A method for manufacturing a local electroplated via filled HDI board

Abstract

The application relates to the field of HDI plate electroplating processing technology and discloses a local electroplating hole-filling HDI plate manufacturing method, which comprises the following steps: conducting conductive gradient adjustment treatment on an HDI plate to make the conductive property of a hole bottom area higher than that of a hole opening area; configuring an electroplating solution containing reversible complexing agent A and potential response release component B; adopting an asymmetric pulse current including a forward deposition stage, a reverse pulse stage and a low-current maintenance stage to conduct electroplating deposition; applying process disturbance to conduct mass transfer regulation during the electroplating process; and conducting termination homogenization deposition treatment when hole filling is close to completion. Through stage-by-stage activation treatment on a hole wall before electroplating, the conductive layer formation rate of the hole bottom area is higher than that of the hole opening area, so that a conductive property distribution state with the hole bottom preferentially conducting is formed in the initial stage of electroplating, current over-concentration in the hole opening area is avoided, and balanced electroplating deposition in the hole depth direction is ensured.

Description

Technical Field

[0001] This invention relates to the field of HDI board electroplating technology, specifically to a method for manufacturing HDI boards with partial electroplating to fill holes. Background Technology

[0002] As high-density interconnect (HDI) printed circuit boards develop towards higher integration, smaller via diameters, and higher layer counts, micro-blind via filling electroplating technology has been widely applied in HDI board manufacturing. Existing HDI boards typically achieve electrical connections between different circuit layers by forming micro-blind vias in the insulating layer and depositing copper layers inside the vias using electroplating.

[0003] Currently, common HDI board via-filling electroplating processes typically employ an acidic copper sulfate system, combined with inhibitors, accelerators, and leveling agents to regulate the deposition process. In the specific process, the HDI board via walls are first degreased, micro-etched, and activated to form a conductive layer on the via surface. Then, direct current or pulsed current is used for electroplating deposition, allowing the copper layer to gradually form a filling structure within the via. During this process, because the via opening is closer to the main electric field region, it usually experiences a higher current density. Ion transport within the via primarily relies on diffusion and liquid flow; therefore, the deposition rate at the via opening is typically higher than that within the via.

[0004] However, the inventors of this application discovered in the process of realizing the technical solution of this application that in the existing hole-filling electroplating process, since the conductive layer formation state of each region of the hole wall is basically the same, the current tends to concentrate in the hole opening region during the initial stage of electroplating, resulting in the preferential formation of a thicker deposition layer in the hole opening region, while the deposition rate in the hole interior region is relatively low. This makes it easy for the hole opening to shrink prematurely during the hole-filling process, affecting the deposition uniformity in the hole depth direction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for manufacturing HDI boards with partial electroplating and hole filling, which solves the problem that existing technologies are prone to premature shrinkage of the hole opening during the hole filling process, affecting the deposition uniformity in the hole depth direction.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for manufacturing an HDI board with partial electroplating for filling holes, comprising the following steps:

[0007] S1. Perform conductivity gradient adjustment on the HDI board by activating the hole walls in stages to make the conductivity of the bottom area of ​​the hole higher than that of the opening area.

[0008] S2. Prepare an electroplating solution, wherein the electroplating solution includes copper ions and organic additives, wherein the organic additives include a reversible complexing agent A and a potential-responsive release component B, wherein the reversible complexing agent A is used to form a reversible complexation state with copper ions, and the potential-responsive release component B is used to regulate the adsorption and release behavior of copper ions.

[0009] S3. Electroplating deposition is performed using an asymmetric pulsed current, which includes a forward deposition stage, a reverse pulse stage, and a low current maintenance stage. The deposition layer is adjusted by alternating the forward deposition stage and the reverse pulse stage to create a differentiated deposition state between the pore and the pore opening area.

[0010] S4. Apply process perturbation during electroplating to control mass transfer;

[0011] S5. When the filling of the well is almost complete, perform a termination homogenization deposition process.

[0012] Preferably, in step S1, the activation time inside the pores during the staged activation process is 60–180 s, and the surface activation time is 30–90 s.

[0013] Preferably, step S1 further includes micro-etching treatment, with a micro-etching solution concentration of 50–120 g / L and a treatment time of 30–120 s.

[0014] Preferably, in step S2, the electroplating solution comprises the following components: 180-260 g / L copper sulfate, 40-90 g / L sulfuric acid, and 30-90 mg / L chloride ions.

[0015] Preferably, in step S2, the concentration of the reversible complexing agent A is 5–25 mg / L, and the concentration of the potential-responsive release component B is 0.5–8 mg / L.

[0016] Preferably, the reversible complexing agent A is a polydentate organic complexing agent containing 2 to 6 carboxyl or hydroxyl coordinating groups, and the potential-responsive release component B is an organic compound containing thioether or amino functional groups.

[0017] Preferably, in step S3, the current density of the forward deposition stage is 1.5–4.0 A / dm² and the duration is 20–80 ms, the reverse current density of the reverse pulse stage is 0.2–1.0 A / dm² and the duration is 5–20 ms, and the current density of the low current maintenance stage is 0.5–1.5 A / dm² and the duration is 20–100 ms.

[0018] Preferably, the cycle period of the asymmetric pulse current is 50–200 ms, and when the aperture is 50–150 μm, the cycle period is 80–180 ms.

[0019] Preferably, in step S4, the process disturbance includes causing the electroplating solution circulation velocity to fluctuate periodically by ±20% within the range of 0.2 to 0.8 m / s, with a period of 5 to 30 s, and / or includes microbubble disturbance, with a bubble diameter of 0.1 to 0.5 mm and an injection frequency of 0.1 to 1 Hz.

[0020] Preferably, in step S5, the current density is adjusted to 0.5 to 1.0 A / dm² and maintained for 2 to 10 minutes, and the reverse pulse phase is stopped.

[0021] This invention provides a method for manufacturing an HDI board by partial electroplating to fill vias. It has the following advantages:

[0022] 1. This invention performs a phased activation treatment on the hole wall before electroplating, so that the formation rate of the conductive layer in the bottom region of the hole is higher than that in the opening region. This results in a conductive distribution state where the bottom of the hole is preferentially conductive in the initial stage of electroplating, avoiding excessive current concentration in the opening region and ensuring that the electroplating deposition process proceeds evenly in the depth direction of the hole.

[0023] 2. This invention introduces a reversible complexing agent A and a potential-responsive release component B into the electroplating solution, so that copper ions are in different binding states under different potential conditions. This allows for the regulation of the copper ion supply state during the electroplating process, thereby coordinating with changes in current distribution to control the deposition process and maintain the difference in deposition rhythm between the pore and pore opening regions.

[0024] 3. This invention employs an asymmetric pulsed current comprising a forward deposition stage, a reverse pulse stage, and a low current maintenance stage, and applies process perturbation during electroplating to regulate mass transfer, thereby periodically adjusting the deposited layer during its formation and improving the solution exchange state within the pores. Finally, at the stage where pore filling is nearing completion, the homogenization deposition process is terminated to achieve overall deposition consistency. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for manufacturing an HDI board with partial electroplating for filling holes, according to the present invention. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The following is in conjunction with the appendix Figure 1 The present application will be further described in detail with reference to the embodiments.

[0028] In the manufacturing process of high-density interconnect (HDI) printed circuit boards, partial electroplating is used to achieve conductive filling of blind or microvias. In existing technologies, an acidic copper sulfate system is typically used, with inhibitors, accelerators, and leveling agents added to regulate the electroplating deposition process. However, under conditions of small aperture and large aspect ratio, the uneven current density distribution between the aperture and the aperture region, as well as the limited mass transfer of additives within the aperture, easily leads to a higher deposition rate at the aperture region than in the aperture region. This results in premature aperture closure during electroplating, affecting the continuous progress of subsequent filling processes.

[0029] Furthermore, in conventional electroplating processes, the supply of copper ions within and around the pores primarily depends on solution diffusion and convection mass transfer. When the pore depth increases or fluid disturbance is insufficient, the copper ion replenishment rate within the pores decreases, resulting in spatial non-uniformity in the deposition process. Simultaneously, the additive systems employed in existing technologies are mostly based on fixed adsorption or desorption mechanisms, making it difficult to dynamically adjust according to changes in the local electric field state. This leads to an inability to synergistically control the deposition behavior in different regions during the electroplating process.

[0030] In response to the above situation, the applicant analyzed the relationship between electric field distribution, ion state and interfacial reaction behavior during the electroplating process. It was found that by constructing a difference in conductivity between the inside and outside of the hole before electroplating, introducing a complexation system that can respond to potential changes during the electroplating process, and combining it with a current input method that has a staged adjustment function, the deposition process can be spatially adjusted, thereby changing the deposition state in the hole and the hole opening area.

[0031] Based on the above understanding, this application proposes a method for manufacturing HDI boards with partial electroplating and hole filling. Through the synergistic effect of conductivity gradient adjustment treatment, dynamic complexation electroplating solution system and asymmetric pulse current, the deposition behavior of different regions during the electroplating process is coordinated in time and space, thereby realizing the continuous operation of the hole filling process.

[0032] In the embodiments of this application, the raw materials and reagents used can be obtained commercially or prepared by conventional methods, as detailed below:

[0033] Copper sulfate (CuSO4·5H2O): analytical grade;

[0034] Sulfuric acid (H2SO4): Industrial grade or analytical grade reagent;

[0035] Chloride ion source: sodium chloride or hydrochloric acid solution;

[0036] Reversible complexing agent A: is an organic complexing agent containing carboxyl or hydroxyl coordination groups, and may be citric acid, tartaric acid or similar polydentate coordination compounds; reversible complexing agent A may be at least one of citric acid, tartaric acid, malic acid, and ethylenediaminetetraacetic acid;

[0037] Potential response release component B: is an organic compound containing a thioether group or an amino group, and may be a thiourea or an amine derivative; potential response release component B may be at least one of thiourea, mercaptoethylamine, dimethylthiourea or ethanolamine;

[0038] Inhibitor: A polyether-based polymeric adsorbent;

[0039] Accelerators: are small-molecule organic compounds containing sulfur;

[0040] Leveling regulator: a nitrogen-containing heterocyclic compound.

[0041] The aforementioned substances are all common components of electroplating systems in this field, and their acquisition methods are clear, which can meet the requirements of those skilled in the art to implement the technical solution of this application.

[0042] Example

[0043] Example 1

[0044] In this embodiment, an FR-4 substrate HDI board is used as the processing object. The surface of the board is provided with a copper foil conductive layer. An HDI board with a micro-blind hole structure is selected as the processing object, with a hole diameter of 60 μm and a hole depth of 70 μm.

[0045] (1) Conductivity gradient adjustment process:

[0046] The HDI board was degreased at 40 ℃ for 3 min.

[0047] Subsequently, micro-etching was performed with a micro-etching solution concentration of 50 g / L and a treatment time of 30 s;

[0048] The activation process is then carried out in stages, including:

[0049] The activation time inside the pores is 60 s;

[0050] The surface activation time is 30 s;

[0051] The above treatment allows for the preferential formation of a conductive layer inside the hole.

[0052] Because the activation time in the pore interior region is longer than that in the pore opening region, the number of activation centers formed in the pore interior region increases, and the conductive layer deposition starts preferentially towards the bottom region of the pore, thus forming a differential distribution of conductivity in the pore depth direction.

[0053] (2) Preparation of electroplating solution:

[0054] The electroplating solution is prepared with the following components:

[0055] Copper sulfate: 180 g / L

[0056] Sulfuric acid: 40 g / L

[0057] Chloride ions: 30 mg / L

[0058] Reversible complexing agent A: 5 mg / L

[0059] Potential response release of component B: 0.5 mg / L

[0060] Inhibitor: 100 mg / L

[0061] Accelerator: 1 mg / L

[0062] Leveling agent: 5 mg / L

[0063] The stirring time was 30 min, followed by a 1 h pre-equilibration treatment.

[0064] (3) Asymmetric pulse electroplating:

[0065] Electroplating using asymmetric pulsed current:

[0066] Forward deposition stage: 1.5 A / dm², 20 ms;

[0067] Reverse pulse phase: 0.2 A / dm², 5 ms;

[0068] Low current sustaining phase: 0.5 A / dm², 20 ms;

[0069] The current cycle period is 50 ms.

[0070] During the reverse pulse phase, local dissolution regulation occurs in the orifice region, while the region inside the orifice remains in a continuous deposition state, thus forming different deposition rates in the depth direction of the orifice.

[0071] (4) Process disturbance:

[0072] The electroplating solution circulation rate is 0.2 m / s, fluctuating by ±20% with a period of 5 s. This process disturbance is used to maintain the mass exchange state between the pore region and the bulk solution.

[0073] (5) Termination of homogenization process:

[0074] When well filling is nearly complete, the current density is adjusted to 0.5 A / dm² and maintained for 2 minutes, at which point the reverse pulse phase is stopped. During the terminating homogenization deposition phase, the current input intensity is reduced to gradually stabilize the deposition state in the wellhead area.

[0075] Example 2

[0076] In this embodiment, an FR-4 substrate HDI board is used as the processing object. The surface of the board is provided with a copper foil conductive layer. An HDI board with a hole diameter of 100 μm and a hole depth of 110 μm is selected.

[0077] (1) Conductivity gradient adjustment process:

[0078] The degreasing temperature was 50 ℃, and the time was 5 min.

[0079] The concentration of the micro-etching solution was 80 g / L, and the treatment time was 60 s;

[0080] The phased activation process is as follows:

[0081] The activation time inside the pores is 120 s;

[0082] The surface activation time is 60 s;

[0083] Because the activation time in the pore interior region is longer than that in the pore opening region, the number of activation centers formed in the pore interior region increases, and the conductive layer deposition starts preferentially towards the bottom region of the pore, thus forming a differential distribution of conductivity in the pore depth direction.

[0084] (2) Preparation of electroplating solution:

[0085] The components are as follows:

[0086] Copper sulfate: 220 g / L

[0087] Sulfuric acid: 65 g / L

[0088] Chloride ions: 60 mg / L

[0089] Reversible complexing agent A: 15 mg / L

[0090] Potential response release component B: 4 mg / L

[0091] Inhibitor: 250 mg / L

[0092] Accelerator: 5 mg / L

[0093] Leveling agent: 10 mg / L

[0094] The stirring time was 60 min, and the pre-equilibration time was 2 h.

[0095] (3) Asymmetric pulse electroplating:

[0096] Forward deposition stage: 2.5 A / dm², 50 ms;

[0097] Reverse pulse phase: 0.5 A / dm², 10 ms;

[0098] Low current sustaining phase: 1.0 A / dm², 50 ms;

[0099] The loop period is 110 ms.

[0100] During the reverse pulse phase, localized dissolution regulation occurs in the orifice region, while continuous deposition continues in the orifice region, resulting in different deposition rates along the orifice depth. During electroplating, the copper ion concentration distribution in the orifice and pore regions dynamically adjusts with the current phase.

[0101] (4) Process disturbance:

[0102] The electroplating solution flow rate is 0.5 m / s, with a periodic fluctuation of ±20% and a period of 15 s;

[0103] Simultaneously, microbubble disturbances are introduced, with a bubble diameter of 0.3 mm and a frequency of 0.5 Hz.

[0104] Process perturbation is used to maintain the mass exchange state between the pore region and the bulk solution.

[0105] (5) Termination of homogenization process:

[0106] The current density was adjusted to 0.8 A / dm² and maintained for 5 min, after which the reverse pulse was stopped. During the termination of the homogenization deposition stage, the deposition state in the pore mouth area was gradually stabilized by reducing the current input intensity.

[0107] Example 3

[0108] In this embodiment, an FR-4 substrate HDI board is used as the processing object. The surface of the board is provided with a copper foil conductive layer. An HDI board with a hole diameter of 150 μm and a hole depth of 160 μm is selected.

[0109] (1) Conductivity gradient adjustment process:

[0110] The degreasing temperature was 60 ℃, and the time was 8 min.

[0111] The concentration of the micro-etching solution was 120 g / L, and the treatment time was 120 s;

[0112] The phased activation process is as follows:

[0113] The activation time inside the pores is 180 s;

[0114] The surface activation time is 90 s;

[0115] Because the activation time in the pore interior region is longer than that in the pore opening region, the number of activation centers formed in the pore interior region increases, and the conductive layer deposition starts preferentially towards the bottom region of the pore, thus forming a differential distribution of conductivity in the pore depth direction.

[0116] (2) Preparation of electroplating solution:

[0117] The components are as follows:

[0118] Copper sulfate: 260 g / L

[0119] Sulfuric acid: 90 g / L

[0120] Chloride ions: 90 mg / L

[0121] Reversible complexing agent A: 25 mg / L

[0122] Potential response release component B: 8 mg / L

[0123] Inhibitor: 400 mg / L

[0124] Accelerator: 10 mg / L

[0125] Leveling agent: 20 mg / L

[0126] The stirring time was 90 min, and the pre-equilibration time was 4 h.

[0127] (3) Asymmetric pulse electroplating:

[0128] Forward deposition stage: 4.0 A / dm², 80 ms;

[0129] Reverse pulse phase: 1.0 A / dm², 20 ms;

[0130] Low current sustaining phase: 1.5 A / dm², 100 ms;

[0131] The loop period is 200 ms.

[0132] During the reverse pulse phase, local dissolution regulation occurs in the orifice region, while the region inside the orifice remains in a continuous deposition state, thus forming different deposition rates in the depth direction of the orifice.

[0133] (4) Process disturbance:

[0134] The electroplating solution flow rate is 0.8 m / s, with a periodic fluctuation of ±20% and a period of 30 s;

[0135] Simultaneously, microbubble perturbations are introduced, with a bubble diameter of 0.5 mm and a frequency of 1 Hz. These perturbations are used to maintain the mass exchange state between the pore region and the bulk solution.

[0136] (5) Termination of homogenization process:

[0137] The current density was adjusted to 1.0 A / dm² and maintained for 10 min, after which the reverse pulse phase was stopped. During the termination of the homogenization deposition phase, the deposition state in the pore mouth area was gradually stabilized by reducing the current input intensity.

[0138] Comparative Example

[0139] Comparative Example 1

[0140] The same HDI board as in Example 2 was selected, with a hole diameter of 100 μm and a hole depth of 110 μm.

[0141] Process steps:

[0142] (1) Pretreatment:

[0143] The HDI board was degreased (50 °C, 5 min), followed by micro-etching (80 g / L, 60 s), and then routine activation treatment. The activation time was uniformly 60 s, without distinguishing between the inside and outside of the hole.

[0144] (2) Preparation of electroplating solution:

[0145] The electroplating solution composition is as follows:

[0146] Copper sulfate: 220 g / L

[0147] Sulfuric acid: 65 g / L

[0148] Chloride ions: 60 mg / L

[0149] Inhibitor: 250 mg / L

[0150] Accelerator: 5 mg / L

[0151] Leveling agent: 10 mg / L

[0152] Reversible complexing agent A and potential response release component B were not added to the electroplating solution.

[0153] (3) Electroplating process:

[0154] Electroplating is performed using a constant DC current with a current density of 2.5 A / dm², and the electroplating continues until the holes are filled.

[0155] (4) Process control:

[0156] During the electroplating process, the flow rate of the electroplating solution is maintained at 0.5 m / s, without periodic fluctuations or bubble disturbances.

[0157] In this comparative example, since no conductivity gradient adjustment was performed and a constant DC current was used, the wellhead area was preferentially deposited, and a thicker deposition layer gradually formed in the wellhead area during the filling process.

[0158] Comparative Example 2

[0159] Select an HDI board with the same specifications as in Example 2.

[0160] Process steps:

[0161] (1) Pretreatment:

[0162] The same conductivity gradient adjustment method as in Example 2 is used:

[0163] Activation time inside the pore: 120 s

[0164] Surface activation time: 60 s

[0165] (2) Preparation of electroplating solution:

[0166] The electroplating solution composition is as follows:

[0167] Copper sulfate: 220 g / L

[0168] Sulfuric acid: 65 g / L

[0169] Chloride ions: 60 mg / L

[0170] Inhibitor: 250 mg / L

[0171] Accelerator: 5 mg / L

[0172] Leveling agent: 10 mg / L

[0173] Reversible complexing agent A and potential response release component B are not added to the electroplating solution.

[0174] (3) Electroplating process:

[0175] The same asymmetric pulsed current as in Example 2 is used:

[0176] Forward deposition stage: 2.5 A / dm², 50 ms;

[0177] Reverse pulse phase: 0.5 A / dm², 10 ms;

[0178] Low current sustaining phase: 1.0 A / dm², 50 ms;

[0179] (4) Process disturbance:

[0180] The electroplating solution flow rate is 0.5 m / s, with a fluctuation of ±20%.

[0181] In this comparative example, although conductivity gradient adjustment and asymmetric pulsed current were used, due to the lack of reversible complexing agent A and potential response release component B, the supply state of copper ions during electroplating mainly relied on diffusion and convection mass transfer, making it difficult to form a stable differentiated ion supply state between the inside region and the orifice region.

[0182] Comparative Example 3

[0183] Select an HDI board with the same specifications as in Example 2.

[0184] Process steps:

[0185] (1) Pretreatment

[0186] The same conductivity gradient adjustment process as in Example 2 was employed:

[0187] Activation time inside the pore: 120 s

[0188] Surface activation time: 60 s

[0189] (2) Preparation of electroplating solution

[0190] The same electroplating solution system as in Example 2 is used, including:

[0191] Copper sulfate: 220 g / L

[0192] Sulfuric acid: 65 g / L

[0193] Chloride ions: 60 mg / L

[0194] Reversible complexing agent A: 15 mg / L

[0195] Potential response release component B: 4 mg / L

[0196] Inhibitor: 250 mg / L

[0197] Accelerator: 5 mg / L

[0198] Leveling agent: 10 mg / L

[0199] (3) Electroplating process

[0200] Electroplating is performed using a constant direct current with a current density of 2.5 A / dm².

[0201] (4) Process disturbance

[0202] The electroplating solution flow rate is 0.5 m / s, with a fluctuation of ±20%.

[0203] In this comparative example, although a dynamic complexation system was introduced and conductivity gradient adjustment was performed, the deposition process was mainly controlled by a single current input because asymmetric pulse current was not used to adjust the deposition process in stages. The deposition state changes in the pore and pore mouth regions were relatively simple.

[0204] Performance testing

[0205] I. Detection Methods / Test Methods

[0206] HDI board samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were selected as test objects to test the filling quality.

[0207] (1) Cross-section filling status detection

[0208] The metallographic sectioning method was used to prepare the cross-section of the sample. The specific steps are as follows:

[0209] Cut the HDI board along the hole axis after electroplating;

[0210] Resin encapsulation followed by grinding and polishing;

[0211] The cross-section was observed using an optical microscope;

[0212] The testing indicators include:

[0213] Continuity of hole filling;

[0214] Morphology of the sedimentary layers at the wellhead and bottom;

[0215] Are there any cavities or discontinuous areas?

[0216] (2) Filling rate determination

[0217] The cross-sectional image was analyzed using image analysis software to calculate the fill rate. The calculation formula is as follows:

[0218] Fill rate η calculation: η = S1 / S2 × 100%

[0219] in:

[0220] S1 is the area of ​​the actual copper deposited region inside the hole;

[0221] S2 is the theoretical cross-sectional area of ​​the hole;

[0222] (3) Surface deposition uniformity detection

[0223] A surface profilometer was used to scan the surface of the HDI board to obtain the thickness distribution data of the deposited layer and to evaluate the thickness difference between the orifice area and the surrounding area.

[0224] Test results

[0225] sample Fill rate (%) Example 1 91 Example 2 96 Example 3 97 Comparative Example 1 78 Comparative Example 2 84 Comparative Example 3 86

[0226] Table 1. Filling Rate Detection Results

[0227] sample Orifice area Inner region of the hole Continuity Example 1 uniform deposition Continuous filling No obvious interruption Example 2 Deposition leveling Continuous filling No obvious cavities Example 3 Deposition leveling Dense filling Uninterrupted structure Comparative Example 1 Local accumulation discontinuous fill There are discontinuous regions Comparative Example 2 Deposition is relatively fast Local unevenness Local gaps exist Comparative Example 3 uneven deposition Unstable filling Structural fluctuations exist

[0228] Table 2 Observation results of cross-sectional structure

[0229] sample Orifice thickness deviation (μm) Example 1 4.5 Example 2 2.8 Example 3 2.2 Comparative Example 1 9.5 Comparative Example 2 6.8 Comparative Example 3 5.9

[0230] Table 3 Surface Deposition Uniformity

[0231] Results Analysis

[0232] Combining Examples 1 to 3 with Comparative Example 1 and Tables 1 to 3, it can be seen that under the condition of no conductivity gradient adjustment and constant DC current, the deposition process in the orifice area is faster, the filling continuity in the orifice area is poor, the filling rate is relatively low, there are discontinuous areas in the cross-sectional structure, and the surface deposition thickness distribution is uneven.

[0233] Combining Example 2 and Comparative Example 2 with Tables 1-3, it can be seen that under the condition of only using conductivity gradient adjustment and asymmetric pulse current, the filling process is improved compared with Comparative Example 1. However, due to the lack of reversible complexing agent A and potential response release component B, the supply state of copper ions in the pore region mainly depends on the mass transfer process, and the filling uniformity still varies.

[0234] Combining Example 2 and Comparative Example 3 with Tables 1 to 3, it can be seen that when a dynamic complexation system is introduced and a constant DC current is used, the deposition process lacks phased adjustment, the deposition state changes in the pore and pore opening regions are relatively simple, and the filling structure fluctuates.

[0235] Further, by combining Examples 1 to 3 and Tables 1 to 3, it can be seen that under the synergistic effect of conductivity gradient adjustment, dynamic complexation system and asymmetric pulse current, the deposition process in the pore and pore opening regions exhibits coordinated changes, and the filling continuity and surface deposition uniformity remain stable.

[0236] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing an HDI board with partial electroplating for filling holes, characterized in that, Includes the following steps: S1. Perform conductivity gradient adjustment on the HDI board by activating the hole walls in stages to make the conductivity of the bottom area of ​​the hole higher than that of the opening area. S2. Prepare an electroplating solution, wherein the electroplating solution includes copper ions and organic additives, wherein the organic additives include a reversible complexing agent A and a potential-responsive release component B, wherein the reversible complexing agent A is used to form a reversible complexation state with copper ions, and the potential-responsive release component B is used to regulate the adsorption and release behavior of copper ions. S3. Electroplating deposition is performed using an asymmetric pulsed current, which includes a forward deposition stage, a reverse pulse stage, and a low current maintenance stage. The deposition layer is adjusted by alternating the forward deposition stage and the reverse pulse stage to create a differentiated deposition state between the pore and the pore opening area. S4. Apply process perturbation during electroplating to control mass transfer; S5. When the filling of the well is almost complete, perform a termination homogenization deposition process.

2. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 1, characterized in that, In step S1, the activation time inside the pores during the staged activation process is 60–180 s, and the surface activation time is 30–90 s.

3. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 1, characterized in that, Step S1 also includes micro-etching treatment, with a micro-etching solution concentration of 50–120 g / L and a treatment time of 30–120 s.

4. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 1, characterized in that, In step S2, the electroplating solution comprises the following components: copper sulfate 180-260 g / L, sulfuric acid 40-90 g / L, and chloride ions 30-90 mg / L.

5. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 1, characterized in that, In step S2, the concentration of the reversible complexing agent A is 5–25 mg / L, and the concentration of the potential-responsive release component B is 0.5–8 mg / L.

6. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 5, characterized in that, The reversible complexing agent A is a polydentate organic complexing agent containing 2 to 6 carboxyl or hydroxyl coordinating groups, and the potential-responsive release component B is an organic compound containing thioether or amino functional groups.

7. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 1, characterized in that, In step S3, the current density of the forward deposition stage is 1.5–4.0 A / dm² and the duration is 20–80 ms; the reverse current density of the reverse pulse stage is 0.2–1.0 A / dm² and the duration is 5–20 ms; and the current density of the low current maintenance stage is 0.5–1.5 A / dm² and the duration is 20–100 ms.

8. The method for manufacturing an HDI board with partial electroplating and hole filling according to claim 7, characterized in that, The cycle period of the asymmetric pulse current is 50–200 ms, and when the aperture is 50–150 μm, the cycle period is 80–180 ms.

9. The method for manufacturing an HDI board with partial electroplating for filling holes according to claim 1, characterized in that, In step S4, the process disturbance includes causing the electroplating solution circulation velocity to fluctuate periodically by ±20% within the range of 0.2 to 0.8 m / s, with a period of 5 to 30 s, and / or includes microbubble disturbance, with a bubble diameter of 0.1 to 0.5 mm and an injection frequency of 0.1 to 1 Hz.

10. The method for manufacturing an HDI board with partial electroplating for filling holes according to claim 1, characterized in that, In step S5, the current density is adjusted to 0.5–1.0 A / dm² and maintained for 2–10 min, and the reverse pulse phase is stopped.

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