explosive foil initiators are expensive and bulky, making it difficult to meet my country's requirements for low-cost, miniaturized weaponry. Summary of the Invention

[0005] The purpose of this invention is to provide a miniaturized explosive foil initiator to meet the requirements of low cost and miniaturization in explosive foil initiation systems.

[0006] The technical solutions for achieving the purpose of the present invention are:

[0007] A miniaturized explosive foil initiator includes:

[0008] Plastic-encapsulated blocks, used for encapsulating explosive foil detonators;

[0009] The substrate serves as the carrier for the explosive foil initiator;

[0010] The metal bridge foil, located on the substrate, consists of two parts: bridge wings and bridge area. The bridge wings are arranged symmetrically with the bridge area as the center. The bridge wings include a rectangular second bridge wing and a trapezoidal first bridge wing. The second bridge wing transitions to the middle bridge area through the first bridge wing.

[0011] Two metal pads are located below the substrate and correspond to the positions of the second bridge wings of the metal bridge foil, respectively.

[0012] Two sets of second guide posts are located inside the substrate and are connected to the lower surface of the second bridge wing of the metal bridge foil and the upper surface of the metal pad, respectively.

[0013] Two first guide posts are located below the metal pads and are connected to the lower surface of the metal pads. They correspond to the positions of the second bridge wings of the metal bridge foil and are used to connect the trigger current.

[0014] The flyer layer, located above the metal bridge foil, is used to generate flyers by an electrical explosion that occurs in the bridge area under the action of trigger current.

[0015] The acceleration chamber, located above the flyer layer, has bores that correspond to the bridge area of ​​the metal bridge foil. It is used to accelerate the flyer and then impact the insensitive explosive, thereby detonating the main charge.

[0016] The significant advantages of this invention compared to existing technologies are:

[0017] (1) By combining MEMS and LTCC technologies, the volume of the explosive foil initiator is greatly reduced, with the overall volume (excluding the two copper pillars) controlled to within 9mm. 3 Within this range, the volume after injection molding (excluding the two copper pillars) is controlled within 100mm. 3 (1) The volume of the initiator is greatly reduced compared to the previous one; (2) The structure is simple and easy to mass-produce, which greatly reduces the cost; (3) The insensitive explosive is detonated by direct impact of the flying piece, instead of using the more sensitive pyrotechnic agent or initiator as the starting charge to detonate the insensitive explosive, which can greatly ensure its performance, safety, reliability and detectability. Attached Figure Description

[0018] Figure 1 This is a outline diagram of a miniaturized explosive foil detonator.

[0019] Figure 2 This is a three-dimensional structural diagram of a miniaturized explosive foil initiator.

[0020] Figure 3 This is a three-dimensional structural diagram of a miniaturized explosive foil initiator.

[0021] Figure 4This is a three-dimensional structural diagram of a miniaturized explosive foil initiator.

[0022] Figure 5 An exploded view of a miniaturized explosive foil initiator.

[0023] Figure 6 An exploded view of a miniaturized explosive foil initiator.

[0024] Figure 7 This is a schematic diagram of a metal bridge foil for a miniaturized explosive foil initiator. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Combination Figures 1 to 7 This invention discloses a miniaturized explosive foil initiator, comprising a molding block 8, a first conductor 7, a metal pad 6, a substrate 4, a second guide post 5, a metal bridge foil 3, a flyer layer 2, and an acceleration chamber 1. The substrate 4, serving as the carrier of the explosive foil initiator, possesses a certain degree of hardness. The second guide post 5, located inside the substrate 4, comprises 18 posts in total, 9 on each side. The second guide post 5 is prepared by drilling through holes in the substrate 4 (a green ceramic sheet) and injecting metal paste into the through holes. The metal pad 6 is located on the bottom side of the substrate 4. The metal bridge foil 3 is screen-printed and bonded to the substrate 4 by hot pressing or static pressing, and then sintered with the substrate 4 and the second guide post 5 in a sintering furnace at approximately 900°C to form a single unit. The flyer layer 2 is etched using ultraviolet lithography and then cured onto the metal bridge foil 3 using development technology. Above; the accelerating chamber 1 uses SU-8 negative photoresist, which is baked on a constant temperature heating stage at 95°C to remove the solvent from the photoresist and cure it. The photoresist is then irradiated with ultraviolet light to transfer the pattern on the mask onto the photoresist. After development, it is left to stand and then baked to cure, thus obtaining the in-situ prepared accelerating chamber; there are two first guide posts 7, which are respectively connected to two metal pads 6 and are made of copper; the molding block 8 is located on the periphery of the explosive foil detonator, but the upper surface of the accelerating chamber 1 and part of the length of the first guide post 7 are exposed on the outside; the molding block 8 is injection molded using epoxy resin at 175°C.

[0027] Example

[0028] Combination Figures 1 to 7This embodiment of a miniaturized explosive foil initiator includes a molding block 8, a first guide post 7, a metal pad 6, a substrate 4, a second guide post 5, a metal bridge foil 3, a flyer layer 2, and an acceleration chamber 1. The substrate 4, serving as the carrier of the explosive foil initiator, is made of aluminum nitride ceramic, microcrystalline glass, or quartz with a certain hardness, measuring 4mm × 2mm and having a thickness of 0.6mm. The metal bridge foil 3 is a 0.1µm thick Au / Cu layer printed onto the substrate 4 using screen printing technology. This thickness results in low resistance and inductance, making it suitable for mass production. The design is a square followed by a trapezoid; simulations show that this design generates a smaller electric field under the same voltage. The square dimensions are 0.2mm × 0.2mm. The second guide post 5, acting as a conductor, is located inside the substrate 4 and is made of Cu. Metal paste is applied by drilling through holes in the substrate 4. The via is made of Cu and has dimensions of φ0.1mm × 0.6mm. The metal pad 6, acting as a conductor, is located on the bottom side of the substrate 4 and is also made of Cu with dimensions of φ1.2mm × 0.3mm. The substrate 4, metal bridge foil 3, second guide post 5, and metal pad are integrally co-fired using LTCC technology. The flyback layer 2 is made of polyimide photoresist with dimensions of 4mm × 2mm and a thickness of 0.03mm. The acceleration chamber 1 is made of SU-8 negative photoresist with dimensions of 4mm × 2mm and a thickness of 0.45mm, and the acceleration chamber aperture is φ0.35mm. The acceleration chamber aperture corresponds to the bridge area of ​​the metal bridge foil. The first guide post 7 is a conductor made of copper with dimensions of φ1.0mm × 20mm. The molding compound 8 is made of epoxy resin with dimensions of φ6mm × 3mm.

[0029] The metal bridge foil 3 comprises a first bridge wing 3-a, a bridge area 3-c, and a second bridge wing 3-b, forming a symmetrical structure centered on the bridge area 3-c. The two rectangular second bridge wings 3-b transition to the central bridge area 3-c via trapezoidal first bridge wings 3-a. The width of the bridge area 3-c is the same as the width of the upper base of the first bridge wing 3-a. This design is simple and easy to manufacture. The dimensions of the first bridge wing 3-a are: upper base 0.2mm, lower base 2mm, and side length 1.39mm. The dimensions of the bridge wing 3-b are 0.95mm (parallel to the width direction of the bridge area 3-c) × 2mm (perpendicular to the width direction of the bridge area 3-c). The bridge area 3-c is the starting point of the entire explosive foil initiator, with dimensions of 0.2mm × 0.2mm. Simulations show that a bridge of this size has sufficient energy to impact the flyer layer 2 with low trigger energy. The bridge wing 3-a is trapezoidal, and the angle between the hypotenuse of the first bridge wing 3-a and the long side of the bridge area 3-c is 45°. The dimensions of the bridge region 3-c are 0.2 mm (length) × 0.2 mm (width) × 0.01 mm (thickness). The metal used in the metal bridge foil 3 is a Cu or Au / Cu composite metal layer.

[0030] The second guide posts 5, serving as conductors, number 18 in total and are located inside the substrate 4. They are fabricated using the LTCC process by drilling through holes in the substrate 4 and injecting metal paste into these holes. Their dimensions are φ0.1mm × 0.6mm. The outermost metal post has a lateral distance of 0.35mm and a longitudinal distance of 0.38mm from the edge of the substrate. The lateral distance between the centers of each metal post is 0.3mm, and the longitudinal distance is 0.6mm. The nine second guide posts 5 on each side correspond to the positions of the second bridge wings 3-b on both sides.

[0031] The metal pads 6, serving as conductors, consist of two pads fabricated on the bottom side of the substrate 4 using the LTCC process. They measure 2mm × 1.5mm and have a thickness of 0.3mm, with a distance of 30mm between each pad. The positions of the two metal pads 6 correspond to the positions of the second bridge wings 3-b on both sides.

[0032] The first guide post 7 serves as a conductor, and there are two of them. They are welded to two metal pads 6 respectively. The material is copper, and the size is φ1mm×20mm. The distance between the two first guide posts is 30mm.

[0033] The first guide post 7 of the explosive foil initiator was connected to an external high-voltage release unit for performance testing. Specifically, the two first guide posts were connected to a trigger capacitor. Under a trigger condition of 0.4μF / 1700V, a current instantaneously flowed through the bridge region 3-c, causing an electrical explosion. This transformed the bridge region from a solid state to a plasma state. The plasma impacted the flyer layer 2, which then impacted the insensitive explosive via the acceleration chamber 1. Testing showed that a current of 2000A could be generated in the circuit, successfully initiating the insensitive explosive.

[0034] Preparation process flow

[0035] (1) Using ceramic as a base, ceramic powder and organic binder are first mixed into a slurry in proportion, wherein the ceramic powder accounts for 50% to 70% of the total weight of the slurry and the organic binder accounts for 30% to 50% of the total weight of the slurry. The slurry is then cast into a green ceramic tape and cut into green sheets according to the design size (150 to 280 green ceramic sheets can be generated per plate according to the LTCC process requirements).

[0036] (2) Cut the green ceramic strip into green ceramic sheets and drill through holes in the green ceramic sheets. Insert the metal paste into the through holes. Print the shape of metal bridge foil on the upper surface of the green ceramic sheets by screen printing. Print the solder pads on the lower surface of the green ceramic sheets by screen printing. Bond the green ceramic sheets together by hot pressing or static pressing. Perform the LTCC process in a sintering furnace at about 900°C and wait for curing.

[0037] (3) Coat the prepared metal bridge foil with polyimide photoresist, and then pre-bake to remove the solvent;

[0038] (4) Use ultraviolet lithography to etch out the flyer layer and perform development treatment;

[0039] (5) After development, the wafer is cured to obtain the in-situ prepared flysheet layer;

[0040] (6) SU-8 negative photoresist is used, and the thickness of the accelerating chamber is controlled by controlling the coating quality;

[0041] (7) Using ultraviolet lithography, the pattern on the photomask is transferred to the photoresist;

[0042] (8) Immerse the substrate in the developer to remove the photoresist in the exposed areas, leaving the exposed areas intact;

[0043] (9) After standing, the chamber is then dried and cured to obtain the in-situ prepared acceleration chamber;

[0044] (10) Using mechanical cutting, all explosive foil detonator array units are decomposed into independent units;

[0045] (11) After cutting, the copper pillars of the detonator of the independent unit are welded.

[0046] (12) After welding, injection molding is performed in the mold to obtain an independent unit explosive foil detonator.

Claims

1. A miniaturized explosive foil initiator, characterized in that, include: Plastic-encapsulated blocks, used for encapsulating explosive foil detonators; The substrate serves as the carrier for the explosive foil initiator; The metal bridge foil, located on the substrate, consists of two parts: bridge wings and bridge area. The bridge wings are arranged symmetrically with the bridge area as the center. The bridge wing includes a rectangular second bridge wing and a trapezoidal first bridge wing, with the second bridge wing transitioning to the middle bridge area through the first bridge wing; Two metal pads are located below the substrate and correspond to the positions of the second bridge wings of the metal bridge foil, respectively. Two sets of second guide posts are located inside the substrate and are connected to the lower surface of the second bridge wing of the metal bridge foil and the upper surface of the metal pad, respectively. Two first guide posts are located below the metal pads and are connected to the lower surface of the metal pads. They correspond to the positions of the second bridge wings of the metal bridge foil and are used to connect the trigger current. The flyer layer, located above the metal bridge foil, is used to generate flyers by an electrical explosion that occurs in the bridge area under the action of trigger current. The acceleration chamber, located above the flyer layer, has bores that correspond to the bridge area of ​​the metal bridge foil. It is used to accelerate the flyer and then impact the insensitive explosive, thereby detonating the main charge.

2. The miniaturized explosive foil initiator according to claim 1, characterized in that, The metal bridge foil, the second guide post, and the metal pad are integrally sintered using the LTCC process. The second guide post is prepared by drilling through holes in the substrate of the green ceramic sheet and injecting metal paste into the through holes. The metal bridge foil is printed and bonded to the green sheet by screen printing and sintered with the substrate and the second guide post into a whole.

3. The miniaturized explosive foil initiator according to claim 1, characterized in that, The flyback layer is coated with polyimide photoresist on a metal bridge foil, etched with ultraviolet light, and cured on the metal bridge foil after development.

4. The miniaturized explosive foil initiator according to claim 1, characterized in that, The accelerating chamber uses SU-8 negative photoresist. Ultraviolet light is used to etch the pattern on the photomask onto the photoresist, and the pattern is obtained after development and curing.

5. The miniaturized explosive foil initiator according to claim 1, characterized in that, The width of the bridge section 3-c is the same as the width of the upper bottom of the first bridge wing, and the angle between the hypotenuse of the first bridge wing and the long side of the bridge section is 45°.

6. The miniaturized explosive foil initiator according to claim 1, characterized in that, The second guide post is a copper post, with a total of 18 posts, 9 on each side.

7. The miniaturized explosive foil initiator according to claim 1, characterized in that, The encapsulated block is injection molded using epoxy resin at 175°C.

8. The miniaturized explosive foil initiator according to claim 1, characterized in that, The substrate is made of aluminum nitride ceramic, microcrystalline glass, or quartz.

9. The miniaturized explosive foil initiator according to claim 1, characterized in that, The metal used in the metal bridge foil is Cu or an Au / Cu composite metal layer.

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