A leveler for glass-based deep blind via re-manufacturing filling electroplating

Abstract

The application provides a kind of flattening agent for glass-based deep blind hole remanufacturing filling electroplating.The flattening agent is a kind of polymer with pyrrolopyrazine structural unit.The application applies the flattening agent to the remanufacturing filling electroplating process, and carries out surface repair and re-metallization on the failed glass-based deep blind hole.The acidic copper electroplating composition containing the flattening agent can effectively inhibit the excessive deposition of hole copper when repairing high aspect ratio glass-based deep blind hole, avoid the generation of " pinch-off " and secondary cavity in the repair layer, and realize the dense filling from bottom to top.Experiments prove that after using the electroplating solution of the application to remanufacture and fill the failed TGV, there is no gap in a wide current density range, the amount of depression after repair is very small, the electrical interconnection performance of TGV is restored, and the reliability and service life of the substrate after remanufacturing are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of copper electroplating technology, and more specifically, to a leveling agent for filler electroplating in the remanufacturing of deep blind vias on glass substrates. Background Technology

[0002] With the rapid development of fifth-generation mobile communication technology (5G), millimeter-wave radar, advanced sensors, and 3D integration, glass substrates have become a core material for next-generation high-performance packaging due to their excellent high-frequency electrical performance, high dimensional stability, and adjustable coefficient of thermal expansion. TGV (Through Glass Vias) is a key structure for realizing electrical interconnection on glass substrates.

[0003] However, in actual service, TGVs face severe reliability challenges: thermal cycling-induced copper-glass interface stress can cause the copper layer to crack or peel off; electromigration under high current density can create voids within the vias; and long-term humid and hot environments may induce electrochemical corrosion. These failure modes lead to increased resistance, deterioration of signal integrity, and even complete open circuits in the TGV, ultimately rendering the entire packaging substrate unusable.

[0004] The traditional approach is to directly discard the failed substrate, resulting in significant resource waste and increased costs. Therefore, developing remanufacturing and surface repair technologies for TGV (Through Silicon Vias) has important economic and environmental significance. The core of remanufacturing lies in removing the failed copper filler layer (or repairing only local defects) and then re-metallizing it. However, existing copper plating solutions—whether for PCB through-hole (PTH) or through-silicon via (TSV)—are not optimized for remanufacturing scenarios. When used directly for repair, factors such as residues inside the hole, uneven seed layer, and hole wall damage often lead to low filling efficiency, numerous voids in the repair layer, and severe hole protrusion, making it difficult to restore the original electrical performance.

[0005] Therefore, developing a leveling agent specifically for electroplating filling in the remanufacturing of deep blind holes in glass substrates to achieve high-quality surface repair of failed TGVs is a pressing technical challenge. An ideal leveling agent for repair must be able to achieve uniform adsorption and desorption on the defective hole walls, inhibit premature closure of the hole openings during the repair process, and ensure seamless bottom-up filling. Summary of the Invention

[0006] This invention provides a copper plating leveling agent for filling deep blind holes in glass substrates, to solve the problems of voids, large depressions, and poor filling effect that are easily generated during TGV electroplating copper filling in the prior art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a polymer having pyrrolopyrazine structural units, said polymer having the molecular structure shown in formula (1): (1) Where n is an integer greater than or equal to 2.

[0008] Preferably, the polymer is prepared by reacting diglycidyl ether with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine; the diglycidyl ether has the structure shown in formula (12): (12) Wherein, R is selected from an organic group with 2-20 carbon atoms, more preferably an alkyl group with 2-10 carbon atoms; most preferably, the diglycidyl ether is selected from one or more of butanediol diglycidyl ether, dipropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, pentylene glycol diglycidyl ether, 1,4-cyclohexanediethanol diglycidyl ether, 1,2-cyclohexanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentylene glycol diglycidyl ether, and resorcinol diglycidyl ether.

[0009] In a second aspect, the present invention provides a copper electroplating solution comprising a copper ion source, an electrolyte, an accelerator, an inhibitor, and a leveling agent, wherein the leveling agent is a polymer having pyrrolopyrazine structural units as described in the first aspect.

[0010] As a preferred embodiment, the copper ion source is selected from one or more of copper sulfate, copper chloride, copper nitrate, copper aminosulfonate, and copper methanesulfonate, preferably copper sulfate and / or copper methanesulfonate; the copper ion content in the copper electroplating solution is 40-70 g / L, preferably 50-60 g / L.

[0011] As a preferred embodiment, the electrolyte is an acidic electrolyte selected from one or more of sulfuric acid, acetic acid, and methanesulfonic acid, preferably sulfuric acid; the acid content in the copper electroplating solution is 5-20 g / L, preferably 8-12 g / L.

[0012] As a preferred embodiment, the electrolyte further includes a halide ion source, preferably a chloride ion source, more preferably copper chloride or hydrochloric acid; the concentration of halide ions in the copper electroplating solution is 20-120 ppm, preferably 40-100 ppm, more preferably 60-80 ppm.

[0013] As a preferred embodiment, the accelerator is a compound containing a sulfide or sulfonic acid group, preferably one or more of the compounds shown in formulas (2) to (5): (2) (3) (4) (5) Wherein, M is selected from hydrogen atoms and alkali metals, a is selected from integers from 1 to 8, and b and c are independently selected from 0 or 1 respectively; more preferably, the accelerator is sodium polydisulfide dipropane sulfonate and / or sodium 3-mercapto-1-propane sulfonate; the content of the accelerator in the electroplating solution is 0.5-100 ppm, preferably 0.5-10 ppm, more preferably 1-4 ppm.

[0014] As a preferred embodiment, the inhibitor is selected from one or more compounds represented by formulas (6) to (11): (6) (7) (8) (9) (10) (11) In Equations (6) and (7), a is an integer from 10 to 500; in Equations (8) and (9), a, b, and c are each independently selected from integers from 10 to 100; in Equation (10), a and b are each independently selected from integers from 10 to 100; in Equation (11), n ​​is an integer from 10 to 500; the content of the inhibitor in the electroplating solution is 50-1500 ppm, preferably 200-800 ppm.

[0015] As a preferred embodiment, the polymer having formula (1) is prepared by the following method: diglycidyl ether is mixed with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine, heated to 70-80°C under stirring, kept at the temperature for 4-6 hours, then cooled to room temperature, diluted with water, and the pH is adjusted to 6.5-7.5 with sulfuric acid to obtain the polymer.

[0016] Thirdly, the present invention provides a remanufacturing filling electroplating method for repairing failed glass-based deep blind holes, comprising the step of immersing a glass-based deep blind hole substrate having a failed copper filling layer into the copper electroplating solution described in the second aspect for electroplating.

[0017] As a preferred embodiment, the electroplating conditions are: current density of 0.05-1.0 A / dm², preferably 0.2-0.4 A / dm²; and electroplating solution temperature of 18-35℃, preferably 23-25℃.

[0018] As a preferred embodiment, the glass substrate has a deep blind hole with a depth of 250 µm and a diameter of 45 µm.

[0019] In summary, this application has the following beneficial effects: 1. This invention provides a novel polymer leveling agent with pyrrolopyrazine structural units. When applied to the electroplating repair of failed glass-based deep blind holes, it can effectively fill defects such as voids and cracks in the holes and restore the electrical continuity of the through holes. 2. The acidic electroplating copper composition containing the leveling agent of the present invention can effectively inhibit the excessive deposition of the repair layer at the orifice during remanufacturing filler electroplating, avoid the generation of "pinch-off" and secondary voids, and at the same time does not hinder the transfer of copper ions to the bottom of the hole, thus achieving a perfect repair and filling mode from bottom to top. 3. Experimental results show that the TGV deep blind vias repaired using the electroplating solution of this invention have no voids within a wide current density range (0.2-0.8 A / dm²), and the surface depression is extremely small (-8 µm to 5 µm), which is far superior to the comparative example using traditional leveling agents (such as Jenners Green) (depression of 45 µm and voids). The resistivity, thermal cycling resistance, and electromigration lifetime of the repaired vias are restored to near-new product levels, significantly improving the reliability and service life of the remanufactured substrate and reducing the generation of electronic waste. Attached Figure Description

[0020] Figure 1 This is a synthetic route diagram of polymer P1 in Example 1 of the present invention; Figure 2 Schematic diagram for filling voids in deep blind holes; Figure 3 A schematic diagram for measuring the filling depth of deep blind holes. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are only intended to help those skilled in the art understand the present invention and are not intended to limit the invention in any way. Any improvements and modifications made without departing from the concept of the present invention should fall within the protection scope of the present invention.

[0022] Example 1: Preparation of leveling agent polymer P1 This embodiment provides a polymer P1 having pyrrolopyrazine structural units, the structural formula of which is as follows: n is an integer greater than or equal to 2.

[0023] See the synthesis route. Figure 1 The specific preparation steps are as follows: Water (50 mL) was added to the reaction flask, followed by butanediol diglycidyl ether (10.11 g, 50 mmol) and 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine (6.06 g, 50 mmol). Stirring was started, and the mixture was heated to 75 °C and stirred at this temperature for 5 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature to obtain the target product P1.

[0024] Product characterization: ¹H NMR (400 MHz, ), δ 8.33 (d, 2H), 5.03 (s, 2H), 4.50 (s, 4H), 3.50–3.20 (m, 14H), 1.50 (t, 4H). Elemental analysis calculated values. : C59.24, H 8.08, N 12.95; Measured value: C 59.21, H 8.01, N 12.92.

[0025] Dilute the target product P1 with pure water (1500 mL) and add sulfuric acid to adjust the pH of the solution to 6.5-7.5 to obtain the leveling agent solution for later use.

[0026] Example 2: Preparation of other leveling polymers P2-P5 Following the synthesis steps of Example 1, polymers P2 to P5 were prepared by reacting different diglycidyl ether raw materials with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine. Their structural formulas and the maximum absorption wavelengths (λ_max) of their UV absorption spectra (measured in aqueous solution) are shown in Table 1.

[0027] Table 1. Structure and characterization of polymers P2-P5

[0028] Example 2A: Preparation of leveling agent polymer P6 (using diglycidyl ethers of different molecular weights) This embodiment provides another polymer P6 having pyrrolopyrazine structural units, the structural formula of which is shown below (a polymer generated by reacting polypropylene glycol diglycidyl ether with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine, wherein the molecular weight of the polypropylene glycol segment is approximately 400, i.e., the degree of polymerization is approximately 7): The specific preparation steps are the same as in Example 1, except that the raw material "butanediol diglycidyl ether" is replaced with an equimolar amount (based on epoxy groups) of "polypropylene glycol diglycidyl ether" (brand name DGE-400, average molecular weight approximately 400, epoxy value approximately 0.31 mol / 100g). The reaction conditions remain unchanged. The product, as determined by GPC, has a weight-average molecular weight (Mw) of approximately 8500 and a distribution index (PDI) of 1.8.

[0029] Example 2B: Preparation of leveling agent polymer P7 (using diglycidyl ether containing an aromatic ring structure) This embodiment provides another polymer P7 having pyrrolopyrazine structural units, the structural formula of which is shown below (a polymer generated by reacting resorcinol diglycidyl ether with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine): The specific preparation steps are the same as in Example 1, except that the raw material "butanediol diglycidyl ether" is replaced with an equimolar amount (based on the epoxy group) of "resorcinol diglycidyl ether". Because the aromatic ring structure has slightly higher reactivity, the reaction temperature can be adjusted to 70°C and maintained at that temperature for 4 hours. Elemental analysis and infrared spectroscopy (IR) confirmed the introduction of the aromatic ring structure in the product.

[0030] Example 3: Copper plating solution containing leveling agent P1 (standard formulation) A copper plating solution was prepared by mixing the following components: Copper source: Copper sulfate pentahydrate, concentration of 240 g / L (providing a copper ion concentration of approximately 60 g / L); Electrolyte: Sulfuric acid, concentration 10 g / L; Halogen ions: Chloride ions (from hydrochloric acid or copper chloride), concentration 60 ppm; Accelerator: Sodium polydisulfide dipropane sulfonate (SPS), concentration 1 ppm; Inhibitor: Polyethylene glycol 20000 (PEG 20000), concentration 400 ppm; Leveling agent: The reaction product (P1 solution) prepared in Example 1 was added at a rate of 5 mL / L.

[0031] Example 3A (Effect of different leveling agent concentrations) Referring to the basic formulation of Example 3, only the amount of leveling agent P1 prepared in Example 1 was changed to prepare the following electroplating solutions: Example 3A-1: The amount of P1 added was 1 mL / L.

[0032] Example 3A-2: The amount of P1 added was 3 mL / L.

[0033] Example 3A-3: The amount of P1 added was 8 mL / L.

[0034] Example 3A-4: P1 addition amount is 10 mL / L.

[0035] Example 3B (Different combinations of accelerators and inhibitors) Referring to the basic formulation of Example 3, the types and concentrations of accelerators and inhibitors were adjusted: Example 3B-1: The accelerator was sodium 3-mercapto-1-propanesulfonate (MPS) at a concentration of 2 ppm; the inhibitor was polyethylene glycol 10000 (PEG 10000) at a concentration of 600 ppm; the leveling agent was P1 at an addition amount of 5 mL / L. Other components remained unchanged.

[0036] Example 3B-2: The accelerator was a mixture of sodium polydithiopropane sulfonate (SPS, 1 ppm) and MPS (1 ppm); the inhibitor was an ethylene oxide-propylene oxide block copolymer (EO / PO copolymer, average molecular weight about 8000, a=60, b=30) as shown in formula (8), at a concentration of 500 ppm; the leveling agent was P2, added at 5 mL / L. Other components remained unchanged.

[0037] Example 4: Copper plating solution containing other leveling agents Referring to the formulation and preparation method of Example 3, the only difference is that the leveling agent is replaced with the P2, P3, P4 and P5 solutions prepared in Example 2, and the addition amount is 5 mL / L, respectively, to obtain the corresponding copper electroplating solutions.

[0038] Example 5 (Comparative Example) Comparative Example 1 (blank control, without leveling agent) The copper plating solution was prepared according to Example 3, but without any leveling agent. Specifically: 240 g / L copper sulfate pentahydrate, 10 g / L sulfuric acid, 60 ppm chloride ions, 1 ppm SPS, and 400 ppm PEG 20000.

[0039] Comparative Example 2 (using a polymer leveling agent not of this invention) A copper plating solution was prepared according to Example 3, but the leveling agent was replaced with polyethyleneimine (PEI, molecular weight 2000) at an addition amount of 5 ppm.

[0040] Comparative Example 3 (using monomer polymers instead of polymers) Copper plating solution was prepared according to Example 3, but the leveling agent was replaced with an unpolymerized starting material mixture: 2.5 mM butanediol diglycidyl ether + 2.5 mM 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine (equivalent to the monomer unit concentration of the product of Example 1).

[0041] Comparative Example 4 (Jenners Green) A copper plating solution was prepared according to Example 3, but the leveling agent was replaced with 5 ppm Janus Green B.

[0042] Example 6: TGV Deep Blind Hole Plating Filling Performance Test (Standard Conditions) Electroplating filling tests were performed on TGV glass substrates with deep blind vias using each of the plating solutions prepared in Examples 3, 4, 3A-1 to 3A-4, 3B-1 to 3B-2, and Comparative Examples 1-4. The deep blind via specifications were: depth 250 µm, diameter 45 µm (aspect ratio approximately 5.6:1).

[0043] Electroplating is carried out in a Haring bath under the following process conditions: Current density: 0.5 A / dm² Electroplating time: 150 minutes Plating bath temperature: 24℃ After electroplating is completed, the filling effect is evaluated. See the evaluation criteria below. Figure 2 (Gap) and Figure 3 (Dent Amount). A positive dent amount indicates that the copper layer protrudes from the hole opening, while a negative value indicates that the copper layer is below the hole opening. The smaller the absolute value, the smoother the filling. Each data point was tested three times, and the average value was taken. The specific results are shown in Table 2.

[0044] Table 2. Effects of different leveling agents and dosages on the filling effect of TGV deep blind holes (standard conditions)

[0045] Example 7: Comparative Test of Filling Performance under Different Current Densities To verify the stability of the leveling agent of the present invention within a wider process window, Example 3 (P1, 5 mL / L) and Comparative Example 4 (Janners Green, 5 ppm) were selected and fill tests were conducted at different current densities (other conditions were the same as the standard conditions of Example 6). The results are shown in Table 3.

[0046] Table 3: Comparison of filling performance under different current densities

[0047] Results analysis: Concentration dependence of leveling agent: As can be seen from Examples 3 and 3A-1 to 3A-4 in Table 2, the leveling agent P1 of the present invention can achieve void-free filling within a wide addition range of 1-10 mL / L. The depression amount transitions smoothly from positive (protrusion) to negative (depression), indicating that its inhibition ability increases with increasing concentration. The optimal addition window is 3-8 mL / L, at which point the absolute value of the depression is the smallest (≤ 2.8 µm).

[0048] Formulation versatility: Examples 3B-1 and 3B-2 show that when the accelerator (such as MPS) and inhibitor (such as EO / PO copolymer) are changed, the same excellent filling effect (depression < 2 µm) can be obtained when combined with the leveling agents (P1, P2) of the present invention, demonstrating the compatibility of the leveling agents of the present invention with conventional electroplating additives.

[0049] Significant differences in proportions: Comparative Example 1 (without leveling agent): The filling failed completely, resulting in severe voids, proving that the leveling agent is a necessary component in TGV filling.

[0050] Comparative Example 2 (PEI): Another commonly used polymer leveling agent still showed voids, and the amount of depression (22 µm) was much greater than that in the embodiments of the present invention, indicating that the polymer with the specific structure of the present invention has unexpected advantages.

[0051] Comparative Example 3 (monomer mixture): Unpolymerized monomers could not provide effective leveling, proving that the macromolecular structure formed by polymerization is key to achieving excellent performance. This aligns with the electrochemical principle that leveling agents require long chains and multi-site adsorption.

[0052] Comparative Example 4 (Jenners Green): A traditional small-molecule leveling agent, exhibiting voids and significant depressions even under standard conditions. Its performance deteriorates drastically under high current (0.8 A / dm²).

[0053] Process window advantage: The results in Table 3 are crucial. The leveling agent (P1) of this invention achieves void-free filling across a wide current density range of 0.2–0.8 A / dm², with a gradual change in indentation (-4.2 µm to 2.0 µm). In contrast, Jenners Green can only barely fill at extremely low currents (0.2 A / dm²) (with indentations still as high as 15 µm), and its performance deteriorates rapidly with increasing current. This demonstrates that the leveling agent of this invention has superior mass transfer characteristics and adsorption / desorption kinetics, can adapt to current fluctuations that may occur in industrial production, and possesses greater practical application value.

[0054] In summary, the copper plating composition for filling through-holes in glass substrates involved in this invention is characterized by containing a polymer with pyrrolopyrazine structural units as a leveling agent, exhibiting excellent TGV deep blind via filling electroplating effect. The technical solution of this invention represents a significant technological advancement and has industrial applicability.

[0055] It should be noted that the embodiments described above are only for explaining this application and do not constitute any limitation on this application. This application has been described with reference to typical embodiments, but it should be understood that the terms used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to this application within the scope of the claims, and amendments can be made without departing from the scope and spirit of this application. Although the application described herein relates to specific raw materials, processes, and embodiments, it does not mean that this application is limited to the specific examples disclosed herein; on the contrary, this application can be extended to all other raw materials and applications with the same function.

Claims

1. A copper plating leveling agent for filling deep blind holes in glass substrates, characterized in that, The leveling agent is a polymer having pyrrolopyrazine structural units, and the polymer has the following molecular structure: Where n is an integer greater than or equal to 2; The polymer was prepared by reacting diglycidyl ether with 6,7-dihydro-5H-pyrrolo[3,4-B]pyrazine; the diglycidyl ether has the following structure: R is selected from organic groups with 2 to 20 carbon atoms.

2. A copper electroplating solution, characterized in that, It comprises a copper ion source, an electrolyte, an accelerator, an inhibitor, and the copper plating leveling agent for filling deep blind holes in glass substrates as described in claim 1.

3. The copper electroplating solution according to claim 2, characterized in that, The copper ion source is selected from one or more of copper sulfate, copper chloride, copper nitrate, copper aminosulfonate, and copper methanesulfonate, and the copper ion content in the copper electroplating solution is 40-70 g / L; the electrolyte is an acidic electrolyte, selected from one or more of sulfuric acid, acetic acid, and methanesulfonic acid, and the acid content in the copper electroplating solution is 5-20 g / L; the electrolyte also includes chloride ions, with a concentration of 20-120 ppm.

4. The copper electroplating solution according to claim 2, characterized in that, The accelerator is a compound containing a sulfide or sulfonic acid group, selected from one or more compounds listed below: ； Wherein, M is selected from hydrogen atoms and alkali metals, a is selected from integers from 1 to 8, and b and c are independently selected from 0 or 1 respectively; the content of the accelerator in the electroplating solution is 0.5-100 ppm.

5. The copper electroplating solution according to claim 2, characterized in that, The inhibitor is selected from one or more of the following compounds: , where a is an integer between 10 and 500; , where a is an integer between 10 and 500; , where a, b, and c are each independently selected from integers between 10 and 100; , where a, b, and c are each independently selected from integers between 10 and 100; , where a and b are independently selected from integers between 10 and 100; , where n is an integer selected from 10 to 500.

6. A remanufacturing filling electroplating method for repairing deep blind holes in failed glass substrates, characterized in that, The method includes immersing a glass substrate with a failed copper filler layer in the copper plating solution according to any one of claims 2 to 5 for electroplating; the electroplating conditions are: current density 0.05-1.0 A / dm², and plating solution temperature 18-35°C.

7. The method according to claim 6, characterized in that, The glass substrate has a deep blind hole with a depth of 250 µm and a diameter of 45 µm.

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