A method and system for manufacturing a drive circuit PCB finished board

Abstract

The embodiment of the application provides a kind of drive circuit PCB finished plate manufacturing method and system, belong to circuit board manufacturing technical field.The method comprises: obtaining the circuit pattern of drive circuit PCB, solder mask window pattern and carbon oil circuit pattern, and determining carbon oil circuit step boundary area based on circuit pattern, solder mask window pattern and carbon oil circuit pattern;Boundary transition processing is executed to carbon oil circuit step boundary area, and form the gentle slope transition interface for bearing carbon oil circuit;Carbon oil adsorption bottom line is made on gentle slope transition interface, and carbon oil circuit is printed based on carbon oil adsorption bottom line, and form step carbon oil circuit structure;Segmented solidification processing is executed to step carbon oil circuit structure, and drive circuit PCB finished plate is obtained.The application scheme reduces the edge ink shrinkage, ink stacking and thermal cycle cracking risk of carbon oil circuit in vehicle-mounted drive circuit PCB, improves the conductive stability under wide temperature vibration working condition.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and more specifically to a method and system for manufacturing a finished PCB board for a drive circuit. Background Technology

[0002] Automotive drive circuit PCBs typically need to support functions such as power device driving, relay control, and motor drive signal transmission. The board surface includes copper traces, pads, solder mask openings, and may also feature carbon solder mask traces for button contacts, resistance adjustment, or local conductive connections. Compared to ordinary consumer electronics PCBs, automotive drive circuit PCBs operate under long-term conditions of wide temperature cycling, humidity, vibration, and alternating pulsed current, demanding higher reliability from local structural elements.

[0003] Current carbon ink trace manufacturing primarily employs conventional screen printing and overall thermosetting processes. While this process typically meets conductivity and adhesion requirements on flat copper surfaces or single-substrate surfaces, in automotive drive circuit PCBs, carbon ink traces often need to cross copper surfaces, solder mask edges, and solder mask opening areas. These locations exhibit significant steps, with inconsistent surface energy and roughness. During carbon ink printing, ink shrinkage, ink buildup, or weak edge bands are prone to occur at the solder mask edges. After curing, the thickness and shrinkage of the carbon ink layer at the step boundaries are uneven, making it susceptible to problems such as fine cracks, warping, and unstable local contact after high and low temperature cycling and vibration.

[0004] For drive circuits, the aforementioned defects may not be immediately apparent during routine visual inspections, but may manifest as sheet resistance drift, abnormal localized temperature rise, or intermittent conduction abnormalities during pulsed power-on or long-term automotive service. Existing processes focus more on the carbon ink material formulation, printing thickness, or curing temperature itself, lacking specialized manufacturing methods for the carbon ink's cross-step boundary regions. Therefore, there is an urgent need for a manufacturing method for drive circuit PCBs that can improve the load-bearing condition at cross-step boundaries, reduce the risk of carbon ink edge cracking, and enhance conductivity stability under automotive conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for manufacturing a finished PCB board for a drive circuit, so as to at least solve the problems of ink shrinkage, ink buildup, edge cracking and sheet resistance drift that easily occur when carbon oil lines cross the boundary between the copper surface and the solder mask layer in the PCB of an automotive drive circuit.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for manufacturing a finished PCB board for a driving circuit, the method comprising: Obtain the circuit pattern, solder mask window pattern, and carbon oil circuit pattern of the drive circuit PCB, and determine the step-crossing boundary region of the carbon oil circuit based on the circuit pattern, the solder mask window pattern, and the carbon oil circuit pattern. Boundary transition treatment is performed on the step boundary area of ​​the carbon oil line to form a gentle slope transition interface for supporting the carbon oil line; A carbon oil adsorption pattern is made on the gentle slope transition interface, and carbon oil lines are printed based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure. The cross-step carbon oil circuit structure is subjected to segmented curing process to obtain the finished PCB board of the drive circuit.

[0007] Optionally, the step boundary region of the carbon oil line is determined, including: The circuit pattern, the solder mask opening pattern, and the carbon oil circuit pattern are superimposed. The graphic segment of the carbon oil circuit that simultaneously crosses the outer copper surface, the edge of the solder mask layer, and the solder mask opening area is extracted. The corresponding position of the graphic segment is determined as the step boundary area of ​​the carbon oil circuit.

[0008] Optionally, the boundary transition treatment includes: performing plasma cleaning treatment on the carbon oil line across the step boundary area, with a treatment power of 200W-500W and a treatment time of 30s-120s; Insulating transition ink is printed at the edge of the solder mask layer and pre-cured at 80℃-100℃ for 10min-20min to form the gentle slope transition interface.

[0009] Optionally, the process of creating the carbon oil adsorption pattern includes: printing a low-viscosity carbon oil pattern material on the gentle slope transition interface to form multiple spaced carbon oil adsorption patterns. The carbon oil adsorption pattern has a line width of 40μm-120μm and a spacing of 80μm-250μm, and is pre-baked at 70℃-90℃ for 5min-15min.

[0010] Optionally, printing carbon ink lines includes: printing a first carbon ink layer within the carbon ink line pattern area, wherein the thickness of the first carbon ink layer is 8μm-18μm; A second carbon oil layer is printed on the surface of the first carbon oil layer. The second carbon oil layer avoids the step boundary region of the carbon oil line by 0.2mm-0.8mm, and the thickness of the second carbon oil layer is 5μm-12μm.

[0011] Optionally, the segmented curing process includes: allowing the material to stand and level for 5 to 15 minutes; Pre-cur at 80℃-100℃ for 10-25 minutes; Main curing at 140℃-160℃ for 25-45 minutes; The carbon oil line cross-step boundary area is subjected to thermal insulation and stress relief treatment at 110℃-130℃ for 8min-20min.

[0012] Optionally, the cross-step carbon oil circuit structure is subjected to visual inspection before the segmented curing process is performed; When the ink shrinkage width of the carbon oil circuit across the step boundary area is greater than 50μm or the ink buildup height is greater than 25μm, the corresponding area is locally erased and reprinted.

[0013] Optionally, after obtaining the finished PCB board of the driving circuit, the sheet resistance and local energized thermal response of the carbon oil circuit across the step boundary area are detected. When the sheet resistance change rate is greater than 5%, or the temperature rise in the step boundary area of ​​the carbon oil circuit is more than 3°C higher than the temperature rise in the middle area of ​​the same carbon oil circuit, the corresponding drive circuit PCB finished board will be judged as an abnormal finished board.

[0014] A second aspect of the present invention provides a finished PCB board for a driving circuit, which is manufactured based on the above-described manufacturing method for a finished PCB board for a driving circuit.

[0015] A third aspect of the present invention provides a manufacturing system for a finished PCB board of a driving circuit, the system being used to perform the above-described manufacturing method for a finished PCB board of a driving circuit, the system comprising: The first module is used to acquire the circuit pattern, solder mask window pattern and carbon oil circuit pattern of the drive circuit PCB, and to determine the step boundary region of the carbon oil circuit based on the circuit pattern, the solder mask window pattern and the carbon oil circuit pattern. The second module is used to perform boundary transition processing on the carbon oil line across the step boundary area to form a gentle slope transition interface for supporting the carbon oil line. The third module is used to create a carbon oil adsorption pattern on the gentle slope transition interface, and to print carbon oil lines based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure. The fourth module is used to perform segmented curing processing on the cross-step carbon oil circuit structure to obtain the finished PCB board of the drive circuit.

[0016] Through the above technical solution, the present invention can accurately locate the easily failed cross-step boundary area before carbon ink circuit printing, and transform the originally abrupt copper surface and solder mask interface into a smoother bearing interface through boundary transition treatment, reducing ink shrinkage and ink buildup at the step. Carbon ink adsorption texture can improve the continuity of carbon ink spreading and enhance the adhesion stability of the carbon ink layer in the boundary area. Segmented curing treatment helps reduce the residual stress caused by uneven curing shrinkage of carbon ink circuits. The resulting drive circuit PCB can reduce the risk of edge cracking, warping, and sheet resistance drift of carbon ink circuits, and improve the conductivity stability under wide temperature and vibration conditions in automotive applications.

[0017] Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate embodiments of the present invention and form part of the specification. They are used together with the following detailed description to explain the embodiments of the present invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the steps of a method for manufacturing a finished PCB board for a driving circuit according to one embodiment of the present invention; Figure 2 This is a schematic diagram of the formation process of the step-cross carbon oil circuit structure of the drive circuit PCB provided in one embodiment of the present invention; Figure 3 This is a system structure diagram of a driving circuit PCB finished board manufacturing system provided in one embodiment of the present invention. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] like Figure 1 As shown, an embodiment of the present invention provides a method for manufacturing a finished PCB board for a driving circuit, the method comprising: Step S100: Obtain the circuit pattern, solder mask window pattern, and carbon oil circuit pattern of the drive circuit PCB, and determine the carbon oil circuit cross-step boundary region based on the circuit pattern, the solder mask window pattern, and the carbon oil circuit pattern.

[0021] Specifically, determining the step-crossing boundary region of the carbon oil circuit includes: overlaying the circuit pattern, the solder mask opening pattern, and the carbon oil circuit pattern; extracting the graphic segment of the carbon oil circuit that simultaneously crosses the outer copper surface, the edge of the solder mask layer, and the solder mask opening region; and determining the corresponding position of the graphic segment as the step-crossing boundary region of the carbon oil circuit.

[0022] In step S100, the circuit pattern of the drive circuit PCB can be derived from the circuit data used in the outer layer circuit fabrication, the solder mask window pattern can be derived from solder mask film data or solder mask exposure data, and the carbon ink circuit pattern can be derived from carbon ink printing screen data. After importing, the above patterns are unified according to the same board edge reference, positioning hole reference, or process target reference, so that the patterns formed by different processes can correspond to the actual board surface position under the same plane coordinate.

[0023] In the specific processing, the circuit pattern, solder mask opening pattern, and carbon oil circuit pattern are overlaid. The circuit pattern is used to determine the position of the outer copper layer, the solder mask opening pattern is used to determine the position of the exposed copper layer or pad opening, and the carbon oil circuit pattern is used to determine the subsequent carbon oil coverage path. After overlay, if a carbon oil circuit pattern segment extends from the surface of the solder mask layer to the solder mask opening area and passes through the area adjacent to the outer copper layer or pad, then in actual manufacturing, this pattern segment will cross the height change area formed by the edge of the solder mask layer. The board surface position corresponding to this pattern segment can be determined as the carbon oil circuit step-crossing boundary area.

[0024] The term "carbon ink trace crossing step boundary area" does not refer to all carbon ink traces, nor is it defined solely by trace width. Instead, it identifies locations where there is an actual height difference and abrupt change in surface condition between the carbon ink trace and the solder mask edge or the outer copper surface. For example, in motor drive boards, seat control boards, or automotive button drive boards, carbon ink traces may need to extend from the solder mask coverage area to the pad opening area. The solder mask boundary at this point is prone to creating printing discontinuities, affecting subsequent carbon ink spreading and curing shrinkage. By identifying this area before manufacturing, a clear processing location can be provided for subsequent boundary transition treatment, carbon ink adsorption pattern creation, and carbon ink trace printing.

[0025] In this embodiment, the overlap identification can be completed by CAM software, or the manufacturing execution system can automatically generate area markers after reading the circuit pattern, solder mask window pattern, and carbon oil circuit pattern. The scope of protection is not limited to a specific software type; as long as the graphic segment of the carbon oil circuit crossing the outer copper surface, the edge of the solder mask layer, and the solder mask window area can be determined based on the above three types of graphics, it falls under the determination method described in this step.

[0026] In another embodiment, after the circuit pattern, solder mask window pattern, and carbon oil circuit pattern are superimposed, the power device layout information and high-current loop routing information in the drive circuit PCB are further read, and the main heat flow propagation direction on the board surface is determined based on the heating direction of the power devices. Subsequently, the angular relationship between the carbon oil circuit's step-crossing boundary region and the main heat flow propagation direction is analyzed.

[0027] For carbon oil circuit boundary regions crossing steps with an angle of less than 30° to the main heat flow propagation direction, these are marked as thermally coupled step-crossing regions. These regions are more susceptible to thermal cycling and localized thermal expansion and contraction during vehicle operation, making the carbon oil layer at the boundary more prone to long-term fatigue shrinkage. Based on this identification, the coverage width of the insulating transition ink can be increased in subsequent boundary transition processing, or the coverage allowance of the first carbon oil layer in the corresponding region can be increased during subsequent carbon oil circuit printing.

[0028] For example, in motor driver boards, there is often significant heat flow concentration near the MOS driving area, and the boundary region of some carbon oil circuits across the step is basically aligned with the heat dissipation path. After long-term power-on, fine cracks extending along the circuit direction are more likely to form at this location. By identifying the thermally coupled step-crossing region in advance in step S100, subsequent processes can be adjusted accordingly, rather than applying uniform manufacturing parameters to all step-crossing regions.

[0029] Step S200: Perform boundary transition processing on the carbon oil line across the step boundary area to form a gentle slope transition interface for supporting the carbon oil line.

[0030] Specifically, the boundary transition treatment includes: performing plasma cleaning on the carbon oil line across the step boundary area, with a processing power of 200W-500W and a processing time of 30s-120s; printing insulating transition ink on the edge of the solder resist layer and pre-curing it at 80℃-100℃ for 10min-20min to form the gentle slope transition interface.

[0031] In step S200, the boundary transition processing is performed on the carbon ink trace crossing step boundary region determined in step S100. This region is typically located at the junction of the solder mask edge, the outer copper surface, and the solder mask opening area, where the board height and surface energy state change. If carbon ink printing is performed directly, the carbon ink is prone to accumulate at the edge of the solder mask or form an insufficiently spread empty edge on the copper side. Therefore, before printing the carbon ink trace, it is necessary to first form a relatively continuous bearing interface in this region.

[0032] In practice, plasma cleaning is performed on the boundary area of ​​the carbon oil circuit across the step. The processing power can be controlled between 200W and 500W, and the processing time can be controlled between 30s and 120s. This treatment is used to remove residual organic contaminants, additive residues, and slight oxides from the edge of the solder mask layer, while improving the wetting state between the solder mask surface and the outer copper surface. The power and time should not be too high to avoid excessive etching of the solder mask surface or aggravation of copper surface oxidation; nor should they be too low, otherwise it will be difficult to stably remove contaminant residues in the boundary area.

[0033] After plasma cleaning, an insulating transition ink is printed at the edge of the solder mask layer. The insulating transition ink is preferably located in the non-conductive load-bearing area at the edge of the solder mask layer and covers the abrupt height change at the edge, creating a continuous transition between the solder mask edge and the adjacent board surface. The insulating transition ink should not cover the contact areas where the carbon traces need to be directly connected to the outer copper surface, to avoid affecting subsequent electrical connections. Printing methods can include partial screen printing, dispensing, or inkjet printing; the specific method can be selected based on the board space and mass production equipment conditions.

[0034] After printing, the insulating transition ink undergoes pre-curing. The pre-curing temperature is 80℃-100℃, and the pre-curing time is 10-20 minutes. This allows the insulating transition ink to achieve basic shape retention and maintains a surface condition suitable for subsequent carbon ink adhesion. After this treatment, the original near-right-angled solder resist steps are transformed into a gently sloping transition interface. This gently sloping transition interface serves as the foundation for subsequent carbon ink adsorption patterns and carbon ink lines, reducing abrupt thickness changes and shrinkage concentration of the carbon ink at the boundary.

[0035] In another embodiment, after plasma cleaning, continuous or intermittently distributed micro-pressure relief grooves are formed at the junction of the solder mask edge and the outer copper surface. These micro-pressure relief grooves are located within the coverage area of ​​the subsequent insulating transition ink. The micro-pressure relief grooves can be formed by laser micro-etching, micro-grinding, or localized chemical etching, and their width can be controlled to be 30μm-80μm, and their depth can be controlled to be 5μm-20μm.

[0036] This micro-relief groove is not used to form a conductive structure, but rather to provide localized stress release space during the subsequent curing of insulating transition inks and carbon-based circuitry. Because the edges of the solder mask layer in automotive drive circuit PCBs typically exhibit changes in material modulus and abrupt height variations, carbon-based circuitry is prone to forming concentrated tensile stress along the solder mask edge during thermosetting shrinkage. Especially in motor drive boards or relay control boards, the step-crossing boundary region is subjected to long-term pulse current and thermal cycling, and localized fine cracks often propagate along the solder mask edge.

[0037] In this embodiment, after the micro-pressure relief groove is formed, a portion of the insulating transition ink fills into the groove, creating a more stable mechanical bond between the gradual transition interface and the board surface. When the carbon oil circuit undergoes thermal shrinkage, the localized shrinkage stress can be released along the direction of the micro-pressure relief groove, rather than concentrating on the edge of the solder mask layer. For carbon oil circuits with long cross-step boundary lengths, intermittent micro-pressure relief grooves can be used; for high-current driven areas, continuous micro-pressure relief grooves can be used. The protection scope is not limited to a specific groove shape; any microstructure formed during the boundary transition process to release the curing shrinkage stress in the cross-step boundary region can be included within the protection scope of this embodiment.

[0038] Step S300: Create a carbon oil adsorption pattern on the gentle slope transition interface, and print carbon oil lines based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure.

[0039] Specifically, the process of creating the carbon oil adsorption pattern includes: printing a low-viscosity carbon oil pattern material on the gentle slope transition interface to form multiple spaced carbon oil adsorption patterns; the line width of the carbon oil adsorption pattern is 40μm-120μm, the spacing is 80μm-250μm, and it is pre-baked at 70℃-90℃ for 5min-15min.

[0040] The process of printing carbon ink circuitry includes: printing a first carbon ink layer within the carbon ink circuitry pattern area, the first carbon ink layer having a thickness of 8μm-18μm; and printing a second carbon ink layer on the surface of the first carbon ink layer, the second carbon ink layer avoiding the step boundary region of the carbon ink circuitry by 0.2mm-0.8mm, and the second carbon ink layer having a thickness of 5μm-12μm.

[0041] In step S300, the carbon ink adsorption pattern is created on the gently sloping transition interface formed in step S200. Although the gently sloping transition interface weakens the height abrupt change at the edge of the solder mask layer, this area still contains solder mask material, insulating transition ink, and adjacent outer copper surface, and the surface wetting state is not completely consistent. If the entire carbon ink circuit is printed directly, the carbon ink may still exhibit edge retraction, local empty edges, or thickness accumulation at the step boundaries. Based on this, this step forms the carbon ink adsorption pattern before printing the main carbon ink circuit, so that the subsequent carbon ink paste can spread along the preset pattern.

[0042] Specifically, a low-viscosity carbon oil base material is printed on the gently sloping transition interface to form multiple spaced carbon oil adsorption base lines. These carbon oil adsorption base lines are located within the coverage area of ​​the carbon oil circuit pattern and do not extend beyond non-carbon oil circuit areas to avoid forming unintended conductive paths. The linewidth of the carbon oil adsorption base lines can be controlled between 40μm and 120μm, and the spacing between adjacent carbon oil adsorption base lines can be controlled between 80μm and 250μm. This size range is suitable for conventional precision screen printing or partial inkjet printing, providing continuous wetting traction points on the gently sloping transition interface without causing excessively thick local carbon oil layers due to overly dense base lines. After printing, the carbon oil adsorption base lines are pre-baked at 70℃-90℃ for 5-15 minutes to achieve a preliminary set while retaining a certain level of surface activity, facilitating bonding with the subsequent first carbon oil layer.

[0043] After completing the carbon ink adsorption base pattern, the first carbon ink layer is printed within the carbon ink circuit pattern area. This first carbon ink layer covers the entire carbon ink circuit pattern and extends across the step boundary area; its thickness can be 8μm-18μm. As a continuous conductive base layer, this first carbon ink layer needs to ensure circuit continuity from the solder mask coverage area to the solder mask opening area. Because a gentle slope transition interface and carbon ink adsorption base pattern already exist, the spreading edge of the first carbon ink layer at the step boundary is more easily maintained intact, eliminating the need for a one-time thickening to compensate for insufficient printing at the step.

[0044] Subsequently, a second carbon ink layer is printed on the surface of the first carbon ink layer. This second carbon ink layer, with a thickness of 5μm-12μm, is used to supplement the conductive cross-section of the central region of the carbon ink circuit. The second carbon ink layer does not cover the step-crossing boundary region of the carbon ink circuit and maintains a clearance distance of 0.2mm-0.8mm from it. This clearance distance can be determined based on the width of the carbon ink circuit, the edge height of the solder mask layer, and the printing alignment accuracy. Through this staggered overprinting method, a relatively thin carbon ink thickness is maintained in the step-crossing boundary region, while a more stable conductive thickness is achieved in the central region. In other words, the carbon ink circuit is not stacked with equal thickness at all locations; instead, thickness abrupt changes are reduced at boundary locations prone to shrinkage and concentration, while the required cross-sectional area is retained in the main conductive areas.

[0045] In some embodiments, the first and second carbon oil layers can be made of the same carbon oil material, or they can be made of carbon oil materials with different viscosities or solid contents. For vehicle-mounted button driver boards, relay driver boards, or motor control auxiliary boards, when the width of the carbon oil lines is small, the avoidance distance of the second carbon oil layer can be smaller; for drive circuit PCBs where the carbon oil lines need to pass through a wider solder mask opening boundary, the avoidance distance of the second carbon oil layer can be appropriately increased. The protection scope is not limited to specific printing equipment; as long as a cross-step carbon oil line structure is formed by using carbon oil adsorption patterns in conjunction with the first carbon oil layer and the second carbon oil layer that avoids the cross-step boundary area, it can be included in the implementation method of this step.

[0046] Step S400: Perform segmented curing treatment on the cross-step carbon oil circuit structure to obtain the finished PCB board of the drive circuit.

[0047] Specifically, the segmented curing process includes: static leveling for 5 to 15 minutes; pre-curing at 80℃-100℃ for 10 to 25 minutes; main curing at 140℃-160℃ for 25 to 45 minutes; and performing thermal insulation and stress relief treatment on the carbon oil circuit cross-step boundary area at 110℃-130℃ for 8 to 20 minutes.

[0048] Before performing the segmented curing process, the appearance of the cross-step carbon oil circuit structure is inspected; when the ink shrinkage width of the cross-step boundary area of ​​the carbon oil circuit is greater than 50μm or the ink buildup height is greater than 25μm, the corresponding area is locally erased and reprinted.

[0049] In step S400, after the cross-step carbon ink circuit structure is formed, the printing state needs to be visually inspected before proceeding to the curing process. This inspection mainly focuses on the cross-step boundary area of ​​the carbon ink circuit, and includes checking whether the carbon ink edge is continuous, whether there are ink shrinkage gaps, and whether there is obvious ink buildup near the step. The inspection can be completed using an industrial camera with a side light source, or by using a three-dimensional contour measurement device to read the local height. For areas with ink shrinkage width greater than 50μm or ink buildup height greater than 25μm, it indicates that the carbon ink is not sufficiently spread on the gentle slope transition interface or the local thickness is too large. Direct curing in this case can easily lead to edge cracks or shrinkage concentration. In this case, the corresponding area can be locally erased, and then reprinted according to the aforementioned carbon ink adsorption pattern and carbon ink circuit printing rules.

[0050] After visual inspection, the cross-step carbon ink circuit structure enters the segmented curing process. The printed board is first allowed to stand and level for 5 to 15 minutes, allowing the ink in the first and second carbon ink layers to spread naturally within the screen printing pattern, reducing squeegee marks and localized thickness abrupt changes. The standing time should not be too long to avoid further diffusion of the carbon ink at the edges; nor should it be too short, otherwise, if the solvent has not migrated evenly before entering the heating stage, a surface skin may easily form.

[0051] Pre-curing is performed at 80℃-100℃ for 10-25 minutes. This stage primarily allows for the slow release of some solvent from the carbon oil circuitry and provides initial morphological stability to the cross-step carbon oil circuitry structure. For carbon oil slurries containing resin carriers, excessively rapid heating will cause the surface layer to cure first, resulting in insufficient solvent removal from the interior. Therefore, a relatively mild pre-curing temperature range is more suitable for cross-step structures.

[0052] The primary curing process is carried out at 140℃-160℃ for 25-45 minutes to fully cure the resin system in the carbon oil and form a stable conductive network. This temperature range matches common PCB carbon oil curing processes, balancing conductivity and solder mask tolerance. After primary curing, the carbon oil traces at the step boundary are subjected to a thermal stress relief treatment at 110℃-130℃ for 8-20 minutes. This treatment can be achieved using localized infrared heating, hot air zone insulation, or a thermal insulation platform during the overall board cooling process, to reduce residual stress in the step boundary area caused by thickness differences, material interface differences, and curing shrinkage differences.

[0053] After the above-described segmented curing process, the cross-step carbon oil circuit structure forms a stable bond with the outer copper surface, solder mask edge, and gentle slope transition interface of the drive circuit PCB, resulting in the finished drive circuit PCB board. The protection scope is not limited to a specific furnace type or heating method. As long as the curing process includes leveling, pre-curing, main curing, and heat preservation and stress relief treatment for the cross-step boundary area of ​​the carbon oil circuit, it can be used as an implementation method for this step.

[0054] Preferably, after obtaining the finished PCB board of the drive circuit, the sheet resistance and local power-on thermal response of the carbon oil circuit across the step boundary area are detected; when the sheet resistance change rate is greater than 5%, or the temperature rise of the carbon oil circuit across the step boundary area is more than 3°C higher than the temperature rise of the middle area of ​​the same carbon oil circuit, the corresponding finished PCB board of the drive circuit is determined to be an abnormal finished board.

[0055] After obtaining the finished PCB board of the drive circuit, sheet resistance and local thermal response testing are performed on the carbon oil circuitry crossing the step boundary area. Sheet resistance testing can be performed using a four-probe test, a dedicated fixture crimping test, or a flying probe test. Test points are set on both sides of the carbon oil circuitry crossing the step boundary area, and the results are compared with the test results of the central area of ​​the same carbon oil circuitry. For boards in the same batch, the initial sheet resistance value after curing can also be selected as the baseline value, and then the sheet resistance change rate of subsequent test values ​​relative to the initial sheet resistance value can be calculated.

[0056] Localized thermal response testing is used to observe the heating state of the carbon oil circuit's step-crossing boundary region under current loading. During testing, a preset test current can be applied to the corresponding carbon oil circuit. The preset test current can be 50%-80% of the rated operating current of the carbon oil circuit, and the energizing time can be controlled between 1s and 5s. The temperature rise of the carbon oil circuit's step-crossing boundary region is collected using an infrared thermal imager or a spot temperature sensor. For ease of judgment, the middle area of ​​the same carbon oil circuit can be used as a reference area. The reference area should avoid the edges of the solder mask layer, pad boundaries, and adjacent positions of vias to reduce interference caused by differences in board surface structure.

[0057] When the sheet resistance change rate is greater than 5%, or the temperature rise in the boundary region of the carbon oil circuit crossing the step is more than 3°C higher than the temperature rise in the middle region of the same carbon oil circuit, it indicates that there may be localized poor contact, fine cracks, abnormal carbon oil thickness, or insufficient interface bonding in the boundary region of the step. In this case, the corresponding driver circuit PCB finished board is judged as an abnormal finished board. Abnormal finished boards can enter the re-inspection, rework, or scrapping process, and the test results can also serve as the basis for subsequent adjustment of boundary transition processing, carbon oil adsorption pattern creation, and segmented curing parameters.

[0058] The above-mentioned testing is not limited to a specific testing equipment model. As long as the sheet resistance change rate and local energized temperature rise of the carbon oil circuit across the step boundary region can be obtained, and the abnormality of the finished PCB board of the drive circuit can be judged based on a set threshold, it can be used as the testing scheme of this embodiment.

[0059] Example: This explanation uses a new energy vehicle seat control drive board as an example. This drive board controls the seat motor drive and button feedback signals. It has a board thickness of 1.6mm, uses FR-4 high-TG board as the substrate, and has an outer copper layer thickness of 1oz. The board surface has both a solder mask coverage area and a MOS driver pad opening area. Because the carbon ink circuitry needs to extend from the solder mask coverage area to the adjacent area of ​​the pads, in actual production, obvious steps easily form at the edge of the solder mask layer. After conventional carbon ink printing, ink shrinkage and localized ink buildup occur at the boundary positions, and fine cracks easily form at the edges after high and low temperature cycling.

[0060] In this embodiment, the circuit pattern, solder mask opening pattern, and carbon oil circuit pattern of the driving circuit PCB are first acquired, and then the patterns are overlaid in CAM processing software. Based on the overlay result, the position where the carbon oil circuit crosses the edge of the solder mask layer is identified, and the corresponding area is determined as the carbon oil circuit step boundary region. This region is approximately 0.6 mm wide and is located between the MOS driving pad and the solder mask coverage area.

[0061] Boundary transition treatment was performed on the carbon oil circuitry crossing the step boundary area. Specifically, an atmospheric plasma device was used to clean the surface of this area, with a treatment power set to 350W and a treatment time of 60 seconds, to remove solder resist edge residue and a slight oxide layer on the copper surface. After plasma treatment, insulating transition ink was printed on the edge of the solder resist layer using a localized screen printing method. The width of the insulating transition ink was approximately 0.25mm, and it was pre-cured at 90℃ for 15 minutes to form a gentle slope transition interface at the edge of the solder resist layer.

[0062] like Figure 2 As shown in (a) and (b), (a) represents the original state of the cross-step region, and (b) represents the state after the boundary transition treatment is completed. It can be seen that a continuous transition region is formed at the edge of the solder mask layer, and the originally steep boundary is softened.

[0063] A carbon oil adsorption pattern was created on the gently sloping transition interface. A low-viscosity carbon oil pattern material was used for localized printing to form multiple spaced carbon oil adsorption patterns. The pattern line width was 80 μm, the adjacent spacing was 150 μm, and it was pre-baked at 80℃ for 10 min. Then, the main carbon oil circuitry was printed. The first carbon oil layer thickness was controlled at 12 μm, covering the entire carbon oil circuitry area; the second carbon oil layer thickness was controlled at 7 μm, avoiding the carbon oil circuitry boundary area crossing the step by 0.5 mm. Figure 2 (c) in the diagram corresponds to the formation state of the carbon oil adsorption pattern. Figure 2 (d) in the text corresponds to the state after the formation of the cross-step carbon oil circuit structure.

[0064] After printing, the carbon oil circuit structure spanning the steps underwent segmented curing. First, it was allowed to stand and level for 10 minutes, then pre-cured at 90℃ for 20 minutes, followed by main curing at 150℃ for 35 minutes. Subsequently, the boundary area spanning the steps was subjected to thermal insulation and stress relief treatment at 120℃ for 12 minutes. After curing, the board underwent sheet resistance testing and localized thermal response testing. The test current was set to 60% of the rated operating current, and the energizing time was 3 seconds. The test results showed that the sheet resistance change rate in the boundary area spanning the steps was 2.8%, and the temperature rise difference between the boundary area and the middle area of ​​the circuit was approximately 1.2℃, meeting the process requirements of the automotive drive board.

[0065] A second aspect of the present invention provides a finished PCB board for a driving circuit, which is manufactured based on the above-described manufacturing method for the finished PCB board for a driving circuit.

[0066] like Figure 3 As shown, an embodiment of the present invention provides a manufacturing system for a finished PCB board of a driving circuit, the system comprising: The first module is used to acquire the circuit pattern, solder mask window pattern and carbon oil circuit pattern of the drive circuit PCB, and to determine the step boundary region of the carbon oil circuit based on the circuit pattern, the solder mask window pattern and the carbon oil circuit pattern. The second module is used to perform boundary transition processing on the carbon oil line across the step boundary area to form a gentle slope transition interface for supporting the carbon oil line. The third module is used to create a carbon oil adsorption pattern on the gentle slope transition interface, and to print carbon oil lines based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure. The fourth module is used to perform segmented curing processing on the cross-step carbon oil circuit structure to obtain the finished PCB board of the drive circuit.

[0067] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. This program is stored in a storage medium and includes several instructions to cause a microcontroller, chip, or processor to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as a USB flash drive, a portable hard drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0068] The optional embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details described above. Within the scope of the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all fall within the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe the various possible combinations.

[0069] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the embodiments of the present invention, they should also be regarded as the content disclosed by the embodiments of the present invention.

Claims

1. A method for manufacturing a finished PCB board for a driving circuit, characterized in that, The method includes: Obtain the circuit pattern, solder mask window pattern, and carbon oil circuit pattern of the drive circuit PCB, and determine the step-crossing boundary region of the carbon oil circuit based on the circuit pattern, the solder mask window pattern, and the carbon oil circuit pattern. Boundary transition treatment is performed on the step boundary area of ​​the carbon oil line to form a gentle slope transition interface for supporting the carbon oil line; A carbon oil adsorption pattern is made on the gentle slope transition interface, and carbon oil lines are printed based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure. The cross-step carbon oil circuit structure is subjected to segmented curing process to obtain the finished PCB board of the drive circuit.

2. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, Determine the boundary region of the carbon oil pipeline crossing the step, including: The circuit pattern, the solder mask opening pattern, and the carbon oil circuit pattern are superimposed. The graphic segment of the carbon oil circuit that simultaneously crosses the outer copper surface, the edge of the solder mask layer, and the solder mask opening area is extracted. The corresponding position of the graphic segment is determined as the step boundary area of ​​the carbon oil circuit.

3. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, The boundary transition treatment includes: performing plasma cleaning treatment on the carbon oil line's step boundary area, with a treatment power of 200W-500W and a treatment time of 30s-120s; Insulating transition ink is printed at the edge of the solder mask layer and pre-cured at 80℃-100℃ for 10min-20min to form the gentle slope transition interface.

4. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, The process of creating the carbon oil adsorption pattern includes: printing a low-viscosity carbon oil pattern material on the gentle slope transition interface to form multiple spaced carbon oil adsorption patterns. The carbon oil adsorption pattern has a line width of 40μm-120μm and a spacing of 80μm-250μm, and is pre-baked at 70℃-90℃ for 5min-15min.

5. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, Printing carbon ink circuits includes: printing a first carbon ink layer within the carbon ink circuit pattern area, wherein the thickness of the first carbon ink layer is 8μm-18μm; A second carbon oil layer is printed on the surface of the first carbon oil layer. The second carbon oil layer avoids the step boundary region of the carbon oil line by 0.2mm-0.8mm, and the thickness of the second carbon oil layer is 5μm-12μm.

6. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, The segmented curing process includes: static leveling for 5 to 15 minutes; Pre-cur at 80℃-100℃ for 10-25 minutes; Main curing at 140℃-160℃ for 25-45 minutes; The carbon oil line cross-step boundary area is subjected to thermal insulation and stress relief treatment at 110℃-130℃ for 8min-20min.

7. The method for manufacturing a finished PCB board for a driving circuit according to claim 1, characterized in that, Before performing the segmented curing process, the cross-step carbon oil circuit structure was visually inspected. When the ink shrinkage width of the carbon oil circuit across the step boundary area is greater than 50μm or the ink buildup height is greater than 25μm, the corresponding area is locally erased and reprinted.

8. The method for manufacturing a finished PCB board of a driving circuit according to claim 1, characterized in that, After obtaining the finished PCB board of the drive circuit, the sheet resistance and local energized thermal response of the carbon oil circuit across the step boundary area are detected. When the sheet resistance change rate is greater than 5%, or the temperature rise in the step boundary area of ​​the carbon oil circuit is more than 3°C higher than the temperature rise in the middle area of ​​the same carbon oil circuit, the corresponding drive circuit PCB finished board will be judged as an abnormal finished board.

9. A finished PCB board for a driving circuit, characterized in that, The finished PCB board of the driving circuit is manufactured based on the manufacturing method of the finished PCB board of the driving circuit according to any one of claims 1-8.

10. A manufacturing system for a finished PCB board of a driving circuit, characterized in that, The system is used to perform the method for manufacturing a finished PCB board of a driving circuit according to any one of claims 1-8, and the system includes: The first module is used to acquire the circuit pattern, solder mask window pattern and carbon oil circuit pattern of the drive circuit PCB, and to determine the step boundary region of the carbon oil circuit based on the circuit pattern, the solder mask window pattern and the carbon oil circuit pattern. The second module is used to perform boundary transition processing on the carbon oil line across the step boundary area to form a gentle slope transition interface for supporting the carbon oil line. The third module is used to create a carbon oil adsorption pattern on the gentle slope transition interface, and to print carbon oil lines based on the carbon oil adsorption pattern to form a cross-step carbon oil line structure. The fourth module is used to perform segmented curing processing on the cross-step carbon oil circuit structure to obtain the finished PCB board of the drive circuit.

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