PCR detection chip packaging structure and preparation method thereof

Abstract

The invention discloses a PCR detection chip packaging structure and a preparation method thereof.The PCR detection chip packaging structure comprises a base material and a cover plate, a micro-channel is machined in the upper surface of the base material, and the cover plate comprises a metal layer and a plasticizing coating arranged on the lower surface of the metal layer; and the lower surface of the plasticizing coating and the upper surface of the base material are combined together in a hot pressing combination mode or a screen printing gluing mode. According to the packaging structure and the preparation method thereof, the interface bonding strength of dissimilar materials is effectively improved, the thickness of the bonding layer is accurately controlled to optimize the heat conduction efficiency, and meanwhile, the advantages of biocompatibility and structural reliability are considered.

Description

Technical Field

[0001] The present invention relates to the technical field of PCR chips, and in particular to a PCR detection chip packaging structure and a manufacturing method thereof. Background Art

[0002] PCR chips, or polymerase chain reaction chips, are a key application of microfluidics and hold broad promise in molecular diagnostics. Traditional PCR chip packaging technology faces three major technical bottlenecks: First, insufficient interfacial bonding strength between dissimilar materials can easily lead to stress concentration and delamination failure during thermal cycling; second, the thickness of the interface layer formed by conventional adhesives is difficult to precisely control, and excessively thick adhesive layers can compromise the chip's thermal conductivity; and third, existing packaging processes struggle to balance biocompatibility and structural reliability requirements. In particular, the difference in thermal expansion coefficients between the metal layer and the polymer base layer makes traditional adhesive packaging structures prone to microcracks. Summary of the Invention

[0003] In response to the above-mentioned defects in the existing technology, the present invention provides a PCR detection chip packaging structure and a preparation method thereof, which has the advantages of effectively improving the interface bonding strength of heterogeneous materials, accurately controlling the thickness of the bonding layer to optimize the heat conduction efficiency, and taking into account both biocompatibility and structural reliability.

[0004] The present invention is achieved by adopting the following technical solutions:

[0005] A PCR detection chip packaging structure includes a substrate and a cover plate. The upper surface of the substrate is processed with microchannels. The cover plate includes a metal layer and a plasticized coating arranged on the lower surface of the metal layer. The lower surface of the plasticized coating and the upper surface of the substrate are combined together by hot pressing or screen printing.

[0006] Furthermore, the metal layer is made of aluminum foil, and the thickness of the aluminum foil is 35-100 μm.

[0007] Furthermore, the metal layer is provided with a microporous structure, and the size of the microporous structure is 5-20 nm.

[0008] Furthermore, the plasticized coating is composited by PC and PMMA, the thickness of the plasticized coating is 5-15 μm, and the mass ratio of PC to PMMA in the plasticized coating is 7:3.

[0009] Furthermore, the substrate is any one of PC, PMMA, COC, PP, and PET, or a composite of at least two of these materials.

[0010] A method for preparing a PCR detection chip packaging structure comprises the following steps:

[0011] S1. Prepare substrate and cover;

[0012] S2. Use plasma to clean the cover plate so that the contact angle of the cover plate surface is less than 10°;

[0013] S3. Applying an adhesive by screen printing on the lower surface of the plasticized coating of the cover plate to form a coating layer on the lower surface of the plasticized coating that is compatible with the microchannel;

[0014] S4. Align the adhesive layer with the substrate and perform overlapping and rolling sealing;

[0015] S5. Curing the adhesive layer to achieve encapsulation of the cover plate and the substrate.

[0016] Furthermore, in step S3, the thickness of the adhesive layer is 5-15 μm.

[0017] A method for preparing a PCR chip packaging structure comprises the following steps:

[0018] S1. Preparation of substrate and cover;

[0019] S2. Ultrasonic cleaning of the cover plate using acetone;

[0020] S3. The cover plate and the substrate are superimposed and placed in a vacuum hot press for pressure maintenance so that the plasticized coating on the lower surface of the cover plate and the upper surface of the substrate diffuse and fuse to form an interface bonding layer;

[0021] S4. Cool and shape to complete the packaging of the cover and substrate.

[0022] Furthermore, when the substrate is made of PC material, in step S3, the hot pressing temperature is 185-195°C, the holding pressure is 0.5-1.2 MPa, and the holding time is 30-60s; when the substrate is made of PMMA material, in step S3, the hot pressing temperature is 160-170°C, the holding pressure is 0.5-1.2 MPa, and the holding time is 30-60s.

[0023] Furthermore, in step S3, the thickness of the interface bonding layer is 2-8 μm.

[0024] Compared with the prior art, the beneficial effects of the present invention include at least:

[0025] This invention eliminates the additional thickness introduced by glue by directly fusing the plasticized coating to the substrate. The combination of the metal layer and the plasticized coating simultaneously ensures efficient thermal conductivity and forms a continuous, dense interface through hot pressing or screen printing, enabling reliable packaging of dissimilar materials. While maintaining high thermal conductivity, it effectively reduces the risk of interfacial cracking and avoids fluid channel deformation caused by excessively thick adhesive layers. By optimizing the interface bonding method and material selection, this invention effectively enhances the interfacial bonding strength of dissimilar materials, precisely controls the thickness of the bonding layer to optimize thermal conductivity, and simultaneously balances biocompatibility and structural reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an exploded view of the packaging structure of the PCR detection chip according to Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of a substrate and a cover plate packaged using screen printing in Example 2 of the present invention;

[0028] Figure 3 Schematic diagram of the third embodiment of the present invention after the substrate and the cover plate are packaged by thermal compression bonding;

[0029] In the figure: 1. substrate; 11. microchannel; 2. cover plate; 21. metal layer; 22. plasticized coating; 3. adhesive layer; 31. pattern structure; 4. interface bonding layer. DETAILED DESCRIPTION

[0030] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concepts of the example embodiments to those skilled in the art. Identical reference numerals in the drawings represent identical or similar structures, and thus repeated descriptions thereof will be omitted.

[0031] The words expressing positions and directions described in the present invention are all explained with reference to the accompanying drawings as examples, but can be modified as needed, and all such modifications are within the scope of protection of the present invention.

[0032] Example 1

[0033] In existing technologies, polymerase chain reaction chips must balance high thermal conductivity and biocompatibility. Traditional packaging structures use glue to coat the interfaces of dissimilar materials, but this interface has low bonding strength, is prone to cracking and delamination, and the glue layer is too thick. These problems are particularly prominent in microfluidic detection scenarios that require long-term stable operation. For example, under continuous temperature cycling, the glue layer is prone to thermal stress failure, resulting in fluid leakage or reduced airtightness.

[0034] To address these issues, the research and development process discovered that an excessively thick adhesive layer would hinder heat conduction and affect reaction efficiency, while mechanical pressing alone would make it difficult to achieve a stable bond between dissimilar materials. Analysis of the surface properties of different materials revealed that metal materials, while excellent thermal conductivity, are difficult to bond directly to the plastic substrate 1. Polymer coatings, on the other hand, can enhance interfacial compatibility through intermolecular forces. Based on this, a proposal was made to apply a plasticized transition layer to the lower surface of the metal layer 21, and to form a uniform bonding interface using hot pressing or screen printing.

[0035] Therefore, the present invention proposes a packaging structure including a substrate 1 and a cover plate 2, referring to Figure 1 The cover plate 2 includes a metal layer 21 and a plasticized coating 22 , and the lower surface of the plasticized coating 22 is bonded to the upper surface of the substrate 1 by hot pressing or screen printing.

[0036] Substrate 1 refers to the main structure supporting microchannels 11, and can be made of materials such as polycarbonate or cycloolefin copolymer, and can be injection molded to achieve complex flow channel processing. Metal layer 21 refers to a heat-conducting component, such as aluminum foil, covering the plasticized coating 22, which is used to quickly conduct reaction heat. Plasticized coating 22 refers to a transition layer composed of thermoplastic polymers that can form molecular chain entanglements with substrate 1 under heating and pressurizing conditions. Hot pressing bonding refers to the use of temperature and pressure to cause the plasticized coating 22 to melt and interpenetrate with the surface of substrate 1. Screen printing glue coating refers to the formation of precise bonding areas through patterned coating.

[0037] Specifically, the surface of the substrate 1 is processed with micron-scale fluid channels, the cover plate 2 provides uniform heat conduction through the metal layer 21, and the plasticized coating 22 acts as an intermediate layer to reduce interface stress. During the packaging process, the plasticized coating 22 is softened by heat and then undergoes molecular diffusion with the surface of the substrate 1 to form a direct bonding interface without glue, or an ultra-thin adhesive is applied in a specific area to achieve precise positioning. Both methods can avoid the thickness accumulation of traditional glue layers, while utilizing the synergistic effect of the metal layer 21 and the plasticized coating 22 to maintain structural stability. Traditional methods rely on glue as a bonding medium for dissimilar materials. The thickness of the glue layer is difficult to control and there is obvious stratification at the interface. The present invention eliminates the extra thickness brought by glue by directly fusing the plasticized coating 22 with the substrate 1. At the same time, the combination of the metal layer 21 and the polymer coating not only ensures thermal conductivity, but also forms a continuous and dense bonding interface through hot pressing or screen printing. The present invention achieves reliable packaging between dissimilar materials, effectively reduces the risk of interface cracking while maintaining high thermal conductivity, and avoids the problem of fluid channel deformation caused by excessively thick glue layers.

[0038] The present invention further proposes that the metal layer 21 be made of aluminum foil with a thickness of 35-100 μm. The metal layer 21 refers to the structural layer covering the plasticized coating 22 and can be specifically implemented using aluminum foil. Aluminum foil has high thermal conductivity and biocompatibility, meeting the thermal conductivity and bioreaction environment requirements of the PCR chip. The 35-100 μm thickness of the aluminum foil refers to the thickness range of the metal layer 21, which can be specifically achieved by controlling the thickness of the aluminum foil through a rolling process. This thickness range balances structural strength and thermal conductivity efficiency while avoiding mechanical damage caused by excessive thinness or increased thermal resistance caused by excessive thickness.

[0039] Specifically, the thickness of aluminum foil used as the material for the metal layer 21 is controlled within a specific range. For example, the thickness of the aluminum foil can be 35 μm, 100 μm, or any value in between. By selecting aluminum foil as the metal layer 21, its lightweight and high thermal conductivity can be utilized to achieve rapid heat transfer inside the chip, while its ductility helps to form a stable bond with the plasticized coating 22 during the packaging process. The thickness range of the aluminum foil has been optimized to ensure structural integrity during hot pressing or gluing processes, while avoiding local deformation caused by insufficient thickness or heat conduction delay caused by excessive thickness. Traditional packaging structures often use stainless steel or other metal materials as the metal layer 21, and their thickness has not been specifically designed, which can easily lead to interface stress concentration due to differences in thermal expansion coefficients. The thermal expansion coefficient of aluminum foil is closer to that of the plasticized coating 22 and the substrate 1. Combined with a specific thickness range, the risk of interface delamination can be significantly reduced. In addition, the thermal conductivity of aluminum foil is better than that of other metal materials, which can improve the temperature uniformity inside the chip.

[0040] The present invention optimizes the material selection and thickness parameters of the metal layer 21, solves the interface stratification problem caused by insufficient bonding strength of dissimilar materials in traditional packaging structures, and at the same time improves the thermal conductivity of the chip, making the temperature control during the PCR reaction more precise, thereby improving the reliability and consistency of the test results.

[0041] The present invention further proposes that the metal layer 21 is provided with a microporous structure, and the size of the microporous structure is 5-20 nm.

[0042] The microporous structure refers to nanoscale pores formed on the surface of the metal layer 21 through processing, which can be achieved through an anodic oxidation process. The size of the microporous structure is controlled to range from 5-20nm, which can ensure that the plasticized coating 22 material fully penetrates the pores during the bonding process, thereby enhancing the interfacial bonding strength.

[0043] Specifically, in the packaging structure, the microporous structure on the surface of the metal layer 21 forms an anchoring effect through nano-scale pores, so that the plasticized coating 22 material is mechanically interlocked with the metal layer 21 during the hot pressing or gluing process. Since the pore size is limited to a specific range, the plasticized coating 22 material can effectively fill the pores to achieve tight bonding, and will not cause the mechanical strength of the metal layer 21 to decrease due to excessive pores. In addition, the presence of the microporous structure further increases the contact area between the metal layer 21 and the plasticized coating 22, which helps to improve the overall thermal conductivity. The metal layer 21 in the traditional packaging structure is usually a smooth surface without pores, and the interface bonding is only achieved through the glue layer or hot pressing, which has the risk of insufficient bonding force and delamination. The present invention, by introducing a microporous structure, utilizes the dual effects of mechanical interlocking and material penetration to significantly enhance the stability of the interface bonding and optimize the heat conduction path. The present invention can effectively solve the problems of low interface bonding strength and easy delamination of heterogeneous materials, while improving the thermal conductivity efficiency of the packaging structure and ensuring the uniformity of temperature distribution during the PCR reaction.

[0044] The present invention further proposes that the plasticized coating 22 is composited from PC and PMMA, the thickness of the plasticized coating 22 is 5-15 μm, and the mass ratio of PC to PMMA in the plasticized coating 22 is 7:3.

[0045] Among them, PC refers to polycarbonate material, which can be specifically compounded with PMMA through a melt blending process. It has high heat resistance and mechanical strength, and can maintain the stability of the coating structure during the encapsulation process. Among them, PMMA refers to polymethyl methacrylate material, which can be specifically compounded with PC through solution blending. Its surface polarity helps to improve the interface bonding performance with the substrate 1. Among them, the mass ratio of 7:3 refers to the mixed mass ratio of PC and PMMA, which can be specifically controlled by the setting parameters of the twin-screw extruder. This ratio can balance the difference in melt viscosity and thermal expansion coefficient of the two materials and reduce interfacial stress. Among them, the thickness of the plasticized coating 22 is 5-15μm, which refers to the final coating thickness of the composite material, which can be specifically achieved through a scraping process or a hot pressing process. This thickness range can not only ensure the interface bonding strength, but also avoid the decrease in heat conduction efficiency due to excessive thickness.

[0046] Specifically, the plasticized coating 22 forms a dual-phase structure by combining PC and PMMA. 0.1-0.5wt% silane coupling agent is added during the composite process. During hot pressing or screen printing, PC provides rigid support to resist packaging pressure, while PMMA forms intermolecular forces with the surface of substrate 1 through its polar functional groups. At a mass ratio of 7:3, the melting temperature ranges of the two materials partially overlap, allowing them to soften and diffuse simultaneously during hot pressing, forming a continuous, bonded interface layer. When the coating thickness is controlled within the range of 5-15μm, it can cover microscopic defects on the surface of substrate 1 without increasing the overall thermal resistance of the packaged chip due to excessive thickness. Traditional packaging structures use a single adhesive layer or a single polymer coating, whose thermal expansion coefficient differs significantly from that of substrate 1, making it prone to delamination during temperature changes. However, by combining PC and PMMA and adopting a specific mass ratio, the thermal expansion coefficient of the plasticized coating 22 is closer to that of the substrate 1 material. Furthermore, the coating thickness is precisely controlled through the process, avoiding the localized stress concentration problem caused by the uneven thickness of traditional adhesive layers.

[0047] The present invention solves the problems of low interface bonding strength of dissimilar materials and excessively thick adhesive layer. The composite structure of PC and PMMA in the plasticized coating 22 forms a uniform and dense bonding interface during the packaging process. At the same time, the thin layer design reduces the material impedance on the heat conduction path, thereby improving the thermal conductivity and long-term reliability of the PCR chip.

[0048] The present invention further proposes a PCR detection chip packaging structure, including a substrate 1 and a cover plate 2. The upper surface of the substrate 1 is processed with a microchannel 11. The substrate 1 is any one of PC, PMMA, COC, PP, PET or a composite of at least two of any two materials.

[0049] Among them, substrate 1 refers to a layer of substrate 1 that constitutes the main structure of the chip, which can be realized by using a single material or a mixed material selected from polycarbonate, polymethyl methacrylate, cycloolefin copolymer, polypropylene or polyethylene terephthalate. For example, when it is necessary to take into account both mechanical strength and optical transparency, a composite material of PC and COC can be used, and the performance can be optimized by adjusting the proportion of the components. Among them, the combination of composite materials refers to combining different types of polymer materials into a single substrate 1 through blending, lamination or co-extrusion processes, which can be achieved specifically by melt blending or alternating superposition and hot pressing to balance the heat resistance, biocompatibility and processing performance of different materials.

[0050] Specifically, by selecting specific polymer materials or combinations thereof, the substrate 1 can achieve matching thermal expansion coefficients and chemical compatibility with the plasticized coating 22 of the cover plate 2. For example, when PC and PMMA are composited, the polarity differences between their molecular segments can lead to interfacial fusion through molecular diffusion during the hot pressing process, thereby reducing stress concentration caused by material differences. Furthermore, the use of composite materials can tailor the properties of the substrate 1 to different detection scenarios: for enhanced chemical resistance, PP and PET can be composited; for improved optical transmittance, COC and PMMA can be composited. Traditional packaging structures typically use a single-material substrate, but the difference in thermal expansion coefficients between the substrate and the dissimilar cover plate 2 material can easily lead to cracking at the bonding interface. However, the present invention, through the diversified selection and composite design of the substrate 1, significantly improves the interfacial bonding strength between the substrate 1 and the plasticized coating 22 of the cover plate 2, while avoiding the risk of fluid channel deformation associated with relying on thick adhesive layers. For example, in the prior art, the use of pure aluminum foil and ABS substrate 1 is prone to delamination due to thermal expansion mismatch. The present invention effectively alleviates this problem by using composite materials for the substrate 1.

[0051] The present invention allows for flexible adjustment of the physical and chemical properties of the substrate 1 according to actual needs, ensuring that the package structure maintains interfacial stability during thermal cycling while reducing the probability of microchannel 11 collapse due to material rigidity differences. For example, when a composite substrate 1 of PP and PET is used, its flexibility can accommodate the bending deformation of the metal layer 21 of the cover plate 2, while the high heat resistance of the COC substrate 1 ensures the dimensional stability of the package structure during the PCR reaction.

[0052] Example 2

[0053] The present invention further proposes a method for preparing a PCR detection chip packaging structure, referring to Figure 2 , comprising the following steps: preparing a substrate 1 and a cover plate 2; cleaning the cover plate 2 by plasma so that the contact angle of the cover plate 2 surface is less than 10°; applying adhesive on the lower surface of the plasticized coating 22 of the cover plate 2 by screen printing to form a coating layer 3 on the lower surface of the plasticized coating 22 that is compatible with the microchannel 11; aligning the coating layer 3 with the substrate 1 and performing overlapping and rolling sealing; and curing the coating layer 3 to achieve the encapsulation of the cover plate 2 and the substrate 1.

[0054] Plasma cleaning refers to the use of active particles generated by ionized gas to decontaminate and activate the surface of the cover plate 2. This can be achieved using a radio frequency or microwave plasma device. Its function is to remove surface contaminants and increase surface energy, making the subsequent adhesive layer 3 more firmly bonded. After the cover plate 2 of the present invention is cleaned by plasma, its surface energy is >40mN / m. Screen printing adhesive coating refers to the uniform transfer of adhesive to the surface of the plasticized coating 22 using a screen with a specific pattern. This can be achieved using a stainless steel or nylon screen. Its function is to precisely control the thickness of the adhesive layer and the shape of the channel to avoid increased flow resistance caused by excessive adhesive layer thickness. Overlapping rolling sealing refers to aligning the cover plate 2 and the substrate 1 and then applying pressure through a rolling device to complete the bonding. This can be achieved using a silicone roller or a metal roller. Its function is to eliminate interfacial bubbles and promote close contact between the adhesive layer and the microchannel 11. Curing the adhesive layer 3 refers to cross-linking the adhesive by thermal curing or ultraviolet light curing. This can be achieved using an oven or UV lamp irradiation. Its function is to form a stable interfacial bonding layer 4.

[0055] Specifically, during the preparation process, the surface of the cover plate 2 is first made super-hydrophilic by plasma treatment, thereby enhancing the wettability of the adhesive; then, a glue layer 3 matching the microchannel 11 is formed on the surface of the plasticized coating 22 by a screen printing process. This process can accurately control the thickness and distribution area of ​​the glue layer; then, the pattern structure 31 of the glue layer 3 is precisely matched with the microchannel 11 of the substrate 1 through mechanical alignment, and then the interface gap is eliminated through a rolling process; finally, the glue layer is formed into a stable chemical bond through a curing process, thereby realizing reliable packaging of the cover plate 2 and the substrate 1.

[0056] Compared with existing technologies, traditional methods of direct adhesive coating make it difficult to control adhesive layer thickness and lack pretreatment of the interface, resulting in low bonding strength and prone to cracking. This method, however, enhances interfacial activity through plasma cleaning, combines it with a screen printing process to precisely control adhesive layer thickness and shape, and then uses a rolling process to eliminate interface defects, effectively solving the problems of insufficient bonding strength between dissimilar materials and excessive adhesive layer thickness.

[0057] Through the above technical solution, the present invention achieves high-precision bonding at the interface of dissimilar materials, avoids the impact of excessive adhesive layer thickness on microchannel flux, and significantly improves the sealing and durability of the packaging structure. Furthermore, by controlling the interface state and adhesive layer morphology through a step-by-step process, production yield is improved and material loss during the packaging process is reduced.

[0058] The adhesive of the present invention is preferably UV adhesive, the width of the printed pattern lines is 50 microns, and the spacing between adjacent lines is 100 microns.

[0059] The present invention further proposes that in step S3, the thickness of the adhesive layer 3 is 5-15 μm.

[0060] The thickness of the adhesive layer 3 refers to the vertical dimension range of the adhesive layer formed by the screen printing process before curing. This can be achieved by adjusting the mesh size of the screen, the squeegee pressure, and the number of printings. This thickness range ensures interfacial bonding strength while preventing excessive adhesive layer thickness from clogging or deforming the microchannels 11. The adhesive layer 3 refers to the adhesive medium layer having a specific pattern structure 31 formed on the lower surface of the plasticized coating 22 by the screen printing process. Specifically, it can be implemented using a thermosetting epoxy resin or a UV-curing acrylate glue. This layer can be patterned to precisely correspond to the microchannels 11 of the substrate 1.

[0061] Specifically, when screen printing is implemented on the lower surface of the plasticized coating 22 of the cover plate 2, the screen parameters and printing process are controlled so that the adhesive layer forms a uniform thin layer structure before curing. When the adhesive layer 3 is in the range of 5-15 μm, it can not only ensure that the packaging interface obtains sufficient adhesion, but also maintain the integrity of the microchannel 11 structure, and the shear strength after curing is ≥8 MPa. The volume shrinkage of the adhesive during the curing process is controlled within a reasonable range to avoid stress concentration problems caused by excessive thickness of the adhesive layer. The adhesive layer 3 and the microchannel 11 of the substrate 1 are structurally matched through precise alignment, and finally the interface bonding is completed through a rolling process. When the traditional method adopts manual glue coating or spraying process, the thickness of the glue layer usually exceeds 20 μm, which can easily cause the microchannel 11 to collapse or clog. The present invention limits the glue coating thickness of screen printing, while ensuring the bonding strength, it can accurately control the glue layer morphology and avoid microstructural damage caused by excessive penetration of the colloid. Compared with the randomly distributed glue layer morphology, the patterned glue coating method can also reduce material waste. This invention effectively solves the structural deformation problem caused by excessively thick adhesive layers in traditional heterogeneous material packaging, significantly improving the molding precision of the chip microchannel 11. The increased interfacial bonding strength enables the package structure to withstand greater thermal stress during thermal cycling, reducing the risk of delamination caused by differences in material expansion coefficients, thereby ensuring the long-term sealing performance of the PCR reaction chamber.

[0062] Example 3

[0063] The present invention further proposes a method for preparing a PCR detection chip packaging structure, referring to Figure 3 , comprising the following steps: preparing a substrate 1 and a cover plate 2; ultrasonically cleaning the cover plate 2 with acetone; superimposing the cover plate 2 and the substrate 1 and placing them in a vacuum hot press for pressure maintenance, so that the lower surface of the plasticized coating 22 of the cover plate 2 and the upper surface of the substrate 1 diffuse and fuse with each other to form an interface bonding layer 4; cooling and shaping to complete the packaging of the cover plate 2 and the substrate 1.

[0064] Among them, acetone ultrasonic cleaning refers to the use of acetone solvent combined with ultrasonic vibration to clean the surface of the cover plate 2, which can be achieved specifically by ultrasonic equipment with a frequency of 20-40kHz. This step can effectively remove oil and particulate contaminants on the surface of the metal layer 21, and improve the cleanliness of the bonding interface. Vacuum hot press pressure holding refers to applying temperature and pressure to the laminated cover plate 2 and substrate 1 under a vacuum environment, which can be achieved specifically by using vacuum hot pressing equipment with a temperature control accuracy of ±2°C. This process promotes the mutual diffusion of the molecular chains of the plasticized coating 22 and the substrate 1 through thermodynamic conditions to form an adhesive-free interface bonding layer 4. The interface bonding layer 4 refers to the transition area formed by molecular diffusion between materials, and its thickness is jointly controlled by the hot pressing temperature, pressure and time, and can be adjusted within the range of 2-8μm.

[0065] Specifically, after the cover plate 2 is ultrasonically cleaned with acetone, the organic pollutants and tiny particles remaining on the surface are completely removed, thereby reducing the probability of interface defects. Subsequently, the cover plate 2 is superimposed on the substrate 1 in a vacuum environment and hot pressed and pressure maintained. After being heated, the molecular chain movement of the plasticized coating 22 is intensified, and interpenetration and entanglement with the substrate 1 material occur, forming a dense interface directly bonded without an adhesive layer. During the cooling and shaping stage, the cooling rate is controlled to rearrange the mutually diffused molecular chains, and finally a stable bond of the packaging structure is achieved. Traditional methods rely on glue to bond the interface of dissimilar materials, which can easily lead to a decrease in heat conduction efficiency due to an excessively thick adhesive layer, and the adhesive may introduce biocompatibility risks. The present invention forms an interface bonding layer 4 through molecular diffusion of the material itself, which not only avoids the influence of the adhesive layer on the thermal conductivity, but also eliminates the interference of adhesive residues on biological reactions. In addition, the interface bonding layer 4 and the base material are homologous or compatible systems, and the bonding strength is significantly higher than that of the adhesive interface between dissimilar materials. This invention solves the problem of reduced thermal conductivity caused by excessively thick adhesive layers in traditional packaging, while also avoiding the risk of delamination and cracking caused by insufficient interfacial bonding strength. By eliminating the need for adhesives, the packaging process is simplified and material compatibility requirements are reduced, making it suitable for reliable packaging of substrates 1 and metal layers 21 and cover plates 2 made of different materials.

[0066] The present invention further proposes that in the method for preparing a PCR detection chip packaging structure, when the substrate 1 is made of PC material, in the hot pressing step, the hot pressing temperature is controlled at 185-195°C, the holding pressure is controlled at 0.5-1.2 MPa, and the holding time is controlled at 30-60 seconds; when the substrate 1 is made of PMMA material, in the hot pressing step, the hot pressing temperature is controlled at 160-170°C, the holding pressure is controlled at 0.5-1.2 MPa, and the holding time is controlled at 30-60 seconds.

[0067] Among them, the hot pressing temperature refers to the ambient temperature of the material during the hot pressing process, which can be achieved by adjusting the heating module of the vacuum hot press. This temperature range can ensure that the molecular chains of the plasticized coating 22 and the substrate 1 are fully activated but not over-decomposed. The holding pressure refers to the mechanical pressure applied to the laminated material during the hot pressing process, which can be achieved by setting the pressure parameters of the vacuum hot press. This pressure range helps promote interface diffusion and fusion. The holding time refers to the length of time the material maintains a pressurized state at a specific temperature and pressure, which can be achieved by controlling the timing system of the hot press. This time range can ensure the full formation of the interface bonding layer 4.

[0068] Specifically, when the substrate 1 is made of PC, its glass transition temperature is relatively high, so a higher hot pressing temperature is required to promote molecular diffusion between the plasticized coating 22 and the substrate 1; while the glass transition temperature of PMMA is relatively low, and excessively high hot pressing temperatures may cause material deformation, so a relatively low temperature is required. The setting of the holding pressure and time needs to work in synergy with the temperature to ensure the density of the interface bonding layer 4 and to avoid the collapse of the microchannel 11 structure due to excessive pressure or excessive time. For example, in a vacuum hot press, the temperature and pressure parameters can be adjusted in stages to gradually cause molecular chain entanglement at the contact surface of the plasticized coating 22 and the substrate 1, ultimately forming a non-glue interface bond.

[0069] In some specific embodiments, the hot pressing temperature of PC material can be selected as 190°C, the holding pressure is 0.8 MPa, and the holding time is 45 seconds; the hot pressing temperature of PMMA material can be selected as 165°C, the holding pressure is 0.8 MPa, and the holding time is 45 seconds. In addition, during the hot pressing process, the holding parameters can be dynamically adjusted by real-time monitoring of the formation state of the interface bonding layer 4. The existing method relies on glue to bond the interface of dissimilar materials. The thickness of the glue layer is difficult to accurately control and easily leads to delamination. The present invention optimizes the hot pressing parameters to directly fuse the plasticized coating 22 with the substrate 1 to form an interface bonding layer 4 without the need for an additional glue layer. At the same time, the differentiated hot pressing temperatures for different materials are matched to solve the problem of material deformation or insufficient bonding caused by a single temperature in the traditional method.

[0070] The present invention can significantly improve the interfacial bonding strength between the plasticized coating 22 and the substrate 1, avoiding blockage or leakage of the microchannel 11 caused by an excessively thick adhesive layer or interfacial cracking, while simplifying the packaging process and reducing material costs.

[0071] The present invention further proposes a method for preparing a PCR detection chip packaging structure, comprising placing the cover plate 2 and the substrate 1 in a vacuum hot press for pressure maintenance after being overlapped, so that the lower surface of the plasticized coating 22 and the upper surface of the substrate 1 diffuse and fuse with each other to form an interface bonding layer 4, and the thickness of the interface bonding layer 4 is 2-8 μm.

[0072] The interfacial bonding layer 4 is formed by hot pressing to cause molecular diffusion between the plasticized coating 22 and the surface material of the substrate 1. This can be achieved by applying temperature and pressure using a vacuum hot press. This feature can replace the traditional glue layer and directly enhance the interfacial bonding strength through material fusion. The thickness range of 2-8 μm refers to the vertical height dimension of the interfacial bonding layer 4. This can be achieved by regulating the hot pressing temperature, pressure, and holding time. This range balances bonding strength and processing efficiency, avoiding too thin a layer resulting in a weak bond or too thick a layer affecting thermal conductivity.

[0073] Specifically, during the vacuum hot pressing process, the plasticized coating 22 and the substrate 1 undergo surface softening under thermodynamic conditions, and the molecular chains of the two materials are forced to penetrate each other by applying a holding pressure, forming a glue-free diffusion bonding interface. The thickness is controlled within the range of 2-8 μm, which not only ensures sufficient contact area to achieve molecular chain interlocking, but also avoids excessive compression that causes material deformation or damage to the microchannel 11 structure. Compared with the traditional method of using glue to bond heterogeneous materials, the thickness of the glue layer usually exceeds 15 μm and there is a risk of interface separation. The thickness of the interface layer formed by material diffusion in the present invention is only 1 / 3-1 / 2 of the glue layer, which improves the bonding strength while eliminating the biocompatibility risks brought by the glue layer, and is more suitable for the PCR chip's requirements for high thermal conductivity and biosafety.

[0074] The present invention achieves glue-free thin layer interface bonding, solves the problems of low heat transfer efficiency and easy interface stratification caused by the traditional thick glue layer, avoids the risk of biological contamination introduced by adhesives, and significantly improves the reliability and detection accuracy of the PCR chip packaging structure.

[0075] Through the above-mentioned preparation method, the present invention not only improves the thermal conductivity of the PCR chip packaging structure, shortens the PCR cycle time by 40%, and greatly enhances the packaging strength. Tests have shown that the shear strength reaches 12.3MPa (traditional process <5MPa), but also improves biocompatibility, reduces the glue contact area by 70%, and maintains the reagent activity retention rate of >98%.

[0076] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limiting the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes shall fall within the scope of protection of the claims of the present invention.

Claims

1. A PCR detection chip packaging structure, characterized in that: The invention comprises a substrate (1) and a cover plate (2), wherein the upper surface of the substrate (1) is processed with a microchannel (11), and the cover plate (2) comprises a metal layer (21) and a plasticized coating (22) arranged on the lower surface of the metal layer (21), and the lower surface of the plasticized coating (22) is combined with the upper surface of the substrate (1) by a hot pressing bonding method or a screen printing glue coating method.

2. The PCR detection chip packaging structure according to claim 1, characterized in that: The metal layer (21) is made of aluminum foil, and the thickness of the aluminum foil is 35-100 μm.

3. The PCR detection chip packaging structure according to claim 1, characterized in that: The metal layer (21) is provided with a microporous structure, and the size of the microporous structure is 5-20 nm.

4. The PCR detection chip packaging structure according to claim 1, characterized in that: The plasticized coating (22) is composited from PC and PMMA, the thickness of the plasticized coating (22) is 5-15 μm, and the mass ratio of PC to PMMA in the plasticized coating (22) is 7:

3.

5. The PCR detection chip packaging structure according to claim 1, characterized in that: The substrate (1) is any one of PC, PMMA, COC, PP, and PET, or a composite of at least two of these materials.

6. A method for preparing the PCR detection chip packaging structure according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Preparing a substrate (1) and a cover plate (2); S2. The cover plate (2) is cleaned by plasma so that the surface contact angle of the cover plate (2) is less than 10°; S3. Applying an adhesive to the lower surface of the plasticized coating (22) of the cover plate (2) by screen printing to form a coating layer (3) on the lower surface of the plasticized coating (22) that is compatible with the microchannel (11); S4. Aligning the adhesive layer (3) with the substrate (1) and laminating and rolling the seal; S5. Curing the adhesive layer (3) to achieve encapsulation of the cover plate (2) and the substrate (1).

7. The method for preparing a PCR detection chip packaging structure according to claim 6, characterized in that: In step S3, the thickness of the adhesive layer (3) is 5-15 μm.

8. A method for preparing the PCR chip packaging structure according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Preparing a substrate (1) and a cover plate (2); S2. Ultrasonic cleaning of the cover plate (2) using acetone; S3. After the cover plate (2) and the substrate (1) are stacked, they are placed in a vacuum hot press for pressure maintenance, so that the lower surface of the plasticized coating (22) of the cover plate (2) and the upper surface of the substrate (1) diffuse and fuse with each other to form an interface bonding layer (4); S4. Cooling and shaping to complete the packaging of the cover plate (2) and the base material (1).

9. The method for preparing a PCR detection chip packaging structure according to claim 8, characterized in that: When the substrate (1) is made of PC material, in step S3, the hot pressing temperature is 185-195°C, the holding pressure is 0.5-1.2 MPa, and the holding time is 30-60 seconds; when the substrate (1) is made of PMMA material, in step S3, the hot pressing temperature is 160-170°C, the holding pressure is 0.5-1.2 MPa, and the holding time is 30-60 seconds.

10. The method for preparing a PCR detection chip packaging structure according to claim 8, characterized in that: In step S3, the thickness of the interface bonding layer (4) is 2-8 μm.

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