CN116002991A - A multi-layer composite film and its application in laser precision forming - Google Patents

Abstract

The invention relates to the technical field of laser precision machining, in particular to a multilayer composite film and its application in laser precision forming. A multilayer composite film, attached to a transparent substrate, the multilayer composite film includes an oxide layer, a metal layer, a working layer and an outer protective layer, and the transparent substrate is provided with a first surface and a second surface oppositely arranged , the first surface faces the laser beam, the oxide layer is attached to the second surface, the metal layer is attached to the surface of the oxide layer away from the transparent substrate, and the working layer is attached to the The surface of the metal layer away from the transparent substrate. The multi-layer composite film can realize a stable and repeatable transfer process during laser-induced forward transfer, obtain a transfer structure with high conductivity, and solve the problem of the gap between the metal film and the transparent substrate in the existing laser-induced forward transfer. The poor adhesion and poor uniformity of adhesion lead to poor stability of the film donor transfer process.

Description

A multi-layer composite film and its application in laser precision forming

technical field

The invention relates to the technical field of laser precision machining, in particular to a multilayer composite film and its application in laser precision forming.

Background technique

Laser-induced forward transfer technology was first demonstrated in 1986. J.Bohandy et al. (Metal deposition from a supported metal film using an excimer laser) of Johns Hopkins University in the United States used focused excimer molecules with a wavelength of 193nm in a vacuum environment. A thin film of copper deposited on the quartz substrate is irradiated with laser pulses through the quartz substrate, causing it to melt and spray onto the substrate below the film, thereby depositing a copper layer on the substrate. Among them, the copper film is called the donor, and the substrate is called the acceptor. Since then, the method has been continuously developed and derived into a series of manufacturing methods. For example, in 1999, in the research of A.Pique et al. (A novel laser transfer process for directwriting of electronic and sensor materials), the vacuum environment was no longer used, and the above process was directly realized in the air, which used focused excimers with a wavelength of 248nm The laser completed the above process in the air, and realized the precise molding of the three-dimensional structure of gold and nickel-chromium alloy on glass, FR-4 and other substrates; in the follow-up research, the available laser wavelength was extended to 355nm-1064nm, The available laser pulse width has expanded from the early nanoseconds to picoseconds or even femtoseconds, and the available donor types have expanded from copper thin films to silver pastes, periodic bulk metal films, etc. Achieving a stable and high-quality transfer process is the key to the industrial application of the above technologies. When using metal thin films as donors, due to the interaction between laser and materials involving heating, expansion, melting, gasification, phase explosion, photomechanical stress release, etc. A series of processes, these processes are sensitive to laser pulse parameters, due to the natural fluctuation of laser beam quality and pulse parameters, the stability and repeatability of the transfer process are poor, and they face great technical challenges in industrial applications. A feasible idea to solve the above problems is to replace the coated metal film with high-viscosity metal paste as the donor. These metal pastes are mainly composed of nanoparticles and polymers. The paste is more likely to form a stable liquid column under the action of a laser. , thereby increasing the stability of the transfer process. The process can also be made more stable by using delayed multi-pulse lasers. In the technical route of using metal paste, the composition and preparation technology of the paste has become an important core technology, and its physical and chemical properties directly determine the transfer effect, and a large number of patented technologies have also appeared in the field. However, due to the limitation of paste preparation technology, silver paste is still the main application object in the current technical route of using metal paste.

Although the transfer of various metals can be realized by laser-induced forward transfer technology, the precision forming of conductive lines using this technology is still one of the most important potential application directions, and copper is the first choice for low-cost preparation of high-performance conductive lines Materials, the use of copper-based thin films or bulk copper-based thin films as donors is still the mainstream technology choice. In related technical solutions reported so far, the donors used include single-layer copper thin films, copper-silver-copper three-layer thin films, copper-bismuth double-layer thin films, and the like. For example, the paper Laser Transfer of Metals and Metal Alloys for Digital Microfabrication of 3D Objects reported a copper-silver-copper three-layer thin film, each layer thickness is 100nm, 7nm and 400nm. Compared with single-layer copper thin-film systems, these multilayer thin-film systems can improve the structural properties after transfer through alloying due to the addition of other metals. However, these film donors still have outstanding problems such as unstable transfer process and poor film stability. Typically, the laser beam penetrates the transparent substrate material and enters the donor, and the donor film undergoes physical processes such as expansion and melting after absorbing the laser energy. These processes are accompanied by the generation and release of local stress. Controlled sputtering, electron beam evaporation, etc., during the preparation process, because the copper and the transparent substrate only rely on van der Waals force to adhere, the adhesion is low and uneven. Under the same laser parameters, with the generation and release of stress caused by processes such as expansion and melting, the area with low adhesion will detach quickly, and this detachment may even occur when the laser pulse is not completely incident, resulting in incomplete ejection products. Melting or lower flight speed will eventually affect the density, strength, porosity and other indicators of the deposition product; on the other hand, the area with strong adhesion may detach later or not, resulting in transfer failure. At the same time, copper is generally used for the contact surface between these film systems and the air. In industrial environments such as high humidity and acidity, the outer metal is easy to oxidize and corrode. Conductivity, adhesion, strength drop and other issues. These problems will seriously affect the process stability and industrial applicability of the process, restricting its application.

Contents of the invention

In view of the problems raised by the background technology, the purpose of the present invention is to propose a multilayer composite film, which can realize a stable and repeatable transfer process during laser-induced forward transfer, and obtain a transfer structure with high conductivity, which is suitable for harsh In the industrial environment, the problem of poor adhesion and poor adhesion uniformity between the metal film and the transparent substrate in the existing laser-induced forward transfer is solved, which leads to poor stability of the transfer process of the film donor.

Another object of the present invention is to propose an application of a multi-layer composite film in laser precision forming. Applying the above-mentioned multi-layer composite film to laser precision forming based on the principle of laser-induced forward transfer can realize a stable and repeatable transfer process. .

For reaching this purpose, the present invention adopts following technical scheme:

A multilayer composite film, attached to a transparent substrate, the multilayer composite film includes an oxide layer, a metal layer, a working layer and an outer protective layer, and the transparent substrate is provided with a first surface and a second surface oppositely arranged , the first surface faces the laser beam, the oxide layer is attached to the second surface, the metal layer is attached to the surface of the oxide layer away from the transparent substrate, and the working layer is attached to the the surface of the metal layer away from the transparent substrate, the outer protective layer is attached to the surface of the working layer away from the transparent substrate;

The transparent substrate contains silicon and oxygen;

The oxide layer is a heterogeneous material, the oxide layer contains silicon, oxygen and chromium, and the total atomic percentage of silicon, oxygen and chromium in the oxide layer is ≥ 90%, the The heterogeneous material refers to that the composition of the regions with different distances from the second surface in the oxide layer is different, and the closer to the second surface in the oxide layer, the higher the content of silicon and oxygen elements, so The farther away from the second surface in the oxide layer, the higher the content of chromium element;

The metal layer contains chromium element, and the atomic percentage of chromium element in the metal layer is ≥99%;

The working layer contains copper element, the atomic percentage of the copper element in the working layer is ≥95%, and the thickness of the working layer is 0.1-2 μm;

The outer protective layer is silver, gold or gold-silver alloy, and the thickness of the outer protective layer is ≤30nm.

To further illustrate, the transparent substrate is an amorphous material, and the softening point of the transparent substrate is ≥500°C.

To further illustrate, the atomic percentage of oxygen in the transparent substrate is ≥30%.

To further illustrate, the oxide layer also contains any one or more of calcium, boron, magnesium, potassium and aluminum elements, and the thickness of the oxide layer is ≤30nm.

To further illustrate, the thickness of the metal layer is ≤15nm.

To further illustrate, the working layer is single-layer metal, multi-layer metal or alloy, and the working layer also contains chromium, silver, nickel, tin, aluminum, bismuth, zinc and cobalt elements any one or more of.

To further illustrate, the thickness of the outer protective layer is 8-30 nm.

An application of a multilayer composite film in laser precision forming, the multilayer composite film is applied to laser precision forming based on the principle of laser-induced forward transfer, and the laser precision forming is to use a focused pulsed laser beam to pass through The first surface and the second surface of the transparent substrate irradiate the multilayer composite film to form a two-dimensional or three-dimensional structure on the receptor.

Preferably, the laser pulse width of the pulsed laser beam is 0.1-30 ns, and the energy flux density of the focused pulsed laser beam is ≤10 J/cm ² .

Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

The above-mentioned multi-layer composite film has good adhesion of the oxide layer on the transparent substrate during the transfer process, and the adhesion of the metal layer and the working layer in different regions of the transparent substrate is good, and it is applied to laser-induced forward transfer It can achieve a stable and repeatable transfer process and obtain a transfer structure with high conductivity, which is suitable for harsh industrial environments and solves the poor adhesion between the metal film and the transparent substrate in the existing laser-induced forward transfer. 1. Poor adhesion uniformity leads to poor stability of film donor transfer process.

Description of drawings

Fig. 1 is the structural representation of the multilayer composite film of an embodiment of the present invention;

Fig. 2 is a schematic structural view of a laser precision forming device according to an embodiment of the present invention;

Fig. 3 is the temperature profile of the multilayer composite film of the embodiment of the present invention 1;

Fig. 4 is a structural diagram formed by deposition in Example 1 of the present invention;

Fig. 5 is a structural diagram formed by deposition in Example 3 of the present invention;

Among them: transparent substrate 1, first surface 11, second surface 12, oxide layer 2, metal layer 3, working layer 4, outer protective layer 5, beam expander 6, dichroic mirror 7, achromatic lens group 8 , an imaging chip 9, a scanning galvanometer 10, a flat field mirror 11, a multilayer composite film 12, a receptor 13, and a pulse laser 14.

Detailed ways

As shown in Figure 1, a kind of multilayer composite film is attached to transparent substrate 1, and described multilayer composite film comprises oxide layer 2, metal layer 3, working layer 4 and outer protection layer 5, and described transparent substrate 1 A first surface 101 and a second surface 102 are arranged oppositely, the first surface 101 faces the laser beam, the oxide layer 2 is attached to the second surface 102, and the metal layer 3 is attached to the oxide layer 2 on the surface away from the transparent substrate 1, the working layer 4 is attached to the surface of the metal layer 3 away from the transparent substrate 1, and the outer protective layer 5 is attached on the working layer 4 away from the surface of the transparent substrate 1;

The transparent substrate 1 contains silicon and oxygen;

The oxide layer 2 is a heterogeneous material, the oxide layer 2 contains silicon, oxygen and chromium, and the total atomic percentage of silicon, oxygen and chromium in the oxide layer 2 is ≥ 90% , the heterogeneous material refers to the different compositions of regions in the oxide layer 2 that are at different distances from the second surface 102 , the closer to the second surface 102 in the oxide layer 2 is the silicon element and oxygen The higher the content of the element, the higher the content of chromium element in the oxide layer 2 farther away from the second surface 102;

The metal layer 3 contains chromium element, and the atomic percentage of the chromium element in the metal layer 3 is ≥99%;

The working layer 4 contains copper element, the atomic percentage of the copper element in the working layer 4 is ≥95%, and the thickness of the working layer 4 is 0.1-2 μm;

The outer protection layer 5 is silver, gold or gold-silver alloy, and the thickness of the outer protection layer 5 is ≤30nm.

It should be noted that the transparent substrate 1 refers to a solid sheet that is transparent to laser beams, and the laser beams are laser beams used in laser precision molding, and the transparency refers to that the laser beams pass through the transparent substrate. The power after passing through is not lower than 90% of the power before passing through the transparent substrate 1 .

When the laser is precisely formed, a focused pulsed laser beam is used to pass through the first surface 101 and the second surface 102 of the transparent substrate 1 to irradiate the multilayer composite film, because the oxide layer 2 is heterogeneous material, the composition of the regions with different distances from the second surface 102 in the oxide layer 2 is different, the closer to the second surface 102 in the oxide layer 2, the higher the content of silicon and oxygen elements, The content of the chromium element in the oxide layer 2 is higher the farther away from the second surface 102, so that the absorption ability of the pulsed laser is different in the region of different distances from the second surface 102 in the oxide layer 2, and the closer to the second surface 102 The higher the oxygen content in the region of the second surface 102, the weaker the light absorption capacity. Due to the composition and thickness limitations of the oxide layer 2 and the metal layer 3 in the present invention, the laser energy will be mainly absorbed by the metal layer 3 and the part of the working layer 4 that is close to the metal layer 3, As a result of the temperature rise in these areas, other areas of the working layer 4 and the outer protective layer 5 are heated by heat conduction.

To further illustrate, in the present invention, the melting point of the oxide layer 2 is higher than the melting point of the metal layer 3, and the melting point of the metal layer 3 is higher than the melting point of the working layer 4 and the melting point of the outer protective layer 5 , the oxide layer 2 has the highest melting point. Typically, the melting point of chromium trioxide is as high as 2435°C. If the oxygen content decreases, the melting point will decrease, and other elements contained will also affect the melting point of the oxide layer 2; The metal layer 3 has a relatively high melting point, typically, the melting point of chromium is 1907°C; while the working layer 4 and the outer protective layer 5 have relatively low melting points, typically, the melting point of copper is about 1083°C, The melting point of gold is about 1064°C, and the melting point of silver is about 962°C. Due to the composition distribution characteristics of the oxide layer 2 and the metal layer 3, the melting point of the region closer to the second surface 102 in the multilayer composite film is higher, and the melting point of the region closer to the working layer 4 is higher. The lower the melting point. Due to the thickness limitation of the working layer 4 and the outer protective layer 5, when the outer protective layer 5 reaches the melting point, most parts of the oxide layer 2 will still remain in a solid state. Therefore, the partial area of the metal layer 3 away from the oxide layer 2, the working layer 4 and the outer protective layer 5 will partially melt and form droplets, and the droplets will detach from the film and deposit on the receptor, through The continuous deposition process forms two-dimensional or three-dimensional structures.

According to the above principles, the two-dimensional or three-dimensional structure deposited by the present invention will mainly contain the metal elements in the working layer 4 and the outer protective layer 5 and a small amount of metal elements in the metal layer 3, and only contain a very small amount of metal elements. Elements such as silicon and oxygen in the oxide layer 2 avoid the existence of two harmful elements of silicon and oxygen in the oxide layer 2 in the structure formed by deposition, and greatly improve the stability of the two-dimensional or three-dimensional structure formed by deposition. conductivity. Although the two-dimensional or three-dimensional structure formed by deposition may contain the chromium present in the metal layer 3, the chromium can partially dissolve in the copper to form a solid solution. After chromium dissolves in copper, the alloy formed has extremely high electrical conductivity. After adding 1% chromium in copper, the electrical conductivity of the formed alloy decreased by about 8% compared with that of copper. In contrast, after adding 1% mass fraction of zinc, tin, nickel, aluminum, and titanium to copper, the electrical conductivity of copper will decrease by about 17%, 37%, 33%, 70%, and 92%.

The present invention uses silver, gold, or a gold-silver alloy formed by two elements of gold and silver as the outer protective layer 5. Compared with copper, these metals have better corrosion resistance, and can be used in acidic or high-humidity industrial environments. The internal metal layer 3 is protected from corrosion to the greatest extent, and the stability of the laser precision forming process and various performance indicators of the forming structure are improved. At the same time, the above materials can all dissolve in copper, and the formed alloys all have high electrical conductivity. Typically, when 1% by mass of silver is added to copper, the electrical conductivity of copper only drops by about 3%.

It is worth noting that the existence of the oxide layer 2 in the present invention keeps a smooth composition distribution between the transparent substrate 1 and the metal layer 3, greatly increasing the metal layer 3 and the work. The adhesion of the layer 4 on the transparent substrate 1 significantly improves the consistency of adhesion in different regions, and ensures the adhesion of the oxide layer 2 on the transparent substrate 1 during the transfer process.

In the multi-layer composite film, the oxide layer 2 has good adhesion on the transparent substrate 1 during the transfer process, and the difference between the metal layer 3 and the working layer 4 on the transparent substrate 1 is The area has good adhesion consistency. When applied to laser-induced forward transfer, it can achieve a stable and repeatable transfer process and obtain a transfer structure with high conductivity. It is suitable for harsh industrial environments and solves the problem of existing laser-induced forward transfer. The poor adhesion and poor adhesion uniformity between the metal thin film being transferred and the transparent substrate 1 lead to poor stability of the film donor transfer process.

Preferably, the transparent substrate 1 is an amorphous material, and the softening point of the transparent substrate 1 is ≥500°C.

The transparent substrate 1 is made of an amorphous material, and the softening point of the transparent substrate 1 is preferably ≥500°C. Such materials do not have significant solid-liquid phase mutations, and their properties change gently after heating, which is conducive to the oxidation Stable attachment of the layer 2 on the second surface 102 of the transparent substrate 1 during the transfer process. Specifically, the transparent substrate 1 may be fused silica glass or K9 optical glass or white glass.

Preferably, the atomic percentage of oxygen in the transparent substrate 1 is ≥30%.

Since the transparent substrate 1 contains oxygen with a higher atomic percentage, the oxygen content with a higher atomic percentage is conducive to the formation of the oxide layer 2, thereby further strengthening the transparent substrate 1 and the oxide layer 2. combination.

To further illustrate, the oxide layer 2 also contains any one or more of calcium, boron, magnesium, potassium and aluminum elements, and the thickness of the oxide layer 2 is ≤30nm.

Specifically, the oxide layer 2 may also contain elements such as calcium, boron, magnesium, aluminum, etc., and other metal elements that may be contained in the oxide layer 2 in the present invention can be solid-soluble in copper at low addition amounts. Or form a eutectic product, avoid the formation of brittle compounds in the laser precision forming structure, and ensure the high mechanical properties and high conductivity of the laser precision forming structure. The control of the thickness and composition content of the oxide layer 2 in the present invention ensures that all relevant metals are within the allowable low addition range. Preferably, the oxide layer 2 has a thickness of 5-20 nm.

To further illustrate, the formation of the oxide layer 2 may originate from multiple steps in the preparation process. Typically, the formation of the oxide layer 2 may originate from the deposition process under an oxygen-containing atmosphere on the one hand, and on the other hand may originate from The reaction between the oxide layer 2 or the metal layer 3 formed by deposition and the transparent substrate 1 . In some embodiments, the metal layer 3 is directly deposited on the transparent substrate 1, and the oxygen element in the transparent substrate 1 diffuses to form a certain thickness of the metal layer 3 at the interface contacting the metal layer 3. Oxide layer 2.

Preferably, the thickness of the metal layer 3 is ≤15nm.

In the present invention, by controlling the thickness of the metal layer 3 and the content of chromium in the metal layer 3, even if a part of the metal layer 3 far away from the oxide layer 2 melts and forms droplets, the chromium It can be partially dissolved in copper to form a solid solution to ensure the conductivity of the two-dimensional or three-dimensional structure obtained by laser precision molding. Preferably, the thickness of the metal layer 3 is 7-14 nm.

To further illustrate, the working layer 4 is a single-layer metal, multi-layer metal or alloy, and the working layer 4 also contains chromium, silver, nickel, tin, aluminum, bismuth, zinc and cobalt any one or more of the elements.

Typically, the working layer 4 can be single-layer copper, single-layer copper-bismuth alloy, single-layer copper-silver alloy, silver-copper double-layer structure, copper-bismuth-copper three-layer structure, copper-silver-copper three-layer structure , silver-copper-chrome three-layer structure and copper-copper-silver alloy double-layer structure, etc.

Preferably, the thickness of the outer protective layer 5 is 8-30 nm.

In the present invention, by controlling the thickness of the outer protective layer 5, it is ensured that both the gold element and the silver element are within the allowable low addition range, even if the outer protective layer 5 is melted and deposited on the receptor, it can be solid-dissolved For copper, it ensures the conductivity of the two-dimensional or three-dimensional structure obtained by laser precision forming.

An application of a multilayer composite film in laser precision forming, the multilayer composite film is applied to laser precision forming based on the principle of laser-induced forward transfer, and the laser precision forming is to use a focused pulsed laser beam to pass through The first surface 101 and the second surface 102 of the transparent substrate 1 irradiate the multilayer composite film to form a two-dimensional or three-dimensional structure on the receptor.

Preferably, the laser pulse width of the pulsed laser beam is 0.1-30 ns, and the energy flux density of the focused pulsed laser beam is ≤10 J/cm ² .

The multi-layer composite thin film can be used for laser precision molding based on the principle of laser-induced forward transfer, and forms a two-dimensional or three-dimensional structure with high conductivity on the receptor. Due to the composition distribution characteristics of the oxide layer 2 and the metal layer 3, the melting point of the region closer to the second surface 102 in the multilayer composite film is higher, and the melting point of the region closer to the working layer 4 is higher. The lower the melting point. Due to the thickness limitations of the oxide layer 2 , metal layer 3 , working layer 4 and the outer protection layer 5 , when the outer protection layer 5 reaches the melting point, most regions of the oxide layer 2 will remain solid. Therefore, the partial area of the metal layer 3 away from the oxide layer 2, the working layer 4 and the outer protective layer 5 will partially melt and form droplets, and the droplets will detach from the film and deposit on the receptor, through The continuous deposition process forms two-dimensional or three-dimensional structures.

To further explain, the applicant has found experimentally that it is more favorable to obtain a high-quality molded structure under the preferred laser pulse width and the energy flux density of the focused pulsed laser beam. When the laser pulse width of the pulsed laser beam is too short or the energy flux density of the focused pulsed laser beam is too high, the peak energy flux density increases, causing the oxide layer 2 to melt or even gasify; when the pulsed laser beam When the laser pulse width is too long or the energy flux density of the focused pulsed laser beam is too low, sufficient melting of the working layer 4 or the outer protective layer 5 cannot be achieved.

Specifically, the receptor is any one of metals, polymers, glass, ceramics, semiconductors and organic-inorganic composite materials.

In order to facilitate the understanding of the present invention, a more complete description of the present invention follows. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure of the present invention more thorough and comprehensive.

If no specific technique or condition is indicated in the examples, it shall be carried out according to the technique or condition described in the literature in this field or according to the product specification. The reagents or instruments used were not indicated by the manufacturer, and they were all commercially available conventional products.

Example 1

A kind of multilayer composite film, as shown in Figure 1, is attached to transparent substrate 1, and multilayer composite film comprises oxide layer 2, metal layer 3, working layer 4 and outer protective layer 5, and transparent substrate 1 is provided with relative setting The first surface 101 and the second surface 102 of the first surface 101 face the laser beam, the oxide layer 2 is attached to the second surface 102, the metal layer 3 is attached to the surface of the oxide layer 2 away from the transparent substrate 1, and the working layer 4 is attached On the surface of the metal layer 3 away from the transparent substrate 1, the outer protective layer 5 is attached to the surface of the working layer 3 away from the transparent substrate 1;

The transparent substrate 1 in this embodiment is fused silica glass with a thickness of 2 mm, and the atomic percentage of oxygen in the transparent substrate 1 is about 63%.

The oxide layer 2 in the multilayer composite film of this embodiment is a heterogeneous material, the main components in the oxide layer 2 include silicon, oxygen and chromium, and the silicon, oxygen and chromium in the oxide layer 2 The total atomic percentage is greater than or equal to 99.9%, the remainder is impurities, and the thickness of the oxide layer is 10nm; the composition of the regions with different distances from the second surface 102 in the oxide layer 2 is different, and the silicon in the oxide layer 2 is closer to the second surface 102 The higher the content of element and oxygen, the higher the content of chromium element in the oxide layer 2 farther away from the second surface 102 .

The metal layer 3 in the multilayer composite film of this embodiment contains chromium element, the atomic percentage of the chromium element in the metal layer 3 is 99.5%, the balance is oxygen, and the thickness of the metal layer 3 is 10nm.

The working layer 4 in the multilayer composite film of this embodiment is copper, and the thickness of the working layer 4 is 800 nm.

The outer protective layer 5 in the multilayer composite film of this embodiment is gold, and the thickness of the outer protective layer 5 is 10 nm.

The multilayer composite film of this embodiment is prepared by the following method:

1. Deposit 8nm-thick metal chromium on the surface of the transparent substrate 1 by magnetron sputtering in a vacuum atmosphere containing argon and oxygen. Due to the presence of a small amount of oxygen, the deposited metal chromium will contain oxygen;

2. Deposit chromium with a thickness of 12nm, copper with a thickness of 800nm and gold with a thickness of 10nm by magnetron sputtering in a vacuum atmosphere containing argon;

3. In an argon protective atmosphere, heat the coated transparent substrate to 450°C and keep it for 20 minutes, so that the transparent substrate 1 can further react with the chromium deposited in step 1 and step 2 to form a multilayer composite film. Oxide layer 2 and metal layer 3. Specifically, oxygen and silicon in the transparent substrate 1 diffuse and react with the chromium layer formed in step 1, so that the closer to the second surface 102 of the transparent substrate 1, the higher the content of silicon and oxygen, The farther away from the second surface 102, the higher the content of chromium. In addition, oxygen in the chromium layer formed in step 1 diffuses and reacts with the chromium layer formed in step 2, so that the thickness of the finally formed metal layer 3 is reduced to about 10 nm, and the thickness of oxide layer 2 is increased to about 10 nm. In the above preparation method, the working layer 4 and the outer protective layer 5 in the multilayer composite film are respectively derived from the copper and gold deposited in step 2.

In the above preparation method, the composition of the final formed oxide layer 2 and the thickness of the metal layer 3 can be adjusted by three methods, and the adjustment method includes: (1) changing the relative content of argon and oxygen in step 1, increasing the oxygen content, Will increase the oxide layer 2 thickness and oxygen content that finally forms, reduce the thickness of final metal layer 3; (2) change the thickness of the metallic chromium layer prepared in step 1 and step 2, increase the metallic chromium layer thickness prepared in step 1 and Reducing the metal chromium layer thickness prepared in step 2 will increase the final oxide layer 2 thickness and reduce the thickness of the final metal layer 3; (3) change the heating temperature and the soaking time in the step 3, increase the heating temperature and the soaking time will The thickness and oxygen content of the oxide layer 2 is increased and the thickness of the final metal layer 3 is reduced.

In the above preparation method, fused silica glass is used for the transparent substrate 1, and the softening point of the fused silica glass is higher than 500° C., and will maintain a solid state without deformation during steps 1-3. At the same time, the temperature in step 3 is close to the softening point of fused silica glass, which is beneficial to the formation of the oxide layer 2 in the multilayer composite film.

Among the oxide layer 2 and the metal layer 3 in the multilayer composite film prepared by the above preparation method, the closer to the second surface 102 of the transparent substrate 1, the lower the absorbance and the higher the melting point.

The multi-layer composite film of this embodiment has excellent durability, and in an industrial environment of 30° C. and 80% relative humidity, no significant composition change occurs on the surface within one month. As a comparison, if a 10nm thick gold layer is not deposited in step 2, the prepared film will form patina, oxide, etc. on the surface within a week under the same environment. These surface products contain harmful elements such as oxygen and hydrogen, which will affect Subsequent precision molding process.

Apply the multilayer composite thin film of the present embodiment to laser precision molding based on the principle of laser-induced forward transfer, and carry out laser precision molding by the device shown in Figure 2. The pulsed laser 14 emits a pulsed laser beam with a wavelength of 1064nm and a pulse width of 10ns. After beam expansion by the beam expander 6, it passes through the dichroic mirror 7 and enters the scanning galvanometer 10, and then focuses through the flat field lens 11, and the focused pulsed laser beam passes through the first surface 101 and the second surface of the transparent substrate 1. The surface 102 is irradiated on the multi-layer composite film 12 to partially melt the film in the irradiated area and form droplets, which are detached from the film and deposited on the receptor 13 . The control system of the device controls the scanning galvanometer 10 to perform two-dimensional scanning, so that droplets are continuously formed on the multilayer composite film 12 and deposited on the receptor 13 to form a two-dimensional pattern. After the control system of the device controls the feeding movement of the transparent substrate 1 attached with the multi-layer composite film 12, the above two-dimensional scanning steps are repeated to form a three-dimensional pattern. Dichroic mirror 7 reflects visible light through 1064nm wavelength light, and the light reflected by the sample surface successively passes through flat field mirror 11, scanning galvanometer 10, dichroic mirror 7 and achromatic lens group 8, and enters imaging chip 9 (imaging The chip is a CMOS imaging chip) to form image information on the surface of the sample for positioning or process monitoring.

In this embodiment, the wavelength λ of the pulsed laser 14 used is 1064 nm, and its optical penetration depth can be calculated by λ/4πk, where λ and k represent the laser wavelength and extinction coefficient, respectively. For chromium material, its k is about 4.29, and the calculated optical penetration depth is about 19.73nm; for dichromium trioxide material, its k is about 1.2, and the calculated optical penetration depth is about 70.56nm; for copper, its k It is about 6, and the calculated optical penetration depth is about 14.11nm. It can be seen that the laser energy in this embodiment will be mainly absorbed by the metal layer 3 and the part of the working layer 4 that is close to the metal layer 3 .

In this embodiment, the preferred energy flux density of the focused laser pulse is about 2-3 J/cm ² . When the laser pulse energy flux density is 3 J/cm ² , the typical temperature distribution in the multilayer composite film 12 is shown in FIG. 3 . The temperature distribution is simulated by the finite element method. In the constructed model, it is assumed that the optical penetration depth in the oxide layer 2 changes linearly, that is, the optical penetration depth of the second surface 102 closest to the transparent substrate 1 in the oxide layer 2 The penetration depth is 70.56nm, the optical penetration depth closest to the metal layer 3 is 19.73nm, and the optical penetration depth of other positions in the oxide layer 2 decreases linearly with the distance from the second surface 102 of the transparent substrate 1 . This model does not consider the phase transition process, but only considers the temperature field distribution formed by laser heating. According to the calculated results, the maximum temperature in the oxide layer 2 is lower than 2400°C, while the maximum temperature of the outer protective layer 5 has exceeded 1000°C.

In this embodiment, the formed three-dimensional pattern is mainly composed of chromium, copper, and gold, and the mass percentages of the three are about 0.9%, 96.5%, and 2.6%. Since both gold and chromium can be dissolved in copper, the conductivity of the deposited three-dimensional structure is about 35% of that of pure copper.

Example 2

A kind of multilayer composite film, as shown in Figure 1, is attached to transparent substrate 1, and multilayer composite film comprises oxide layer 2, metal layer 3, working layer 4 and outer protective layer 5, and transparent substrate 1 is provided with relative setting The first surface 101 and the second surface 102 of the first surface 101 face the laser beam, the oxide layer 2 is attached to the second surface 102, the metal layer 3 is attached to the surface of the oxide layer 2 away from the transparent substrate 1, and the working layer 4 is attached On the surface of the metal layer 3 away from the transparent substrate 1, the outer protective layer 5 is attached to the surface of the working layer 4 away from the transparent substrate 1;

The transparent substrate 1 in this embodiment is K9 optical glass, calculated by weight percentage, _its chemical composition is as follows: _SiO2 =69.13%, _B2O3 =10.75%, BaO=3.07%, _Na2O =10.40% , K ₂ O=6.29% and As ₂ O ₃ =0.36%, the thickness is 2mm.

The oxide layer 2 in the multilayer composite film of this embodiment is a heterogeneous material, and the total atomic percentage of silicon, oxygen, and chromium in the oxide layer 2 is >90%, and other elements include boron, barium, and sodium element, potassium element and arsenic element, the thickness of the oxide layer is 5nm; the composition of the region with different distances from the second surface 102 in the oxide layer 2 is different, and the closer to the second surface 102 in the oxide layer 2 is the silicon element and the oxygen element The higher the content of chromium, the higher the content of chromium element in the oxide layer 2 that is farther away from the second surface 102 .

The metal layer 3 in the multilayer composite film of this embodiment contains chromium element, the atomic percentage of the chromium element in the metal layer 3 is 99.8%, the balance is oxygen, and the thickness of the metal layer 3 is 10nm.

The working layer 4 in the multilayer composite film of this embodiment is copper, and the thickness of the working layer 4 is 400 nm.

The outer protective layer 5 in the multilayer composite film of this embodiment is silver, and the thickness of the outer protective layer 5 is 8nm.

The multilayer composite film of this embodiment is prepared by the following method:

1. Deposit 15nm-thick metallic chromium on the surface of the transparent substrate 1 by electron beam evaporation in a vacuum atmosphere;

2. Deposit copper with a thickness of 400nm and silver with a thickness of 8nm respectively in a vacuum atmosphere by electron beam evaporation;

3. In a high vacuum environment, heat the coated transparent substrate 1 to 500°C and keep it for 20 minutes, so that the transparent substrate 1 can further react with the chromium deposited in step 1 to form an oxide layer in the multilayer composite film 2 and metal layer 3.

In the above preparation method, the thickness and composition of the finally formed oxide layer 2 and metal layer 3 can be adjusted by changing the heating temperature and holding time in step 3. Increasing the heating temperature and holding time will increase the thickness and oxygen content of the oxide layer 2. amount and reduce the thickness of the final metal layer 3.

In the above preparation method, the working layer 4 and the outer protective layer 5 in the multilayer composite film are derived from the copper and silver deposited in step 2.

In the above preparation method, the transparent substrate 1 uses K9 glass, whose softening point is about 700° C., and will maintain a solid state without deformation during steps 1-3. At the same time, the temperature in step 3 is close to the softening point of the transparent substrate 1, which is beneficial to the formation of the oxide layer 2 in the multilayer composite film.

Among the oxide layer 2 and the metal layer 3 in the multilayer composite film prepared by the above preparation method, the closer to the second surface 102 of the transparent substrate 1, the lower the absorbance and the higher the melting point.

The multilayer composite film of this embodiment has excellent durability, and in an industrial environment of 30° C. and 80% relative humidity, no significant compositional change occurs on the surface within a week. As a comparison, if no 8nm thick silver layer is deposited in step 2, the prepared film will form verdigris, oxides, etc. on the surface within a week under the same environment. These surface products contain harmful elements such as oxygen and hydrogen, which will affect Subsequent precision molding process.

The multilayer composite film of this embodiment is applied to laser precision forming based on the principle of laser-induced forward transfer, and the laser precision forming is carried out by the device shown in Figure 2. In this embodiment, the pulse laser 14 used emits a wavelength of 532nm. Laser pulses with a width of 5 ns. The dichroic mirror 7 in this embodiment transmits light with a wavelength of 532 nm and reflects visible light in other wavelength bands. In this embodiment, the optical penetration depths of several typical materials are about 680 nm for dichromium trioxide, 9.1 nm for chromium, and 15.6 nm for copper. The laser energy will be mainly absorbed by the metal layer 3 and some materials in the working layer 4 close to the metal layer 3 .

In this embodiment, the preferred energy flux density of the focused laser pulse is about 0.5-1 J/cm ² .

In this embodiment, the formed three-dimensional pattern is mainly composed of chromium, copper, and silver, and the mass percentages of the three are about 1.9%, 95.8%, and 2.3%. Since both silver and chromium can be dissolved in copper, the conductivity of the deposited three-dimensional structure is about 28% of that of pure copper.

Example 3

Compared with Example 1, in the preparation method of the multilayer composite film in this example, in step 2, chromium with a thickness of 12nm and chromium with a thickness of 800nm are deposited respectively by magnetron sputtering under a vacuum atmosphere containing argon. Copper-bismuth alloy and 10nm-thick gold, and the rest of the preparation method and raw materials are consistent with Example 1. Wherein, the bismuth content in the copper-bismuth alloy is about 0.75%, and the deposition of the copper-bismuth alloy is achieved by using a copper-bismuth alloy target composed of this composition.

The oxide layer 2, the metal layer 3 and the outer protective layer 5 of the multilayer composite film prepared in this embodiment are consistent with those of the embodiment 1, but the working layer 4 is a copper-bismuth alloy with a bismuth content of about 0.75%.

Laser precision molding was performed using the same device and method as in Example 1, and the laser parameters were also consistent with those in Example 1.

In this embodiment, the two elements of copper and bismuth are dissolved in each other at high temperature and form a eutectic structure in a solid state. The melting point of the eutectic structure is about 300°C, much lower than that of copper.

In Example 1, the component in the working layer 4 is copper. The focused pulsed laser beam passes through the first surface 101 and the second surface 102 of the transparent substrate 1, and irradiates on the multilayer composite film, so that the film part in the irradiated area melts and forms droplets, and the droplets detach from the film and deposit On a receptor or previously deposited copper, the droplet solidifies as it cools rapidly to the freezing point of the copper. Due to the high freezing point of copper, the above-mentioned solidification process is very fast. Pores tend to appear in the structure formed by depositing Example 1, as shown in FIG. 4 .

In this embodiment, using a copper-bismuth alloy as the working layer 4 can improve the above problems. When a droplet of copper-bismuth alloy breaks away from the film and deposits on the acceptor or previously deposited copper, the copper-bismuth alloy in the droplet can remain in the liquid state for a longer period of time, and in the process, even causes the previously deposited copper to The eutectic structure of , melts, and partially fills the packing pores, thereby reducing the pores of the final structure, forming a structure as shown in Figure 5, the structure shown has fewer pores. The droplet of the copper-bismuth alloy may contain a small amount of chromium in the metal layer, but the presence of chromium will not affect the formation of the eutectic structure.

In this embodiment, the formed three-dimensional pattern is mainly composed of copper, bismuth, chromium and gold. Since the structure deposited in Example 3 has fewer pores, the conductivity of the deposited three-dimensional structure is about 38% of that of pure copper, which is about 9% higher than that of Example 1.

The above-mentioned embodiments only express several implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the patent scope of the invention. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent for the present invention should be based on the appended claims.

Claims (8)

1. A multilayer composite film, characterized in that the multilayer composite film is attached to a transparent substrate, the multilayer composite film comprises an oxide layer, a metal layer, a working layer and an outer protective layer, the transparent substrate is provided with a first surface and a second surface which are oppositely arranged, the first surface faces a laser beam, the oxide layer is attached to the second surface, the metal layer is attached to the surface of the oxide layer, which is far away from the transparent substrate, the working layer is attached to the surface of the metal layer, which is far away from the transparent substrate, and the outer protective layer is attached to the surface of the working layer, which is far away from the transparent substrate;

the transparent substrate contains silicon element and oxygen element;

the oxide layer is made of heterogeneous materials, the oxide layer contains silicon element, oxygen element and chromium element, the total atomic percentage of the silicon element, the oxygen element and the chromium element in the oxide layer is more than or equal to 90%, the heterogeneous materials are different in composition from areas with different distances between the oxide layer and the second surface, the content of the silicon element and the oxygen element in the oxide layer is higher when the oxide layer is closer to the second surface, and the content of the chromium element in the oxide layer is higher when the oxide layer is farther from the second surface;

the metal layer contains chromium element, and the atomic percentage of the chromium element in the metal layer is more than or equal to 99%;

the working layer contains copper elements, the atomic percentage of the copper elements in the working layer is more than or equal to 95%, and the thickness of the working layer is 0.1-2 mu m;

the outer protective layer is silver, gold or gold-silver alloy, and the thickness of the outer protective layer is less than or equal to 30nm.

2. The multilayer composite film according to claim 1, wherein the transparent substrate is an amorphous material, and the softening point of the transparent substrate is not less than 500 ℃.

3. The multilayer composite film according to claim 1, wherein the atomic percentage of oxygen element in the transparent substrate is not less than 30%.

4. The multilayer composite film according to claim 3, wherein the oxide layer further contains any one or more of calcium element, boron element, magnesium element, potassium element and aluminum element, and the thickness of the oxide layer is not more than 30nm.

5. The multilayer composite film according to claim 1, wherein the thickness of the metal layer is 15nm or less.

6. The multilayer composite film according to claim 1, wherein the working layer is a single-layer metal, a multilayer metal, or an alloy, and the working layer further contains any one or more of chromium element, silver element, nickel element, tin element, aluminum element, bismuth element, zinc element, and cobalt element.

7. Use of a multilayer composite film according to any one of claims 1 to 6 in laser precision forming based on the principle of laser induced forward transfer, said laser precision forming being such that a focused pulsed laser beam is used to irradiate said multilayer composite film across a first surface and a second surface of said transparent substrate to form a two-or three-dimensional structure on a receiver.

8. The use of the multilayer composite film according to claim 7 in laser precision molding, wherein the pulse width of the pulse laser beam is 0.1-30 ns, and the fluence of the focused pulse laser beam is less than or equal to 10J/cm ² 。

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