Supernormal dry film plug hole device and method

Abstract

The present application relates to printed circuit board manufacturing technology field, specifically said is super conventional dry film plug hole device and method, including: upper die holder, the upper die holder inside is formed with upper chamber, the upper chamber is connected with vacuum / positive pressure switching system, the lower surface of the upper die holder is equipped with the capillary hole that communicates with the upper chamber;And lower die holder, the lower die holder inside is formed with glue injection cavity, the glue injection cavity is connected with glue injection system, the upper surface of the lower die holder is equipped with the glue injection pipe that communicates with the glue injection cavity.The present application is by printed board "inversion", plug hole face down, resin is injected from below, air is discharged from above;Make the hole bubble residual significantly reduce;At the same time, the capillary hole for intercepting resin is arranged in the upper die holder, so that the plug hole of different aperture on the same printed board is filled in turn under the unified negative pressure parameter and glue injection pressure according to the aperture from big to small, solve the problem of big hole in traditional scheme and small hole exhaust deficiency.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board manufacturing technology, specifically to an unconventional dry film via plugging device and an unconventional dry film via plugging method. Background Technology

[0002] In the field of printed circuit board manufacturing, via plugging is one of the key processes, mainly used to fill vias to meet electrical performance and surface flatness requirements. Traditional resin via plugging usually adopts a positive arrangement of "top screen printing and bottom vacuuming", that is, the printed circuit board is placed horizontally with the plugging side facing upwards, and resin is scraped into the hole from above through screen printing. At the same time, negative pressure is applied to the back of the printed circuit board, and the pressure difference is used to assist the resin to fill downwards and expel the air in the hole from the bottom.

[0003] The technical solution has the following problems in actual production:

[0004] Firstly, the buoyancy of air bubbles in the resin is upward, while the evacuation direction is downward. Since the two directions are opposite, the air bubbles need to overcome gravity and the viscous resistance of the resin to pass through the resin layer to be discharged. The venting path is long and the resistance is high, which can easily lead to the formation of residual air bubbles in the pores, affecting the plugging quality and subsequent reliability.

[0005] Secondly, since there are often multiple pore sizes on the same printed circuit board, under the action of uniform negative pressure, the large pores have smooth exhaust paths and fast exhaust, and are preferentially filled by resin. However, the small pores have narrow exhaust paths and high flow resistance, and have not yet been fully filled. If suction continues, it is easy to cause "over-suction" of the large pores and "incomplete filling" of the small pores. Summary of the Invention

[0006] This invention addresses the problems in the prior art by providing an unconventional dry film plugging device and method, the specific technical solution of which is as follows:

[0007] On one hand, the present invention provides an unconventional dry film plugging device, comprising:

[0008] An upper mold base has an upper chamber inside, and a vacuum / positive pressure switching system is connected to the outside of the upper chamber. The lower surface of the upper mold base is provided with capillary pores that communicate with the upper chamber.

[0009] The lower mold base has an injection cavity inside, an injection system is connected to the injection cavity, and an injection tube communicating with the injection cavity is provided on the upper surface of the lower mold base.

[0010] The upper mold base and the lower mold base are arranged opposite each other in the vertical direction, and the upper mold base can move relative to the lower mold base in the vertical direction to switch between the mold opening state and the mold closing state;

[0011] In the mold-closed state, the printed circuit board is horizontally clamped between the upper mold base and the lower mold base with the plug hole face down. The upper end of each plug hole is connected to the corresponding capillary hole to form a gas discharge path; the lower end of each plug hole is connected to the corresponding injection tube to form a resin injection path.

[0012] As a further technical solution of the present invention, a lower film body is provided between the lower surface of the printed circuit board and the upper surface of the lower mold base. A cut is provided on the lower film body corresponding to each of the plug holes. The cut penetrates the lower film body in the vertical direction and forms at least one elastically deformable valve.

[0013] When the injection tube injects glue into the plug hole, the valve flips upward under the injection pressure, the incision opens and forms a channel through which the resin can pass from bottom to top, and after the injection pressure is removed, the valve elastically returns to its original position, the incision closes again, and the channel disappears.

[0014] As a further technical solution of the present invention, a lower chamber is also formed inside the lower mold base, and a vacuum / positive pressure switching system is connected outside the lower chamber. The upper surface of the lower mold base is provided with micropores that communicate with the lower chamber.

[0015] As a further technical solution of the present invention, a plurality of micropores are arranged around the periphery of the top outlet of each of the dispensing tubes.

[0016] As a further technical solution of the present invention, an upper film body is provided between the upper surface of the printed circuit board and the lower surface of the upper mold base. The upper film body has through holes corresponding to the positions of each capillary. In the mold closing state, the upper film body deforms and fills the space between the upper mold base and the printed circuit board, and the upper end of each plug hole communicates with the corresponding capillary through the through hole on the upper film body.

[0017] As a further technical solution of the present invention, the diameter of the through hole is larger than the diameter of the capillary pore and smaller than the diameter of the plug hole.

[0018] As a further technical solution of the present invention, the shape of the cut is one of the following: straight, Y-shaped, cross-shaped, crescent-shaped, multi-segmented, or H-shaped.

[0019] As a further technical solution of the present invention, the upper surface of the lower mold base is formed with a concave positioning groove, the planar shape of the positioning groove matches the shape of the printed circuit board, and the depth of the positioning groove is less than the thickness of the printed circuit board.

[0020] On the other hand, the present invention also provides an unconventional dry film orifice plugging method, employing the unconventional dry film orifice plugging device described in any of the technical solutions, comprising the following steps:

[0021] S1: Apply the film and place it;

[0022] The lower mold body is attached to the lower surface of the printed circuit board, and each cut on the lower mold body is aligned with each plug hole on the printed circuit board. The printed circuit board with the lower mold body is placed between the upper mold base and the lower mold base in the mold-open state with the lower mold body facing down, and is placed on the upper surface of the lower mold base.

[0023] S2: Mold clamping and pressing;

[0024] The drive device drives the upper mold base to move downward to the clamping position, and the device enters the mold closing state. The lower surface of the upper mold body is tightly attached to the upper surface of the printed circuit board, and the lower surface of the lower mold body is tightly attached to the upper surface of the lower mold base. The upper end of each plug hole is connected to the corresponding capillary through the through hole on the upper mold body, and the lower end of each plug hole is connected to the corresponding injection tube through the cut on the lower mold body.

[0025] S3: Pre-absorption sealing and pre-vacuuming;

[0026] Activate the vacuum / positive pressure switching system on the lower mold base side to establish negative pressure in the lower chamber, and adsorb the lower film onto the upper surface of the lower mold base through each micropore, forming an annular seal around the top outlet of each injection tube; activate the vacuum / positive pressure switching system on the upper mold base side to establish negative pressure in the upper chamber, and pre-evacuate the inside of each plug hole through each capillary and each through hole on the upper film.

[0027] S4: Low-pressure injection;

[0028] The resin injection system is started, and the resin is delivered to the bottom of each plug hole through the injection chamber and each injection tube. The resin passes through the opening on the lower membrane body and enters the interior of each plug hole. During the injection process, the negative pressure in the upper chamber continuously acts on the top of each plug hole, drawing the gas in the plug hole upward and expelling it.

[0029] S5: Incision closed;

[0030] After the glue injection is completed, stop the glue injection system, turn off the vacuum supply on the lower mold base side, restore the lower chamber to normal pressure, and the valve of the cut will reset and close under the action of elastic restoring force;

[0031] S6: Air-blown stripping;

[0032] Positive pressure is introduced into the lower chamber, and gas is blown out from each micropore, forming an air cushion between the lower film and the lower mold base, which lifts the lower film away from the upper surface of the lower mold base.

[0033] S7: Take the board;

[0034] The drive unit drives the upper mold base to move upward, removing the printed circuit board with the lower mold body;

[0035] S8: Curing and peeling off the film;

[0036] The printed circuit board with the lower film is cured. After curing, the lower film is removed to obtain a printed circuit board with the vias plugged.

[0037] As a further technical solution of the present invention, after step S7 is completed, it also includes:

[0038] Switch the vacuum / positive pressure switching system on the upper mold base side to positive pressure, introduce positive pressure into the upper chamber, and blow gas downwards from each capillary hole for backflushing cleaning.

[0039] The beneficial effects of this invention are as follows:

[0040] 1. This invention involves "inverting" the printed circuit board, with the plugged hole facing downwards, injecting resin from below and expelling air from above. On one hand, the natural upward direction of the air bubbles aligns with the forced venting direction, allowing the bubbles to be promptly removed simply by rising naturally, significantly reducing residual air bubbles within the holes. On the other hand, the gas in the resin's forward direction continuously decreases as the resin advances, preventing filling delays or bubble rebound caused by the compression of gas at the top forming an air cushion. Simultaneously, the upper mold base is equipped with capillary pores to intercept the resin. When a plugged hole is completely filled with resin first, the corresponding capillary pores, due to their fineness... The capillary interception characteristics of the long channel prevent liquid resin from entering, causing the injection channel to close automatically. The negative pressure in the upper chamber continues to effectively pump out the air from the unfilled plug holes. Driven by the injection pressure, the resin in the injection chamber automatically bypasses the already filled high-resistance holes and flows to the unfilled low-resistance holes. This allows plug holes of different diameters on the same printed circuit board to be automatically filled in descending order of diameter under uniform negative pressure parameters and injection pressure. This fundamentally solves the problems of over-extraction caused by first venting the large-diameter holes and then directly pumping resin under negative pressure in traditional solutions, and incomplete filling caused by insufficient venting of the small-diameter holes.

[0041] (2) The present invention provides an upper film body between the upper mold base and the printed circuit board. The upper film body undergoes elastic deformation under the mold closing pressure, filling the microscopic gap between the lower end face of the upper mold base and the upper surface of the printed circuit board, forming a reliable interface seal. This ensures that the negative pressure in the upper chamber is concentrated on the top of each plug hole through the capillary pores, avoiding negative pressure loss due to interface leakage and improving exhaust efficiency. At the same time, the diameter of the through hole opened on the upper film body is larger than the diameter of the capillary pore and smaller than the diameter of the plug hole. On the one hand, this ensures that the lower opening of the capillary pore falls completely within the upper opening range of the through hole, so that even if there is a slight misalignment during mold closing, there will be no misalignment or obstruction, ensuring unobstructed gas flow path. On the other hand, this ensures that the lower opening of the through hole falls completely within the upper opening boundary of the plug hole. After the liquid resin fills the plug hole, it contacts the lower surface of the upper film body rather than directly impacting the opening of the capillary pore, avoiding the resin from entering and blocking the capillary pore due to capillary action.

[0042] (3) The present invention provides a lower mold body with an elastically openable and closeable slit between the lower surface of the printed circuit board and the lower mold base. When the glue is injected, the slit opens under the injection pressure to form a channel through which the resin can pass from bottom to top, ensuring smooth injection of the resin. After the glue is injected, the injection pressure is removed, and the slit flap automatically resets and closes under its own elastic restoring force, physically sealing the lower outlet of each plug hole and preventing the liquid resin in the plug hole from flowing back downward, thus solving the problem of glue leakage at the bottom of the printed circuit board during transportation.

[0043] (4) The present invention sets up a lower chamber in the lower mold base and arranges multiple micro-holes connected to the lower chamber around the top outlet of each injection tube to form an auxiliary air path independent of the injection system. Before injection, the lower chamber is introduced with negative pressure and the air in the gap between the lower film and the upper surface of the lower mold base is drawn through each micro-hole. An annular sealing surface is formed around the outlet of each injection tube. This not only prevents the resin from overflowing laterally along the interface during injection, causing crosstalk between different plug holes and contamination of the board surface, but also eliminates the risk of air bubbles caused by the trapped air under the film being forced into the resin. After the injection is completed and the cut is closed, the lower chamber is switched to positive pressure and the gas is blown out evenly from each micro-hole to form a uniform air cushion between the lower film and the lower mold base. This lifts the lower film off the surface of the lower mold base in parallel as a whole, achieving stress-free peeling, avoiding disturbance of the uncured resin in the plug hole by mechanical tearing, ensuring the plug hole quality and facilitating board removal. Attached Figure Description

[0044] Figure 1 A schematic diagram showing the upper and lower mold bases in their open states is provided.

[0045] Figure 2 A schematic diagram showing the upper and lower mold bases in the closed state is provided.

[0046] Figure 3 A schematic diagram of the upper mold base is shown;

[0047] Figure 4 A schematic diagram of the lower mold base is shown;

[0048] Figure 5 It shows Figure 4 Enlarged view at point B in the middle;

[0049] Figure 6 A diagram showing the distribution relationship between micropores and dispensing tubes is presented;

[0050] Figure 7 It shows Figure 2 Enlarged view of point A in the middle;

[0051] Figure 8 A schematic diagram showing the incision closed is provided.

[0052] Figure 9 A schematic diagram showing the incision in its open state is provided.

[0053] Explanation of reference numerals in the attached figures:

[0054] 10. Upper mold base; 11. Upper cavity; 12. Capillary pores;

[0055] 20. Upper membrane body; 21. Through-hole;

[0056] 30. Printed circuit board; 31. Via plug;

[0057] 40. Inferior membrane body; 41. Incision; 42. Valve; 43. Channel;

[0058] 50. Lower mold base; 51. Injection cavity; 52. Injection tube; 53. Positioning groove; 54. Lower chamber; 521. Microhole. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0060] Example 1

[0061] This embodiment provides an unconventional dry film via plugging device for resin plugging of vias 31 on a printed circuit board 30. The printed circuit board 30 has a plurality of vias 31, and the diameters of the vias 31 are not exactly the same. This embodiment uses the example of vias 31 on the printed circuit board 30 having different diameters for illustration, but this device is also applicable to printed circuit boards with the same diameter of vias 31.

[0062] Figure 1 and Figure 2 A schematic diagram of the unconventional dry film plugging device is shown; in which, Figure 1 A schematic diagram showing the upper mold base 10 and lower mold base 50 in the mold opening state is shown; Figure 2 A schematic diagram of the upper mold base 10 and lower mold base 50 in the mold-closing state is shown. The plugging device includes an upper mold base 10, an upper mold body 20, a printed circuit board 30, a lower mold body 40, and a lower mold base 50 arranged vertically from top to bottom. Both the upper mold base 10 and the lower mold base 50 are horizontally arranged and are vertically opposite each other. A driving device is connected to the top of the upper mold base 10, and the upper mold base 10 moves vertically towards or away from the lower mold base under the drive of this driving device. 50, thereby switching between the mold opening state and the mold closing state; the printed circuit board 30 is horizontally clamped in the space between the upper mold base 10 and the lower mold base 50, the lower mold body 40 is clamped between the lower surface of the printed circuit board 30 and the upper surface of the lower mold base 50, and the upper mold body 20 is clamped between the lower end face of the upper mold base 10 and the upper surface of the printed circuit board 30; in the mold closing state, the upper mold base 10, the upper mold body 20, the printed circuit board 30, the lower mold body 40 and the lower mold base 50 are stacked and pressed together in sequence.

[0063] like Figure 1 As shown, in the mold-open state, the upper mold base 10 is located at a predetermined height above the lower mold base 50. There is a gap between the upper mold base 10 and the lower mold base 50 to accommodate the printed circuit board 30 and the lower film 40. The printed circuit board 30, together with the lower film 40 attached to its lower surface, is placed between the upper mold base 10 and the lower mold base 50 with the lower film 40 facing downwards, and is placed on the upper surface of the lower mold base 50. At this time, there is a gap between the lower surface of the upper film 20 and the upper surface of the printed circuit board 30.

[0064] like Figure 2 As shown, in the mold-closed state, the upper mold base 10 is driven by the driving device to move downward to the pressing position. At this time, from top to bottom, the components are: upper mold base 10, upper mold body 20, printed circuit board 30, lower mold body 40, and lower mold base 50. The lower surface of the upper mold body 20 is in close contact with the upper surface of the printed circuit board 30, and the lower surface of the lower mold body 40 is in close contact with the upper surface of the lower mold base 50. The device can then perform subsequent steps.

[0065] In this embodiment, the driving device is one of the following: a cylinder, a hydraulic cylinder, a servo electric cylinder, a cam mechanism, a crank-connecting rod mechanism, a lead screw and nut mechanism, or an electromagnetic drive mechanism, without excessive protection or restrictions.

[0066] Figure 3 A schematic diagram of the upper mold base 10 is shown. An upper chamber 11 is formed inside the upper mold base 10. A vacuum / positive pressure switching system is connected to the upper chamber 11. The vacuum / positive pressure switching system is used to selectively introduce negative pressure or positive pressure into the upper chamber 11. A capillary hole 12 corresponding to the plug hole 31 is formed on the lower end face of the upper mold base 10. One end of each capillary hole 12 opens to the lower end face of the upper mold base 10, and the other end communicates with the upper chamber 11. After the mold is closed, the lower end opening of each capillary hole 12 is exactly aligned with the upper end opening of its corresponding plug hole 31, forming a complete gas flow path from the inside of the plug hole 31 through the capillary hole 12 to the upper chamber 11.

[0067] In the above structure, the working mode of the upper chamber 11 and the capillary 12 working together is divided into two stages:

[0068] First stage: Vacuum-assisted degassing during the glue injection process; Before and during glue injection, the vacuum / positive pressure switching system is switched to the vacuum side, and a negative pressure is established in the upper chamber 11. This negative pressure is transmitted to the top of each plug hole 31 through each capillary pore 12, drawing out the air and micro bubbles that may remain in the resin in the plug hole 31 upwards, and assisting the resin to fill smoothly.

[0069] Second stage: Positive pressure backflushing self-cleaning after glue injection; After glue injection is completed and the printed circuit board 30 is removed, the vacuum / positive pressure switching system can be switched to the positive pressure side, and a small amount of positive pressure is introduced into the upper chamber 11. Compressed gas is blown downward from the upper chamber 11 through each capillary pore 12, blowing away any trace amounts of resin droplets or volatiles that may remain near the lower end of the capillary pore 12.

[0070] Figure 4 A schematic diagram of the lower mold base 50 is shown. A glue injection cavity 51 is formed inside the lower mold base 50. The glue injection cavity 51 is connected to a glue injection system through a pipe. A glue injection tube 52 corresponding to the plug hole 31 is embedded on the upper end face of the lower mold base 50. One end of each glue injection tube 52 is open on the upper end face of the lower mold base 50, and the other end is connected to the glue injection cavity 51. After the mold is closed, the top opening of each glue injection tube 52 is exactly aligned with the bottom opening of its corresponding plug hole 31, forming a resin delivery channel from the glue injection cavity 51 through the glue injection tube 52 to the inside of the plug hole 31. The glue injection cavity 51 serves as a common chamber, and the bottom ends of all the glue injection tubes 52 are connected in parallel to the same glue injection pressure source. During glue injection, the resin fills the glue injection cavity 51 under the pressure provided by the glue injection system and is evenly distributed to the bottom of each plug hole 31 through each glue injection tube 52.

[0071] Combination Figure 3 and Figure 4 The cooperation between the upper mold base 10 and the lower mold base 50 is described. After mold closing, the upper end of each plug hole 31 is connected to the corresponding capillary 12 through the upper mold body 20, and the lower end of each plug hole 31 is connected to the corresponding injection tube 52 through the cut 41 on the lower mold body 40. The vacuum / positive pressure switching system on the upper mold base 10 side is activated to establish a negative pressure in the upper chamber 11. This negative pressure is transmitted to the top of each plug hole 31 through each capillary 12 and the upper mold body 20. The injection system is activated to deliver the degassed resin at low pressure through the injection chamber 51 and each injection tube 52 to the bottom of each plug hole 31. The resin flows out from the top outlet of the injection tube 52 and enters the interior of the plug hole 31. During the injection process, the top of each plug hole 31 continuously bears the negative pressure transmitted by the upper chamber 11. This negative pressure continuously removes air and resin impurities from the plug hole 31. The residual microbubbles are drawn upwards, keeping the top of the plug hole 31 under a low back pressure. Under the combined action of the bottom injection pressure and the top negative pressure, the resin fills upwards at a stable flow rate. This invention inverts the printed circuit board 30 with the plug hole facing downwards, injects resin from below and exhausts air from above. On the one hand, the buoyancy of the bubbles in the resin is upward, and the negative pressure applied by the capillary pores 12 at the top of the plug hole 31 also draws the gas upwards. The natural upward direction of the bubbles is completely consistent with the forced exhaust direction. The bubbles do not need to move in the opposite direction through the resin layer; they can be promptly removed simply by rising with the force. The exhaust efficiency is greatly improved, and the residual bubbles in the holes are significantly reduced. On the other hand, the gas in the direction of resin advancement continuously decreases as the resin advances, avoiding filling delays or bubble rebound caused by the compression of the gas at the top to form an "air cushion".

[0072] As the resin injection continues, each plugging hole 31 is gradually filled. Because the pore diameters of each plugging hole 31 are different, their internal volumes and flow resistances vary, resulting in varying filling speeds. When a plugging hole 31 is completely filled with resin first, the internal flow changes from a two-phase gas-liquid flow to a pure liquid single-phase flow, causing a sharp increase in internal flow resistance. At this point, the upper chamber 11, through the capillary characteristics of its capillaries 12, intercepts the liquid resin. The airflow within the capillaries 12 corresponding to the plugging hole 31 spontaneously stops, and the resin also stops flowing into the plugging hole 31. Since all the capillaries 12 are connected in parallel, and all the injection tubes 52 are connected in parallel, other unfilled plugging holes 31, due to their... There are still gas channels inside, and the flow resistance is much lower than that of the already filled plug holes 31. Under the drive of the injection pressure, the resin in the injection chamber 51 automatically bypasses the already filled high flow resistance holes and flows to the unfilled low flow resistance holes until all plug holes 31 are filled. Through the above-mentioned flow resistance adaptive mechanism, plug holes 31 of different diameters on the same printed circuit board 30 are automatically filled in descending order of diameter under the same negative pressure parameters and injection pressure. The first to be filled automatically stops injection and venting, while the last to be filled continues injection and venting. This fundamentally solves the problems of over-extraction caused by first venting the large diameter holes and then directly sucking the resin under negative pressure in the traditional solution, and insufficient venting of the small diameter holes leading to incomplete filling.

[0073] See also Figure 4 A recessed positioning groove 53 is formed on the upper end face of the lower mold base 50. The planar shape of the positioning groove 53 matches the shape of the printed circuit board 30, and is used to accommodate and horizontally position the printed circuit board 30, so that each plug hole 31, each capillary hole 12, and each injection tube 52 remain aligned after mold closing. The depth of the positioning groove 53 is less than the thickness of the printed circuit board 30, so that after the printed circuit board 30 is placed in the positioning groove 53, the upper surface of the printed circuit board 30 is higher than the upper end face of the lower mold base 50. This facilitates the upper mold base 10 to press the printed circuit board 30. In the closed state, the upper mold base 10 moves to the pressing position and presses the printed circuit board 30 into the positioning groove 53. At this time, the upper surface of the printed circuit board 30 is higher than the upper end surface of the lower mold base 50, and the lower end surface of the upper mold base 10 only contacts the upper surface of the printed circuit board 30. A small gap is left between the lower end surface of the upper mold base 10 and the upper end surface of the lower mold base 50 to ensure that the pressing force is concentrated on the printed circuit board 30.

[0074] Figure 5 It shows Figure 4Enlarged view at point B: A lower chamber 54 is formed inside the lower mold base 50. The lower chamber 54 is connected to a vacuum / positive pressure switching system. A microhole 521 is formed on the upper end face of the lower mold base 50. One end of the microhole 521 opens into the upper end face of the lower mold base 50, and the other end connects to the lower chamber 54. On the one hand, before the glue is injected, a negative pressure is formed in the lower chamber 54. The air in the gap between the lower film body 40 and the lower mold base 50 is drawn out through the microhole 521, so that the lower film body 40 and the lower mold base 50 are more tightly bonded, and the resin is prevented from overflowing into the gap between the lower film body 40 and the lower mold base 50. On the other hand, after the glue is injected and the upper mold base 10 and the lower mold base 50 are separated, a positive pressure is formed in the lower chamber 54. The printed circuit board 30 is lifted through the microhole 521, making it easy to remove the glue-injected printed circuit board 30.

[0075] Figure 6 The diagram shows the distribution relationship between the micropores 521 and the injection tube 52; each injection tube 52 is surrounded by multiple micropores 521 at intervals; when the micropores 521 draw in air from the gap between the lower mold body 40 and the lower mold base 50, the multiple micropores 521 surrounding the injection tube 52 can cooperate with each other to form an annular sealing surface, thus forming a sealed protection for the injection port of the injection tube 52.

[0076] Figure 5 Combination Figure 6 The lower chamber 54 and the micropores 521 constitute an auxiliary air path independent of the glue injection system, and its function is divided into two stages:

[0077] First stage: Pre-absorption sealing before glue injection; Before the glue injection begins, the vacuum / positive pressure switching system switches to the vacuum side, establishing a negative pressure in the lower chamber 54. This negative pressure is transmitted through each micropore 521 to the micro gap between the lower surface of the lower mold body 40 and the upper end face of the lower mold base 50. Since each injection tube 52 is surrounded by a ring of micropores 521, each micropore 521 simultaneously draws in the gas from the outer region of its corresponding injection tube 52, forming an annular low-pressure zone around the top outlet of each injection tube 52. This annular low-pressure zone firmly adheres the lower surface of the lower film body 40 to the upper end face of the lower mold base 50, forming an annular sealing surface around the outlet of the injection tube 52. This annular sealing surface confines the outlet of the injection tube 52 to a closed area. During subsequent injection, the resin can only flow upward into the corresponding plug hole 31 after it flows out of the injection tube 52, and cannot overflow laterally along the interface between the lower film body 40 and the lower mold base 50. This avoids crosstalk between different plug holes 31 and resin contamination of the upper end face of the lower mold base 50. At the same time, since the air between the lower film body 40 and the lower mold base 50 is pre-extracted, the risk of air bubbles caused by trapped air under the film being forced into the resin is eliminated.

[0078] The second stage: air-blowing peeling after glue injection; After glue injection is completed and the cut 41 on the lower film 40 is closed, the vacuum / positive pressure switching system is switched to the positive pressure side, and a small amount of positive pressure is introduced into the lower chamber 54. The pressure is preferably 0.01-0.02MPa. Compressed gas is blown out evenly from each micropore 521, forming a uniform air cushion between the lower surface of the lower film 40 and the upper end face of the lower mold base 50. This air cushion overcomes the slight residual vacuum adsorption force that may exist between the lower film 40 and the upper end face of the lower mold base 50, and evenly lifts the lower film 40 from the upper surface of the lower mold base 50. Since the micropores 521 are evenly distributed around each glue injection tube 52, the lifting force acts around each glue injection tube 52, and the lower film 40 is lifted in parallel as a whole. There will be no tilting or tearing caused by local peeling first, avoiding the disturbance of uncured resin in the plug hole 31 by mechanical tearing, and ensuring the plugging quality.

[0079] Figure 7 It shows Figure 2 Enlarged view at point A; the upper film 20 is attached to the lower surface of the upper mold base 10 and rises and falls together with the upper mold base 10. Each time the mold is closed, it undergoes slight deformation under the clamping force of the upper mold base 10, filling any tiny gaps that may exist between the lower end face of the upper mold base 10 and the upper surface of the printed circuit board 30, thus achieving interface sealing between the upper film 20 and the upper surface of the printed circuit board 30; the upper film 20 has through holes 21 corresponding to the capillary pores 12, the diameter of the through holes 21 is larger than the diameter of the capillary pores 12 and smaller than the diameter of the plug holes 31; on the one hand, the diameter of the through holes 21 is larger than the diameter of the capillary pores 12, ensuring that the capillary pores 12 are sealed. The lower opening of 2 falls completely within the upper opening of the through hole 21. Even if there is a slight misalignment during the mold closing process, there will be no misalignment or obstruction between the capillary 12 and the through hole 21, ensuring the smooth flow of gas. On the other hand, the diameter of the through hole 21 is smaller than the diameter of the plug hole 31, so that the lower opening of the through hole 21 falls completely within the upper opening boundary of the plug hole 31 after the mold is closed. After the liquid resin fills the plug hole 31, it contacts the lower surface of the upper film body 20 rather than the hole wall of the through hole 21, preventing the resin from climbing up along the hole wall of the through hole 21 and entering the capillary 12 due to capillary action.

[0080] Figure 8 and Figure 9 A schematic diagram of the lower membrane body 40 is shown; wherein, Figure 8 A schematic diagram of the closed state of incision 41 is shown; Figure 9A schematic diagram of the open state of the incision 41 is shown; the lower membrane body 40 has an incision 41 corresponding to the plug hole 31, the incision 41 penetrates the lower membrane body 40 vertically and forms at least one elastically deformable valve 42; under normal conditions, the valve 42 relies on its own elastic restoring force to keep the incision 41 closed, blocking the fluid communication between the upper and lower spaces of the lower membrane body 40; when the lower surface of the lower membrane body 40 is subjected to the injection pressure from bottom to top, the valve 42 flips up, the incision 41 is in the open state, forming a channel 43 through which the resin can pass from bottom to top; when the external force is removed, the valve 42 resets under the action of the elastic restoring force, the channel 43 disappears, and the incision 41 returns to the closed state.

[0081] like Figure 8 and Figure 9 As shown, in this embodiment, the incision 41 is designed as a Y-shaped structure, wherein the valve 42 is formed of three pieces; while in some other embodiments, the shape of the incision 41 can also be one of the following: straight, cross, crescent, multi-segment, or H-shaped. Among them, the straight-line structure consists of a single slit, with two valves 42. It has the simplest structure, a low opening threshold, and is suitable for low-viscosity resins or small-diameter plugging. The cross-shaped structure consists of two perpendicularly intersecting slits, with four valves 42. It has a longer sealing line when closed and is suitable for medium-viscosity resins. It is another preferred form of this solution. The crescent-shaped structure consists of an arc-shaped slit, with one valve 42. When closed, the valve fits along the arc, providing good sealing. It is suitable for scenarios with high requirements for preventing backflow. The multi-segment structure consists of three or more intersecting slits, with five or more valves 42. It has a large channel cross-sectional area when open and is suitable for high-viscosity resins or scenarios requiring a large injection flow rate. The I-shaped structure consists of three slits, with four valves 42. Its valve shape is rectangular, and the channel cross-section is rectangular when open. It is suitable for specific flow channel matching requirements. The shape of each slit 41 can be flexibly selected according to factors such as the characteristics of the resin used, the plugging orifice diameter, and the injection pressure. It is not exhaustive here.

[0082] Example 2

[0083] This embodiment provides an unconventional dry film via-filling method, employing the unconventional dry film via-filling device described in this embodiment to fill each via 31 on the printed circuit board 30 with resin. The via diameters of each via 31 are not identical. The method includes the following steps:

[0084] S1: Apply the film and place it;

[0085] The lower mold body 40 is attached to the lower surface of the printed circuit board 30, so that each cut 41 on the lower mold body 40 is aligned with each plug hole 31 on the printed circuit board 30. Then, the printed circuit board 30 with the lower mold body 40 is placed between the upper mold base 10 and the lower mold base 50 in the mold opening state with the lower mold body 40 facing downward, and is placed in the positioning groove 53 on the upper surface of the lower mold base 50. The side wall of the positioning groove 53 restricts the horizontal displacement of the printed circuit board 30, so that each plug hole 31 and each capillary hole 12 on the upper mold base 10 and each injection tube 52 on the lower mold base 50 remain aligned during subsequent mold closing.

[0086] S2: Mold clamping and pressing;

[0087] The driving device drives the upper mold base 10 to move downward to the clamping position, and the device enters the mold closing state. At this time, the lower surface of the upper mold body 20 is closely attached to the upper surface of the printed circuit board 30. The upper mold body 20 undergoes slight elastic deformation under the clamping force, filling the micro gap between the lower end face of the upper mold base 10 and the upper surface of the printed circuit board 30, forming an interface seal. The lower surface of the lower mold body 40 is closely attached to the upper surface of the lower mold base 50. The upper end of each plug hole 31 is connected to the corresponding capillary pore 12 through the through hole 21 on the upper mold body 20, and the lower end of each plug hole 31 is connected to the corresponding injection tube 52 through the cut 41 on the lower mold body 40.

[0088] S3: Pre-absorption sealing and pre-vacuuming;

[0089] The vacuum / positive pressure switching system on the lower mold base 50 side is activated to establish a negative pressure in the lower chamber 54. This negative pressure acts on the lower surface of the lower membrane body 40 through each micropore 521, forming an annular sealing surface around the top outlet of each injection tube 52. This prevents the resin from overflowing laterally along the interface between the lower membrane body 40 and the lower mold base 50 during subsequent injection, and also eliminates the risk of air bubbles caused by trapped air under the membrane being forced into the resin. At the same time, the vacuum / positive pressure switching system on the upper mold base 10 side is activated to establish a negative pressure in the upper chamber 11. This negative pressure is transmitted to the top of each plug hole 31 through each capillary pore 12 and each through hole 21 on the upper membrane body 20, pre-vacuuming the inside of each plug hole 31 and venting some of the air inside the hole before resin injection.

[0090] S4: Low-pressure injection;

[0091] The glue injection system is started, and the degassed resin is delivered at low pressure through the glue injection chamber 51 and each glue injection tube 52 to the bottom of each plug hole 31. The resin flows out from the top outlet of the glue injection tube 52. Under the pressure below the lower membrane body 40, the valve 42 of the cut 41 flips up, the cut 41 opens to form a channel 43, and the resin enters the interior of each plug hole 31 through the channel 43.

[0092] During the injection process, the negative pressure in the upper chamber 11 continuously acts on the top of each plug hole 31, continuously drawing out residual air and microbubbles that may be trapped in the resin. Since the printed circuit board 30 adopts an inverted layout with the plug hole surface facing down, the resin is injected from below and the air is discharged from above. The natural upward floating direction of the bubbles is completely consistent with the forced exhaust direction. The bubbles do not need to move in the opposite direction through the resin layer. They can be drawn away in time as they rise, greatly improving the exhaust efficiency. At the same time, the gas in the resin forward direction continues to decrease as the resin advances, avoiding filling delay or bubble rebound caused by the compression of the gas at the top forming an air cushion.

[0093] S5: Flow resistance adaptive filling;

[0094] As the resin injection continues, each plugging hole 31 is gradually filled. Due to the different diameters of the plugging holes 31, their internal volumes and flow resistances vary, resulting in varying filling speeds. When a plugging hole 31 is completely filled with resin first, the internal flow changes from a two-phase gas-liquid flow to a pure liquid single-phase flow, causing a sharp increase in internal flow resistance. At this point, the capillary pores 12 corresponding to this plugging hole 31, due to their slender capillary interception characteristics, prevent liquid resin from entering, causing the airflow to stop spontaneously, and the venting channel of this plugging hole 31 closes automatically. Simultaneously, the resin flow in the injection tube 52 corresponding to this plugging hole 31 spontaneously stops due to the significant viscous resistance of the downstream liquid column, and the injection channel of this plugging hole 31 also closes automatically.

[0095] Since all capillary pores 12 are connected in parallel to the same upper chamber 11, and all dispensing tubes 52 are connected in parallel to the same dispensing cavity 51, and the flow resistance of the filled orifices 31 is much higher than that of the unfilled orifices 31, the negative pressure in the upper chamber 11 continues to effectively pump out the air from the unfilled orifices 31. Driven by the dispensing pressure, the resin in the dispensing cavity 51 automatically bypasses the filled high-flow-resistance orifices and flows towards the unfilled low-flow-resistance orifices. Under uniform negative pressure parameters and dispensing pressure, the orifices 31 of different diameters on the same printed circuit board 30 are automatically filled in descending order of diameter. The orifices filled first automatically stop dispensing and venting, while the orifices filled later continue dispensing and venting until all orifices 31 are filled. This process is entirely driven by the difference in flow resistance, without the need for any sensors to detect the filling status, without the need to set up partitioned pipelines or independent valves for different orifice diameters, and without the need to dynamically adjust process parameters during the dispensing process.

[0096] S6: Incision closed;

[0097] After the glue injection is completed, the glue injection system is stopped. The vacuum supply on the lower mold base 50 side is turned off, the lower chamber 54 returns to normal pressure, and the valve 42 of the incision 41 resets under the action of the elastic restoring force of the lower membrane body 40. The incision 41 returns from the open state to the closed state, physically sealing the lower outlet of each plug hole 31 and preventing the liquid resin in the plug hole 31 from flowing back downward. This closing action is completed spontaneously, with a fast response speed, and requires no external driving force or control signal.

[0098] S7: Air-blown stripping;

[0099] Switch the vacuum / positive pressure switching system on the lower mold base 50 side to the positive pressure side, introduce a small amount of positive pressure into the lower chamber 54, and blow compressed gas evenly out from each micropore 521 to form a uniform air cushion between the lower surface of the lower film body 40 and the upper surface of the lower mold base 50. This air cushion overcomes the slight adsorption force that may exist between the lower film body 40 and the upper end face of the lower mold base 50, and evenly lifts the lower film body 40 from the upper surface of the lower mold base 50. Since the micropores 521 are evenly distributed around each injection tube 52, the lifting force acts around each injection tube 52, and the lower film body 40 is lifted in parallel as a whole. There will be no tilting or tearing caused by local peeling, and mechanical tearing will avoid disturbing the uncured resin in the plug hole 31.

[0100] S8: Remove board;

[0101] The drive device drives the upper mold base 10 to move upward, and the upper film body 20, the printed circuit board 30 and the lower film body 40 rise together with the upper mold base 10 and separate from the lower mold base 50, so that the printed circuit board 30 with the lower film body 40 is taken out from the device.

[0102] S9: Curing and peeling off the film;

[0103] The printed circuit board 30 with the lower film 40 is sent into a curing oven for heat curing. During the curing process, the lower film 40 is always attached to the lower surface of the printed circuit board 30, and the cut 41 remains closed at high temperature to continuously provide leak protection. After curing, the lower film 40 is peeled off from the lower surface of the printed circuit board 30 to obtain the printed circuit board 30 with the hole plugged. The lower film 40 is discarded as a disposable consumable.

[0104] S10: Backflush cleaning;

[0105] After the printed circuit board 30 is removed, a backflushing cleaning step can be performed: switch the vacuum / positive pressure switching system on the upper mold base 10 side to the positive pressure side, introduce a small amount of positive pressure into the upper chamber 11, and blow compressed gas downward from each capillary 12 to blow away any trace amounts of resin droplets or volatiles that may remain near the lower end of the capillary 12, keeping the capillary 12 clean and unobstructed, and preparing for the next working cycle. This step can be performed after each plugging cycle or once after several cycles.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A sub- conventional dry film plug device, characterized in that, include: An upper mold base has an upper chamber inside, and a vacuum / positive pressure switching system is connected to the outside of the upper chamber. The lower surface of the upper mold base is provided with capillary pores that communicate with the upper chamber. The lower mold base has an injection cavity inside, an injection system is connected to the injection cavity, and an injection tube communicating with the injection cavity is provided on the upper surface of the lower mold base. The upper mold base and the lower mold base are arranged opposite each other in the vertical direction, and the upper mold base can move relative to the lower mold base in the vertical direction to switch between the mold opening state and the mold closing state; In the mold-closed state, the printed circuit board is horizontally clamped between the upper mold base and the lower mold base with the plug hole face down. The upper end of each plug hole is connected to the corresponding capillary hole to form a gas discharge path; the lower end of each plug hole is connected to the corresponding injection tube to form a resin injection path.

2. The unconventional dry film plugging device according to claim 1, characterized in that, A lower film is provided between the lower surface of the printed circuit board and the upper surface of the lower mold base. A cut is provided on the lower film corresponding to each of the plug holes. The cut penetrates the lower film in the vertical direction and forms at least one elastically deformable valve. When the injection tube injects glue into the plug hole, the valve flips upward under the injection pressure, the incision opens and forms a channel through which the resin can pass from bottom to top, and after the injection pressure is removed, the valve elastically returns to its original position, the incision closes again, and the channel disappears.

3. The unconventional dry film plugging device according to claim 1, characterized in that, The lower mold base also has a lower chamber, which is connected to a vacuum / positive pressure switching system. The upper surface of the lower mold base is provided with micropores that communicate with the lower chamber.

4. The unconventional dry film plugging device according to claim 3, characterized in that, Each of the dispensing tubes has a plurality of micropores arranged around its top outlet.

5. The unconventional dry film plugging device according to claim 1, characterized in that, An upper film is provided between the upper surface of the printed circuit board and the lower surface of the upper mold base. The upper film has through holes corresponding to the positions of each capillary. In the mold-closed state, the upper film deforms and fills the space between the upper mold base and the printed circuit board, and the upper end of each plug hole communicates with the corresponding capillary through the through hole on the upper film.

6. The unconventional dry film plugging device according to claim 5, characterized in that, The diameter of the through hole is larger than the diameter of the capillary pore and smaller than the diameter of the plug hole.

7. The unconventional dry film plugging device according to claim 2, characterized in that, The shape of the cut is one of the following: straight, Y-shaped, cross-shaped, crescent-shaped, multi-segmented, or I-shaped.

8. The unconventional dry film plugging device according to claim 1, characterized in that, The upper surface of the lower mold base has a recessed positioning groove, the planar shape of which matches the shape of the printed circuit board, and the depth of the positioning groove is less than the thickness of the printed circuit board.

9. An unconventional dry film orifice plugging method, employing the unconventional dry film orifice plugging device according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1: Apply the film and place it; The lower mold body is attached to the lower surface of the printed circuit board, and each cut on the lower mold body is aligned with each plug hole on the printed circuit board. The printed circuit board with the lower mold body is placed between the upper mold base and the lower mold base in the mold-open state with the lower mold body facing down, and is placed on the upper surface of the lower mold base. S2: Mold clamping and pressing; The drive device drives the upper mold base to move downward to the clamping position, and the device enters the mold closing state. The lower surface of the upper mold body is tightly attached to the upper surface of the printed circuit board, and the lower surface of the lower mold body is tightly attached to the upper surface of the lower mold base. The upper end of each plug hole is connected to the corresponding capillary through the through hole on the upper mold body, and the lower end of each plug hole is connected to the corresponding injection tube through the cut on the lower mold body. S3: Pre-absorption sealing and pre-vacuuming; Activate the vacuum / positive pressure switching system on the lower mold base side to establish negative pressure in the lower chamber, and adsorb the lower film onto the upper surface of the lower mold base through each micropore, forming an annular seal around the top outlet of each injection tube; activate the vacuum / positive pressure switching system on the upper mold base side to establish negative pressure in the upper chamber, and pre-evacuate the inside of each plug hole through each capillary and each through hole on the upper film. S4: Low-pressure injection; The resin injection system is started, and the resin is delivered to the bottom of each plug hole through the injection chamber and each injection tube. The resin passes through the opening on the lower membrane body and enters the interior of each plug hole. During the injection process, the negative pressure in the upper chamber continuously acts on the top of each plug hole, drawing the gas in the plug hole upward and expelling it. S5: Incision closed; After the glue injection is completed, stop the glue injection system, turn off the vacuum supply on the lower mold base side, restore the lower chamber to normal pressure, and the valve of the cut will reset and close under the action of elastic restoring force; S6: Air-blown stripping; Positive pressure is introduced into the lower chamber, and gas is blown out from each micropore, forming an air cushion between the lower film and the lower mold base, which lifts the lower film away from the upper surface of the lower mold base. S7: Take the board; The drive unit drives the upper mold base to move upward, removing the printed circuit board with the lower mold body; S8: Curing and peeling off the film; The printed circuit board with the lower film is cured. After curing, the lower film is removed to obtain a printed circuit board with the vias plugged.

10. The unconventional dry film plugging method according to claim 9, characterized in that, After step S7 is completed, the following steps are also included: Switch the vacuum / positive pressure switching system on the upper mold base side to positive pressure, introduce positive pressure into the upper chamber, and blow gas downwards from each capillary hole for backflushing cleaning.

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