Method for fabricating a semi-plugging structure with solder resist ink

Abstract

This invention provides a method for manufacturing a semi-plugged via structure using solder resist ink. The method includes: providing a circuit board having through-holes, a windowed area, and a copper layer on the hole wall; applying solder resist ink material to the circuit board, such that the solder resist ink material includes a semi-plugged via ink portion located within the through-hole and a surface solder resist ink layer located on the surface of the circuit board; performing a first solder resist exposure on the surface solder resist ink layer, wherein the windowed area is an unexposed area; performing a second solder resist exposure on the central region corresponding to the through-hole opening after the first solder resist exposure and before solder resist development, so that the semi-plugged via ink portion cures from the central region outwards to form a partially cured ink resin plugging portion sealing the hole opening; and performing solder resist development, so that the copper layer on the hole wall has an exposed copper surface in the windowed area. This allows the formation of a semi-plugged via structure that combines an ink retention portion within the hole and an exposed copper surface in the windowed area.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a circuit board structure, and more particularly to a method for manufacturing a solder resist ink semi-plug structure. Background Technology

[0002] The solder resist process for printed circuit boards (PCBs) typically involves forming a solder resist ink layer on the PCB surface and then exposing and developing specific areas according to product design requirements to create the desired solder resist pattern. In some PCB products, solder resist ink material needs to be placed inside through-holes to form a semi-plugged via structure. Simultaneously, a window area may need to be formed near the via opening to expose the copper layer on the via wall or extending to the surface. In such structures, the requirements for ink retention within the via and the surface windowing requirements must be considered simultaneously. If the ink near the via opening is not properly cured before development, it may be lost during the solder resist development process due to the developer, thus affecting the degree of ink retention. On the other hand, if excessive ink curing occurs in the window area to increase the curing degree near the via opening, it may affect the exposure of the copper layer on the via wall in the window area. Therefore, how to maintain copper layer exposure in the window area while ensuring a structure at the via opening that can retain the ink within the via remains an area for improvement in related technologies. Summary of the Invention

[0003] This invention discloses a method for manufacturing a semi-plugging structure of solder resist ink, which is mainly used to improve the technical problems existing in the prior art.

[0004] One embodiment of the present invention discloses a method for fabricating a solder resist ink semi-plug structure, comprising: providing a circuit board having a through hole, at least one window area corresponding to at least one opening of the through hole, and a hole wall copper layer, the hole wall copper layer being disposed on the hole wall of the through hole and extending to at least one of the window areas; disposing a solder resist ink material on the circuit board, such that the solder resist ink material includes a semi-plug ink portion located within the through hole and a surface solder resist ink layer located on a surface of the circuit board; performing a first solder resist exposure on the surface solder resist ink layer, wherein the window area is located within the through hole. The first solder resist exposure is an unexposed area; after the first solder resist exposure and before solder resist development, a second solder resist exposure is performed on a central area corresponding to at least one of the orifices, so that the semi-plugging ink portion located at at least one of the orifices is cured from the central area outward to form a partially cured ink resin plugging portion, and the partially cured ink resin plugging portion seals at least one of the orifices of the through hole; and the circuit board is solder resist developed so that the copper layer of the hole wall has an exposed copper surface in at least one of the window areas, and the partially cured ink resin plugging portion remains at at least one of the orifices.

[0005] Optionally, the second solder resist exposure has a second exposure area located in the central region of the orifice, and the second exposure area is smaller than the diameter of the through hole at the orifice.

[0006] Optionally, the second exposure area is a dotted exposure area, and the diameter of the dotted exposure area is between 1 mil and 5 mil.

[0007] Optionally, the diameter of the dotted exposure area is between 1.5 mil and 3 mil.

[0008] Optionally, the maximum width of the locally cured ink resin plug is greater than the maximum width of the second exposure area.

[0009] Optionally, the partially cured ink resin plug extends across the opening of the through hole, protrudes from the opening, and contacts the periphery of the opening.

[0010] Optionally, the exposure pattern of the second solder resist exposure is different from the exposure pattern of the first solder resist exposure, and the second solder resist exposure is performed by laser direct imaging exposure, film exposure or shielding exposure.

[0011] Optionally, the exposure energy of the second solder resist exposure is greater than the exposure energy of the first solder resist exposure.

[0012] Optionally, the exposure energy of the first solder resist exposure is 150 mJ / cm. 2 Up to 250 mJ / cm 2 The exposure energy for the second solder resist exposure is 550 mJ / cm². 2 Up to 650 mJ / cm 2 .

[0013] Optionally, the semi-filled ink portion includes a filling ink, the surface solder resist ink layer includes a surface solder resist ink, and the filling ink and the surface solder resist ink are different types of solder resist inks.

[0014] Optionally, the surface solder resist ink is a liquid photosensitive solder resist ink, and the surface solder resist ink includes D10ME2, EG70M or a combination thereof; the via plug ink includes SR-500 HFK21; wherein the diameter of the via is not greater than 0.25 mm, the thickness of the circuit board is not less than 1.8 mm, and the thickness of the copper layer on the via wall is not less than 600 microinches.

[0015] Optionally, the through hole has two opposite ends of the opening, and the second solder resist exposure is performed on the central area of ​​the opposite ends of the opening, so that the half-plug ink portion located at the opposite ends of the opening forms the locally cured ink resin plug portion.

[0016] In summary, this invention performs a second solder resist exposure on the central area of ​​the via opening after the first exposure and before development. This causes the semi-plugged ink portion at the via opening to cure outwards from the central area, forming a locally cured ink resin plug. Furthermore, the locally cured ink resin plug seals the via opening and prevents the ink inside the via from overflowing, making it easier for the ink to remain inside the via after solder resist development. On the other hand, since the locally cured ink resin plug does not cover the entire windowed area, the copper layer on the via wall can still have an exposed copper surface in the windowed area. Therefore, this invention can balance the ink plug configuration at the via opening with the requirement for copper layer exposure in the windowed area, and can reduce ink loss during development, improving the process stability and structural integrity of the solder resist semi-plugged via structure.

[0017] To further understand the features and technical content of this invention, please refer to the following detailed description and accompanying drawings. However, these descriptions and drawings are only for illustrating the invention and are not intended to limit the scope of protection of the invention in any way. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the method for fabricating a solder resist ink semi-plug structure according to an embodiment of the present invention.

[0019] Figure 2 This is a schematic diagram of a circuit board provided in one embodiment of the present invention.

[0020] Figure 3 This is a schematic diagram of the solder resist ink material after it has been formed according to one embodiment of the present invention.

[0021] Figure 4 This is a schematic diagram of the first exposure of the solder mask in one embodiment of the present invention.

[0022] Figure 5 This is a schematic diagram of the second solder mask exposure in one embodiment of the present invention.

[0023] Figure 6 This is a top view of the second exposure area in one embodiment of the present invention.

[0024] Figure 7 This is a schematic diagram of post-exposure curing and diffusion in one embodiment of the present invention.

[0025] Figure 8 This is a schematic diagram of a solder resist ink semi-plugging structure according to an embodiment of the present invention.

[0026] Figure 9 This is a schematic diagram of a solder resist ink semi-plug structure according to another embodiment of the present invention.

[0027] Figure 10 This is a cross-sectional photograph of a solder resist ink semi-plugging structure according to an embodiment of the present invention. Detailed Implementation

[0028] In the following description, if a specific drawing is indicated or shown in a specific drawing, it is only to emphasize that most of the relevant content mentioned in the following description appears in that specific drawing, but does not limit the following description to refer only to that specific drawing.

[0029] The following description, in conjunction with the accompanying drawings, illustrates the solder resist ink semi-plugging structure and its manufacturing method of the present invention. It should be understood that the following embodiments are merely illustrative of the technical content of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the spirit of the present invention, those skilled in the art can make appropriate changes based on actual processes, materials, equipment, or product specifications.

[0030] This invention relates to a solder resist semi-plug structure for circuit boards and its manufacturing method. In some embodiments, the circuit board has through holes, and the walls of the through holes are provided with a copper layer. A window area may be provided on the surface of the circuit board corresponding to the opening of the through hole, so that the copper layer of the hole wall can have an exposed copper surface in the window area after solder resist development.

[0031] A technical feature of this invention is that, after the first solder resist exposure and before the solder resist development, a second solder resist exposure is performed on the central area of ​​the through hole opening, so that the solder resist ink material located at the opening is cured from the central area outward, thereby forming a locally cured ink resin plug that seals the through hole opening.

[0032] Another technical feature of this invention is that the exposure area of ​​the second solder resist exposure can be smaller than the aperture of the via at the orifice, and can be located in the central region of the orifice. Therefore, the second solder resist exposure provides localized exposure to the central region of the orifice, rather than exposing the entire window area or the entire circuit board surface.

[0033] Another technical feature of the present invention is that, although the second solder resist exposure is performed on the central area of ​​the orifice, the solder resist ink material located at the orifice can be cured and diffused outward from the central area, so that the size of the locally cured ink resin plug is larger than the size of the second exposure area, and the orifice of the through hole is sealed.

[0034] In some embodiments, after solder resist development, a locally cured ink resin plug is left at the opening of the through-hole, and the copper layer of the hole wall still has an exposed copper surface in the window area that is not covered by the locally cured ink resin plug. Therefore, the present invention can provide a plugging structure at the opening while still allowing the exposed copper surface of the hole wall copper layer to extend to the circuit board surface in the window area.

[0035] like Figure 1As shown, a method for fabricating a solder resist ink semi-plug structure according to an embodiment of the present invention includes steps S110 to S160. The order of each step can be adjusted according to process requirements, but the second solder resist exposure is preferably performed after the first solder resist exposure and before solder resist development.

[0036] like Figure 1 See also Figure 2 As shown, step S110 involves providing a circuit board 100. The circuit board 100 has at least one through hole 110, at least one opening area 130 located at at least one opening 111 of the through hole 110, and a hole wall copper layer 120 disposed on the hole wall 112 of the through hole 110 and extending to the opening area 130.

[0037] like Figure 1 See also Figure 3 As shown, step S120 involves configuring a solder resist ink material 140 on the circuit board 100, such that the solder resist ink material 140 includes a half-hole plug ink portion 141 located in the through hole 110 and a surface solder resist ink layer 150 located on a surface 101 of the circuit board 100.

[0038] like Figure 1 See also Figure 4 As shown, step S130 is to perform the first solder resist exposure on the surface solder resist ink layer 150. In the first solder resist exposure, the window area 130 can be an unexposed area, so that the window area 130 can form the exposed copper surface 121 of the corresponding hole wall copper layer 120 in the subsequent solder resist development.

[0039] like Figure 1 See also Figures 5 to 7 As shown, step S140 involves performing a second solder resist exposure on a central region 161 corresponding to the orifice 111 of the via 110 after the first solder resist exposure and before solder resist development. In some embodiments, the second solder resist exposure has a second exposure area 160, which corresponds to the central region 161 of the orifice 111.

[0040] like Figure 1 See also Figure 8 As shown, step S150 involves developing the solder resist on the circuit board 100. After the solder resist is developed, the copper layer 120 on the hole wall has an exposed copper surface 121 in the window area 130, and a partially cured ink resin plug 170 is left at the hole opening 111.

[0041] Step S160 involves performing solder resist baking. In some embodiments, solder resist baking can further cure the ink retention portion 142 inside the hole, the partially cured ink resin plugging portion 170, and the surface solder resist ink layer 150. However, in other embodiments, the conditions, time, and temperature of solder resist baking can be adjusted according to the solder resist ink material 140 used.

[0042] In some embodiments, the solder resist ink semi-plug structure obtained after solder resist development may include an ink retention portion 142 inside the hole and a partially cured ink resin plugging portion 170. The ink retention portion 142 inside the hole is located inside the through hole 110, and the partially cured ink resin plugging portion 170 is located at the orifice 111 and seals the orifice 111 to prevent the ink retention portion 142 inside the hole from flowing out of the through hole 110.

[0043] The following will provide a more detailed explanation of the technical details of each step, such as... Figure 2 As shown, in step S110, the circuit board 100 has at least one surface 101. A through hole 110 is provided in the circuit board 100 and has at least one opening 111 located on the surface 101. The through hole 110 has a hole wall 112, and a copper layer 120 is provided on the hole wall 112.

[0044] In some embodiments, the via wall copper layer 120 may extend from the via wall 112 of the via 110 to the surface 101 of the circuit board 100 and be located within the window area 130. The window area 130 may be configured corresponding to the aperture 111, so that the via 110 has a region near the surface 101 of the circuit board 100 that can be developed.

[0045] The through-hole 110 may have at least one opening 111. The at least one opening 111 may be an opening at one end of the through-hole 110 located on the surface 101 of the circuit board 100. In a specific embodiment, the through-hole 110 may also have openings 111 at opposite ends located on opposite side surfaces (e.g., ...). Figure 2 Furthermore, the two opposite openings can correspond to different window areas 130. In other words, the opening 111 referred to in this invention can refer to one end of the through hole 110, or it can cover the two opposite openings 111 of the through hole 110 according to the actual product structure.

[0046] From another perspective, the through hole 110 can be a through hole that penetrates the circuit board 100. In other embodiments, the through hole 110 can be any other hole structure that requires partial plugging with solder resist ink, as long as it has an opening 111 on the surface 101 and a copper layer 120 on the hole wall 112.

[0047] In some embodiments, the through hole 110 has a diameter D1 at the opening 111. The diameter D1 can be determined according to the product specifications of the circuit board 100, the hole structure design, or the need for plugging. In one embodiment, the diameter D1 may not be greater than 0.25 mm, but the present invention is not limited thereto.

[0048] The circuit board 100 has a board thickness T1. The board thickness T1 can be determined according to the number of product layers, application requirements, or mechanical strength. In a preferred embodiment, the board thickness T1 may be not less than 1.8 mm, but the present invention is not limited thereto.

[0049] The via wall copper layer 120 has a via wall copper layer thickness T2. The via wall copper layer thickness T2 can be determined according to conductivity requirements, plating conditions, or reliability specifications. In one embodiment, the via wall copper layer thickness T2 may be not less than 600 microinches, approximately not less than 15 micrometers, but the present invention is not limited thereto.

[0050] The window area 130 is located on the surface 101 of the circuit board 100 and corresponds to the opening 111 of the through hole 110. The window area 130 allows the copper layer 120 of the hole wall to have an exposed copper surface 121 after subsequent solder resist development. The exposed copper surface 121 can be the area of ​​the copper layer 120 of the hole wall that is not covered by the solder resist ink material 140.

[0051] It should be understood that, Figure 2 The circuit board 100, through-hole 110, copper layer 120 on the hole wall, and window area 130 shown are for illustrative purposes only. The relative dimensions, thicknesses, proportions, and shapes of the components in the figure are not intended to limit the invention. In actual manufacturing processes, the number of through-holes 110, hole diameter D1, board thickness T1, and copper layer thickness T2 on the hole wall can all be adjusted according to requirements.

[0052] In some embodiments, the via wall copper layer 120 may include a conductive metal layer formed on the via wall 112 of the via 110. The via wall copper layer 120 provides conductivity for the via 110 and may extend to the opening area 130 of the surface 101. Furthermore, the opening area 130 may be located at the position where the subsequent surface solder resist ink layer 150 is predetermined to form an opening. That is, the opening area 130 is the area corresponding to the formation of the exposed copper surface 121 after subsequent solder resist development (e.g., Figure 8 ).

[0053] The method of the present invention can be based on the above-mentioned circuit board 100, by configuring the solder resist ink material 140, performing a first solder resist exposure, a second solder resist exposure, and solder resist development, so as to form a solder resist ink semi-filled hole structure.

[0054] The "solder resist ink material" referred to in this invention may have different names depending on its location and structural form. For example, the portion located within the through-hole 110 before development may be called the semi-plugged ink portion 141 (e.g., Figure 4 and Figure 5 After development, it can be referred to as the ink retention section 142 inside the hole (e.g. Figure 8 The layer located on the surface 101 of the circuit board 100 can be called the surface solder resist ink layer 150 (e.g., Figure 8 ).

[0055] Therefore, in this invention, the names of the semi-filled ink portion 141, the ink retention portion 142 inside the hole, and the surface solder resist ink layer 150 are mainly distinguished according to their location, process stage, and structural configuration, and do not necessarily indicate that they must be formed from different materials.

[0056] Further cooperation as follows Figure 3 and Figure 4 This describes the preparation of solder resist ink material 140 and the implementation method of the first solder resist exposure.

[0057] like Figure 3 As shown, in step S120, solder resist ink material 140 is disposed on circuit board 100, such that solder resist ink material 140 includes a semi-plug ink portion 141 located in the through hole 110, and a surface solder resist ink layer 150 located on the surface 101 of circuit board 100.

[0058] In some embodiments, the solder resist ink material 140 can be formed by printing, coating, plugging, scraping, or other methods that allow the ink to be disposed on the circuit board 100 and within the through holes 110. The configuration of the solder resist ink material 140 can be adjusted according to the hole diameter D1, board thickness T1, ink viscosity, and process equipment of the circuit board 100.

[0059] The solder resist ink material 140 can simultaneously form a semi-filled ink portion 141 located within the through hole 110 and a surface solder resist ink layer 150 located on the surface 101 in the same process step. In other embodiments, the semi-filled ink portion 141 and the surface solder resist ink layer 150 can also be formed in different process stages.

[0060] The semi-filled ink portion 141 and the surface solder resist ink layer 150 can be formed from the same type of solder resist ink. That is, the solder resist ink material 140 can be a single ink material, and the ink material can form the semi-filled ink portion 141 and the surface solder resist ink layer 150 respectively depending on the placement position.

[0061] In other embodiments, the semi-filled ink portion 141 may include a filling ink, the surface solder resist ink layer 150 may include a surface solder resist ink, and the filling ink and the surface solder resist ink may be different types of solder resist inks.

[0062] The surface solder resist ink may be a liquid photosensitive solder resist ink. The surface solder resist ink may contain D10ME2, EG70M, or combinations thereof (such as PSR-4000 D10ME or PSR-4000 EG70M manufactured by TAIYO). In other embodiments, the via-filling ink included in the semi-via ink section 141 may contain SR-500 HFK21 via-filling solder resist ink.

[0063] The aforementioned D10ME2, EG70M, and SR-500 HFK21 are merely examples of usable ink types and are not intended to limit the present invention. Any ink that can form a semi-filled ink portion 141, a surface solder resist ink layer 150, and a partially cured ink resin plugging portion 170 can be used as the solder resist ink material 140 of the present invention.

[0064] like Figure 3 As shown, the partially plugged ink portion 141 is located within the through-hole 110. In some embodiments, the partially plugged ink portion 141 may fill a portion of the through-hole 110. The partially plugged ink portion 141 may be formed after subsequent solder resist development or transformed into an in-hole ink retention portion 142 (e.g., Figure 8 ).

[0065] A surface solder resist ink layer 150 is located on the surface 101 of the circuit board 100. In some embodiments, the surface solder resist ink layer 150 covers a portion of the surface 101 and can form a predetermined solder resist pattern in response to subsequent first solder resist exposure and solder resist development.

[0066] In some embodiments, the surface solder resist ink layer 150 may cover at least a portion of the window area 130, and after subsequent solder resist development, form an opening 151 corresponding to the window area 130 (see also...). Figure 8 ).but Figure 3 The image shown is only of the structural state before development.

[0067] The boundary between the semi-filled ink section 141 and the surface solder resist ink layer 150 may vary depending on the type, viscosity, printing pressure, aperture D1 or plate thickness T1 of the solder resist ink material 140 or the application method. Figure 3 The boundary lines shown are for illustrative purposes only and do not necessarily indicate that the actual material boundary lines are clearly separated.

[0068] Next, as Figure 4 As shown, in step S130, the surface solder resist ink layer 150 undergoes its first solder resist exposure. This first exposure allows the predetermined exposure area of ​​the surface solder resist ink layer 150 to solidify, facilitating the subsequent formation of the solder resist pattern.

[0069] In this process, the windowed area 130 is an unexposed area during the first solder resist exposure. In other words, the exposure pattern of the first solder resist exposure allows the windowed area 130 to correspond to an unexposed or low-exposed area, so that the windowed area 130 can be developed and revealed in the subsequent solder resist development.

[0070] The first exposure of the solder resist mainly corresponds to the surface solder resist ink layer 150 to form the solder resist pattern on the surface 101 of the circuit board 100. The window area 130 is reserved as an unexposed area to facilitate the subsequent exposure of the hole wall copper layer 120 to have an exposed copper surface 121 in the window area 130.

[0071] In some embodiments, after the first solder resist exposure, the semi-plugged ink portion 141 near the orifice 111 of the through-hole 110 may be in a state awaiting further curing, or its degree of curing may differ from the exposed area of ​​the surface solder resist ink layer 150. In subsequent steps, the central region 161 of the orifice 111 can be treated by a second solder resist exposure.

[0072] The exposure conditions for the first solder resist exposure can be set according to the material properties of the surface solder resist ink layer 150. When the surface solder resist ink layer 150 contains liquid photosensitive solder resist ink, the exposure energy for the first solder resist exposure can be adjusted according to the type, thickness, and equipment conditions of the liquid photosensitive solder resist ink.

[0073] In some embodiments, the exposure energy for the first solder resist exposure can be 150 mJ / cm². 2 Up to 250 mJ / cm 2 For example, the exposure energy for the first solder resist exposure can be approximately 200 mJ / cm². 2 However, the present invention is not limited thereto.

[0074] like Figure 4 As shown, the window area 130 is configured correspondingly to the orifice 111 of the through-hole 110. Since the window area 130 is an unexposed area during the first solder resist exposure, subsequent solder resist development can remove the uncured or insufficiently cured ink located in the window area 130, thereby forming the hole wall copper layer 120 extending to the exposed copper surface 121 of the surface 101 (please refer to [reference needed]). Figure 8 ).

[0075] It should be understood that, although Figure 4 The state after the first solder resist exposure is shown in cross-section, but the exposure pattern of the first solder resist exposure is not limited to the shape shown in the figure. As long as the windowed area 130 corresponds to the unexposed area in the first solder resist exposure, it can be used in the manufacturing method of the present invention.

[0076] In some embodiments, the first solder resist exposure can be performed by film exposure, direct imaging exposure, or other solder resist exposure methods. The present invention does not limit the exposure equipment used for the first solder resist exposure. After the first solder resist exposure, the circuit board 100 has not yet undergone solder resist development. In this state, the semi-filled via ink portion 141 remains within the through-hole 110, and the surface solder resist ink layer 150 remains on the surface 101.

[0077] like Figures 5 to 7 As shown, the present invention performs a second solder resist exposure after the first exposure and before the solder resist development. The second solder resist exposure is performed on the central region 161 of the orifice 111, so that the semi-plugged ink portion 141 at the orifice 111 can form the subsequently sealed part of the partially cured ink resin plug 170.

[0078] In some embodiments, the second solder resist exposure may use an exposure pattern different from the first solder resist exposure. Specifically, the exposure pattern of the first solder resist exposure may correspond to the solder resist pattern of the surface solder resist ink layer 150, while the exposure pattern of the second solder resist exposure may correspond to the central region 161 of the orifice 111.

[0079] The exposure energy of the second solder resist exposure can be greater than that of the first solder resist exposure. This allows the semi-plugged ink portion 141 at the orifice 111 to cure outward from the central region 161, forming a locally cured ink resin plug portion 170.

[0080] If the semi-filled hole ink portion 141 and the surface solder resist ink layer 150 are formed of the same type of solder resist ink, the second solder resist exposure can still provide partial exposure to the central region 161 of the hole opening 111. In other embodiments, if the semi-filled hole ink portion 141 and the surface solder resist ink layer 150 are formed of different types of ink, the second solder resist exposure can be set according to the ink type of the semi-filled hole ink portion 141.

[0081] Therefore, the manufacturing method of the present invention does not require that the semi-filled ink portion 141 and the surface solder resist ink layer 150 necessarily use different materials, nor does it require that they necessarily be formed in different process steps. The solder resist ink material 140 can be formed into different structural portions depending on its location, and the same or different inks can be used depending on the implementation requirements.

[0082] Figure 3 and Figure 4 The implementation method is mainly used to illustrate the preparation of the solder resist ink material 140 and the state of the first solder resist exposure. Further details will follow. Figures 5 to 7 This describes the formation state of the second exposure area 160, the central area 161, the second solder resist exposure, and the locally cured ink resin plug 170.

[0083] Since the second solder resist exposure is performed before the solder resist development, it allows the semi-plugged ink portion 141 at the orifice 111 to form a locally cured structure that can remain at the orifice 111 before the window area 130 is developed and opened. The specific configuration of this locally cured structure will be further explained in subsequent paragraphs.

[0084] like Figure 5 and Figure 6 As shown, more specifically, the second solder resist exposure has a second exposure area 160. The second exposure area 160 is configured corresponding to a central region 161 of the orifice 111 of the through-hole 110. Figure 6 In the top view shown, the second exposure area 160 may be located at the center of the aperture 111 or at a location adjacent to it.

[0085] In some embodiments, the second exposure area 160 has a second exposure area size D2 that is smaller than the aperture D1 of the through hole 110 at the orifice 111 (e.g., D2 / D1 is about 3% to 40%, preferably 3% to 20%). Therefore, the second solder resist exposure does not fully expose the entire orifice 111 or the entire window area 130, but rather exposes a localized area corresponding to the central region 161 of the orifice 111.

[0086] The second exposure area 160 can be a dot-shaped exposure area. The dot-shaped exposure area can be circular, elliptical, polygonal, or other local exposure shapes that correspond to the central region 161 of the aperture 111. Figure 5 and Figure 6 The second exposure area 160 shown is for illustrative purposes only and does not limit its actual shape.

[0087] When the second exposure area 160 is a dot-shaped exposure area, the size D2 of the second exposure area can be the diameter or maximum width of the dot-shaped exposure area. The size D2 of the second exposure area can be between 1 mil (approximately 25 micrometers) and 5 mil (approximately 125 micrometers). In a preferred embodiment, the size D2 of the second exposure area can be between 1.5 mil (approximately 38 micrometers) and 3 mil (approximately 76 micrometers). In one embodiment, the size D2 of the second exposure area can be 2 mil, but the invention is not limited thereto.

[0088] The second exposure area 160 is located in the central region 161 of the aperture 111, allowing the exposure energy of the second solder resist exposure to act on the semi-filled ink portion 141 from the center of the aperture 111. This avoids the second exposure area 160 from being too close to the outer periphery of the window area 130.

[0089] The configuration of the second exposure area 160 having a size D2 smaller than the aperture D1 at the orifice 111 of the via 110 reduces the possibility of over-curing at unintended locations in the window area 130 due to an excessively large exposure range. After subsequent solder resist development, the copper layer 120 on the hole wall can still have an exposed copper surface 121 in the window area 130.

[0090] Furthermore, such as Figure 6 As shown, in step S140, after the first solder resist exposure and before the solder resist development, a second solder resist exposure is performed on the central region 161 of the orifice 111 of the through-hole 110. The second solder resist exposure can apply exposure energy to the second exposure area 160 through an exposure pattern.

[0091] In some embodiments, the second solder resist exposure may be performed on the central region 161 of at least one orifice 111 of the through-hole 110. In other embodiments, the second solder resist exposure may also be performed on the central regions 161 of the orifices 111 at opposite ends, so that the half-plug ink portions 141 located at the opposite ends of the orifices are cured outward from their respective central regions 161.

[0092] The exposure pattern for the second solder resist exposure differs from that for the first. The exposure pattern for the first solder resist exposure corresponds to the solder resist pattern of the surface solder resist ink layer 150 (e.g., Figure 4 The exposure pattern of the second solder resist exposure can correspond to the central area 161 of the orifice 111 (e.g. Figure 5 and Figure 6 ).

[0093] The second exposure of the solder mask can be performed using direct laser imaging. Direct laser imaging can be aligned according to the position of the orifice 111 or the edge contour on the circuit board 100, and the central area 161 can be locally exposed.

[0094] In other embodiments, the second solder resist exposure can also be performed by film exposure, shielding exposure, or other exposure methods that can form the second exposure area 160. As long as the second exposure area 160 corresponds to the central region 161 of the aperture 111, it can be used in this invention.

[0095] Since the second solder resist exposure is performed before the solder resist development, the partially plugged ink section 141 can form a locally cured structure at the orifice 111 before entering the solder resist development.

[0096] Furthermore, the exposure energy of the second solder resist exposure can be greater than that of the first solder resist exposure. The exposure energy of the second solder resist exposure can be set according to the material, thickness, location, and curing requirements of the semi-filled ink section 141.

[0097] In some embodiments, the exposure energy for the first solder resist exposure can be 150 mJ / cm². 2 Up to 250 mJ / cm 2 The exposure energy for the second weld bead exposure can be 550 mJ / cm². 2 Up to 650 mJ / cm 2 For example, the exposure energy for the first solder resist exposure can be approximately 200 mJ / cm². 2 The exposure energy for the second solder resist exposure can be approximately 600 mJ / cm². 2 In some implementations, the exposure energy of the second solder resist exposure can be 2 to 4.5 times that of the first solder resist exposure.

[0098] The semi-filled ink portion 141 and the surface solder resist ink layer 150 can be formed from the same solder resist ink material 140. In this case, the second solder resist exposure can still be performed by applying higher or different exposure energy locally, so that the semi-filled ink portion 141 at the orifice 111 has a different curing state than other areas and has a higher degree of curing.

[0099] In other embodiments, the semi-filled ink layer 141 may contain filler ink, the surface solder resist ink layer 150 may contain surface solder resist ink, and the filler ink and the surface solder resist ink may be different types of solder resist ink. In this case, the exposure energy of the second solder resist exposure can be set according to the type of filler ink.

[0100] The second solder resist exposure is performed on the central region 161 of the orifice 111, and its exposure range is smaller than the aperture D1 of the orifice 111. However, the curing range after the second solder resist exposure is not limited to the second exposure area 160 itself.

[0101] like Figure 7 As shown, after the second solder resist exposure, the semi-plugging ink portion 141 located at the orifice 111 can be cured from the central region 161 outwards, thereby forming a partially cured ink resin plug portion 170. The partially cured ink resin plug portion 170 is located at the orifice 111 and can seal the orifice 111 of the through hole 110.

[0102] In some embodiments, the locally cured ink resin plug 170 may include a central cured region 171 and a peripheral cured region 172. The central cured region 171 may correspond to the second exposure region 160 or its adjacent area. The peripheral cured region 172 may extend from the central cured region 171 toward the periphery of the aperture 111.

[0103] The distinction between the central curing zone 171 and the peripheral curing zone 172 is for ease of explanation regarding the curing state of the partially cured ink resin plug 170. In an actual structure, the central curing zone 171 and the peripheral curing zone 172 can be interconnected ink resin structures. For example... Figure 10 The slice photographs show that there is an identifiable boundary between the central curing area 171 and the peripheral curing area 172, with the curing degree of the central curing area 171 being higher than that of the peripheral curing area 172.

[0104] The plugging dimension D3 of the locally curable ink resin plugging portion 170 is larger than the dimension D2 of the second exposure area. That is, although the second solder resist exposure exposes the central region 161 of the orifice 111 with a smaller second exposure area 160, the curing range can expand outwards from the central region 161 after exposure energy. The plugging thickness of the locally curable ink resin plugging portion 170 is approximately 150 to 250 micrometers, and the ratio between its thickness and the plugging portion dimension D3 (plugging portion width) is approximately between 1.2 and 4.0.

[0105] The locally curable ink resin plug 170 protrudes outward across the opening 111 of the through hole 110 and contacts the periphery of the opening 111. In this configuration, the locally curable ink resin plug 170 can seal the opening 111 of the through hole 110. The locally curable ink resin plug 170 is continuously connected to the partially plugged ink portion 141. After subsequent solder resist development, the ink that is not removed by development and remains in the through hole 110 can form the in-hole ink retention portion 142.

[0106] The partially cured ink resin plug 170 is mainly located at the orifice 111. Although the partially cured ink resin plug 170 can seal the orifice 111 of the through hole 110, it does not cover the entire window area 130.

[0107] The second exposure area 160 is smaller than the aperture D1, and the configuration of the locally cured ink resin plug 170 curing outward from the central area 161 allows the locally cured ink resin plug 170 to seal the aperture 111, while the window area 130 still retains an area where the copper layer 120 of the hole wall can be exposed after solder resist development.

[0108] The curing range of the partially cured ink resin plug 170 can be changed according to the exposure energy of the second solder resist exposure, the size D2 of the second exposure area, the material of the semi-plug ink part 141, the thickness of the semi-plug ink part 141, or the alignment accuracy of the exposure equipment.

[0109] If the size of the second exposure area D2 is too large, it may cause unintended locations in the window area 130 to cure; if the size of the second exposure area D2 is too small, the locally cured ink resin plug 170 may not be able to fully cross the orifice 111. Therefore, the size of the second exposure area D2 can be set according to product specifications and process conditions.

[0110] The plugging portion size D3 of the locally cured ink resin plugging portion 170 can be larger than the second exposure area size D2, and can be equal to or larger than the local opening width of the orifice 111, so as to close the orifice 111 of the through hole 110.

[0111] The shape of the locally cured ink resin plug 170 may vary depending on the shape of the orifice 111, the flowability of the solder resist ink material 140, the shape of the second exposure zone 160, and the distribution of exposure energy. Figure 7 This is for illustrative purposes only and does not limit the actual outline of the locally cured ink resin plug 170.

[0112] The locally curing ink resin plug 170 can be a cured ink resin structure that substantially closes the orifice 111. As used herein, "closed" means that the locally curing ink resin plug 170 is located at and across the orifice 111, so that the orifice 111 of the through hole 110 is plugged or blocked by the locally curing ink resin plug 170.

[0113] Through the aforementioned second solder resist exposure and curing diffusion configuration, a locally cured ink resin plug 170 can be formed at the orifice 111 before solder resist development. The following will be used in conjunction with... Figure 8 Explain the semi-filled hole structure of the solder resist ink after solder resist development.

[0114] like Figure 8As shown, in step S150, the circuit board 100 is subjected to solder resist development. After solder resist development, the surface solder resist ink layer 150 may have an opening 151 corresponding to the window area 130.

[0115] In some embodiments, the via wall copper layer 120 has an exposed copper surface 121 in the window area 130. The exposed copper surface 121 refers to the area on the surface 101 of the circuit board 100 where the via wall copper layer 120 extends and is not covered by the surface solder resist ink layer 150, the locally cured ink resin plug 170, or other ink resins.

[0116] The exposed copper surface 121 is located within the window area 130 and can be exposed through the opening 151 of the surface solder resist ink layer 150. The opening 151 can correspond to the window area 130, which is a non-exposed area during the first solder resist exposure.

[0117] A locally curable ink resin plug 170 is located at the orifice 111 and seals the orifice 111 of the through hole 110. The locally curable ink resin plug 170 may be adjacent to the ink retention portion 142 located within the through hole 110. In some embodiments, such as Figure 8 The locally cured ink resin plug 170 may be provided at one end opening 111 of the through hole 110. In other embodiments, such as Figure 9 The two opposite ends of the through hole 110 can also be provided with locally cured ink resin plugs 170, and each locally cured ink resin plug 170 can respectively close the corresponding opening 111. Each locally cured ink resin plug 170 can be connected to the ink retention part 142 inside the through hole 110, or have a gap with the ink retention part 142 inside the hole (e.g., the bottom of the ink retention part 142 inside the hole is connected to the locally cured ink resin plug 170 below, while there is a gap between the top of the ink retention part 142 inside the hole and the locally cured ink resin plug 170 above), but the present invention is not limited thereto.

[0118] The ink retention portion 142 is located within the through hole 110 and can extend from the partially cured ink resin plug portion 170 toward the interior of the through hole 110. The ink retention portion 142 may be composed of a semi-plug ink portion 141 that is retained in the through hole 110 after solder resist development.

[0119] In some embodiments, the locally cured ink resin plugging portion 170 and the ink retention portion 142 inside the hole can be a plugging structure formed from the same solder resist ink material 140. The locally cured ink resin plugging portion 170 and the ink retention portion 142 inside the hole can have different degrees of curing or different material states.

[0120] The locally curable ink resin plug 170 has a central curing region 171 and a peripheral curing region 172. The central curing region 171 may be located in the central region 161 of the orifice 111, and the peripheral curing region 172 may extend from the central curing region 171 to the periphery of the orifice 111. The maximum width of the locally curable ink resin plug 170 may be greater than the maximum width of the central curing region 171.

[0121] In some embodiments, the locally curable ink resin plug 170 extends across the opening 111 of the through hole 110, presenting a plug structure protruding from the opening 111 with an arc-shaped surface, and contacting the periphery of the opening 111. In this way, the locally curable ink resin plug 170 can seal the opening 111 of the through hole 110.

[0122] The locally cured ink resin plug 170 is located inside the opening 151 of the surface solder resist ink layer 150, and the exposed copper surface 121 of the hole wall copper layer 120 is also located inside the opening 151. That is to say, the locally cured ink resin plug 170 and the exposed copper surface 121 can coexist inside the opening 151 of the surface solder resist ink layer 150.

[0123] Furthermore, the exposed copper surface 121 may be located in the window area 130 and adjacent to the aperture 111. In some embodiments, the exposed copper surface 121 may surround at least a portion of the aperture 111. In other embodiments, the exposed copper surface 121 may be located on one or more sides of the aperture 111.

[0124] In some embodiments, the locally cured ink resin plug 170 seals the opening 111 of the through hole 110, but does not cover the entire window area 130. Thus, the copper layer 120 of the hole wall can still have an exposed copper surface 121 in the window area 130. For example, at least 80% of the surface area of ​​the exposed copper surface 121 is not covered by the locally cured ink resin plug 170, while less than 20% of the surface area near the opening 111 can be covered by the locally cured ink resin plug 170, forming an interlocking structure. The height of the locally cured ink resin plug 170 may be higher than the exposed copper surface 121, and it is a plug structure with an arc-shaped surface.

[0125] The ink retention portion 142 inside the hole fills a portion of the through hole 110, while a portion of the through hole 110 is not completely filled by the ink retention portion 142. Therefore, the structure can be a semi-plugged hole structure.

[0126] like Figure 9 The ink retention portion 142 inside the hole may have a plugging depth H1. The plugging depth H1 may be the depth to which the ink retention portion 142 inside the hole extends from the orifice 111 toward the interior of the through hole 110.

[0127] In some embodiments, the ratio of the hole-filling depth H1 to the hole depth (or plate thickness T1) of the through hole 110 can be used as an indicator of the fullness of the semi-filled hole ink. In one embodiment, the ratio of the hole-filling depth H1 to the hole depth of the through hole 110 after solder resist development can be greater than 40%, preferably greater than 50%.

[0128] Solder resist ink semi-plug structure

[0129] like Figure 8 and Figure 9 As shown, an embodiment of the present invention provides a solder resist ink semi-plugging structure P. This solder resist ink semi-plugging structure includes a circuit board 100, a through hole 110, a copper layer 120 on the hole wall, solder resist ink material 140, an ink retention portion 142 inside the hole, a surface solder resist ink layer 150, and a partially cured ink resin plugging portion 170.

[0130] In some embodiments, the solder resist ink material 140 includes an in-hole ink retention portion 142 located within the through-hole 110 and a surface solder resist ink layer 150 located on the surface 101. The in-hole ink retention portion 142 and the surface solder resist ink layer 150 may be formed of the same or different types of solder resist ink.

[0131] In other embodiments, the in-hole ink retention portion 142 may contain solder resist ink for plugging holes, and the surface solder resist ink layer 150 may contain liquid photosensitive solder resist ink. The liquid photosensitive solder resist ink may contain D10ME2, EG70M, or a combination thereof, and the solder resist ink for plugging holes may contain SR-500 HFK21.

[0132] The diameter D1 of the through hole 110 may not exceed 0.25 mm, the thickness T1 of the circuit board 100 may not be less than 1.8 mm, and the thickness T2 of the copper layer on the hole wall 120 may not be less than 600 microinches (not less than 15 micrometers). The aforementioned dimensional parameters may be adjusted according to product specifications and process conditions.

[0133] In the final product structure, it can be observed that the locally cured ink resin plug 170 is located at the orifice 111 and is connected to or has a gap with the ink retention part 142 inside the orifice.

[0134] In some embodiments, the locally cured ink resin plug 170 seals the orifice 111, leaving the ink retention portion 142 inside the orifice 110 (e.g., both the upper and lower orifices 111 of the through-hole 110 are sealed by the locally cured ink resin plug 170); simultaneously, the window area 130 still has an exposed copper surface 121 (not covered by the locally cured ink resin plug 170 or the surface solder resist ink layer 150) extending from the hole wall copper layer 120 onto the surface 101 of the orifice 111. In this way, both the locally cured ink resin plug 170 at the orifice 111 and the exposed copper surface 121 in the window area 130 can be simultaneously configured.

[0135] The solder resist ink semi-plug structure of the present invention is applicable to circuit board processes involving full ink semi-plugging, partial ink full plugging, and a combination of partial ink semi-plugging. In some embodiments, the semi-plug structure may require the ratio of the plug depth H1 to the hole depth of the through hole 110 to be greater than 40%.

[0136] If the product includes a fully plugged hole structure, the plugging ratio of the fully plugged hole structure can also be different according to actual needs. However, this embodiment is mainly described using the example of a partially cured ink resin plugging part 170 at the orifice 111 of the through hole 110, and an ink retention part 142 in the hole forming a semi-plugged hole structure.

[0137] In a reference test, if the central region 161 of the orifice 111 is not subjected to a second solder resist exposure after the first exposure and before the solder resist development, a corresponding locally cured ink resin plug 170 may not form at the orifice 111, causing the solder resist ink material 140 to overflow outside the through hole 110. This reference test is only used to illustrate the structural differences under different process conditions and is not intended to limit the present invention.

[0138] The present invention performs partial exposure on the central region 161 of the corresponding orifice 111 by second solder resist exposure, and cures the semi-plugged ink portion 141 from the central region 161 outward, so that a partially cured ink resin plug portion 170 can be formed at the orifice 111 before solder resist development.

[0139] Because the locally cured ink resin plug 170 seals the orifice 111, the ink retention portion 142 inside the orifice can remain inside the through-hole 110 after solder resist development. This improves the stability of the ink retention state within the through-hole 110.

[0140] In some embodiments, since the second exposure area 160 is located in the central region 161 of the aperture 111 and is smaller than the aperture diameter D1, the locally cured ink resin plug 170 can seal the aperture 111 without covering the entire window area 130. Therefore, after solder resist development, the copper layer 120 on the hole wall can still have an exposed copper surface 121 in the window area 130.

[0141] This invention, through the coordination of the second exposure zone size D2, the second solder resist exposure energy, and the solder resist ink material 140, enables the central curing zone 171 and the outer peripheral curing zone 172 to form a locally cured ink resin plugging portion 170 that seals the orifice 111. This configuration can be applied to circuit board structures that require both ink retention within the orifice and copper layer exposure in the window area.

[0142] In summary, the solder resist ink semi-plugging structure and its manufacturing method of the present invention can be achieved by performing a second solder resist exposure on the central region 161 of the orifice 111 after the first solder resist exposure and before the solder resist development, so that a partially cured ink resin plugging part 170 is formed at the orifice 111, and a semi-plugging structure with an ink retention part 142 inside the orifice and an exposed copper surface 121 is formed after the solder resist development.

[0143] Beneficial effects of the embodiments of the present invention

[0144] With the above configuration, after the first solder resist exposure and before the solder resist development, the present invention performs a second solder resist exposure on the central region of the orifice opening. This causes the semi-plugged ink portion at the orifice opening to cure outward from the central region, forming a locally cured ink resin plug. Since the second exposure area is smaller than the orifice diameter and is located in the central region of the orifice opening, the curing effect can be concentrated on the semi-plugged ink portion at the orifice opening, without having to fully expose the entire windowed area.

[0145] Furthermore, the locally cured ink resin plug can seal the opening of the through hole and prevent the ink inside the through hole from overflowing out of the through hole, making it easier for the ink inside the hole to remain inside the through hole after solder resist development. On the other hand, since the locally cured ink resin plug does not cover the entire window area, the copper layer on the hole wall can still have exposed copper surface in the window area.

[0146] Therefore, the present invention can take into account both the ink plugging configuration at the orifice and the copper layer exposure requirements of the window area, and can reduce the loss of ink in the orifice during the development process, thereby improving the process stability and structural integrity of the solder resist ink semi-plug structure.

[0147] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Therefore, all equivalent technical changes made based on the description and drawings of the present invention are included within the protection scope of the present invention.

Claims

1. A method for manufacturing a solder resist ink semi-plug structure, characterized in that, The method for fabricating the solder resist ink semi-plug structure includes: A circuit board is provided, the circuit board having a through hole, at least one opening area corresponding to at least one opening of the through hole, and a hole wall copper layer, the hole wall copper layer being disposed on the hole wall of the through hole and extending to at least one of the opening areas. A solder resist ink material is disposed on the circuit board, such that the solder resist ink material includes a half-hole plugging ink portion located in the through hole and a surface solder resist ink layer located on a surface of the circuit board; The surface solder resist ink layer is subjected to a first solder resist exposure, wherein the windowed area is an unexposed area in the first solder resist exposure; After the first solder resist exposure and before solder resist development, a second solder resist exposure is performed on a central region corresponding to at least one of the orifices, causing the semi-plugged ink portion located at the at least one orifice to cure outward from the central region to form a partially cured ink resin plugging portion, and the partially cured ink resin plugging portion seals at least one orifice of the through-hole; and The circuit board is subjected to solder resist development so that the copper layer of the hole wall has an exposed copper surface in at least one of the opening areas, and the locally cured ink resin plug is left at at least one of the hole openings.

2. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The second solder resist exposure has a second exposure area, which is located in the central region of the orifice, and the second exposure area is smaller than the diameter of the through hole at the orifice.

3. The method for manufacturing the solder resist ink semi-plug structure according to claim 2, characterized in that, The second exposure area is a dotted exposure area, and the diameter of the dotted exposure area is between 1 mil and 5 mil.

4. The method for manufacturing the solder resist ink semi-plug structure according to claim 3, characterized in that, The diameter of the dotted exposure area is between 1.5 mil and 3 mil.

5. The method for manufacturing the solder resist ink semi-plug structure according to claim 2, characterized in that, The maximum width of the locally cured ink resin plug is greater than the maximum width of the second exposure area.

6. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The partially cured ink resin plug extends across the opening of the through hole, protrudes from the opening, and contacts the periphery of the opening.

7. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The second solder resist exposure pattern is different from the first solder resist exposure pattern, and the second solder resist exposure is performed by laser direct imaging exposure, film exposure or shielding exposure.

8. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The exposure energy of the second solder resist exposure is greater than the exposure energy of the first solder resist exposure.

9. The method for manufacturing the solder resist ink semi-plug structure according to claim 8, characterized in that, The exposure energy for the first solder resist exposure was 150 mJ / cm. 2 Up to 250 mJ / cm 2 The exposure energy for the second solder resist exposure is 550 mJ / cm². 2 Up to 650 mJ / cm 2 .

10. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The semi-filled ink portion includes a filling ink, the surface solder resist ink layer includes a surface solder resist ink, and the filling ink and the surface solder resist ink are different types of solder resist inks.

11. The method for manufacturing the solder resist ink semi-plug structure according to claim 10, characterized in that, The surface solder resist ink is a liquid photosensitive solder resist ink, and the surface solder resist ink contains D10ME2, EG70M or a combination thereof; the via plug ink contains SR-500 HFK21; wherein the diameter of the via is not greater than 0.25 mm, the thickness of the circuit board is not less than 1.8 mm, and the thickness of the copper layer on the via wall is not less than 600 microinches.

12. The method for manufacturing the solder resist ink semi-plug structure according to claim 1, characterized in that, The through hole has two opposite openings. The second solder resist exposure is performed on the central areas of the opposite two openings respectively, so that the half-plug ink portion located at the opposite two openings respectively forms the locally cured ink resin plug portion.

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