WO2021227183A1

WO2021227183A1 - Thermally compounded grating manufacturing technology

Info

Publication number: WO2021227183A1
Application number: PCT/CN2020/095995
Authority: WO
Inventors: 郭金川; 宗方轲; 杨君; 吴浩; 罗琨皓
Original assignee: 深圳大学
Priority date: 2020-05-12
Filing date: 2020-06-13
Publication date: 2021-11-18
Also published as: CN111522086B; CN111522086A

Abstract

A thermally compounded grating manufacturing technology, comprising: prefabrication of metal films, manufacturing of a composite film, thermal compounding, cutting, and packaging. Heavy metal films (2) strongly absorbing X-rays and light metal films (1) weakly absorbing X-rays are alternately stacked together, and then the light metal films (1) and the heavy metal films (2) are bonded together in a thermal compounding mode; and finally, a composite film stack (3) is cut and then packaged to obtain a grating. Manufacturing of the heavy metal films (2) and the light metal films (1) is separated from manufacturing of the grating in the whole technological process, and a specific environment is provided for each technological process; mass production of an assembly line is facilitated; moreover, the light metal films (1) and the heavy metal films (2) are bonded together by using a thermal bonding technology, the thickness of the metal films is easy to control, and errors are small in the grating manufacturing process; and mass production of the assembly line is facilitated.

Description

Thermal composite grating manufacturing process

Technical field

The invention relates to the technical field of optical elements, in particular to a thermal composite grating manufacturing process.

Background technique

X-ray imaging technology has been rapidly developed as a brand new discipline since the German researcher Roentgen discovered X-ray in 1895. It can detect internal defects of welds and equipment, and is widely used in machinery manufacturing, pressure vessels, and aviation. Aerospace, petroleum, chemical, railway transportation, metallurgy, shipbuilding, military industry and other industrial sectors.

... At present, X-ray phase contrast imaging mainly uses grating imaging methods based on Talbot-Lau interferometry. This kind of imaging system uses three gratings: source grating, phase grating, and absorption grating; in this grating imaging method, the absorption grating is an important part of the imaging system, and its parameters play a decisive role in the quality of the image. ; It is particularly important for X-ray grating phase contrast imaging to make a large aspect ratio grating by improving the processing technology.

... LIGA processing technology is one of the traditional methods of making absorption gratings. It is often used to make gratings with large aspect ratio structures. The principle of LIGA technology is to combine lithography (Lithographie), electroforming (Galvanoformung) and injection molding (Abformung). Combine the three. However, in the process of research, it was found that when gratings are made by this method, the grating fractures and collapses often cause structural failure.

... Another traditional method for making absorption gratings, photo-assisted electrochemical etching technology is often used to make large aspect ratio microstructures. Electrochemical etching is widely used in the production of microstructures, especially for the production of gratings with large aspect ratio structures. ;Switzerland Paul Scherer Institute (PSI) has developed the use of metal-assisted chemical corrosion (MACE) technology to produce X-ray diffraction gratings.

... However, the production cost of LIGA technology is relatively high, and the production area is small. The photo-assisted electrochemical etching method has a complicated process, and the silicon-based resistivity, temperature, and etching solution have a greater impact on the etching structure during the production process. It is difficult to control. In the later high atomic number metal filling process, the required filling process is complicated and the conditions are relatively harsh.

technical problem

In view of the shortcomings in the above technology, the present invention provides a thermal composite grating manufacturing process, which uses a thermal bonding process to bond light metals and heavy metals together, the thickness of the metal film is easy to control, and the error in the grating manufacturing process is small; And it is conducive to mass production of assembly lines.

Technical solutions

... In order to achieve the above objective, the present invention provides 1. A thermal composite grating manufacturing process, which is characterized in that it includes

Prefabricated metal film: select a heavy metal film with strong X-ray absorption and a light metal film with weak X-ray absorption, and adjust the heavy metal film and light metal film to a preset size;

Production of composite membranes: heavy metal membranes and light metal membranes are alternately stacked to form a composite membrane stack;

Thermal composite: The composite membrane stack is clamped with a clamp and placed in a heating furnace, heated until the heavy metal film and the light metal film are bonded to each other, and then the composite membrane stack is cooled in a vacuum environment and taken out;

Cutting: The composite film stack is cut according to the set size to obtain the quasi-grating;

Packaging: Use the X-ray weak absorption material to package the quasi-grating to obtain the grating.

... Among them, when adjusting the heavy metal film and light metal film to the preset size, the dimensions of the heavy metal film and the light metal film include the thickness size and the plane size. The plane dimensions of the membrane are exactly the same.

... Wherein, when the composite film is made, the heavy metal film and the light metal film are stacked orthogonally, and the sum of the thickness of a single piece of heavy metal and a single piece of light metal is the length of a single period of the grating.

... Among them, after the composite membrane is made, the thickness of the composite membrane stack is pressed to a set value, and when the composite membrane stack is compressed, the thickness of each layer of the metal film changes uniformly.

Wherein, when the composite membrane stack is clamped by a clamp, a semiconductor or ceramic material with a high melting point is placed between the contact surface of the clamp and the composite membrane stack.

... Among them, the lowest melting point of light metals and heavy metals in the composite membrane stack is C1 degrees Celsius. When heating during thermal compounding, the heating temperature is C2 degrees Celsius, where C2 is not higher than C1; the heating time is 2 hours 40 minutes to 3 hours 20 minutes.

... Among them, during thermal compounding, the composite membrane stack is heated in a vacuum; and the composite membrane stack is cooled in a vacuum.

To Among them, when the composite membrane stack is clamped by the clamp, the pressure of the clamp on the composite membrane stack is 50-80N, which limits the thickness of the composite membrane stack during the heating process.

Among them, when cutting the composite membrane stack, first cut the edge of the composite membrane stack to obtain the composite membrane stack of the first shape, and then cut the composite membrane stack of the first shape according to the set size to obtain the quasi-grating.

Among them, in the packaging process, the cut surface of the quasi-grating is clamped by the carbon fiber material plate until the carbon fiber is bonded to each composite film to complete the packaging.

Beneficial effect

The beneficial effects of the present invention are: the process of the present invention includes: prefabricating metal film, making composite film, thermal compounding, cutting and packaging; after alternately stacking heavy metal films that absorb X-rays and light metal films that absorb X-rays alternately , And then bond the light metal film and the heavy metal film together by thermal compounding; finally, the composite film stack is cut by a cold cutting process such as laser or wire cutting, and packaged together to obtain a grating. The heavy metal film and light metal film are combined in the whole process The separation of film production and grating production provides a specific environment for each process; it is more conducive to mass production of pipelines; at the same time, the thermal bonding process is used to bond light metals and heavy metals together, and the thickness of the metal film is easy to control. The medium error is small; and it is conducive to the mass production of the assembly line.

Description of the drawings

Figure 1 is a process flow diagram of the present invention;

Figure 2 is a schematic diagram of the directly purchased metal film drum structure;

Figure 3 is a schematic diagram of the composite membrane stack structure of the present invention;

4 is a schematic diagram of the composite membrane stack clamped by the clamp of the present invention;

5 is a schematic diagram of the edge of the cutting composite membrane stack of the present invention;

6 is a schematic diagram of the quasi-grating obtained by cutting the first shape composite film stack according to the present invention;

Fig. 7 is a schematic diagram of the quasi-grating structure of the present invention;

Fig. 8 is a schematic diagram of the grating structure of the present invention.

The main component symbols are explained as follows:

1. Light metal film; 2. Heavy metal film; 3. Composite film stack; 4. First shape composite film stack; 5. Quasi-grating; 6. Carbon fiber; 7. Grating; 8. Clamp.

Embodiments of the present invention

In order to express the present invention more clearly, the present invention will be further described below with reference to the accompanying drawings.

As mentioned in the background art, the existing grating manufacturing process is not only complicated and inconvenient for mass production, but also has harsh process conditions and large errors in the grating manufacturing process; light meets the formula in the diffraction process

(A+b)(sinφ+sinθ)=k λ; where a represents the slit width, b represents the slit spacing, φ is the diffraction angle, and θ is the clamp between the incident direction of the light and the grating plane normal Angle, k is the spectral order of the bright fringe (k=0, ±1, ±2...), λ is the wavelength, and a+b is called the grating constant; the characteristics of the fringes produced by the grating are: the bright fringes are very bright and narrow. The dark area between adjacent light lines is very wide, and the diffraction pattern is very clear; if the deviation of the slit width and the slit spacing is too large due to manufacturing errors, it will cause the image to be blurred during diffraction, and the final image obtained by X-ray will be It is fuzzy and unclear; especially in medical applications, unclear images can easily lead to a very high error rate in disease inspection; therefore, how to mass-produce gratings accurately has become a technological point with great market prospects.

... To this end, this application proposes a thermal composite grating manufacturing process, please refer to Figure 1, which includes

Prefabricated metal film: select a heavy metal film 2 that strongly absorbs X-rays and a light metal film 1 that absorbs X-rays weakly, and adjust the heavy metal film 2 and light metal film 1 to a preset size;

Making a composite film: the heavy metal film 2 and the light metal film 1 are alternately stacked to form a composite film stack 3;

Thermal composite: the composite membrane stack 3 is clamped by the clamp 8 and placed in a heating furnace, heated until the heavy metal film 2 and the light metal membrane 1 are bonded to each other, and then the composite membrane stack 3 is cooled in the environment and taken out;

Cutting: Use the laser to cut the composite film stack 3 according to the set size to obtain the quasi-grating 5;

Packaging: The quasi-grating 5 is packaged with a weak X-ray absorbing material to obtain the grating 7.

In this embodiment, the thickness of the prefabricated metal film is usually 50-80 microns; the width is about 5-10 cm; it is wound on the drum like a roll of paper; the length is cut from the drum as much as necessary; The metal film is made through a drawing and pressing process, and the finished products are directly sold on the market; the metal film is prefabricated, separating the production of the heavy metal film 2 and the light metal film 1 from the grating production, providing an independent environment for each process. It is more conducive to mass production in an assembly line; and the size of the heavy metal film 2 and the light metal film 1 can be preset to better control the accuracy, so that the error in the grating production is smaller.

In this embodiment, heavy metals that strongly absorb X-rays include high atomic number metals such as gold, lead, and bismuth, and light metal materials can be low atomic number metals such as aluminum and tin; the melting point of lead in these metals is about 327 degrees Celsius. The melting point of bismuth is 1064 degrees Celsius; the melting point of bismuth is 271 degrees Celsius; the melting point of aluminum is about 660 degrees Celsius; the melting point of tin is 232 degrees Celsius; preferably, the heavy metal film 2 can be lead, and the light metal can be aluminum.

Refer to Figure 2. When adjusting the heavy metal film 2 and the light metal film 1 to the preset size, the dimensions of the heavy metal film 2 and the light metal film 1 include the thickness size and the plane size. For example, the thickness of the lead film purchased directly is 80 microns, and the thickness of the aluminum film is 50 microns; but the slit width of the target grating 7 that needs to be produced is 40 microns, and the slit spacing is 50 microns; The light metal mold or heavy metal film 2 is stretched and pressed to obtain a metal mold of the required thickness. You can also directly request the metal film manufacturer to process the metal film according to the target thickness; when cutting the metal film from the roll, directly follow the width direction of the metal film Cut to obtain a rectangular metal film; among them, the plane size of the lead film and the aluminum film are exactly the same; specifically, the length of the lead film and the aluminum film are both 10cm, the width is 8cm, the thickness of the lead film is 50 microns, and the thickness of the aluminum film is 40 microns.

Please refer to Figure 3, when the composite film is made, the heavy metal film 2 and the light metal film 1 are stacked orthogonally, and the sum of the thickness of a single piece of heavy metal and a single piece of light metal is the length of a single period of the grating 7; the orthogonal stack structure is compared with the conventional The stacking method is more stable, which can make the error in the subsequent compounding smaller and the structure more stable; the plane size of the lead film and the aluminum film are exactly the same, and the plane of the lead film and the aluminum film are completely overlapped, and the thickness direction of the lead film It is perpendicular to the plane of the aluminum film to form an orthogonal stack; for example, when the total thickness of the required composite film stack is 9 mm, a total of 100 layers of lead film are selected, and 100 layers of lead film and aluminum film are alternately stacked; one of the layers is lead The film and a layer of aluminum film form a grating with 7 periods, the slit width of the grating 7 periods is 40 microns, and the slit pitch is 50 microns; a total of 100 periods.

In this embodiment, if the thickness of each metal film is not processed before the composite film is made, the thickness of the composite film stack 3 can also be pressed to the set value after the composite film is made, and when the composite film stack 3 is compressed , The thickness of each layer of metal film changes uniformly; for example, the thickness of the lead film purchased directly is 70 microns, and the thickness of the aluminum film is 40 microns. It needs to make 200 cycles of grating 7 with a thickness of 1.8 cm; you can first combine the lead film with aluminum The membranes are alternately stacked with 200 layers to obtain a 2.2 cm thick composite membrane stack 3, and then the composite membrane stack 3 is compressed by rolling technology to compress the composite membrane stack 3 to 1.8 cm; the thickness of the metal film of each layer changes uniformly to obtain the thickness of the lead film Composite membrane stack 3 with a thickness of 60 microns and an aluminum film thickness of 30 microns.

Please refer to Figure 4, when the composite membrane stack 3 is clamped by the clamp 8, the contact surface between the fixture 8 and the composite membrane stack 3 is filled with a material with high melting point, high hardness, and not easy to be thermally diffused with metal, such as high melting point Semiconductor or ceramic materials; semiconductor materials with high melting points include crystalline silicon, germanium, and tellurium, but not limited to these; after matting the material, avoid bonding the metal film and the fixture 8 together during the heating process, and the composite film cannot be completely removed after cooling. The clamp 8 is taken out; the semiconductor or ceramic material with high melting point will not bond with the metal film at high temperature, which is beneficial to take out the complete composite membrane stack 3 after heating; in this embodiment, the clamping thickness of the clamp 8 is set For the composite membrane stack 3 value, if the required target thickness is 9 mm, the clamping thickness of the clamp 8 is 9 mm.

In this embodiment, the lowest melting point of light metals and heavy metals in the composite membrane stack 3 is a degree Celsius, and when heating during thermal recombination, the heating temperature is b degree Celsius, where b is not lower than a-120 degrees and not higher than a-80 degrees. ; The heating time is 2 hours 40 minutes-3 hours 20 minutes; for example, the melting point of lead is about 327 degrees Celsius, and the melting point of aluminum is about 660 degrees Celsius; the temperature in the heating furnace is about 207-247 degrees Celsius; at this temperature, due to metal Thermoplasticity, lead will change from solid state to fluid state and exchange with the molecules on the surface of the aluminum film, making the aluminum film and the lead film adhere to each other; the best heating temperature is 100 degrees Celsius lower than the melting point of the lower melting point metal , Which is 227 degrees; the entire heating time is 2 hours 40 minutes-3 hours 20 minutes, and the effect is best. If the heating time is too short, the aluminum film and the lead film cannot be completely bonded, and the aluminum film and the lead film are likely to separate after cooling. It is impossible to make a qualified grating 7; if the heating time is too long, the molecular exchange between the aluminum film and the lead film will be too violent, and the thickness of the aluminum film and the lead film will easily become thinner, which changes the slit width and the representative narrowness of the grating 7 The gap between the slits still cannot reach the set value, which affects the imaging effect of the grating 7; therefore, the heating time and temperature control are particularly important in the entire process!

In this embodiment, during thermal recombination, the composite membrane stack 3 is heated in a vacuum or an inert gas; and the composite membrane stack 3 is cooled in a vacuum or an inert gas; to prevent the metal from being oxidized during heating; the inert gas includes helium, neon When cooling, just cool to room temperature; after cooling to room temperature, measure the thickness of the composite membrane stack 3, the thickness of the composite membrane stack 3 does not change, when it is still at the set value, it is deemed to be after thermal composite The composite membrane stack 3 is qualified; proceed to the next step of the process.

Please refer to Figures 5 and 6, when cutting the composite membrane stack 3, first cut the edge of the composite membrane stack 3 to obtain the first shape composite membrane stack 3, and then cut the first shape composite membrane stack 3 according to the set size to obtain the quasi grating 5 ; Because in the process of making the composite membrane, the metal membrane cannot be completely aligned with the edges, so it is necessary to cut off the edges that conform to the membrane first, leaving only the completely overlapped middle part, where the position of the cut is the composite membrane stack 3 Preferably, the composite film stack 3 after removal is rectangular parallelepiped shape; laser removal or wire cutting machine or milling cutter is used for removal; preferably, high-power laser cutting is used, and the cutting accuracy can reach 0.01mm.

In this embodiment, the first shape can be a polygon, rectangle, triangle or other shapes; the preferred first shape is a rectangle; please refer to FIG. The first shape is cut in the width direction to obtain a plurality of quasi gratings 5, the thickness direction of the first shape is the width of the quasi grating 5, the width direction of the first shape is the length direction of the quasi grating 5; the cutting pitch is the thickness of the quasi grating 5 Direction; the length of the grating 7 obtained after cutting is the same; during the entire cutting process, the thickness direction of the grating 7 does not need to be cut, and only the number of cuts is small, and the production accuracy is high.

In this embodiment, when cutting the first shape, the cutting direction and angle can be adjusted arbitrarily, and after cutting, it is not limited to vertical cutting;

Please refer to FIG. 8, in the packaging process, the carbon fiber 6 material film is used to clamp the cut surface in the width direction of the first shape until the carbon fiber 6 adheres to the composite film of each layer to complete the packaging, and the grating 7 is obtained.

Example 1:

The slit width value of the target grating 7 is 40 μm, the slit pitch is 60 μm, and the period of the grating 7 is 100.

Choose aluminum film and lead film, the thickness of the aluminum film is 40 microns, the thickness of the lead film is 60 microns; the length of the aluminum film and the lead film is 10cm, and the width is 5cm; the lead film and the aluminum film are alternately stacked for 100 layers; the thickness is obtained It is a 1.1cm composite membrane stack 3.

Then put the composite membrane stack 3 into a heating furnace, the heating temperature of the heating furnace is 227 degrees Celsius; the heating time is 3 hours, and the heating furnace is in a vacuum environment; after heating, the composite membrane is placed in a vacuum and cooled to room temperature, which is about 25 degrees. Measure the thickness of the composite membrane stack 3, the thickness of the composite membrane stack 3 is still 11000 microns; push the metal membrane with external force, the metal membrane is firmly bonded together without separation or falling, which meets the requirements of the target grating 7.

The edge of the composite film stack 3 is further cut, and the cutting position is 1 cm away from the edge to obtain a rectangular parallelepiped quasi-grating 5 with a length of 8 cm, a width of 3 cm and a thickness of 1.1 cm; and then use a high-power laser knife to cut multiple times along the width of the rectangular parallelepiped. The grating 5 has a cutting pitch of 5 mm to obtain a plurality of quasi-gratings 5; the length of the quasi-gratings 5 is 3 cm, the width is 1.1 cm, and the thickness is 5 mm.

Finally, the carbon fiber 6 material film is used to clamp the cutting surface in the width direction of the first shape until the carbon fiber 6 adheres to the composite film of each layer, and the packaging is completed, and the target grating 7 is obtained.

Example 2:

Then put the composite membrane stack 3 into a heating furnace, the heating temperature of the heating furnace is 247 degrees Celsius; the heating time is 3 hours, and the heating furnace is in a vacuum environment; after heating, the composite membrane is placed in a vacuum and cooled to room temperature, which is about 25 degrees; The thickness of the composite membrane stack 3 is measured. The thickness of the composite membrane stack 3 is 10900 microns; it does not meet the requirements of the target grating 7; it is made again.

Example 3:

Then put the composite membrane stack 3 into a heating furnace, the heating temperature of the heating furnace is 207 degrees Celsius; the heating time is less than 3 hours, and the heating furnace is in a vacuum environment; after heating, the composite membrane is placed in a vacuum and cooled to room temperature, which is about 25 degrees. ; Measure the thickness of the composite membrane stack 3, the thickness of the composite membrane stack 3 is 11,000 microns; push the metal film with external force, the metal film is firmly separated or fall, which does not meet the requirements of the target grating 7. Does not meet the requirements of the target grating 7; remake.

Industrial applicability

The advantages of the present invention are:

... 1. Separate heavy metal film and light metal film production from grating production to provide a specific environment for each process. It is more conducive to mass production of assembly lines.

... 2. The size of heavy metal film and light metal film can be set in advance, and the precision can be better controlled, so that the error in the grating production is smaller.

... 3. Compared with the conventional stacking method, the orthogonal stacking structure is more stable, which can make the error in the subsequent compounding smaller and the structure more stable; the whole grating manufacturing process has less cutting times, which makes its manufacturing accuracy more advantageous.

... 4. The use of thermal composite technology ensures the accuracy of grating production.

Sequence Listing Free Content

The above disclosures are only a few specific embodiments of the present invention, but the present invention is not limited thereto, and any changes that can be thought of by those skilled in the art should fall into the protection scope of the present invention.

Claims

A thermal composite grating manufacturing process, which is characterized in that it comprises

Prefabricated metal film: select a heavy metal film with strong X-ray absorption and a light metal film with weak X-ray absorption, and adjust the heavy metal film and light metal film to a preset size;

Production of composite membranes: heavy metal membranes and light metal membranes are alternately stacked to form a composite membrane stack;

Thermal composite: The composite membrane stack is clamped with a clamp and placed in a heating furnace, heated until the heavy metal film and the light metal film are bonded to each other, and then the composite membrane stack is cooled in a vacuum environment and taken out;

Cutting: The composite film stack is cut according to the set size to obtain the quasi-grating;

Packaging: Use the X-ray weak absorption material to package the quasi-grating to obtain the grating.
The thermal composite grating manufacturing process according to claim 1, wherein when the heavy metal film and the light metal film are adjusted to a preset size, the sizes of the heavy metal film and the light metal film include the thickness size and the plane size, and each heavy metal film is combined with The thickness of the easy metal film is respectively pressed to the set value, and the plane size of the heavy metal film and the light metal film are exactly the same.
The thermal composite grating manufacturing process according to claim 1, wherein when the composite film is made, the heavy metal film and the light metal film are stacked orthogonally, and the sum of the thickness of a single piece of heavy metal and a single piece of light metal is a single period of the grating. length.
The thermal composite grating manufacturing process according to claim 3, characterized in that after the composite film is manufactured, the thickness of the composite film stack is pressed to a set value, and when the composite film stack is compressed, the thickness of each layer of the metal film changes uniformly.
The thermal composite grating manufacturing process according to claim 1, wherein when the composite membrane stack is clamped by a clamp, a semiconductor or ceramic material with a high melting point is placed between the contact surface of the clamp and the composite membrane stack.
The thermal composite grating manufacturing process according to claim 1, wherein the lowest melting point of light metals and heavy metals in the composite film stack is C1 degrees Celsius, and when heating during thermal composite, the heating temperature is C2 degrees Celsius, where C2 is not higher than C1: The heating time is 2 hours and 40 minutes to 3 hours and 20 minutes.
The thermal composite grating manufacturing process according to claim 6, characterized in that, during thermal composite, the composite membrane stack is heated in a vacuum; and the composite membrane stack is cooled in a vacuum.
The thermal composite grating manufacturing process according to claim 1, wherein when the composite membrane stack is clamped by a clamp, the pressure of the clamp on the composite membrane stack is 50-80N, which limits the thickness of the composite membrane stack during heating. .
The thermal composite grating manufacturing process according to claim 1, wherein when cutting the composite film stack, first cut the edge of the composite film stack to obtain the composite film stack of the first shape, and then cut the composite film stack of the first shape according to the set size. Composite membrane stack to obtain quasi-grating.
The thermal composite grating manufacturing process according to claim 1, characterized in that, during the packaging process, a carbon fiber material plate is used to clamp the cut surface of the quasi-grating until the carbon fiber is bonded to each composite film to complete the packaging.