Single Strip plate and manufacturing process

Abstract

The invention relates to the technical field of circuit board manufacturing, in particular to a single Strip plate and a manufacturing process thereof, and the process comprises the following steps: S1, carrying plate pretreatment: selecting an insulating carrying plate, and polishing and cleaning the surface of the insulating carrying plate to remove greasy dirt and impurities; s2, arranging the plates: uniformly arranging the single-Strip plates on the surface of the pretreated bearing plate according to a preset interval, and reserving machining and plate separation allowances between the plates; and S3, the surfaces of the arranged single Strip plates are sequentially covered with a hot melting bonding layer and a surface restraint layer, and after the hot melting bonding layer is melted through hot pressing, the surface restraint layer, the single Strip plates and the bearing plate are bonded to form an integrated composite structure. According to the invention, the PI film and PP thermocompression bonding fixing process is adopted to replace the traditional acrylic adhesive, the PP layer is fused to fill tiny gaps and eliminate bubbles and local bulges, and the PI film is adopted to restrain the surface of the plate, so that the surface height difference of the fixed single Strip plate is less than or equal to 0.03 mm and is far superior to 0.15 mm of the traditional process, and the flatness of the plate surface is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of circuit board manufacturing technology, and in particular to a single strip board and its manufacturing process. Background Technology

[0002] In the circuit board manufacturing process, solder mask printing and exposure is one of the key steps. Its purpose is to form an insulating protective film on the circuit board surface to prevent solder bridging during soldering, protect the circuit board from environmental corrosion, and ensure the stability of the circuit's electrical performance. For circuit boards with a single strip structure (i.e., a single-strip structure) and no mounting holes (hereinafter referred to as "single strip boards"), due to their special structure and lack of effective mechanical fixing points, traditional processes typically use acrylic adhesive to attach them to a carrier substrate for subsequent printing, exposure, and other processing.

[0003] However, existing acrylic adhesive-based fixing processes have many insurmountable technical defects in practical applications, which seriously affect product quality and production efficiency, as follows:

[0004] 1. Poor board surface flatness leads to questionable solder resist printing quality: As an adhesive material, acrylic adhesive itself is difficult to guarantee absolute thickness uniformity during production. In practical applications, thickness deviation is usually between 0.05-0.1mm. When bonding single strip boards, air bubbles can easily form between the adhesive layer and the board surface or the substrate due to loose adhesion, or uneven pressure can cause local bulges, resulting in obvious height differences on the board surface. This flatness defect directly leads to extremely poor film thickness uniformity during solder resist printing. Some areas are too thin, failing to form effective insulation protection; other areas are too thick, easily resulting in defects such as sagging and pinholes, seriously affecting the insulation performance and appearance quality of the solder resist layer, and consequently causing solder overflow and bridging in subsequent welding processes.

[0005] 2. High rate of strip breakage and deformation, affecting subsequent assembly: In traditional processes, after printing and exposure, single strip boards need to be peeled off from the substrate manually or mechanically. During peeling, the adhesive pull between the acrylic glue and the board surface acts on the edges and the overall structure of the board. Due to the narrow and elongated structure and weak rigidity of the single strip board, this pull force easily leads to permanent creases on the edges or warping of the board as a whole. Broken and deformed boards cannot meet the dimensional accuracy requirements of subsequent assembly and must be scrapped, further increasing production costs. Even if they are assembled, the loose fit between the board and other components will cause stress concentration inside the electronic device, affecting the overall stability and service life of the equipment.

[0006] To address the aforementioned technical shortcomings, the industry has attempted improvements such as optimizing the acrylic adhesive formulation and modifying bonding process parameters, but the results have been unsatisfactory. For example, some companies use high-viscosity acrylic adhesive to reduce micro-movement of the boards, but this further exacerbates the adhesive pulling during separation, actually increasing the board deformation rate. Some companies improve the surface unevenness of the boards by increasing the flatness of the supporting substrate, but the improvement is limited by the inherent thickness uniformity of the acrylic adhesive.

[0007] Therefore, there is an urgent need for a single strip board and its manufacturing process to solve the above problems. Summary of the Invention

[0008] To achieve the above objectives, the present invention provides the following technical solution: a manufacturing process for a single strip board, comprising the following steps:

[0009] S1: Pretreatment of bearing plate: Select insulating bearing plate and grind and clean its surface to remove oil and impurities;

[0010] S2: Panel Arrangement: Arrange the single strip panels evenly on the surface of the pre-treated support plate at a preset spacing, with allowance reserved between the panels for processing and separation.

[0011] S3: A hot-melt adhesive layer and a surface constraint layer are sequentially covered on the surface of the arranged single strip panels. After the hot-melt adhesive layer is melted by hot pressing, the surface constraint layer, the single strip panels and the load-bearing plate are bonded together to form an integrated composite structure.

[0012] S4: Laser positioning hole processing: The preset optical reference points within a single strip are identified by a CCD vision positioning system and a coordinate reference is established. Laser processing equipment is used to process laser positioning holes of preset diameter at the corresponding positions on the carrier plate.

[0013] S5: Solder resist printing: Using the laser positioning hole as a reference, solder resist of a preset film thickness is printed on the surface of a single strip board.

[0014] S6: Exposure Alignment: The solder mask pattern is aligned and exposed with the single strip board pad by using the positioning pin and the laser positioning hole.

[0015] S7: Development and Curing: The exposed composite structure is developed to remove uncured solder resist, and then cured at high temperature to form a solder resist layer.

[0016] S8: Separation: Separating the single strip from the supporting plate to obtain the finished strip.

[0017] Preferably, in step S1, the grinding process uses an 800-1000 grit diamond grinding wheel for dry grinding, and the surface roughness Ra of the bearing plate after grinding is ≤0.3μm; the cleaning process includes ultrasonic cleaning and hot air drying. The ultrasonic cleaning uses deionized water as the cleaning medium, the cleaning temperature is 40-50℃, and the cleaning time is 15-20min. The hot air drying temperature is 80-100℃, and the drying time is 30-40min.

[0018] Preferably, in S3, the hot-melt adhesive layer is a PP layer with a thickness of 0.08-0.2 mm; the surface constraint layer is a PI film with a thickness of 0.04-0.1 mm.

[0019] Preferably, in step S5, a screen printing machine is used for printing, with a screen mesh count of 280-420 mesh, a squeegee hardness of Shore A 65-85 degrees, a printing speed of 4-12 mm / s, and a squeegee pressure of 0.08-0.35 MPa; the solder resist is a photosensitive epoxy resin, and the printed film thickness is 8-18 μm.

[0020] Preferably, in step S6, the wavelength of the exposure light source is 350-370 nm, and the exposure energy is 80-180 mJ / cm². 2 Exposure time is 8-40s; the tolerance fit between the positioning pin and the laser positioning hole is H7 / h6 or H7 / g6.

[0021] Preferably, in the developing process of S7, the concentration of the developing solution is 0.8-1.8wt%, the developing temperature is 28-38℃, and the developing time is 50-120s; the high-temperature curing temperature is 140-190℃, the curing time is 40-150min, and the heating rate is 1.5-4℃ / min; the adhesion of the solder resist layer after curing is ≥5B grade.

[0022] Preferably, the S8 process uses a CNC depaneling machine or a laser depaneling machine for depaneling, with the depaneling table being a vacuum adsorption table and the adsorption pressure being -0.05 to -0.09 MPa; the depaneling cutter has a cutting speed of 8-25 mm / s and the cutting depth is adapted to the thickness of the supporting plate.

[0023] A single strip board is manufactured using the above-mentioned technical solution.

[0024] The beneficial effects of this invention are:

[0025] 1. This invention uses a PI film and PP hot-pressing bonding process to replace traditional acrylic adhesive. After the PP layer melts, it fills the tiny gaps, eliminates air bubbles and local protrusions, and constrains the surface of the board through the PI film. This results in a surface height difference of ≤0.03mm after the single strip board is fixed, which is far better than the 0.15mm of the traditional process, thereby effectively improving the flatness of the board surface.

[0026] 2. This invention eliminates the need to peel off the adhesive layer during board separation by pressing and fixing the PI film and PP, thus avoiding damage to the boards caused by adhesive pulling in traditional processes. Combined with the vacuum adsorption positioning and precise cutting of CNC board separation machine, it effectively reduces the bending and warping deformation rate of single strip boards, thereby significantly improving the product appearance qualification rate and dimensional stability, reducing scrap due to board damage, and lowering production costs. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is a schematic diagram illustrating the principle of the present invention. Detailed Implementation

[0029] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention relates to single-strip panels and their manufacturing processes, such as... Figure 1 As shown, it includes the following steps:

[0031] Pretreatment of the carrier plate: FR-4 board with a thickness of 1.2mm is selected as the carrier plate. The preferred size of the FR-4 board is 500mm×500mm, with a warpage of ≤0.1% and a dielectric constant of 4.2-4.5 (1MHz), to ensure that the carrier plate itself has good flatness and structural stability.

[0032] Dry grinding is performed on both sides of the support plate using an 800-1000 grit diamond grinding wheel at a grinding speed of 10-15 m / min and a grinding pressure of 0.1-0.2 MPa to remove the surface oxide layer and impurities, so that the surface roughness Ra of the support plate is Ra≤0.3μm, thereby improving the subsequent bonding strength with the PP layer.

[0033] Place the polished support plate into an ultrasonic cleaner, using deionized water as the cleaning medium and adding 0.5-1.0wt% of neutral cleaning agent. The cleaning temperature is 40-50℃, the cleaning time is 15-20 minutes, and the power is 300-500W to remove surface oil and polishing dust. Place the cleaned support plate into a hot air drying oven and dry it at 80-100℃ for 30-40 minutes to ensure that there is no moisture residue on the surface of the support plate and to avoid the formation of air bubbles during the subsequent pressing process.

[0034] Board arrangement: Select a single strip board without fixing holes to be processed. The board has a thickness of 0.2-1.0mm, a width of 10-50mm, and a length of 100-300mm. The board surface is free of oxide layer, scratches, and oil stains. The board has a preset optical reference point to be identified (preset during the circuit board design stage, which is a circular light spot with a diameter of 0.1-0.2mm).

[0035] Single strip panels are evenly arranged on the surface of the pre-treated support plate at a preset spacing of 5mm. At least 2mm of laser processing allowance and 3mm of panel separation allowance are reserved between the panels to avoid damage during subsequent processing. Positioning fixtures are used during the arrangement process to assist in positioning, ensuring that the parallelism error between the panels is ≤0.02mm and the spacing error is ≤±0.1mm, thus guaranteeing consistency in batch processing.

[0036] PI film and PP lamination and fixation: Select a PP (polypropylene) layer with a thickness of 0.1-0.15mm and a PI (polyimide) film with a thickness of 0.05-0.08mm. The PP layer has a melting temperature of 110-130℃ and a melt index of 2-5g / 10min (190℃, 2.16kg), exhibiting good fluidity and adhesion. The PI film has a temperature resistance range of 260-300℃ and a tensile strength at break of ≥150MPa, demonstrating excellent high-temperature resistance and mechanical strength, and protecting the surface of the board from damage during subsequent processing.

[0037] The pressing and fixing process is as follows: Lamination: On the surface of the carrier plate with the arranged single strip panels, first evenly cover with a layer of PP, ensuring the PP layer completely covers all single strip panels and the edges of the carrier plate (extending 5-10mm beyond the edges of the carrier plate); then cover the PP layer with a layer of PI film, again ensuring complete coverage, and no air bubbles or wrinkles between the PI film and the PP layer; Hot pressing: Place the laminated composite structure into a hot press, setting the pressing parameters: pressing temperature 120-150℃, pressing pressure 2-3MPa, pressing time 30-60s, heating rate 5-8℃ / s, cooling rate 3-5℃ / s. During hot pressing, the PP layer melts upon heating, filling the tiny gaps between the carrier plate, single strip panels, and the PI film. After cooling, it solidifies, forming an integrated composite structure of "carrier plate-PP layer-single strip panel-PI film," achieving a firm fixation of the single strip panels. Compared to traditional acrylic adhesives, this composite fixing structure has the following advantages: the PP layer has good fluidity after melting. It can effectively fill gaps and prevent air bubbles; the PI film has high flatness, which can constrain the surface of the board and eliminate height differences; the structure after pressing has strong stability and is not affected by the ambient temperature and humidity, which can effectively prevent the board from micro-movement.

[0038] Laser positioning hole processing: A CCD vision positioning system is used in conjunction with laser processing equipment to process high-precision laser positioning holes on the carrier plate. The specific steps are as follows: 1. Reference establishment: The integrated composite structure after pressing is placed on the worktable of the laser processing equipment. The CCD vision positioning system (resolution ≥ 10 million pixels, positioning response time ≤ 0.5s) is activated. The lens captures the preset optical reference points within the single strip plate. At least two optical reference points are identified for each plate. A three-dimensional coordinate reference system is established based on the coordinate information of the optical reference points. The recognition accuracy of the optical reference points can reach ±0.005mm. 2. Laser processing: According to the established coordinate reference, the position parameters of the laser positioning holes are set (the number is 4, located in the four corner areas of the carrier plate, and the spacing error between adjacent positioning holes ≤ 0.01mm). The fiber laser marking machine (laser wavelength 1064nm, output power 50-100W, pulse frequency 10-50kHz) is activated to process the laser positioning holes at the corresponding positions on the carrier plate. The hole diameter is φ0.5mm, and the positioning accuracy is controlled within ±0.025mm. During the processing, air blowing protection is used (air blowing pressure 0.3-0.5MPa, gas is dry nitrogen) to prevent processing dust from adhering to the surface of the board.

[0039] The laser positioning holes are processed based on the inherent optical reference points within the board, ensuring a precise correlation between the positioning reference and the board itself, and providing a reliable guarantee for accurate alignment in subsequent printing and exposure processes.

[0040] Solder resist printing: Solder resist printing is performed using a screen printing machine. The specific process is as follows: Equipment debugging: Set the screen mesh count of the screen printing machine to 300-400 mesh, the screen tension to 25-30 N / cm, the squeegee hardness to Shore A 70-80 degrees, the printing speed to 5-10 mm / s, and the squeegee pressure to 0.1-0.3 MPa; Positioning and clamping: Install the integrated composite structure with laser positioning holes on the printing machine's worktable, and use the positioning pins of the printing machine to engage with the laser positioning holes. To achieve precise positioning of the composite structure; solder resist coating, photosensitive epoxy resin solder resist ink is selected as the solder resist, with a solid content of 70-80% and a viscosity of 10000-15000 mPa·s (25℃), and the solder resist is evenly coated on the screen; printing, the screen printing machine is started, and the solder resist is printed on the surface of the single strip board according to the set parameters. The thickness of the printed solder resist film is controlled at 10-15μm, the film thickness uniformity error is ≤±1μm, and there are no pinholes, bubbles and sagging.

[0041] Printing is performed using the laser positioning holes as a reference, ensuring precise correspondence between the solder resist printing area and the board pads, thus avoiding printing misalignment issues.

[0042] Exposure Alignment: The printed integrated composite structure is transferred to a parallel light exposure machine for exposure processing. The specific steps are as follows: Exposure machine parameters are set, with the exposure light source set to a UV mercury lamp at a wavelength of 365nm and an exposure energy of 100-150mJ / cm². 2 The exposure time is 10-30 seconds; precise alignment is achieved by placing the composite structure on the exposure machine's worktable and precisely engaging the positioning pins of the exposure machine with the laser positioning holes on the carrier plate. The positioning pins are made of hard alloy, and their diameter is H7 / g6 to match the diameter tolerance of the laser positioning holes, ensuring an alignment error of ≤±0.005mm; exposure is achieved by starting the exposure machine and allowing UV light to pass through the film with the solder resist pattern and irradiate the solder resist surface, causing the solder resist in the exposed area to undergo a photopolymerization reaction, thus transferring the solder resist pattern.

[0043] Since the positional accuracy between the laser positioning hole and the board pad has been strictly controlled by CCD vision positioning and laser processing, no additional adjustment is required during the exposure process to achieve precise alignment between the solder mask pattern and the pad.

[0044] Developing and Curing: After exposure, the composite structure undergoes developing and curing processes sequentially, as follows: Developing: The composite structure is placed in a spray developing machine, using a 1.0-1.5wt% sodium carbonate aqueous solution as the developing solution. The developing temperature is 30-35℃, the developing time is 60-90s, and the spray pressure is 0.2-0.4MPa. During developing, the unexposed solder resist (non-patterned areas) is dissolved and removed by the developing solution, while the exposed and cured solder resist (patterned areas) remains on the board surface. After developing, the residual solder resist area on the board surface is ≤0.1%. Washing: The developed composite structure is rinsed with deionized water at a pressure of 0.1-0.2MPa for 30-60s to remove residual developing solution. Curing: The washed composite structure is placed in a hot air circulating oven for high-temperature curing at 150-180℃ for 60-120min, with a heating rate of 2-3℃ / min. After curing, a stable solder resist layer is formed, with an adhesion of ≥5B grade (GB / T9286-1998) and a solderability that meets the requirement of no lifting or peeling at 288℃ / 10s.

[0045] Separation: A CNC stripper is used to separate the single strip board from the carrier plate. The specific steps are as follows: Clamping and positioning: The cured composite structure is placed on the vacuum adsorption table of the CNC stripper. The vacuum adsorption system is started, and the adsorption pressure is -0.06 to -0.08 MPa to ensure that the composite structure is firmly fixed and without displacement; Separation parameter setting: A diamond cutting blade is selected, the cutting speed is 10-20 mm / s, and the cutting depth is set to 1.2 mm (consistent with the thickness of the carrier plate) to avoid damaging the single strip board; Separation processing: The CNC stripper is started, and the cutting is carried out according to the preset cutting path (cutting along the reserved separation allowance between the boards) to separate the single strip board from the carrier plate; Material inspection: After the separation is completed, the single strip board is removed and its appearance and dimensions are inspected to ensure that the board is free of creases, warping (warping degree ≤ 0.1°), and the solder mask layer is undamaged.

[0046] Example 1

[0047] This embodiment targets a single-strip multilayer circuit board with a thickness of 0.5mm, a width of 30mm, and a length of 200mm without mounting holes. The solder resist printing and exposure process of this invention is employed, and the specific steps are as follows:

[0048] (1) Pretreatment of bearing plate

[0049] An FR-4 bearing plate with dimensions of 500mm × 500mm × 1.2mm was selected, with a warpage of 0.08% and a dielectric constant of 4.3 (1MHz). Both sides of the bearing plate were dry-polished using an 800-grit diamond grinding wheel at a speed of 12m / min and a pressure of 0.15MPa, resulting in a surface roughness Ra of 0.25μm. The polished bearing plate was then placed in an ultrasonic cleaner with 0.8wt% neutral cleaning agent and deionized water as the medium. Cleaning was performed at 45℃ for 18 minutes at a power of 400W. After cleaning, the plate was placed in a hot air drying oven and dried at 90℃ for 35 minutes to ensure no moisture residue remained on the surface.

[0050] (2) Arrangement of panels

[0051] Select a single-strip multilayer circuit board without mounting holes to be processed. The board surface should be free of oxide layer, scratches, and oil stains. Two optical reference points with a diameter of 0.15mm are pre-set inside the board. Use a positioning fixture to evenly arrange the boards on the surface of the carrier board at a spacing of 5mm, for a total of 8 boards. Leave a 2mm laser processing allowance and a 3mm board separation allowance between the boards. The parallelism error of the boards is 0.015mm, and the spacing error is ±0.08mm.

[0052] (3) PI film and PP are pressed and fixed.

[0053] A 0.12mm thick PP layer (melting temperature 120℃, melt index 3g / 10min) and a 0.06mm thick PI film (temperature resistance 280℃, tensile strength at break 160MPa) were selected. The PP layer and PI film were sequentially applied to the surface of the support plate, ensuring complete coverage of all plates and the edges of the support plate (extending 8mm beyond the edges). The composite structure was placed in a hot press, with the pressing temperature set at 135℃, pressing pressure at 2.5MPa, pressing time at 45s, heating rate at 6℃ / s, and cooling rate at 4℃ / s. After pressing, an integrated composite structure was formed.

[0054] (4) Laser positioning hole machining

[0055] A 12-megapixel CCD vision positioning system is used to identify optical reference points within the board with an accuracy of ±0.004mm, establishing a three-dimensional coordinate reference. A fiber laser marking machine (laser wavelength 1064nm, output power 80W, pulse frequency 30kHz) is used to process four laser positioning holes at the four corners of the carrier plate. The hole diameter is φ0.5mm, the positioning accuracy is ±0.02mm, and the distance error between adjacent positioning holes is 0.008mm. During the processing, dry nitrogen gas at 0.4MPa is used for protection.

[0056] (5) Solder resist printing

[0057] A screen printing machine was used with a screen mesh count of 350, a screen tension of 28 N / cm, a squeegee hardness of Shore A 75, a printing speed of 8 mm / s, and a squeegee pressure of 0.2 MPa. Photosensitive epoxy resin solder resist ink (75% solids content, viscosity 12000 mPa·s (25℃)) was selected. A positioning composite structure was used with positioning pins and laser positioning holes, with a positioning error of ±0.008 mm. The printing machine was started to print solder resist on the surface of the board, with the film thickness controlled at 12 μm and the film thickness uniformity error ±0.8 μm, without pinholes, bubbles, or sagging.

[0058] (6) Exposure alignment

[0059] A parallel light exposure machine was used, with a UV mercury lamp as the exposure light source, a wavelength of 365nm, and an exposure energy of 120mJ / cm². 2 Exposure time 20s; alignment error ±0.004mm is achieved by using a carbide positioning pin (tolerance fit H7 / g6) to align with the laser positioning hole; exposure machine is started to achieve solder resist pattern transfer.

[0060] (7) Development and curing

[0061] The exposed composite structure was placed in a spray developer, using a 1.2wt% sodium carbonate aqueous solution as the developer. The developing temperature was 32℃, the developing time was 75s, and the spray pressure was 0.3MPa. After developing, it was rinsed with deionized water for 45s at a pressure of 0.15MPa. The board was then placed in a hot air circulating oven and cured at 160℃ for 90min at a heating rate of 2.5℃ / min. After curing, the solder resist adhesion was grade 5B, the solder resistance was 288℃ / 10s without lifting or peeling, and the residual solder resist area was 0.08%.

[0062] (8) Plate splitting

[0063] A CNC stripping machine is used, with a vacuum adsorption table pressure of -0.07MPa, a diamond cutting blade cutting speed of 15mm / s, and a cutting depth of 1.2mm. The machine cuts along the pre-reserved stripping allowance between the boards to separate the 8 single strip boards from the support plate. After stripping, the boards have no creases, a warpage of 0.08°, and no damage to the solder mask layer.

[0064] Example 2

[0065] This embodiment is for a single-strip flexible circuit board without fixing holes, with a thickness of 0.8mm, a width of 40mm, and a length of 250mm. It is processed using the process of the present invention, and the specific parameters are adjusted as follows:

[0066] Pre-treatment of the bearing plate: Grinding is performed using a 1000-grit diamond grinding wheel at a grinding speed of 15 m / min, ultrasonic cleaning is performed for 20 min, and drying is carried out at 100℃;

[0067] Panel arrangement: A total of 6 panels are arranged with a spacing of 5mm and a parallelism error of 0.01mm.

[0068] PI film and PP are pressed and fixed: PP layer thickness 0.15mm (melting temperature 125℃, melt index 4g / 10min), PI film thickness 0.08mm (temperature resistance 300℃, tensile strength at break 170MPa), pressing temperature 140℃, pressing pressure 2.8MPa, pressing time 50s;

[0069] Laser positioning hole processing: CCD vision positioning system with a resolution of 15 million pixels, laser processing equipment with an output power of 100W, a pulse frequency of 40kHz, and a positioning accuracy of ±0.018mm;

[0070] Solder resist printing: 400 mesh screen, 7 mm / s printing speed, 0.25 MPa squeegee pressure, 14 μm solder resist film thickness;

[0071] Exposure alignment: Exposure energy 140mJ / cm², exposure time 25s;

[0072] Developing and curing: Developer concentration 1.4wt%, developing time 85s, curing temperature 170℃, curing time 100min;

[0073] Plate separation: cutting speed 12mm / s, adsorption pressure -0.075MPa.

[0074] After processing, the surface height difference of the board is 0.022mm, the alignment deviation between the solder mask pattern and the pad is 0.015mm, the batch production yield is 95%, the production efficiency is 22% higher than that of traditional processes, the board bending and deformation rate is 0.6%, the solder mask adhesion is 5B grade, and the solderability meets the requirements.

[0075] Example 3

[0076] This embodiment is for a single-strip high-density interconnect circuit board with a thickness of 0.3mm, a width of 20mm, and a length of 150mm. The process parameters are adjusted as follows:

[0077] Pre-treatment of the bearing plate: Grinding is carried out with a 900-grit diamond grinding wheel at a grinding speed of 10 m / min, ultrasonic cleaning time is 15 min, and drying temperature is 80℃.

[0078] Panel arrangement: A total of 10 panels are arranged with a spacing of 5mm and a parallelism error of 0.012mm.

[0079] PI film and PP are pressed and fixed: PP layer thickness 0.1mm (melting temperature 115℃, melt index 2.5g / 10min), PI film thickness 0.05mm (temperature resistance 260℃, tensile strength at break 155MPa), pressing temperature 125℃, pressing pressure 2.2MPa, pressing time 35s;

[0080] Laser positioning hole processing: CCD vision positioning system with a resolution of 10 million pixels, laser processing equipment with an output power of 60W, a pulse frequency of 20kHz, and a positioning accuracy of ±0.022mm;

[0081] Solder resist printing: 300 mesh screen, 10 mm / s printing speed, 0.15 MPa squeegee pressure, 11 μm solder resist film thickness;

[0082] Exposure alignment: Exposure energy 110mJ / cm 2 Exposure time: 15 seconds;

[0083] Developing and curing: Developer concentration 1.1wt%, developing time 65s, curing temperature 150℃, curing time 70min;

[0084] Plate separation: cutting speed 18mm / s, adsorption pressure -0.065MPa.

[0085] After processing, the surface height difference of the board is 0.028mm, the alignment deviation between the solder mask pattern and the pad is 0.019mm, the batch production yield is 94%, the production efficiency is increased by 21%, the board bending and deformation rate is 0.7%, and all performance indicators meet the requirements of high-end electronic components.

[0086] Comparative Example 1 (Traditional Acrylic Adhesive Fixing Process)

[0087] To more intuitively demonstrate the technical advantages of this invention, a comparative example is provided. A single-strip board without mounting holes (a multilayer circuit board with a thickness of 0.5mm, a width of 30mm, and a length of 200mm) of the same specifications as in Embodiment 1 of this invention is subjected to solder mask printing exposure using a traditional acrylic adhesive fixing process. The specific process steps and parameters are as follows:

[0088] Pretreatment of the bearing plate: A 500mm×500mm×1.2mm FR-4 bearing plate with the same specifications as in the embodiment of the present invention was selected. The surface was simply cleaned by wiping with alcohol and no polishing was performed. The surface roughness of the bearing plate was Ra=1.0μm.

[0089] Acrylic adhesive bonding and fixing: Select 0.1mm thick acrylic film, cut it to the size that matches the carrier plate, and cover the surface of the carrier plate. Manually press and stick the single strip without fixing holes onto the acrylic film. The spacing between the panels is controlled at 5mm. Without the assistance of special positioning fixtures, the parallelism error of the panels is 0.12mm, and the spacing error is ±0.3mm.

[0090] Manual positioning and calibration: The operator visually observes the relative position of the edge of the plate and the edge of the supporting plate, and manually adjusts the position of the plate to achieve positioning. There is no uniform reference in the positioning process, and the positioning error is 0.15mm.

[0091] Solder resist printing: The same model of screen printing machine as in Example 1 of this invention was used, with a screen mesh of 350 mesh. The printing parameters (squeegee hardness, printing speed, squeegee pressure) were the same as in Example 1. The same model of photosensitive epoxy resin solder resist ink as in Example 1 was selected. The printing was carried out with the edge of the board after manual positioning as the reference. The target value of the solder resist film thickness was 12μm, but there was no precise control method.

[0092] Exposure alignment: The same parallel light exposure machine as in Embodiment 1 of this invention is used, and the exposure parameters (exposure light source, wavelength, energy, time) are the same as in Embodiment 1. The position of the film is adjusted by manually moving it to achieve alignment between the solder mask pattern and the board pad. The alignment process depends on the operator's experience and there is no precise positioning reference.

[0093] Developing and curing: The developing and curing parameters are completely consistent with those of Example 1 of this invention, namely, the developing solution is a 1.2wt% sodium carbonate aqueous solution, the developing temperature is 32℃, the developing time is 75s, and the spraying pressure is 0.3MPa; the curing temperature is 160℃, the curing time is 90min, and the heating rate is 2.5℃ / min.

[0094] Strip peeling: The single strip is peeled off from the acrylic film on the carrier plate by hand. During the peeling process, the edges of the strip are pulled apart by external force to achieve separation.

[0095] After the comparative processing is completed, the key performance indicators of the plates are tested. The testing method is the same as that in Examples 1-3 of this invention (based on the industry standard GB / T9286-1998). The test results are compared with those in Examples 1-3 of this invention in Table 1 below:

[0096] Table 1

[0097] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a single strip board, characterized in that, Includes the following steps: S1: Pretreatment of bearing plate: Select insulating bearing plate and grind and clean its surface to remove oil and impurities; S2: Panel arrangement: Arrange the single strip panels evenly on the surface of the pre-treated support plate at a preset spacing, with allowance reserved between the panels for processing and separation; S3: A hot-melt adhesive layer and a surface constraint layer are sequentially covered on the surface of the arranged single strip panels. After the hot-melt adhesive layer is melted by hot pressing, the surface constraint layer, the single strip panels and the load-bearing plate are bonded together to form an integrated composite structure. S4: Laser positioning hole processing: The preset optical reference point in the single strip board is identified by the CCD vision positioning system and a coordinate reference is established. Laser processing equipment is used to process laser positioning holes of preset diameter at the corresponding positions on the carrier plate. S5: Solder resist printing: Using the laser positioning hole as a reference, a solder resist of a preset film thickness is printed on the surface of a single strip board. S6: Exposure Alignment: The solder mask pattern is aligned and exposed with the single strip board pad by using the positioning pin and the laser positioning hole. S7: Development and Curing: The exposed composite structure is developed to remove uncured solder resist, and then cured at high temperature to form a solder resist layer. S8: Separation: Separating the single strip from the supporting plate to obtain the finished strip.

2. The manufacturing process of the single strip board as described in claim 1, characterized in that: The grinding process in S1 uses an 800-1000 grit diamond grinding wheel for dry grinding, resulting in a surface roughness Ra ≤ 0.3 μm for the bearing plate after grinding. The cleaning process includes ultrasonic cleaning and hot air drying. Ultrasonic cleaning uses deionized water as the cleaning medium, with a cleaning temperature of 40-50℃ and a cleaning time of 15-20 minutes. The hot air drying temperature is... Drying temperature: 80-100℃, drying time: 30-40 minutes.

3. The manufacturing process of the single strip board as described in claim 1, characterized in that: The hot-melt adhesive layer in S3 is a PP layer with a thickness of 0.08-0.2mm; The surface constraint layer is a PI film with a thickness of 0.04-0.1 mm.

4. The manufacturing process of the single strip board as described in claim 1, characterized in that: The S5 process uses a screen printing machine with a screen mesh count of 280-420 mesh, a squeegee hardness of Shore A 65-85 degrees, a printing speed of 4-12 mm / s, and a squeegee pressure of 0.08-0.35 MPa; the solder resist is a photosensitive epoxy resin, and the printed film thickness is 8-18 μm.

5. The manufacturing process of the single strip board as described in claim 1, characterized in that: The exposure light source in S6 has a wavelength of 350-370nm and an exposure energy of 80-180mJ / cm². 2 Exposure time is 8-40s; the tolerance fit between the positioning pin and the laser positioning hole is H7 / h6 or H7 / g6.

6. The manufacturing process of the single strip board as described in claim 1, characterized in that: In the developing process of S7, the concentration of the developing solution is 0.8-1.8wt%, the developing temperature is 28-38℃, and the developing time is 50-120s; the high-temperature curing temperature is 140-190℃, the curing time is 40-150min, and the heating rate is 1.5-4℃ / min; after curing, the adhesion of the solder resist layer is ≥5B grade.

7. A single strip board, characterized in that: It is manufactured using the single-strip sheet manufacturing process as described in any one of claims 1-6.

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