A method for preparing a 3D printing-based TMV chip

Abstract

The application discloses a preparation method of a TMV chip based on 3D printing. The method comprises the following steps: forming a three-layer structure conductive column on a specified pad or connecting area of a re-wiring layer structure by 3D printing layer by layer; the conductive column comprises a bottom bonding layer, a middle supporting layer and a top conductive layer in sequence along an axial direction; the 3D printing slurry is a metal powder resin-based composite slurry; the resin system mass ratio of each layer in the bottom bonding layer, the middle supporting layer and the top conductive layer decreases layer by layer upwards, and the metal powder mass ratio increases layer by layer upwards; the rheological property of the metal powder resin-based composite slurry in the middle supporting layer is better than that of the bottom bonding layer and the top conductive layer; the conductive column is formed by 3D printing, the height, diameter, spacing and morphology of the conductive column can be flexibly adjusted at the design level, and the bonding strength, conductive performance and structural stability are all significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of chip packaging technology, and specifically relates to a method for preparing a TMV chip based on 3D printing. Background Technology

[0002] In the existing TMV (Through Mold Via) chip fabrication process, the lack of flexibility in the geometry and material system of the vertical interconnect structure makes it difficult to meet the electrical performance requirements such as impedance matching, insertion loss, and crosstalk suppression in high-frequency and high-speed applications. At the same time, the via filling material is usually fixed to a single metal system, making it difficult to optimize for the differentiated requirements of conductivity, dielectric loss, thermal conductivity, reliability, and cost for different applications. In addition, traditional photolithography, electroplating, or drilling and electroplating processes have problems such as limited process windows, long design iteration cycles, high customization costs, and difficulty in consistency control when forming pillar and via structures with different heights, diameters, and array spacings. These issues limit the promotion of TMV chips in higher frequency bands, more complex packaging forms, and customized applications in multiple scenarios.

[0003] Therefore, this invention needs to propose a method for fabricating TMV chips based on 3D printing to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a method for fabricating TMV chips based on 3D printing. This invention enables the adjustable and controllable size (height, diameter, spacing, and morphology) of conductive pillars to adapt to high-frequency signal transmission and impedance design, and allows the selection or replacement of through-hole filling metal paste according to the application scenario, thereby improving high-frequency interconnect performance, material compatibility, and manufacturing flexibility.

[0005] To address the aforementioned technical problems, this invention provides a method for fabricating a TMV chip based on 3D printing, comprising:

[0006] Provide a redistribution layer structure;

[0007] On designated pads or connection areas of the redistribution layer structure, a three-layer conductive pillar is formed by 3D printing, stacking layer by layer. The conductive pillar sequentially includes a bottom bonding layer, a middle support layer, and a top conductive layer along the axial direction. The 3D printing slurry is a metal powder resin-based composite slurry. In the bottom bonding layer, the middle support layer, and the top conductive layer, the mass percentage of the resin system decreases layer by layer upwards, while the mass percentage of the metal powder increases layer by layer upwards. The rheological properties of the metal powder resin-based composite slurry in the middle support layer are better than those of the bottom bonding layer and the top conductive layer.

[0008] Post-processing is performed on the conductive column;

[0009] The redistribution layer structure is molded together with the conductive pillar to form a molding layer;

[0010] Grind the molding layer to expose the top of the conductive post.

[0011] Preferably, in the bottom bonding layer, the metal powder accounts for 60wt% to 70wt% by mass, and the resin system accounts for 30wt% to 40wt% by mass.

[0012] In the central support layer, the metal powder accounts for 85wt% to 90wt% by mass; the resin system accounts for 10wt% to 15wt% by mass.

[0013] In the top conductive layer, the metal powder accounts for 96wt% to 98wt% by mass; the resin system accounts for 2wt% to 4wt% by mass.

[0014] Preferably, in the bottom bonding layer, the viscosity of the metal powder resin-based composite slurry is 300 Pa·s to 600 Pa·s; in the middle support layer, the viscosity of the metal powder resin-based composite slurry is 100 Pa·s to 400 Pa·s; and in the top conductive layer, the viscosity of the metal powder resin-based composite slurry is 80 Pa·s to 150 Pa·s.

[0015] Preferably, in the bottom bonding layer, the metal powder is dendritic electrolytic copper powder with a particle size D50 of 5μm~10μm; the resin system includes epoxy-phenolic resin and functional additives; the functional additives account for 2%~8% of the total mass of the resin system, including silane coupling agents, curing agents, accelerators, and dispersants; the silane coupling agent is γ-aminopropyltrimethoxysilane, and the amount used is 1%~3% of the mass of epoxy-phenolic resin; the curing agent is ethylenediamine, and the amount used is 1%~2.5% of the mass of epoxy-phenolic resin; the accelerator is 2-ethyl-4-methylimidazole, and the amount used is 0.1%~1% of the mass of epoxy-phenolic resin; the dispersant is polyethylene glycol, and the amount used is 0.5%~2% of the mass of epoxy-phenolic resin.

[0016] In the central support layer, the metal powder is spherical atomized copper powder with a particle size D50 of 2μm~5μm; the resin system includes thermosetting epoxy resin and functional additives; the functional additives account for 3%~10% of the total mass of the resin system, including fumed silica thixotropic agent, curing agent, defoamer, and leveling agent; the fumed silica thixotropic agent is selected as hydrophilic fumed silica, and its dosage is 2%~6% of the mass of thermosetting epoxy resin; the curing agent is selected as 4,4-diaminodiphenylmethane, and its dosage is 1%~3% of the mass of thermosetting epoxy resin; the defoamer is selected as an organosilicon defoamer, and its dosage is 0.1%~0.5% of the mass of thermosetting epoxy resin; the leveling agent is selected as polyether-modified polysiloxane, and its dosage is 0.3%~1% of the mass of thermosetting epoxy resin.

[0017] In the top conductive layer, the metal powder is a mixture of nano-copper powder and nano-silver powder in a mass ratio of 3:1; the nano-copper powder has a particle size of 50nm~100nm, and the nano-silver powder has a particle size of 30nm~50nm; the resin system includes phenolic resin and functional additives; the functional additives account for 1%~5% of the total mass of the resin system, including curing agent, anti-agglomeration agent and surfactant; the curing agent is hexamethylenetetramine, and the amount used is 1.5%~3% of the mass of phenolic resin; the anti-agglomeration agent is polyvinylpyrrolidone, and the amount used is 0.5%~1% of the mass of phenolic resin; the surfactant is polyethylene glycol, and the amount used is 0.2%~0.8% of the mass of phenolic resin.

[0018] Preferably, the overall height of the conductive column is 50μm to 300μm; wherein the height of the bottom bonding layer accounts for 10% to 25% of the total height; the height of the middle support layer accounts for 50% to 70% of the total height; and the height of the top conductive layer accounts for 15% to 30% of the total height.

[0019] Preferably, before forming the redistribution layer structure, the method further includes:

[0020] Provide temporary carrier board;

[0021] A peeling layer is formed on the surface of the temporary carrier plate.

[0022] A rewiring layer structure is formed on the surface of the stripping layer;

[0023] The formation process of the redistribution layer structure includes:

[0024] A dielectric layer is formed on the peeling layer and patterned openings are formed thereon;

[0025] Deposit a seed layer, and form RDL lines and pads through photolithography, metal deposition or electroplating;

[0026] The photoresist is removed and the exposed seed layer is etched to form an RDL structure.

[0027] Preferably, after grinding the molding layer to expose the top of the conductive post, the method further includes:

[0028] The release layer is debonded to remove the temporary carrier plate;

[0029] The chips are diced according to demand to form individual chips.

[0030] Preferably, the 3D printing is jet printing or micro-extrusion printing;

[0031] The post-processing of the conductive column includes, in sequence, curing, sintering and surface metallization.

[0032] Preferably, the conductive column is formed into an integrated metal column after curing or sintering, and its cross-section is circular, square, triangular or hexagonal.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. This invention uses 3D printing to form conductive columns, which can flexibly adjust the height, diameter, spacing and shape of the conductive columns at the design level to achieve more precise impedance matching, reduce loss and crosstalk, and thus adapt to the stable transmission of higher frequency band or higher speed signals.

[0035] 2. The TMV vias of this invention are filled with a replaceable metal paste system, which can make trade-offs between conductivity, thermal conductivity, dielectric loss, process temperature window, reliability (such as thermal cycling, electromigration, etc.) and cost according to different application requirements, thereby improving the material adaptability and application coverage of the solution.

[0036] 3. Compared with traditional electroplating or mechanical hole-making processes, the 3D printing process chain of this invention is more flexible, supports rapid prototyping and multiple version iterations, and facilitates the realization of non-standard arrays, differentiated sizes and local reinforcement structures; at the same time, it can reduce the time and cost threshold for small-batch customization, and improve development efficiency and manufacturability.

[0037] 4. The conductive pillar structure of this invention employs three different functional layers, resulting in higher interface reliability. The high-resin, high-adhesion system in the bottom bonding layer significantly enhances the adhesion strength between the conductive pillar and the RDL substrate. Printing stability is also improved; the specific resin system in the middle support layer enhances shape retention during printing and reduces the risk of collapse. The top layer exhibits superior conductivity, utilizing a high-metal-content paste to reduce resistance and improve interconnect performance. Furthermore, the layered design effectively buffers thermal expansion mismatch, improving thermal cycling reliability. The number of layers, thickness, and paste composition can be flexibly designed according to different packaging scenarios. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the temporary carrier plate provided in an embodiment of the present invention.

[0039] Figure 2 This is a schematic diagram of forming a peeling layer on the surface of a temporary carrier plate, provided in an embodiment of the present invention.

[0040] Figure 3 This is a schematic diagram of a redistribution layer structure formed on the surface of a temporary carrier board, provided in an embodiment of the present invention.

[0041] Figure 4 This is a schematic diagram of forming a conductive pillar provided in an embodiment of the present invention.

[0042] Figure 5 This is a schematic diagram of the formation of the molding layer provided in an embodiment of the present invention.

[0043] Figure 6 This is a schematic diagram of grinding and thinning the molding layer provided in an embodiment of the present invention.

[0044] Figure 7 This is a schematic diagram of debonding and removing the temporary carrier plate from the release layer, provided in an embodiment of the present invention.

[0045] Figure 8 This is a schematic diagram of dicing to form a single chip according to demand, provided in an embodiment of the present invention.

[0046] In the diagram: 1-temporary carrier board, 2-stripping layer, 3-rewiring layer structure, 4-conductive pillar, 41-bottom bonding layer, 42-middle support layer, 43-top conductive layer, 5-molding layer. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0048] This invention specifically provides a method for fabricating a TMV chip based on 3D printing, including the following steps:

[0049] Step 1: Provide a temporary carrier plate 1; the temporary carrier plate 1 can be one of a glass carrier plate, a silicon carrier plate, or a metal carrier plate; for example... Figure 1 As shown.

[0050] Step 2: Form a release layer 2 on the surface of the temporary carrier plate 1 for subsequent carrier plate removal and to improve the adhesion of the medium layer; the release layer 2 can be made of thermal release adhesive, laser release layer, or chemically releaseable layer; for example Figure 2 As shown.

[0051] Step 3: Form a redistribution layer structure 3 on the surface of the temporary carrier 1. This involves forming a dielectric layer and patterning openings on the temporary carrier 1, depositing a seed layer, and then forming RDL lines and pads through photolithography, metal deposition, and electroplating. The resist is then removed and etched to expose the seed layer, allowing the RDL pattern to be independently formed. The RDL can be a single-layer or multi-layer structure. Figure 3 As shown.

[0052] Step 4: On the designated pads or connection areas of the completed RDL, conductive pillars 4 (or conductive pillar precursors) are formed layer by layer by 3D printing to obtain the set pillar height, diameter, and spacing; the 3D printing method can be jet printing, micro-extrusion printing, etc.; Figure 4 As shown.

[0053] The conductive pillar 4 has a structure consisting of three functional layers, each configured with a different metal-resin composite slurry. These functional layers are a bottom bonding layer 41, a middle support layer 42, and a top conductive layer 43. The bottom bonding layer is located at the end of the conductive pillar closest to the RDL (Reverse Column Layer), enhancing the bond between the conductive pillar and the RDL or seed layer. The middle support layer is located in the middle of the conductive pillar, providing shape retention and mechanical support during the printing process. The top conductive layer is located at the top of the conductive pillar, providing excellent conductivity and reliable contact with the upper interconnect structure. Furthermore, the 3D printing design is extremely flexible, enabling the creation of conductive pillars with complex shapes, including circular, triangular, square, hexagonal, or other irregularly shaped pillars.

[0054] Step 5: Moldulate the formed RDL and conductive pillar 4. The molding material can be epoxy molding compound (EMC). After molding and curing, a molded layer 5 covering the structure is formed; Figure 5 As shown.

[0055] Step 6: Grind the molding layer 5 to achieve the target thickness and expose the top of the conductive post 4; as shown Figure 6 As shown.

[0056] Step 7: Debond the release layer 2 and remove the temporary carrier plate 1. The debonding method can be thermal debonding, laser debonding, chemical debonding, etc. Figure 7 As shown.

[0057] Step 8: Divide the wafers according to requirements to form individual chips; for example... Figure 8 As shown.

[0058] In a preferred embodiment of the present invention, when the above-mentioned 3D printing is used to prepare a three-layer conductive column, a micro-extrusion 3D printing device is used to stack the three-layer conductive column layer by layer on the designated pads of the redistribution layer (RDL) structure. The overall height of the conductive column is 100 μm, wherein the bottom bonding layer accounts for 20% (i.e., 20 μm) of the total height, the middle support layer accounts for 60% (i.e., 60 μm) of the total height, and the top conductive layer accounts for 20% (i.e., 20 μm) of the total height.

[0059] The formulations of each layer of slurry are as follows:

[0060] (1) Bottom bonding layer: The metal powder is dendritic electrolytic copper powder (particle size D50 is 8μm), accounting for 65wt% by mass; the resin system is epoxy-phenolic resin, accounting for 35wt% by mass; the functional additives account for 5% of the total mass of the resin system, of which γ-aminopropyltrimethoxysilane (silane coupling agent) accounts for 2% of the mass of epoxy-phenolic resin, ethylenediamine (curing agent) accounts for 1.8% of the mass of epoxy-phenolic resin, 2-ethyl-4-methylimidazolium (accelerator) accounts for 0.6% of the mass of epoxy-phenolic resin, and polyethylene glycol (dispersant) accounts for 1.2% of the mass of epoxy-phenolic resin; the slurry viscosity is adjusted to 450Pa·s.

[0061] Preparation method: First, epoxy-phenolic resin is placed in a constant temperature stirring tank and stirred at 60℃ and 300 r / min. Then, γ-aminopropyltrimethoxysilane, ethylenediamine, 2-ethyl-4-methylimidazolium and polyethylene glycol are added in sequence, and stirring is continued to obtain a homogeneous resin system. Dendritic electrolytic copper powder is added to the resin system in 3 portions, and stirring and ultrasonic dispersion are performed after each addition to remove air bubbles in the slurry. Finally, an appropriate amount of anhydrous ethanol is added to adjust the viscosity to 450 Pa·s, and stirring is performed to obtain the bottom bonding layer slurry for later use.

[0062] (2) Middle support layer: The metal powder is spherical atomized copper powder (particle size D50 is 3μm), accounting for 88wt% by mass; the resin system is thermosetting epoxy resin, accounting for 12wt% by mass; the functional additives account for 6% of the total mass of the resin system, of which the amount of hydrophilic fumed silica (thixotropic agent) is 4% of the mass of thermosetting epoxy resin, the amount of 4,4-diaminodiphenylmethane (curing agent) is 1.5% of the mass of thermosetting epoxy resin, the amount of organosilicon defoamer is 0.3% of the mass of thermosetting epoxy resin, and the amount of polyether modified polysiloxane (leveling agent) is 0.6% of the mass of thermosetting epoxy resin; the slurry viscosity is adjusted to 250Pa·s.

[0063] Preparation method: First, the thermosetting epoxy resin is heated to 55℃ and stirred at 250 r / min until the system is homogeneous; then, hydrophilic fumed silica is added and stirred at 500 r / min to disperse the thixotropic agent evenly; then, 4,4-diaminodiphenylmethane, organosilicon defoamer and polyether-modified polysiloxane are added sequentially and stirred; spherical atomized copper powder is added in 4 portions, and after each addition, it is stirred and then ultrasonically dispersed to eliminate agglomeration and bubbles; finally, a small amount of acetone is added to adjust the viscosity to 250 Pa·s and stirred to obtain the middle support layer slurry for later use.

[0064] (3) Top conductive layer: The metal powder is a mixture of nano copper powder (particle size 80nm) and nano silver powder (particle size 40nm) in a mass ratio of 3:1, accounting for 97wt% of the total mass; the resin system is phenolic resin, accounting for 3wt% of the total mass; the functional additives account for 3% of the total mass of the resin system, of which hexamethylenetetramine (curing agent) accounts for 2.2% of the mass of phenolic resin, polyvinylpyrrolidone (anti-agglomeration agent) accounts for 0.6% of the mass of phenolic resin, and polyethylene glycol (surfactant) accounts for 0.5% of the mass of phenolic resin; the slurry viscosity is adjusted to 110Pa·s.

[0065] Preparation method: First, phenolic resin is dissolved in anhydrous ethanol at a controlled temperature of 45℃ and stirred at 200 r / min until completely dissolved. Then, hexamethylenetetramine, polyvinylpyrrolidone, and polyethylene glycol are added and stirred to obtain a resin additive solution. Nano copper powder and nano silver powder are mixed evenly at a mass ratio of 3:1 and added to the resin additive solution in two portions. After each addition, the mixture is first ultrasonically dispersed and then stirred to prevent the nano powder from agglomerating. Finally, an appropriate amount of anhydrous ethanol is added to adjust the viscosity to 110 Pa·s and stirred to obtain a top conductive layer slurry, which is prepared and used immediately.

[0066] The process also includes post-processing of the conductive pillars prepared above: the printed conductive pillars are sequentially cured, sintered and surface metallized; the curing conditions are 150℃ for 2 hours, the sintering conditions are 400℃ for 1 hour under nitrogen protection, and the surface metallization is chemical silver plating with a silver plating thickness of 50nm.

[0067] In a preferred embodiment of the present invention, when the above-mentioned 3D printing is used to prepare the three-layer conductive column, a jetting 3D printing device is used to stack the three-layer conductive column layer by layer on the designated pads of the redistribution layer structure. The overall height of the conductive column is 200μm, of which the bottom bonding layer accounts for 15% (i.e., 30μm) of the total height, the middle support layer accounts for 70% (i.e., 140μm) of the total height, and the top conductive layer accounts for 15% (i.e., 30μm) of the total height.

[0068] The formulations of each layer of slurry are as follows:

[0069] (1) Bottom bonding layer: The metal powder is dendritic electrolytic copper powder (particle size D50 is 5μm), accounting for 60wt% by mass; the resin system is epoxy-phenolic resin, accounting for 40wt% by mass; the functional additives account for 2% of the total mass of the resin system, of which γ-aminopropyltrimethoxysilane accounts for 1% of the mass of epoxy-phenolic resin, ethylenediamine accounts for 1% of the mass of epoxy-phenolic resin, 2-ethyl-4-methylimidazolium accounts for 0.1% of the mass of epoxy-phenolic resin, and polyethylene glycol accounts for 0.5% of the mass of epoxy-phenolic resin; the slurry viscosity is adjusted to 300Pa·s.

[0070] Preparation method: First, epoxy-phenolic resin is placed in a constant temperature stirring tank and stirred at 65℃ and 300 r / min. Then, γ-aminopropyltrimethoxysilane, ethylenediamine, 2-ethyl-4-methylimidazolium and polyethylene glycol are added in sequence and stirred to form a homogeneous resin system. Dendritic electrolytic copper powder is added in three portions, and after each addition, it is stirred and then ultrasonically dispersed. The viscosity is adjusted to 300 Pa·s with anhydrous ethanol and stirred to obtain the bottom binding layer slurry for later use.

[0071] (2) Middle support layer: The metal powder is spherical atomized copper powder (particle size D50 is 2μm), accounting for 85wt% by mass; the resin system is thermosetting epoxy resin, accounting for 15wt% by mass; the functional additives account for 3% of the total mass of the resin system, of which the amount of hydrophilic fumed silica is 2% of the mass of thermosetting epoxy resin, the amount of 4,4-diaminodiphenylmethane is 1% of the mass of thermosetting epoxy resin, the amount of organosilicon defoamer is 0.1% of the mass of thermosetting epoxy resin, and the amount of polyether modified polysiloxane is 0.3% of the mass of thermosetting epoxy resin; the slurry viscosity is adjusted to 100Pa·s.

[0072] Preparation method: First, the thermosetting epoxy resin is heated to 50℃ and stirred at 250 r / min until the system is homogeneous; then, hydrophilic fumed silica is added and stirred at a high speed of 500 r / min to disperse the thixotropic agent evenly. Then, 4,4-diaminodiphenylmethane, organosilicon defoamer and polyether-modified polysiloxane are added in sequence and stirred; then, spherical atomized copper powder is added in 4 portions, and after each addition, it is stirred and ultrasonically dispersed; finally, the viscosity is adjusted to 100 Pa·s with acetone and stirred to obtain the middle support layer slurry for later use.

[0073] (3) Top conductive layer: The metal powder is a mixture of nano copper powder (particle size 50nm) and nano silver powder (particle size 30nm) in a mass ratio of 3:1, accounting for 96wt% of the total mass; the resin system is phenolic resin, accounting for 4wt% of the total mass; the functional additives account for 1% of the total mass of the resin system, of which hexamethylenetetramine accounts for 1.5% of the mass of phenolic resin, polyvinylpyrrolidone accounts for 0.5% of the mass of phenolic resin, and polyethylene glycol accounts for 0.2% of the mass of phenolic resin; the slurry viscosity is adjusted to 80Pa·s.

[0074] Preparation method: First, phenolic resin is dissolved in anhydrous ethanol and stirred at 45℃ and 200 r / min until dissolved; then hexamethylenetetramine, polyvinylpyrrolidone, and polyethylene glycol are added and stirred continuously; nano copper powder and nano silver powder are mixed at a mass ratio of 3:1 and added in two portions, with ultrasonic dispersion and stirring after each addition; finally, the viscosity is adjusted to 80 Pa·s with anhydrous ethanol and stirred to obtain the top conductive layer slurry, which is prepared and used immediately.

[0075] It also includes post-processing of the conductive columns: the printed conductive columns are sequentially cured, sintered and surface metallized; the curing conditions are 140℃ for 3 hours, the sintering conditions are 380℃ for 1.5 hours under argon protection, and the surface metallization treatment uses chemical nickel plating with a nickel plating thickness of 60nm.

[0076] In some specific preferred embodiments of the present invention, when the above-mentioned 3D printing is used to prepare the three-layer conductive column: a micro-extrusion 3D printing device is used to stack the three-layer conductive column layer by layer on the designated pads of the redistribution layer structure. The overall height of the conductive column is 300μm, of which the bottom bonding layer accounts for 25% (i.e. 75μm) of the total height, the middle support layer accounts for 50% (i.e. 150μm) of the total height, and the top conductive layer accounts for 25% (i.e. 75μm) of the total height.

[0077] The formulations of each layer of slurry are as follows:

[0078] (1) Bottom bonding layer: The metal powder is dendritic electrolytic copper powder (particle size D50 is 10μm), accounting for 70wt% by mass; the resin system is epoxy-phenolic resin, accounting for 30wt% by mass; the functional additives account for 8% of the total mass of the resin system, of which γ-aminopropyltrimethoxysilane accounts for 3% of the mass of epoxy-phenolic resin, ethylenediamine accounts for 2.5% of the mass of epoxy-phenolic resin, 2-ethyl-4-methylimidazolium accounts for 1% of the mass of epoxy-phenolic resin, and polyethylene glycol accounts for 2% of the mass of epoxy-phenolic resin; the slurry viscosity is adjusted to 600Pa·s.

[0079] Preparation method: First, epoxy-phenolic resin is stirred at 60℃ and 300r / min until melted; γ-aminopropyltrimethoxysilane, ethylenediamine, 2-ethyl-4-methylimidazolium and polyethylene glycol are added in sequence and stirred to form a uniform resin system; then dendritic electrolytic copper powder is added in 3 portions, and stirred and ultrasonically dispersed after each addition; the viscosity is adjusted to 600Pa·s and stirred to obtain the bottom binding layer slurry for later use.

[0080] (2) Middle support layer: The metal powder is spherical atomized copper powder (particle size D50 is 5μm), accounting for 90wt% of the mass; the resin system is thermosetting epoxy resin, accounting for 10wt% of the mass; the functional additives account for 10% of the total mass of the resin system, of which the amount of hydrophilic fumed silica is 6% of the mass of thermosetting epoxy resin, the amount of 4,4-diaminodiphenylmethane is 3% of the mass of thermosetting epoxy resin, the amount of organosilicon defoamer is 0.5% of the mass of thermosetting epoxy resin, and the amount of polyether modified polysiloxane is 1% of the mass of thermosetting epoxy resin; the slurry viscosity is adjusted to 400Pa·s.

[0081] Preparation method: First, the thermosetting epoxy resin is stirred at 55℃ and 250r / min. Then, hydrophilic fumed silica is added and stirred at 500r / min. Next, 4,4-diaminodiphenylmethane, organosilicon defoamer, and polyether-modified polysiloxane are added in sequence and stirred. Then, spherical atomized copper powder is added in 4 portions, and stirred and ultrasonically dispersed after each addition. The viscosity is adjusted to 400Pa·s with an appropriate amount of acetone and stirred to obtain the middle support layer slurry for later use.

[0082] (3) Top conductive layer: The metal powder is a mixture of nano copper powder (particle size 100nm) and nano silver powder (particle size 50nm) in a mass ratio of 3:1, accounting for 98wt% of the total mass; the resin system is phenolic resin, accounting for 2wt% of the total mass; the functional additives account for 5% of the total mass of the resin system, of which hexamethylenetetramine accounts for 3% of the mass of phenolic resin, polyvinylpyrrolidone accounts for 1% of the mass of phenolic resin, and polyethylene glycol accounts for 0.8% of the mass of phenolic resin; the slurry viscosity is adjusted to 150Pa·s.

[0083] Preparation method: First, phenolic resin is dissolved in anhydrous ethanol and stirred at 45℃ and 200 r / min until the resin is dissolved; then hexamethylenetetramine, polyvinylpyrrolidone, and polyethylene glycol are added and stirred; then nano copper powder and nano silver powder are mixed at a ratio of 3:1 and added in two portions, ultrasonically dispersed and stirred after each addition; the viscosity is adjusted to 150 Pa·s with anhydrous ethanol and stirred to obtain the top conductive layer slurry, which is prepared and used immediately.

[0084] It also includes post-processing of the conductive pillars: the printed conductive pillars are sequentially cured, sintered and surface metallized; the curing conditions are 160℃ for 1.5h, the sintering conditions are 420℃ under nitrogen + argon mixed gas protection for 0.8h, and the surface metallization treatment uses chemical silver plating with a silver plating thickness of 40nm.

[0085] In summary, this invention innovatively proposes a three-layer conductive pillar design with a progressively decreasing resin content and a progressively increasing metal content. Simultaneously, it optimizes the rheological properties and composition of each layer of slurry. Specifically, the bottom bonding layer uses a higher resin content (30wt%~40wt%) and dendritic electrolytic copper powder, significantly improving the bonding strength with the redistribution layer pads and preventing pillar detachment and delamination during subsequent molding and grinding processes. The middle support layer optimizes rheological properties (viscosity 100Pa·s~400Pa·s) and uses spherical atomized copper powder with a high metal content (85wt%~90wt%), ensuring forming accuracy during the 3D printing process. This design provides stable structural support for the entire pillar, resisting molding pressure and grinding stress. The top conductive layer uses a nano-copper-silver mixed powder with an extremely high metal content (96wt%~98wt%), significantly reducing volume resistivity and improving the electrical transmission efficiency of the chip, meeting the needs of high-density interconnection. This forms an integrated functional system of "bonding-supporting-conductivity," which significantly improves bonding strength, conductivity, and structural stability compared to existing single-structure or double-layer conductive pillars. Moreover, the bonding strength between the conductive pillar and the redistribution layer prepared by this invention can reach 12~18MPa, and the volume resistivity is as low as 1.8×10⁻⁶. -8 Ω·m can effectively improve the lifespan and operational stability of TMV chips.

[0086] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A method for fabricating a TMV chip based on 3D printing, characterized in that, include: Provide a redistribution layer structure; On the designated pads or connection areas of the redistribution layer structure, a three-layer conductive pillar is formed by 3D printing and stacking layer by layer. The conductive column comprises, along its axial direction, a bottom bonding layer, a middle support layer, and a top conductive layer; the 3D printing slurry is a metal powder resin-based composite slurry; in the bottom bonding layer, the middle support layer, and the top conductive layer, the mass percentage of the resin system decreases layer by layer upwards, while the mass percentage of the metal powder increases layer by layer upwards; the rheological properties of the metal powder resin-based composite slurry in the middle support layer are superior to those of the bottom bonding layer and the top conductive layer; Post-processing is performed on the conductive column; The redistribution layer structure is molded together with the conductive pillar to form a molding layer; Grind the molding layer to expose the top of the conductive post.

2. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, In the bottom bonding layer, the metal powder accounts for 60wt% to 70wt% by mass, and the resin system accounts for 30wt% to 40wt% by mass. In the central support layer, the metal powder accounts for 85wt% to 90wt% by mass; the resin system accounts for 10wt% to 15wt% by mass. In the top conductive layer, the metal powder accounts for 96wt% to 98wt% by mass; the resin system accounts for 2wt% to 4wt% by mass.

3. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, In the bottom bonding layer, the viscosity of the metal powder resin-based composite slurry is 300 Pa·s to 600 Pa·s; in the middle support layer, the viscosity of the metal powder resin-based composite slurry is 100 Pa·s to 400 Pa·s; and in the top conductive layer, the viscosity of the metal powder resin-based composite slurry is 80 Pa·s to 150 Pa·s.

4. The method for fabricating a TMV chip based on 3D printing as described in claim 2, characterized in that, In the bottom bonding layer, the metal powder is dendritic electrolytic copper powder with a particle size D50 of 5μm~10μm; the resin system includes epoxy-phenolic resin and functional additives; the functional additives account for 2%~8% of the total mass of the resin system, including silane coupling agents, curing agents, accelerators, and dispersants; the silane coupling agent is γ-aminopropyltrimethoxysilane, and the amount used is 1%~3% of the mass of epoxy-phenolic resin; the curing agent is ethylenediamine, and the amount used is 1%~2.5% of the mass of epoxy-phenolic resin; the accelerator is 2-ethyl-4-methylimidazole, and the amount used is 0.1%~1% of the mass of epoxy-phenolic resin; the dispersant is polyethylene glycol, and the amount used is 0.5%~2% of the mass of epoxy-phenolic resin. In the central support layer, the metal powder is spherical atomized copper powder with a particle size D50 of 2μm~5μm; the resin system includes thermosetting epoxy resin and functional additives; the functional additives account for 3%~10% of the total mass of the resin system, including fumed silica thixotropic agent, curing agent, defoamer, and leveling agent; the fumed silica thixotropic agent is selected as hydrophilic fumed silica, and its dosage is 2%~6% of the mass of thermosetting epoxy resin; the curing agent is selected as 4,4-diaminodiphenylmethane, and its dosage is 1%~3% of the mass of thermosetting epoxy resin; the defoamer is selected as an organosilicon defoamer, and its dosage is 0.1%~0.5% of the mass of thermosetting epoxy resin; the leveling agent is selected as polyether-modified polysiloxane, and its dosage is 0.3%~1% of the mass of thermosetting epoxy resin. In the top conductive layer, the metal powder is a mixture of nano-copper powder and nano-silver powder in a mass ratio of 3:1; the nano-copper powder has a particle size of 50nm~100nm, and the nano-silver powder has a particle size of 30nm~50nm; the resin system includes phenolic resin and functional additives; the functional additives account for 1%~5% of the total mass of the resin system, including curing agent, anti-agglomeration agent and surfactant; the curing agent is hexamethylenetetramine, and the amount used is 1.5%~3% of the mass of phenolic resin; the anti-agglomeration agent is polyvinylpyrrolidone, and the amount used is 0.5%~1% of the mass of phenolic resin; the surfactant is polyethylene glycol, and the amount used is 0.2%~0.8% of the mass of phenolic resin.

5. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, The overall height of the conductive column is 50μm to 300μm; wherein the height of the bottom bonding layer accounts for 10% to 25% of the total height; the height of the middle support layer accounts for 50% to 70% of the total height; and the height of the top conductive layer accounts for 15% to 30% of the total height.

6. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, Before forming the redistribution layer structure, the method further includes: Provide temporary carrier board; A peeling layer is formed on the surface of the temporary carrier plate. A rewiring layer structure is formed on the surface of the stripping layer; The formation process of the redistribution layer structure includes: A dielectric layer is formed on the peeling layer and patterned openings are formed thereon; Deposit a seed layer, and form RDL lines and pads through photolithography, metal deposition or electroplating; The photoresist is removed and the exposed seed layer is etched to form an RDL structure.

7. The method for fabricating a TMV chip based on 3D printing as described in claim 6, characterized in that, After grinding the molding layer to expose the top of the conductive post, the process further includes: The release layer is debonded to remove the temporary carrier plate; The chips are diced according to demand to form individual chips.

8. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, The 3D printing is either jet printing or micro-extrusion printing; The post-processing of the conductive column includes, in sequence, curing, sintering and surface metallization.

9. The method for fabricating a TMV chip based on 3D printing as described in claim 1, characterized in that, The conductive column is solidified or sintered to form an integrated metal column with a cross-section that is circular, square, triangular or hexagonal.

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