Laminated composite material multi-layer circuit and metallization method of vertical interconnection micropores of laminated composite material multi-layer circuit

Abstract

The invention belongs to the related technical field of micropore metallization, and discloses a laminated composite material multilayer circuit and a metallization method of vertical interconnection micropores of the laminated composite material multilayer circuit, which comprises the following steps of: filling solid solder balls into the vertical interconnection micropores of the laminated composite material multilayer circuit; laser is adopted to heat the solder balls, so that the solder balls are fused to fill the micropores, and metallization of the vertically interconnected micropores is achieved; or the tin balls are heated through laser in the atmosphere of high-pressure protective gas, so that the molten tin balls are sprayed into the micropores under the action of the high-pressure protective gas, and metallization of the vertically-interconnected micropores is achieved. According to the invention, rapid metallization of the vertical interconnection micropores of the multilayer circuit of the laminated composite material is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field related to micro-hole metallization, and more specifically, relates to a laminated composite multi-layer circuit and a method for metallizing vertical interconnect micro-holes thereof. Background Art

[0002] In the fields of aerospace, weapon equipment manufacturing, etc., products, components, and assemblies are developing towards miniaturization, lightweight, multi-functionality, and high reliability, which leads to higher requirements for the integrated technology of electronic product structures and functions. The integrated manufacturing technology of multi-layer three-dimensional circuits has become an important guarantee for products, their components, and assemblies to meet the above requirements, and requires related three-dimensional circuit manufacturing and packaging technologies to meet the needs of multi-layer wiring and high-density interconnection. As an intermediate layer structure for vertical interconnection, the vertical interconnection structure plays an irreplaceable role in 3D packaging integration capabilities and system integration.

[0003] As an intermediate layer structure for vertical interconnection, the vertical interconnection structure plays an irreplaceable role in 3D packaging integration capabilities and system integration. The key lies in the production of circuit lines and interconnection holes on high-density interconnection printed circuit boards. Drilling holes and metallizing the hole walls are the main ways to achieve electrical interconnection between layers of multi-layer circuit boards, and require efficient and low-cost through-hole preparation processes and defect-free filling processes. Usually, methods such as mechanical drilling, ultrasonic drilling, ultrasonic high-speed drilling, wet etching, deep reactive ion etching, laser etching, and laser-induced deep etching are used to make holes, and chemical copper plating is used to achieve through-hole electrical interconnection.

[0004] High-density micro-hole metallization for preparing complex curved multi-layer interconnected micro-holes is a prerequisite. The interconnection holes in printed circuit boards include through-holes (via holes connecting the top layer and the bottom layer of the printed circuit board), buried holes (holes embedded inside the printed circuit board and not visible on the surface), and blind holes (holes that do not penetrate the board). The processing methods for buried holes and through-holes mainly use mechanical drilling methods. For specific via hole sizes, the aperture of the latest generation of precision CNC drilling systems can reach 100 μm.

[0005] Through-hole technology has been widely promoted and mass-produced in various product applications, including fields such as stacked memories, image and optical sensors, inertial sensing microsystems, radio frequency / microwave systems, bio-microsystems, logic and processor systems, and networks-on-chip. The current main through-hole metallization methods include vacuum / pressure filling, electroplating, printing, inkjet printing, etc. Vacuum / pressure filling is mainly used for through-hole filling of planar substrates. Researchers have formed through-silicon vias (TSVs) by pressure infiltration of molten Sn into Si vias, enabling the through-hole filling to be completed within 5 seconds, regardless of the through-hole size. TSVs of different diameters can be infiltrated with molten Sn under external pressure and can be formed within 5 seconds, with a diameter range of 10μm - 200μm. Other research has used vacuum adsorption to fill silver-based epoxy resin into silicon vias, and it can fill more than 450μm in 3 seconds under an adsorption pressure of 1.6 kPa, preparing interconnected vias with a diameter of 100μm and a pitch of 500μm, with an average resistance of 24.83Ω.

[0006] Although the above technologies have their own characteristics, vacuum / pressure equipment is complex and requires a vacuum environment, which is not suitable for through-hole filling of large-area and curved substrates and is mostly in the experimental research stage; although electroplating for vertical interconnection of multi-layer circuits with micro-hole metallization has been widely used in the electronics industry, it is inefficient, time-consuming, and involves electrochemical reactions. Currently, the substrate materials for micro-hole metallization are mainly glass, ceramics, and silicon wafers, and no metallization method suitable for micro-holes in multi-layer circuits of laminated composites has been proposed. The above vertical interconnection micro-hole metallization methods are all through-hole metallization, and one micro-hole can only be used for electrical interconnection between two metal conductive layers, without realizing the interconnection of a single micro-hole through multi-layer circuits to achieve single-hole multi-layer circuit interconnection.

[0007] In summary, the existing technologies face great challenges in achieving rapid metallization of vertical interconnection micro-holes in multi-layer circuits. Therefore, there is an urgent need to develop a new type of rapid metallization high-density micro-hole interconnection process method for multi-layer circuits, which can rapidly and efficiently, at low cost, and with high quality, prepare multi-layer conductive layer vertical interconnection circuits. Summary of the Invention

[0008] In view of the above deficiencies or improvement requirements of the existing technology, the present invention provides a laminated composite multi-layer circuit and a metallization method for its vertical interconnection micro-holes, aiming to solve the problem of how to rapidly achieve metallization of vertical interconnection micro-holes in multi-layer circuits.

[0009] To achieve the above object, according to one aspect of the present invention, there is provided a metallization method for vertical interconnection micro-holes of a laminated composite multi-layer circuit, and the metallization method includes the following steps:

[0010] Fill solid tin balls into the vertical interconnection micro-holes of a laminated composite multi-layer circuit, and use a laser to heat the tin balls so that the tin balls melt to fill the micro-holes, realizing the metallization of the vertical interconnection micro-holes; or, under the atmosphere of a high-pressure protective gas, use a laser to heat the tin balls so that the molten tin balls are sprayed into the micro-holes under the action of the high-pressure protective gas, realizing the metallization of the vertical interconnection micro-holes.

[0011] Further, after placing the solid tin balls in the nozzle of an automated tin feeding mechanism, introduce a high-pressure protective gas into the nozzle, and use a laser to heat the tin balls so that the molten tin balls are sprayed into the micro-holes under the action of the high-pressure protective gas, realizing the metallization of the vertical interconnection micro-holes.

[0012] Further, after filling the solid tin balls into the vertical interconnection micro-holes of a laminated composite multi-layer circuit, place a soldering flux in the micro-holes, heat the laminated composite multi-layer circuit, and then use a laser to heat the tin balls so that the tin balls melt to fill the micro-holes.

[0013] Further, the diameter of the tin balls is larger than the diameter of the nozzle of the automated tin feeding mechanism.

[0014] Further, fill the solid tin balls into an automated tin feeding mechanism, and then connect a high-pressure protective gas to the nozzle of the automated tin feeding mechanism; then, align the nozzle of the automated tin feeding mechanism with the micro-holes, use a laser to heat the tin balls in the nozzle, and the high-pressure protective gas causes the tin ball particles to melt and be sprayed into the micro-holes along with the high-pressure protective gas, contacting the conductive layer in the laminated composite multi-layer circuit, and completing the metallization of the vertical interconnection micro-holes between the inner and outer layers and the intermediate metal conductive layer of the multi-layer circuit.

[0015] Further, the micro-holes are blind holes.

[0016] Further, the diameter of the tin balls is less than 1 / 2 of the diameter of the filled micro-holes.

[0017] Further, the laser is one segment or multiple segments.

[0018] Further, the soldering flux is a liquid soldering flux, and a brush is used to brush the soldering flux into the micro-holes to make the soldering flux fully contact the tin ball particles.

[0019] The present invention also provides a laminated composite multi-layer circuit, and the micro-holes of the multi-layer circuit are metallized by using the method for metallizing the vertical interconnection micro-holes of the laminated composite multi-layer circuit as described above to realize interconnection with the conductive layer.

[0020] Generally speaking, compared with the prior art through the above technical solutions conceived by the present invention, the stacked composite multi-layer circuit provided by the present invention and the metallization method for the vertical interconnection micro-holes mainly have the following beneficial effects:

[0021] 1. By filling the processed blind holes with common tin ball particles, the material price used in processing is reduced, the process cost is reduced, and the rapid metallization of the vertical interconnection micro-holes of the stacked composite multi-layer circuit is realized.

[0022] 2. By heating the bottom plate of the multi-layer circuit material to preheat the tin balls to achieve the rapid metallization of the vertical interconnection micro-holes, the full melting of the tin balls can be realized, and the time and number of times required for laser heating are greatly reduced.

[0023] 3. By melting the tin balls through multi-segment laser heating to achieve the rapid metallization of the vertical interconnection micro-holes, the gaps between the tin balls can be eliminated, so that the melted tin balls are in full contact with the bottom and side surfaces of the micro-holes, and a very low resistance of the micro-hole interconnection can be achieved, realizing the vertical micro-hole interconnection of the multi-layer circuit.

[0024] 4. By adopting an automatic tin feeding mechanism to realize the melting-filling-cooling of the tin balls in a short time with high efficiency, the rapid metallization of the vertical interconnection micro-holes can be achieved, the gaps between the tin balls can be eliminated, so that the melted tin balls are in full contact with the bottom and side surfaces of the micro-holes, and a very low resistance of the micro-hole interconnection can be achieved, realizing the vertical micro-hole interconnection of the multi-layer circuit.

[0025] 5. The present invention can manufacture micro-holes in the stacked composite multi-layer circuit board through a machining center or a high-speed drilling machine. The manufacturing equipment is common, and the manufacturing process is simple, fast and stable.

[0026] 6. According to the different compositions of the tin ball particles, the melting points of the tin ball particles range from 138°C to 217°C. Different tin balls can be selected according to the process temperature that the substrate can withstand and the temperature requirements of the curved circuit working environment to meet the temperature requirements during the processing and the high-temperature stability requirements in the circuit working environment.

[0027] 7. According to the different diameters of the tin ball particles, the diameters of the tin ball particles range from 30μm to 200μm. Different diameters of tin ball particles can be selected according to the requirements of the circuit working environment and the required micro-hole diameter to meet the dimensional requirements during the processing.

[0028] 8. The micro-holes penetrate through multiple conductive metals. The melted solder is co-melted with the circumferential ports of the multiple conductive metal layers, and the interconnection of the multiple conductive metal layers of a single micro-hole can be realized; no electrochemical reaction is involved during the processing, which is suitable for the vertical interconnection high-density micro-hole metallization of the stacked composite multi-layer circuit board with micro-gaps. Description of the Drawings

[0029] Figure 1 It is a flowchart of a method for metallizing vertical interconnection micro-holes of a multi-layer circuit of a laminated composite material provided in Embodiment 1 of the present invention;

[0030] Figure 2 It is a flowchart of a method for metallizing vertical interconnection micro-holes of a multi-layer circuit of a laminated composite material provided in Embodiment 2 of the present invention.

[0031] In all the drawings, the same reference numerals are used to represent the same elements or structures, where: 1 - first insulating layer, 2 - conductive layer, 3 - second insulating layer, 4 - micro-hole, 5 - absolute ethanol, 6 - tin ball, 7 - solder flux, 8 - heating plate, 9 - laser, 10 - laser beam, 11 - automatic tin feeding mechanism, 12 - high-pressure protective gas. Specific Embodiments

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] The present invention provides a method for metallizing vertical interconnection micro-holes of a multi-layer circuit of a laminated composite material, which realizes the rapid laser metallization of vertical interconnection micro-holes of a multi-layer circuit of a laminated composite material, so that a multi-layer circuit of a laminated composite material can be prepared quickly, efficiently, at low cost and with high quality.

[0034] The metallization method mainly includes the following steps:

[0035] Step 1, perform vertical interconnection micro-hole processing on the multi-layer circuit of the laminated composite material.

[0036] Step 2, fill the micro-holes with solid tin balls, and use a laser to heat the tin balls so that the tin balls melt and fill the micro-holes, realizing the metallization of the vertical interconnection micro-holes; or, after placing the solid tin balls in the nozzle of the automatic tin feeding mechanism, introduce high-pressure protective gas into the nozzle, and use a laser to heat the tin balls, so that the molten tin balls are sprayed into the micro-holes under the action of the high-pressure protective gas, realizing the metallization of the vertical interconnection micro-holes.

[0037] For the first method, which is applicable to planar group holes, the distance between the tin ball particles and the upper surface of the multi-layer circuit board of the laminated composite material is less than 200 μm; use a laser to heat the tin ball particles in the micro-holes, so that the tin ball particles melt and contact the conductive layer in the multi-layer circuit of the laminated composite material, completing the rapid metallization of the vertical interconnection micro-holes between the inner and outer layers and the intermediate metal conductive layer of the multi-layer circuit.

[0038] The second method is applicable to the interconnection of a single micro-hole on a plane. Solid tin ball particles are filled into an automatic tin feeding mechanism, and the diameter of the tin ball particles is slightly larger than the diameter of the nozzle of the automatic tin feeding mechanism. Then, a high-pressure protective gas is connected to the nozzle of the automatic tin feeding mechanism. The nozzle of the automatic tin feeding mechanism is aligned with the micro-hole, and the tin ball particles in the nozzle are heated by a laser. The high-pressure protective gas causes the tin ball particles to melt and spray into the micro-hole with the high-pressure protective gas, contacting the conductive layer in the multi-layer circuit of the laminated composite material, and completing the rapid metallization of the vertical interconnection micro-holes between the inner and outer layers and the intermediate metal conductive layer of the multi-layer circuit.

[0039] In one embodiment, the material of the metal conductive layer of the laminated composite material multi-layer circuit is copper, and the material of the insulating layer is glass fiber reinforced laminated composite material; the micro-hole is a blind hole, and the micro-hole penetrates through the dielectric layer and the conductive metal layer of the laminated composite material multi-layer circuit board; the diameter of the tin ball particles is 1 / 2 or less of the diameter of the filled micro-hole; the laser is divided into one or more segments to heat and melt the tin ball particles. For the interconnection of a group of micro-holes on a plane, the soldering flux is a low-viscosity liquid soldering flux, and the soldering flux is brushed into the micro-holes using a brush to make the soldering flux fully contact the tin ball particles; during the process of laser melting the solder particles, a heating plate is provided to heat the laminated composite material multi-layer circuit board.

[0040] For the interconnection of a single micro-hole on a plane: the automatic tin feeding mechanism adopts visual positioning or manual positioning; the air pressure of the high-pressure protective gas is in the range of 200 kPa to 500 kPa; the high-pressure protective gas is nitrogen or helium; the laser heating is one or more segments of heating.

[0041] The present invention also provides a laminated composite material multi-layer circuit, and the micro-holes of the multi-layer circuit are metallized by using the method for metallizing the vertical interconnection micro-holes of the laminated composite material multi-layer circuit as described above to achieve interconnection with the conductive layer.

[0042] The following will further elaborate on the present invention with specific embodiments.

[0043] Embodiment 1

[0044] Please refer to Figure 1 , Embodiment 1 of the present invention is applicable to the rapid filling of the interconnection of a group of micro-holes on a plane. The circuit board structure used in Embodiment 1 is as Figure 1 shown, including a first insulating layer 1, a conductive layer 2, a second insulating layer 3, and micro-holes 4. The material of the conductive layer is copper, with a thickness of 3 μm, and the material of the insulating layer is glass fiber laminated composite material, with a thickness of 500 μm.

[0045] The method provided in Embodiment 1 of the present invention mainly includes the following steps:

[0046] S1. Micro-hole machining of multi-layer circuit board: Use mechanical machining method to perform micro-hole machining on the multi-layer circuit board of laminated composite material. Fix the multi-layer circuit board of laminated composite material on the machining base. After using UG to plan the path of the through-hole machining and importing it into the machining center control software, perform micro-hole machining on the multi-layer circuit board of laminated composite material. As shown in b of Figure 1 , the machined micro-hole 4 is a blind hole with a depth greater than 500 μm. The micro-hole 4 penetrates the conductive layer 2 and the first insulating layer 1 and terminates in the second insulating layer 3. The diameter of the machined micro-hole is 500 microns. After machining, remove the circuit board. Figure 1 As shown in b, the machined micro-hole 4 is a blind hole with a depth greater than 500 μm. The micro-hole 4 penetrates the conductive layer 2 and the first insulating layer 1 and terminates in the second insulating layer 3. The diameter of the machined micro-hole is 500 microns. After machining, remove the circuit board.

[0047] S2. Post-treatment after micro-hole machining of circuit board: As shown in c of Figure 1 , after completing the micro-hole machining, it is necessary to perform post-treatment on the circuit board. Use a high-pressure air nozzle to clean the debris remaining from mechanical machining in the micro-holes; Use a syringe to draw an appropriate amount of oxide layer cleaning solution, inject a small amount of the cleaning solution into the micro-holes, and refine for 10 s to remove the metal oxide at the port of the conductive layer; Use a syringe to draw an appropriate amount of absolute ethanol 5, inject a small amount of absolute ethanol 5 into the micro-holes, and rinse off the remaining oxide layer cleaning solution. Place the multi-layer circuit board of laminated composite material with micro-holes after being cleaned with absolute ethanol in a dry environment for several minutes to allow the remaining absolute ethanol in the blind holes to volatilize. Figure 1 As shown in c, after completing the micro-hole machining, it is necessary to perform post-treatment on the circuit board. Use a high-pressure air nozzle to clean the debris remaining from mechanical machining in the micro-holes; Use a syringe to draw an appropriate amount of oxide layer cleaning solution, inject a small amount of the cleaning solution into the micro-holes, and refine for 10 s to remove the metal oxide at the port of the conductive layer; Use a syringe to draw an appropriate amount of absolute ethanol 5, inject a small amount of absolute ethanol 5 into the micro-holes, and rinse off the remaining oxide layer cleaning solution. Place the multi-layer circuit board of laminated composite material with micro-holes after being cleaned with absolute ethanol in a dry environment for several minutes to allow the remaining absolute ethanol in the blind holes to volatilize.

[0048] S3. Solid tin ball filling: As shown in d of Figure 1 , pour tin balls on the surface of the multi-layer circuit board of laminated composite material, and use a brush to brush the tin balls 6 into multiple blind holes at one time. The tin balls in the through-holes should satisfy the distance less than 200 μm from the surface of the micro-holes and a sufficient height exceeding the conductive layer 1; In this embodiment, the selected tin ball diameter is 200 μm, the material is SAC305, and the melting point is 183 °C. Figure 1 As shown in d, pour tin balls on the surface of the multi-layer circuit board of laminated composite material, and use a brush to brush the tin balls 6 into multiple blind holes at one time. The tin balls in the through-holes should satisfy the distance less than 200 μm from the surface of the micro-holes and a sufficient height exceeding the conductive layer 1; In this embodiment, the selected tin ball diameter is 200 μm, the material is SAC305, and the melting point is 183 °C.

[0049] S4. Flux filling: As shown in e of Figure 1 , pour the flux 7 on the surface of the circuit board, and use a brush to evenly brush the flux 7 into the micro-holes. The flux and the tin balls in the micro-holes should be in full contact to ensure the success rate and conductivity of the subsequent rapid metallization of the vertical interconnect micro-holes. Figure 1 As shown in e, pour the flux 7 on the surface of the circuit board, and use a brush to evenly brush the flux 7 into the micro-holes. The flux and the tin balls in the micro-holes should be in full contact to ensure the success rate and conductivity of the subsequent rapid metallization of the vertical interconnect micro-holes.

[0050] S5. Preheating of multi-layer circuit board of laminated composite material: As shown in f of Figure 1 , place the multi-layer circuit board of laminated composite material on the heating plate 8. The heating temperature of the heating plate 8 should be lower than the melting point of the tin balls and the temperature limit of the multi-layer circuit board of laminated composite material. The heating temperature of the heating plate 8 is 140 °C, and the heating time is 20 s to fully preheat the tin balls in the micro-holes and ensure the efficiency and success rate of the micro-hole filling of the multi-layer circuit board of laminated composite material during subsequent laser heating. Figure 1 As shown in f, place the multi-layer circuit board of laminated composite material on the heating plate 8. The heating temperature of the heating plate 8 should be lower than the melting point of the tin balls and the temperature limit of the multi-layer circuit board of laminated composite material. The heating temperature of the heating plate 8 is 140 °C, and the heating time is 20 s to fully preheat the tin balls in the micro-holes and ensure the efficiency and success rate of the micro-hole filling of the multi-layer circuit board of laminated composite material during subsequent laser heating.

[0051] S6. Melting of tin balls and metallization of micro-holes: As shown in Figure 1 Figure 1As shown by g in [reference], use a laser 9 to heat the micro-holes of the multi-layer circuit board of the laminated composite material at a fixed point, so that the solder balls in the micro-holes melt and co-melt with the metal conductive layer in the multi-layer circuit; bring the laser 10 into contact with the micro-holes, heat at a set temperature of 140 °C for 600 ms, and then continue to heat at a set temperature of 160 °C for 600 ms. During the first heating, the solder balls in the micro-holes melt and drop, and the original gaps between the solder balls are filled. During the second heating, the solder balls completely melt and co-melt at the bottom of the conductive layer, realizing the metallization of the blind holes as Figure 1 shown by h in [reference], realizing the rapid metallization of the vertical interconnection micro-holes between the inner and outer layers and the middle metal conductive layer of the multi-layer circuit.

[0052] Conductivity test after rapid metallization of the vertical interconnection micro-holes of the multi-layer circuit of the laminated composite material: Test the resistance value between the conductive layer 2 and the surface of the blind hole filling to determine the conductivity of the micro-hole metallization. For the blind holes that fail to conduct electricity successfully, repeat steps (3) to (6) to re-metallize the micro-holes and achieve electrical interconnection between the circuit conductive layer 2 and the micro-holes.

[0053] Example 2

[0054] Please refer to Figure 2 , Example 2 of the present invention is applicable to the rapid filling of planar single micro-hole interconnections. The circuit board structure used in Example 2 is as Figure 2 shown, including a first insulating layer 1, a conductive layer 2, and a second insulating layer 3. The material of the conductive layer is copper with a thickness of 3 μm, and the material of the insulating layer is a glass fiber laminated composite material with a thickness of 500 μm.

[0055] The method provided by Example 2 of the present invention mainly includes the following steps:

[0056] S1. Micro-hole processing of the multi-layer circuit board: As Figure 2 shown by b in [reference], use a mechanical processing method to process the micro-holes of the multi-layer circuit board of the laminated composite material. Fix the multi-layer circuit board of the laminated composite material on the processing base, import the path planning of the through-hole processing path into the processing center control software using UG, and process the micro-holes of the multi-layer circuit board of the laminated composite material. As Figure 2 shown by b in [reference], the processed micro-hole 4 is a blind hole with a depth greater than 500 μm. The micro-hole penetrates the conductive layer 1 and the first insulating layer 1 and terminates in the second insulating layer 3. The diameter of the processed micro-hole is 500 microns. After processing, remove the circuit board.

[0057] S2. Post-processing of the micro-holes of the circuit board: As Figure 2As shown in c, after the micro-hole machining is completed, the circuit board needs to be post-processed. Use a high-pressure air nozzle to clean the debris remaining from the machining in the micro-holes. Use a syringe to draw an appropriate amount of oxide layer cleaning solution, inject a small amount of the cleaning solution into the micro-holes, and let it stand for 10 s to remove the metal oxides at the ports of the conductive layer. Use a syringe to draw an appropriate amount of absolute ethanol 5, inject a small amount of absolute ethanol 5 into the micro-holes, rinse off the remaining oxide layer cleaning solution, and place the multi-layer circuit board with micro-holes made of laminated composite materials in a dry environment for several minutes to allow the absolute ethanol remaining in the blind holes to volatilize.

[0058] S3. Positioning of the automatic solder feeding mechanism 11: As Figure 2 shown in d, use an industrial camera for assistance or manual focusing to align the nozzle of the automatic solder feeding mechanism 11 with the center of the micro-hole.

[0059] S4. Solder ball filling of the automatic solder feeding mechanism: As Figure 2 shown in e, adjust the laser focal length of the automatic solder feeding mechanism to the nozzle, load the solder balls into the interior of the automatic solder feeding mechanism so that the solder balls can be stuck at the nozzle of the automatic solder feeding mechanism, and introduce high-pressure protective gas 12 into the automatic solder feeding mechanism 11. In this embodiment, the selected solder ball has a diameter of 200 μm, the material is SAC305, and the melting point is 183 °C.

[0060] S5. Metallization of the micro-holes: As Figure 2 shown in f, turn on the automatic solder feeding mechanism for laser heating. The laser focusing on the solder ball at the nozzle heats the solder ball, so that the molten solder ball is ejected from the nozzle by the high-pressure protective gas and sprayed into the micro-holes in the high-pressure protective gas, realizing the metallization of the blind holes. As Figure 2 shown in g, realize the rapid metallization of the vertical interconnection micro-holes between the inner and outer layers of the multi-layer circuit and the intermediate technical conductive layer.

[0061] Conductivity test of the multi-layer circuit with laminated composite materials after rapid metallization of the vertical interconnection micro-holes: Measure the resistance value between the conductive layer 2 and the surface of the blind hole filling to determine the conductivity of the micro-hole metallization. For the blind holes that fail to conduct electricity successfully, repeat steps (4) and (5) to re-metallize the micro-holes and realize the electrical interconnection between the circuit conductive layer 2 and the micro-holes.

[0062] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for metallizing vertically interconnected microvias in a laminated composite material multilayer circuit, characterized in that: The metallization method comprises the following steps: Solid solder balls are filled into the vertically interconnected micropores of the laminated composite material multilayer circuit, and the solder balls are heated by laser to melt the solder balls and fill the micropores, thereby realizing the metallization of the vertically interconnected micropores; or, the solder balls are heated by laser in a high-pressure protective gas atmosphere so that the molten solder balls are sprayed into the micropores under the action of the high-pressure protective gas, thereby realizing the metallization of the vertically interconnected micropores.

2. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit as claimed in claim 1, characterized in that: After placing a solid solder ball in the nozzle of an automated solder delivery mechanism, high-pressure protective gas is introduced into the nozzle, and the solder ball is heated by a laser, so that the molten solder ball is sprayed into the micropores under the action of the high-pressure protective gas, thereby realizing the metallization of vertically interconnected micropores.

3. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit as claimed in claim 1, characterized in that: After solid solder balls are filled into vertically interconnected micro-holes of a laminated composite multi-layer circuit, solder flux is placed in the micro-holes, and the laminated composite multi-layer circuit is heated, and then the solder balls are heated by laser to melt the solder balls and fill the micro-holes.

4. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit as claimed in claim 1, characterized in that: The diameter of the solder ball is larger than the nozzle diameter of the automatic solder feeding mechanism.

5. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit as claimed in claim 1, characterized in that: Solid solder balls are filled into an automated tin feeding mechanism, and high-pressure protective gas is connected to the nozzle of the automated tin feeding mechanism; then, the nozzle of the automated tin feeding mechanism is aimed at the micropores, and the tin balls in the nozzle are heated by a laser. The high-pressure protective gas causes the tin ball particles to melt and be sprayed into the micropores along with the high-pressure protective gas, contacting the conductive layer in the multi-layer circuit of the laminated composite material, thereby completing the metallization of the vertically interconnected micropores of the inner and outer layers of the multi-layer circuit and the intermediate metal conductive layer.

6. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit according to any one of claims 1 to 5, characterized in that: The microholes are blind holes.

7. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit according to any one of claims 1 to 5, characterized in that: The diameter of the solder ball is less than 1 / 2 of the diameter of the microvia to be filled.

8. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit according to any one of claims 1 to 5, characterized in that: The laser is one or more segments.

9. The method for metallizing vertically interconnected microvias of a laminated composite material multilayer circuit as claimed in claim 3, characterized in that: The soldering flux is liquid soldering flux, and a brush is used to brush the soldering flux into the micropores so that the soldering flux is in full contact with the solder ball particles.

10. A laminated composite material multilayer circuit, characterized in that: The micro-holes of the multi-layer circuit are metallized by the metallization method of vertically interconnected micro-holes of a multi-layer circuit of a laminated composite material as described in any one of claims 1 to 9 to achieve interconnection with the conductive layer.

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