A thick copper half-cut-off minimal solder bridge short jumper automotive sheet and processing method

Abstract

The application discloses a thick copper half-truncated extremely small solder bridge short jumper automobile plate, which comprises a PCB plate, wherein discharge pads are arranged on the PCB plate; and a solder bridge is arranged between adjacent discharge pads, wherein the solder bridge is designed in a disconnected mode, a blind hole is arranged on a base material of the PCB plate, the blind hole is arranged below a top of one end of a disconnected part of the solder bridge, the blind hole is arranged in a roughened area of the base material of the PCB plate, the roughened area comprises a plurality of roughened hole groups arranged concentrically with the blind hole, one roughened hole group comprises a plurality of roughened blind holes arranged along a circumference of the blind hole, the innermost roughened blind hole is communicated with the blind hole, and the roughened blind holes of one roughened hole group are communicated with the roughened blind holes of another adjacent roughened hole group. The application further discloses a thick copper half-truncated extremely small solder bridge short jumper automobile plate processing method. Compared with the prior art, the application solves the problem that pins are prone to tin connection during wave soldering of a thick copper plate of a short jumper design PCB with an extremely small solder bridge SMT.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of PCB production, and particularly relates to a thick copper half-truncated extremely small solder mask bridge short jumper automobile board and a processing method. BACKGROUND

[0002] With the development of electronic products towards high precision, miniaturization and high power, the PCB circuit is highly dense in the space per unit area, the SMD patch pin is smaller and smaller, and the copper thickness on the board is generally 2-4 oz.

[0003] In order to facilitate rapid detection, debugging, diagnosis or maintenance, two welding points are designed on the automobile water pump PCB, and when the water pump circuit is rapidly repaired, a metal conductor (wire) can be welded or fused between two adjacent conductive bodies to realize a path or an open circuit, that is, a short jumper design.

[0004] In the traditional short jumper, the distance between two adjacent pads is large (usually greater than or equal to 10 mil), and a metal conductor (wire) needs to be used for connection or disconnection. After the outer line compensation, a designed whole solder mask bridge (completely passing through the position of two adjacent pad substrates and not being disconnected in the middle) is left, and the width of the solder mask bridge is 4-8 mil (green oil: 3-6 mil, white oil: 5-8 mil).

[0005] Taking a 20Z thick copper plate as an example, the height difference between the copper surface and the substrate between two adjacent pads is about 70-140 um, that is, the thickness of the solder mask ink is about 60-120 um, and the exposure cannot penetrate the UV ultraviolet light. After being washed by the developing chemical, the solder mask bridge is obviously side-etched, and the solder mask bridge and the substrate are side-etched and fall off after being developed or surface treated. When the patch wave soldering is performed, the pins of the short jumper (two adjacent pads) on the board surface will inevitably produce tin connection problems.

[0006] In order to solve the problem that the pins are prone to tin connection in the manufacturing process of the thick copper plate solder mask extremely small solder mask bridge of the short jumper design PCB, the industry generally adopts the following solutions:

[0007] 1) Increase the distance between the short jumpers and the distance between the two adjacent pads, so that the solder mask bridge is wider, but this will cause the distance between the short jumpers to exceed the design specification, be judged as a defective product, and the function of the short jumper is lost. When the circuit is rapidly detected, the metal conductor (wire) needs to be used for connection or disconnection due to the large distance between the two adjacent conductors.

[0008] 2) Replace the ink with enhanced light transmittance to increase the curing effect of the UV ultraviolet light on the ink, but this will cause a large increase in cost, and the color of the ink is generally light and has poor coverage, resulting in red lines.

[0009] 3) Reduce the thickness of the ink, but the ink is too thin, resulting in poor coverage, low resistance to water attack, prone to ink side etching and falling off, and poor heat resistance, the ink is prone to yellowing after high temperature;

[0010] 4) Increase the exposure energy or develop a second whole surface exposure, but it is prone to overexposure and poor exposure, resulting in solder pads on the ink, poor ink resistance, brittle, and prone to hole ink suction, film indentation, and hole overflow. In addition, after developing or exposing, the second exposure is prone to misalignment due to the precision of the equipment, resulting in a shift in the first exposure and the second exposure pattern. SUMMARY

[0011] The purpose of the present application is to provide a thick copper half-truncated extremely small solder bridge short jumper automotive board and processing method to solve the problem of pin continuous soldering during thick copper PCB short jumper design PCB solder mask extremely small solder bridge wave soldering.

[0012] To achieve the above purpose, on the one hand, the present application discloses a thick copper half-truncated extremely small solder bridge short jumper automotive board, comprising:

[0013] PCB board, provided with discharge pads thereon;

[0014] Solder bridge, provided between adjacent discharge pads, the solder bridge is designed to be disconnected, the PCB board substrate is provided with a blind hole, the blind hole is provided below the top of one end of the disconnected solder bridge, the blind hole is provided in the roughened area of the PCB board substrate, the roughened area includes a plurality of roughened hole groups arranged concentrically with the blind hole, a roughened hole group includes a plurality of roughened blind holes arranged along the circumference of the blind hole, the innermost roughened blind hole is connected to the blind hole, and the roughened blind holes of one roughened hole group are connected to the roughened blind holes of the adjacent another roughened hole group.

[0015] The blind hole is drilled in the substrate of the PCB board to increase the adhesion of the solder bridge to the substrate, so that it does not fall off after developing and surface treatment, and the side etching of the solder bridge is reduced. The copper thickness is 2-4 OZ, the solder bridge is 2-6 mil, and the ink side etching is less than or equal to 0.5 mil after surface treatment (tin plating / tinning / OSP / gold plating).

[0016] On the other hand, the present application also discloses a thick copper half-truncated extremely small solder bridge short jumper automotive board processing method, comprising the following steps:

[0017] S1, drilling: drilling a blind hole in the PCB board substrate at the top end of the disconnected solder bridge position 1 mil, and processing a roughened area on the substrate outside the blind hole, the roughened area is processed by laser radiation micro-holes;

[0018] S2, outer layer pretreatment: clean and roughen the copper surface of the PCB substrate, first through the brush wheel mechanical grinding, and then through the acid cleaner for pickling, linear speed 3.0 m / min, mechanical grinding includes 300 mesh brush wheel, 500 mesh brush wheel each one group, pickling concentration 3-5%, drying temperature 85℃, pickling pressure 1.8 kg / cm2;

[0019] S3, outer layer film pressing: attach a layer of photosensitive dry film through hot pressing process, pressure 4.5 kg / cm2, temperature 120℃, speed 2.5±0.5 m / min;

[0020] S4, outer layer exposure: exposure curing line pattern energy 6-7 grids;

[0021] S5, development: development dissolves the uncured dry film, linear speed 3 m / min, sodium carbonate concentration 8-12 g / l, development pressure 1.2 kg / cm2;

[0022] S6, vacuum etching: acid vacuum two-fluid etching exposed copper foil to form a line, add bank protection agent in the acid etching solution, 20Z / 30Z copper thickness linear speed 2.2 m / min, 1.3 m / min, etching pressure 2.3 kg / cm2;

[0023] S7, film stripping;

[0024] S8, AOI / inspection;

[0025] S9, anti-solder pretreatment: first through the brush wheel mechanical grinding, and then through the acid cleaner for pickling, and then spray the copper surface with high pressure with diamond sand suspension, and finally water washing, wherein the linear speed is 2.8 m / min, the mechanical grinding includes 500 mesh brush wheel, 800 mesh brush wheel each one group, pickling concentration 3-5%, drying temperature 85℃, pickling pressure 1.8 kg / cm2, water washing pressure 1.5 kg / cm2, diamond sand content 15-20 ml / l;

[0026] S10, anti-solder screen printing: use 90 mesh screen printing, printing pressure 5 kg / cm2, printing angle 30°, printing speed 2.5 m / min;

[0027] S11, anti-solder pre-baking: pre-baking parameters are 73℃, 50 min;

[0028] S12, solder mask exposure: after the PCB is exposed once in the device, it is not taken out, without secondary positioning, directly for secondary exposure, the first exposure is normal PCB exposure, the second exposure is online secondary exposure of the solder mask position, specifically, retrieve engineering data→edit processing data→load first surface data 1→first exposure→load second surface data 1→second exposure→manual plate turning (surface next)→load first surface data 2→first exposure→load second surface data 2→second exposure, so that the solder mask position ink is completely cured, and the heat shock resistance reaches 288℃, 10S, 3 times;

[0029] S13, solder mask development: line speed 3.5m / min, sodium carbonate concentration 8-12g / l, development pressure 1.8kg / cm²;

[0030] S14, inspection;

[0031] S15, solder mask post-baking: high temperature curing treatment is performed on the solder mask ink, and the high temperature curing treatment is divided into four stages of temperature rise to release the internal stress of the ink and avoid cold and hot impact to cause the ink to crack or adhesion to decrease, the first stage curing parameter is 70℃, 60min, the second stage curing parameter is 90℃, 40min, the third stage curing parameter is 110℃, 40min, and the fourth stage curing parameter is 150℃, 60min.

[0032] As a further description of the above technical solutions:

[0033] In step S1, the blind hole is processed by mechanical drilling or laser drilling. In step S1, a micro-hole drill bit with a diameter of 0.1mm is used for mechanical drilling, the drilling speed is 1500 Krpm / s, the drilling speed is 1.1m / min, and the tool withdrawal speed is 15m / min; in step S1, CO2 laser drilling is used for laser drilling, the wavelength is 9.4um, the energy is 107W / cm2, and the laser drilling is performed three times, the first laser energy density is 17mj / cm², the second laser energy density is 11mj / cm², and the third laser energy density is 6mj / cm².

[0034] When laser drilling, the first laser uses high laser energy density to open the hole, and the second laser and the third laser gradually reduce the laser energy density, and low-energy trimming can improve the hole roundness of the blind hole, and the subsequent low laser energy density is convenient for controlling the depth and bottom shape of the blind hole.

[0035] As a further description of the above technical solutions:

[0036] In step S6, during vacuum etching, the acid etching solution is used to etch the exposed copper surface to form a circuit by vacuum two-fluid etching, and a bank protection agent is added to the acid etching solution. In the acid vacuum etching technology, the bank protection agent and the vacuum two-fluid etching technology are used to precisely control the etching amount, so that the etching factor is greater than or equal to 3, the etching circuit has smaller burrs and higher perpendicularity, the heat resistance and chemical resistance of the ink at the position of the solder bridge are increased, and the problems of excessive side etching of the ink or falling off of the ink are avoided.

[0037] Further description of the above technical solution:

[0038] In step 10, before printing the solder resist layer, an aluminum sheet is used to plug the blind hole on the PCB substrate. The solder resist plug hole design using the aluminum sheet plugs the hole to a fullness of more than 85%, connects the surface solder bridge with the ink in the hole, and makes the adhesion stronger.

[0039] In summary, due to the adoption of the above technical solution, the present application has the following advantages:

[0040] 1. In the present application, the solder bridge is connected with the hole diameter on the substrate at the corresponding position of the top of the disconnected solder bridge by mechanical drilling or laser drilling, which solves the problem of easy side etching and falling off of the top of the disconnected solder bridge, and uses normal ink to make the UV curing of the ink at the position of the solder bridge more sufficient without changing the existing ink model and ink thickness.

[0041] 2. In the present application, the alignment accuracy can be within 15um in the line secondary exposure, which avoids the PCB plate offset problem caused by secondary alignment and improves the production efficiency. In the secondary exposure, the soldering area is exposed separately, which makes the adhesion of the solder bridge better and does not cause exposure problems on the surface of the plate.

[0042] 3. In the present application, in the acid vacuum etching technology, the bank protection agent and the vacuum two-fluid etching technology are used to precisely control the etching amount, so that the etching factor is greater than or equal to 3, the etching circuit has smaller burrs and higher perpendicularity, the heat resistance and chemical resistance of the ink at the position of the solder bridge are increased, and the problems of excessive side etching of the ink or falling off of the ink are avoided.

[0043] 4. In the present application, a new short jumper design is disclosed, which greatly reduces the distance between two adjacent conductors. In the rapid detection of the circuit, the two conductors do not need to be connected or disconnected by metal conductors, but can be directly connected or disconnected by soldering, which further improves the efficiency of the rapid detection of the circuit board. BRIEF DESCRIPTION OF DRAWINGS

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of the structure of a short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge, as described in Example 1. Figure 1 .

[0046] Figure 2 A schematic diagram of the structure of a short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge, as described in Example 1. Figure 2 .

[0047] Figure 3 A schematic diagram of the structure of a short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge, as described in Example 1. Figure 3 .

[0048] Figure 4 for Figure 3 A magnified view of a portion of point A in the middle.

[0049] Figure 5 A schematic diagram of the structure of a short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge, as shown in Example 2. Figure 1 .

[0050] Figure 6 A schematic diagram of the structure of a short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge, as shown in Example 2. Figure 2 .

[0051] Figure 7 This is a structural diagram of a semi-partial weld bridge design.

[0052] Legend:

[0053] 1. PCB board; 11. EDM pad; 12. Blind via; 13. Textured area; 131. Textured blind via; 2. Solder bridge; 9. NPTH via. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0056] Example 1

[0057] Please see Figures 1-4 This invention discloses a short jumper automotive board with a thick copper semi-cut-off minimal weld bridge, comprising:

[0058] PCB board 1, on which discharge pads 11 are provided;

[0059] A solder bridge 2 is disposed between adjacent discharge pads 11. The solder bridge 2 is a disconnected design. A blind via 12 is disposed on the substrate of the PCB board 1. The blind via 12 is located below the top of one end of the disconnected part of the solder bridge 2. The blind via 12 is disposed in the roughened area 13 of the substrate of the PCB board 1. The roughened area 13 includes several rings of roughened vias arranged concentrically with the blind via 12. Each ring of roughened vias includes several roughened blind vias 131 arranged circumferentially along the blind via 12. The innermost ring of roughened blind vias 131 is connected to the blind via 12. The roughened blind vias 131 of one ring of roughened vias are connected to the roughened blind vias 131 of another adjacent ring of roughened vias.

[0060] Blind holes are machined on the substrate at the corresponding position on the top of the disconnected weld bridge, so that the weld bridge and the hole diameter of the board are connected, which solves the problem of easy side corrosion and peeling off the top of the disconnected weld bridge. Furthermore, by arranging several rings of roughened holes around the outside of the blind holes, and making the roughened blind holes 131 below the weld bridge 2 connected to the blind holes, the bonding ability of the ink in the weld bridge, the board surface, and the blind holes is further increased, preventing the side corrosion and peeling off the top of the disconnected weld bridge.

[0061] The diameter of the roughened blind hole 131 gradually increases from the inner ring roughened hole group to the outer ring roughened hole group. The diameter of the outer ring roughened hole group gradually increases. With the number of roughened blind holes 131 remaining unchanged, the increased diameter ensures the contact area with the weld bridge and prevents the top side corrosion and detachment of the disconnected weld bridge.

[0062] The depth of the texturized blind hole 131 gradually decreases from the inner ring texturized hole group to the outer ring texturized hole group. When ink overflows from the blind hole into the texturized blind hole 131, by controlling the gradual decrease in the depth of the texturized blind hole 131, the ink in the outer ring texturized hole group is effectively ensured to be fully filled, thereby preventing the top side etching and detachment of the disconnected weld bridge.

[0063] 3OZ copper thick white oil disconnected 4mil weld bridge design.

[0064] Outer layer / drilling / solder resist, engineering and process parameter design:

[0065] 1) 3OZ copper thickness, white solder resist ink, finished copper thickness 40Z, outer layer spacing 5mil design;

[0066] 1.1 At the top 1 mil of the weld bridge break position, design a drill bit of 0.1 mm;

[0067] 1.2 Drilling parameters: Drilling speed 1500 Krpm / s, down-drilling speed: 1.1m / min, retraction speed: 15m / min;

[0068] 1.3 Weld shielding bridge width design: 4mil;

[0069] 1.4 High-voltage discharge PAD spacing: 2.5mil.

[0070] 2) Exposure method design:

[0071] 2.1 Exposure program design: Two-stage exposure is adopted. The same part number and the same side are exposed twice. The LDI exposure machine exposes the normal data the first time, and only exposes the weld bridge position the second time.

[0072] 2.2 The project uses Genesis software to create two sets of data, labeled as follows: Part Number Name-Surface Number-Exposure Data 1 (normal design full-surface exposure data) and Part Number Name-Surface Number-Exposure Data 2 (only design weld bridge position data).

[0073] 2.2 Using an LDI exposure machine, retrieve the production data and directly load two data samples for exposure on the first side; similarly, load two data samples for exposure on the second side, setting the exposure energy to 11 seconds and 350-450 mJ / cm².

[0074] 3) Production process (drilling / outer layer / solder resist):

[0075] A method for processing short jumper wires for automotive circuit boards with thick copper semi-cut-off minimal weld bridges includes the following steps:

[0076] S1. Drilling: A blind hole 12 is machined on the PCB substrate at the top 1mil of the disconnected position of the solder bridge. A roughened area 13 is machined on the substrate outside the blind hole 12. The roughened area 13 is machined by laser micro-hole.

[0077] S2. Outer layer pretreatment: Clean and roughen the copper surface of the PCB substrate. First, mechanically brush it with a brush wheel, and then pickle it with an acidic cleaning agent. The linear speed is 3.0m / min. The mechanical brushing includes one set of 300-mesh brush wheel and one set of 500-mesh brush wheel. The pickling concentration is 3-5%. The drying temperature is 85℃ and the pickling pressure is 1.8kg / cm².

[0078] S3, Outer lamination: A layer of photosensitive dry film is attached by hot pressing process, with a pressure of 4.5 kg / cm², a temperature of 120℃, and a speed of 2.5 ± 0.5 m / min;

[0079] S4, Outer Layer Exposure: Expose and cure the circuit pattern with 6-7 energy bars;

[0080] S5. Development: Development dissolves uncured dry film, linear speed 3m / min, sodium carbonate concentration 8-12g / l, development pressure 1.2kg / cm²;

[0081] S6. Vacuum etching: Acidic vacuum two-fluid etching is used to expose copper foil to form circuits. A protective agent is added to the acidic etching solution. The line speed is 2.2m / min and 1.3m / min for 3OZ copper thickness, and the etching pressure is 2.3kg / cm².

[0082] S7. Remove film;

[0083] S8, AOI / test;

[0084] S9. Pre-treatment before solder resist application: First, mechanically brush the surface with a brush wheel, then pickle it with an acidic cleaner, followed by spraying a diamond abrasive suspension onto the copper surface under high pressure, and finally rinsing with water. The linear speed is 2.8 m / min. The mechanical brushing includes one set each of 500-mesh and 800-mesh brush wheels. The pickling concentration is 3-5%, the drying temperature is 85℃, the pickling pressure is 1.8 kg / cm², the water rinsing pressure is 1.5 kg / cm², and the diamond abrasive content is 15-20 ml / l.

[0085] S10, Solder resist screen printing: Use 90 mesh screen printing, printing pressure 5kg / cm², printing angle 30°, printing speed 2.5m / min;

[0086] S11. Solder resist pre-baking: Pre-baking parameters are 73℃, 50min;

[0087] S12, Solder Mask Exposure: After the PCB board is aligned and exposed once in the equipment, it is not removed and directly subjected to a second exposure. The first exposure is a normal full-side exposure of the PCB board, and the second exposure is an online secondary exposure of the solder mask bridge position. Specifically, retrieve the project data → edit and process the data → load the first side data 1 → first exposure → load the first side data 2 → second exposure → manually flip the board (side by side) → load the second side data 1 → first exposure → load the second side data 2 → second exposure, so that the ink at the solder mask bridge position is completely cured and the thermal shock resistance reaches 288℃, 10S, 3 times;

[0088] S13, Solder resist developing: linear speed 3.5m / min, sodium carbonate concentration 8-12g / l, developing pressure 1.8kg / cm²;

[0089] S14, Inspection;

[0090] S15. Post-solder resist baking: The solder resist ink is subjected to high-temperature curing treatment. The high-temperature curing treatment is divided into 4 stages of heating to release the internal stress of the ink and avoid thermal shock that may cause the ink to crack or affect adhesion. The curing parameters for the first stage are 70℃ for 60min, the curing parameters for the second stage are 90℃ for 40min, the curing parameters for the third stage are 110℃ for 40min, and the curing parameters for the fourth stage are 150℃ for 60min.

[0091] In step S1, blind holes are machined using either mechanical drilling or laser drilling. In mechanical drilling, a micro-drill bit with a diameter of 0.1 mm is used, with a drilling speed of 1500 Krpm / s, a down-drilling speed of 1.1 m / min, and a retraction speed of 15 m / min. In laser drilling, a CO2 laser is used with a wavelength of 9.4 μm and an energy of 107 W / cm². Laser drilling is performed in three stages: the first laser energy density is 17 mJ / cm², the second is 11 mJ / cm², and the third is 6 mJ / cm².

[0092] When laser drilling, the first laser uses a high laser energy density to open the hole, while the second and third lasers gradually reduce the laser energy density. Low energy trimming can improve the roundness of the blind hole, and subsequent low laser energy densities make it easier to control the depth and bottom shape of the blind hole.

[0093] In step S6, during vacuum etching, the acidic etching solution is used to etch the exposed copper surface to form circuits using a vacuum two-fluid etching method. A protective agent is added to the acidic etching solution. In the acidic vacuum etching technology, the protective agent combined with the vacuum two-fluid etching technology precisely controls the etching amount, making the etching factor ≥3. This results in smaller burrs and higher verticality of the etched circuits, and increases the heat resistance and chemical resistance of the ink at the solder bridge location, avoiding problems such as excessive side etching or ink peeling.

[0094] In step 10, before the solder mask is printed, the blind holes on the PCB substrate are plugged with aluminum sheets. The solder mask plugging design using aluminum sheets ensures that the ink saturation inside the hole reaches more than 85%, establishing a connection between the surface solder bridge and the ink inside the hole, resulting in stronger adhesion.

[0095] Example 2

[0096] Please see Figures 5-6 This invention discloses a short jumper automotive board with a thick copper semi-cut-off minimal weld bridge, comprising:

[0097] PCB board 1, on which discharge pads 11 are provided;

[0098] A solder bridge 2 is disposed between adjacent discharge pads 11. The solder bridge 2 is a disconnected design. A blind via 12 is disposed on the substrate of the PCB board 1. The blind via 12 is located below the top of one end of the disconnected part of the solder bridge 2. The blind via 12 is disposed in the roughened area 13 of the substrate of the PCB board 1. The roughened area 13 includes several rings of roughened vias arranged concentrically with the blind via 12. Each ring of roughened vias includes several roughened blind vias arranged circumferentially along the blind via 12. The innermost ring of roughened blind vias is connected to the blind via 12. The roughened blind vias of one ring of roughened vias are connected to the roughened blind vias of another adjacent ring of roughened vias.

[0099] Blind holes are machined on the substrate at the corresponding position on the top of the disconnected weld bridge, so that the weld bridge and the hole diameter of the board are connected, which solves the problem of easy side corrosion and peeling off the top of the disconnected weld bridge. Furthermore, by arranging several rings of roughened holes around the outside of the blind holes, and making the roughened blind holes below the weld bridge 2 connected to the blind holes, the bonding ability of the ink in the weld bridge, the board surface, and the blind holes is further increased, preventing the side corrosion and peeling off the top of the disconnected weld bridge.

[0100] The diameter of the roughened blind vias gradually increases from the inner ring roughened via group to the outer ring roughened via group. The diameter of the outer ring roughened via group gradually increases. With the number of roughened blind vias remaining constant, the increased diameter ensures the contact area with the weld bridge and prevents the top side corrosion and detachment of the disconnected weld bridge.

[0101] The depth of the textured blind vias gradually decreases from the inner ring textured via group to the outer ring textured via group. When ink overflows from the blind vias into the textured blind vias, by controlling the gradual decrease in the depth of the textured blind vias, the ink in the outer ring textured via group is effectively ensured to be fully filled, thereby preventing the top side etching and detachment of the disconnected weld bridge.

[0102] 2OZ copper thick green oil disconnected 2.5mil weld bridge design.

[0103] Outer layer / drilling / solder resist, engineering and process parameter design:

[0104] 1) 2OZ copper thickness, green solder resist ink, finished copper thickness 2Z, outer layer spacing 3mil design:

[0105] 1.1 At the top 1 mil of the disconnected position of the weld bridge, design a laser blind hole with a diameter of 0.05 mm;

[0106] 1.2 Drilling parameters:

[0107] 1.3 Weld shielding bridge design: 2.5 mil;

[0108] 1.4 High-voltage discharge PAD spacing: 1.5 mil.

[0109] 2) Exposure method design:

[0110] 2.1 Exposure program design: Two-stage exposure is adopted. The same part number and the same side are exposed twice. The LDI exposure machine exposes the normal data the first time, and only exposes the weld bridge position the second time.

[0111] 2.2 The project uses Genesis software to create two sets of data, labeled as follows: Part Number Name-Surface Number-Exposure Data 1 (normal design full-surface exposure data) and Part Number Name-Surface Number-Exposure Data 2 (only design weld bridge position data).

[0112] 2.2 Using an LDI exposure machine, retrieve the production data and directly load two data samples for exposure on the first side; similarly, load two data samples for exposure on the second side, setting the exposure energy to 11 seconds and 350-450 mJ / cm².

[0113] 3) Production process (drilling / outer layer / solder resist):

[0114] A method for processing short jumper wires for automotive circuit boards with thick copper semi-cut-off minimal weld bridges includes the following steps:

[0115] S1. Drilling: Drill blind holes on the PCB substrate 1 mil above the break point of the solder bridge;

[0116] S2. Outer layer pretreatment: Clean and roughen the copper surface of the PCB substrate. First, mechanically brush it with a brush wheel, and then pickle it with an acidic cleaning agent. The linear speed is 3.0m / min. The mechanical brushing includes one set of 300-mesh brush wheel and one set of 500-mesh brush wheel. The pickling concentration is 3-5%. The drying temperature is 85℃ and the pickling pressure is 1.8kg / cm².

[0117] S3, Outer lamination: A layer of photosensitive dry film is attached by hot pressing process, with a pressure of 4.5 kg / cm², a temperature of 120℃, and a speed of 2.5 ± 0.5 m / min;

[0118] S4, Outer Layer Exposure: Expose and cure the circuit pattern with 6-7 energy bars;

[0119] S5. Development: Development dissolves uncured dry film, linear speed 3m / min, sodium carbonate concentration 8-12g / l, development pressure 1.2kg / cm²;

[0120] S6. Vacuum etching: Acidic vacuum two-fluid etching is used to expose copper foil to form circuits. A protective agent is added to the acidic etching solution. The line speed is 2.2m / min and 1.3m / min for 2OZ copper thickness, and the etching pressure is 2.3kg / cm².

[0121] S7. Remove film;

[0122] S8, AOI / test;

[0123] S9. Pre-treatment before solder resist application: First, mechanically brush the surface with a brush wheel, then pickle it with an acidic cleaner, followed by spraying a diamond abrasive suspension onto the copper surface under high pressure, and finally rinsing with water. The linear speed is 2.8 m / min. The mechanical brushing includes one set each of 500-mesh and 800-mesh brush wheels. The pickling concentration is 3-5%, the drying temperature is 85℃, the pickling pressure is 1.8 kg / cm², the water rinsing pressure is 1.5 kg / cm², and the diamond abrasive content is 15-20 ml / l.

[0124] S10, Solder resist screen printing: Use 90 mesh screen printing, printing pressure 5kg / cm², printing angle 30°, printing speed 2.5m / min;

[0125] S11. Solder resist pre-baking: Pre-baking parameters are 73℃, 50min;

[0126] S12, Solder Mask Exposure: After the PCB board is aligned and exposed once in the equipment, it is not removed and directly subjected to a second exposure. The first exposure is a normal full-side exposure of the PCB board, and the second exposure is an online secondary exposure of the solder mask bridge position. Specifically, retrieve the project data → edit and process the data → load the first side data 1 → first exposure → load the first side data 2 → second exposure → manually flip the board (side by side) → load the second side data 1 → first exposure → load the second side data 2 → second exposure, so that the ink at the solder mask bridge position is completely cured and the thermal shock resistance reaches 288℃, 10S, 3 times;

[0127] S13, Solder resist developing: linear speed 3.5m / min, sodium carbonate concentration 8-12g / l, developing pressure 1.8kg / cm²;

[0128] S14, Inspection;

[0129] S15. Post-solder resist baking: The solder resist ink is subjected to high-temperature curing treatment. The high-temperature curing treatment is divided into 4 stages of heating to release the internal stress of the ink and avoid thermal shock that may cause the ink to crack or affect adhesion. The curing parameters for the first stage are 70℃ for 60min, the curing parameters for the second stage are 90℃ for 40min, the curing parameters for the third stage are 110℃ for 40min, and the curing parameters for the fourth stage are 150℃ for 60min.

[0130] Outer layer to solder mask production process: Outer layer pretreatment → lamination → exposure → development → vacuum etching → film removal → AOI / inspection → solder mask pretreatment → screen printing → pre-baking → exposure → development → inspection → post-baking. Mechanical drilling or laser drilling is used on the substrate at the corresponding position on the top of the disconnected solder bridge to establish a connection between the solder bridge and the board hole diameter. This solves the problem of easy lateral etching and detachment of the top of the disconnected solder bridge. Using standard inks, without changing the existing ink type or thickness, the UV curing of the ink at the solder bridge position is more complete. Online secondary exposure achieves alignment accuracy within 15µm, avoiding PCB misalignment caused by secondary alignment and improving production efficiency. Secondary exposure targets the solder bridge area separately, resulting in better adhesion of the solder bridge and preventing poor exposure on the board surface. These technical solutions make the short jumper design of automotive PCBs more reliable, solving the problems of rapid testing, debugging, and fault diagnosis and repair during final assembly and use, while significantly saving costs and improving production efficiency.

[0131] A novel short jumper design has been disclosed, which significantly reduces the distance between two adjacent conductors (from a minimum of 10 mil to a minimum of 3-5 mil). During rapid circuit testing, there is no need to use metal conductors (wires) to connect or disconnect the two conductors. Instead, solder can be used directly to melt and disconnect them, further improving the efficiency of rapid circuit board testing.

[0132] Example 3

[0133] Please see Figure 7 The present invention also discloses a design structure for a semi-interrupted weld bridge, comprising:

[0134] PCB board 1, on which discharge pads 11 are provided;

[0135] Solder bridge 2 is disposed between adjacent discharge pads 11. Solder bridge 2 is a semi-cut-off solder bridge. One end of solder bridge 2 is provided with NPTH hole 9. Blind holes are provided on the substrate of PCB board 1. The blind holes are located below the top of one end of the disconnected solder bridge 2. The blind holes are located in the roughened area of ​​the substrate of PCB board 1. The roughened area includes several rings of roughened hole groups arranged concentrically with the blind holes. Each ring of roughened hole groups includes several roughened blind holes arranged circumferentially along the blind holes. The innermost ring of roughened blind holes is connected to the blind holes. The roughened blind holes of one ring of roughened hole groups are connected to the roughened blind holes of the adjacent ring of roughened hole groups.

[0136] Compared to Examples 1-2, the PCB in Example 3 is not a short jumper design, but the solder bridge 2 adopts the same design as in Examples 1-2, using NPTH holes 9 and roughened areas to solve the problem of easy side corrosion and detachment of the top of the disconnected solder bridge.

[0137] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A short jumper automotive sheet with a thick copper semi-cut-off minimal weld bridge, characterized in that, include: PCB board with electrical discharge pads on it; A solder bridge is provided between adjacent discharge pads. The solder bridge is a disconnected design. Blind vias are provided on the substrate of the PCB board. The blind vias are located below the top of one end of the disconnected solder bridge. The blind vias are located in the roughened area of ​​the PCB board substrate. The roughened area includes several rings of roughened vias arranged concentrically with the blind vias. Each ring of roughened vias includes several roughened blind vias arranged circumferentially along the blind vias. The innermost ring of roughened blind vias is connected to the blind vias. The roughened blind vias of one ring of roughened vias are connected to the roughened blind vias of another adjacent ring of roughened vias.

2. The short jumper automotive sheet of a thick copper semi-cut-off minimal weld bridge according to claim 1, characterized in that, The diameter of the texturized blind holes gradually increases from the inner circle of texturized hole groups to the outer circle of texturized hole groups.

3. A short jumper automotive sheet with a thick copper semi-cut-off minimal weld bridge according to claim 1 or 2, characterized in that, The depth of the texturized blind holes gradually decreases from the inner circle of texturized hole groups to the outer circle of texturized hole groups.

4. A method for processing short jumper wires in automotive steel sheets using a thick copper semi-partial type minimal weld bridge, characterized in that, Includes the following steps: S1. Drilling: A blind hole is processed on the PCB substrate 1 mil above the break point of the solder bridge. A roughened area is processed on the substrate outside the blind hole. The roughened area is processed by laser micro-hole. S2. Outer layer pretreatment: The copper surface of the PCB substrate is cleaned and roughened. First, it is mechanically brushed with a brush wheel, and then acid-washed with an acidic cleaning agent. S3, outer lamination; S4, outer layer exposure; S5, Development; S6, vacuum etching; S7. Remove film; S8, AOI / test; S9. Pre-treatment before soldering; S10, solder resist printing; S11, Pre-baking of solder mask; S12, Solder Mask Exposure: After the PCB board is aligned and exposed once in the equipment, it is not taken out and no second alignment is required. The second exposure is performed directly. The first exposure is a normal full-area exposure of the PCB board, and the second exposure is an online secondary exposure of the solder mask bridge position. S13, Solder resist developer; S14, Inspection; S15, Bake after soldering.

5. The method for processing short jumper wires for automotive steel sheets with a thick copper semi-partial ultra-small weld bridge according to claim 4, characterized in that, In step S1, blind holes are machined by mechanical drilling or laser drilling.

6. The method for processing short jumper wires for automotive steel sheets with a thick copper semi-partial ultra-small weld bridge according to claim 5, characterized in that, In step S1, a micro-hole drill bit with a diameter of 0.1 mm is used for mechanical drilling, with a drilling speed of 1500 Krpm / s, a down-drilling speed of 1.1m / min, and a retraction speed of 15m / min.

7. The method for processing short jumper wires for automotive steel sheets with a thick copper semi-partial ultra-small weld bridge according to claim 5, characterized in that, In step S1, CO2 laser drilling is used for laser drilling, and the laser drilling is performed in three stages: the first laser energy density is 17 mj / cm², the second laser energy density is 11 mj / cm², and the third laser energy density is 6 mj / cm².

8. The method for processing short jumper wires for automotive steel sheets with a thick copper semi-partial ultra-small weld bridge according to claim 4, characterized in that, In step S6, during vacuum etching, the acidic etching solution is used to etch the exposed copper surface to form circuits using a vacuum two-fluid etching method, and a protective agent is added to the acidic etching solution.

9. The method for processing short jumper wires for automotive steel sheets with thick copper semi-partial ultra-small weld bridges according to claim 4, characterized in that, In step S10, before the solder mask layer is printed, the blind holes on the PCB substrate are plugged with aluminum sheets.

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