CN117098326A - PCB green oil bridge anti-drop treatment method - Google Patents

Abstract

The invention relates to a PCB green oil bridge anti-drop treatment method, which is used for carrying out printing reworking treatment on the drop position of a green oil bridge on a PCB, firstly, selecting an alignment hole and a windowing hole on the PCB to be reworked, and designing corresponding exposure data; then, manufacturing a screen plate of a blocking point according to the blocking point of the area, designing an oil discharging area at the falling position of the green oil bridge, and cleaning the PCB; then overprinting, positioning the screen printing plate of the blocking point on the window hole, calibrating and printing ink through the alignment hole, and baking to solidify the ink; then selecting a green oil bridge as an exposure area, manufacturing LDI exposure data, and performing local exposure by using an LDI exposure machine; developing the exposed PCB to show the outer layer pattern; finally, carrying out post-process treatment, checking whether a green oil bridge is attached to the surface of the PCB, and baking at a high temperature, so as to finish the repair work of the green oil bridge; the invention has the advantages of low cost, high efficiency, good product quality and the like.

Description

PCB green oil bridge anti-drop treatment method

Technical Field

The invention relates to the field of PCB green oil bridges, in particular to a PCB green oil bridge anti-falling treatment method.

Background

Solder resist is an extremely important procedure in the PCB manufacturing process, and is not only the guarantee of appearance quality, but also the key station of performance guarantee; the solder mask bridge is also called a green oil bridge and a solder mask dam, is a 'isolation belt' which is made by batch pasting of a plug-in plant and prevents the pin of an SMD component from being connected with a tin short circuit; however, in the actual production process of the industry, the green oil bridge is easily damaged and falls off after being developed due to insufficient pre-curing caused by exposure energy, development parameter variation and the like, so that the performance of the PCB is affected, and the traditional processing method is that: 1. the detection before high-temperature curing can be reworked by adopting a unwashed normal printing exposure developing mode, and the existing texture is exposed and the unwashed direct scrapping treatment can be carried out on the plate with poor high-temperature curing; 2. repairing oil; treatment results: 1. the normal unwashed heavy work printing can be performed without high-temperature curing, but the unwashed plate has hidden quality hazards such as line scratch, red via hole and the like, and the quality cannot be ensured; 2. the PAD on the green oil can appear in the oil supplementing treatment, the thickness of the green oil bridge is insufficient, the quality requirement cannot be met in repairing, the primary yield of the appearance of the solder mask is seriously affected, and the production cost is increased due to scrapping.

Disclosure of Invention

The invention aims to provide a PCB green oil bridge anti-drop treatment method which is low in cost, high in efficiency and high in finished product quality.

The above object is achieved by the following technical solutions.

A PCB green oil bridge anti-falling treatment method is used for carrying out printing reworking treatment on a green oil bridge falling position on a PCB board and is characterized by comprising the following steps:

s1: selecting an alignment hole on a PCB to be reworked to be used as an alignment stop point, opening a skylight hole at the green oil bridge falling position to be used as a regional stop point, and designing corresponding exposure data according to the alignment stop point and the regional stop point;

s2: manufacturing a screen printing plate of a gear point, manufacturing the screen printing plate of the gear point according to the area gear point in the step S1, and designing an oil discharging area at the position of the green oil bridge falling off;

s3: overprinting, namely oiling and curing and baking, wherein the screen printing of the stop point manufactured in the step S2 is mounted on a printing machine, a skylight hole on the screen printing of the stop point is aligned with a green oil bridge falling position on a PCB (printed circuit board) through the alignment hole, after the alignment, a printing machine is started to print ink on an oiling area corresponding to the PCB and the stop point screen, and after printing, the PCB is cured and baked to cure the ink;

s4: local exposure, namely selecting a green oil bridge from the oil discharging area as an exposure area, manufacturing LDI exposure data according to the exposure data, and performing local exposure on the exposure area by using an LDI exposure machine after calibration;

s5: developing, namely performing pattern development on the PCB subjected to the exposure in the step S4;

s6: and (3) post-process treatment, namely checking whether the developed green oil bridge is attached to the surface of the PCB, and performing the next process after high-temperature baking. According to the technical scheme, the shift point and exposure data are designed firstly, the shift point screen is prepared according to the shift point data, and the shift point screen is aligned with the PCB, so that the PCB can realize selective partial oiling in an oiling area during printing, the PCB is baked and solidified after being oiled in the printing partial oiling, the baked and solidified PCB enters an exposure procedure, and the green oil bridge position on the PCB is subjected to partial exposure and development by the exposure procedure, so that the PCB with the green oil bridge falling off is subjected to reworking treatment by adopting a partial anti-welding process, the integrity of the green oil bridge of the PCB is realized, further, the problem that a tin connecting short circuit cannot occur in a PCB paste piece is solved, the reworking treatment of the PCB is greatly reduced compared with the prior art, the product quality is effectively improved, and the scrapping of a green oil bridge falling product is reduced; specifically, firstly, arranging alignment holes on a PCB to be reworked, arranging alignment stop points, providing alignment standards for subsequent work, arranging a window hole at the drop position of a green oil bridge, arranging the window hole as a regional stop point, ensuring that the screen is locally and selectively oiled during printing, and searching corresponding exposure data in an engineering sharing disc according to the alignment stop points and the regional stop points, wherein in order to prevent green oil on a character line from being exposed, the residual coverage influences recognition, the exposure data should avoid a single side of 5mil of the character; then designing a screen plate of a baffle point through the baffle point of the area and the outer layer graph of the PCB, and designing an oil discharging area on the screen plate of the baffle point at the position where the green oil bridge falls off, so as to ensure that the ink is accurately smeared at the position where the green oil bridge falls off, and prevent the ink from remaining at other positions of the PCB, thereby influencing the quality of the PCB; then mounting the manufactured screen printing plate of the shift point on a printer, adopting the alignment holes to perform positioning calibration, printing ink through the oil discharging area, discharging oil through the window opening, wherein the width of the window opening is larger than that of the oil discharging area so as to ensure that the ink is uniformly smeared at the drop-off position of a green oil bridge, and curing and baking the printed PCB, so that the ink drying time can be reduced, the printing speed can be increased, the working efficiency can be improved, the ink after printing can be prevented from being diffused to surrounding areas, and the conductivity can be prevented from being influenced; in order to select the green oil bridge position of the PCB as an exposure area, the exposure area of the PCB is exposed in an LDI exposure machine, so that the exposure area can be precisely exposed, the unexposed area is protected, corresponding LDI exposure data are designed according to the exposure data and area stop points before exposure, and the exposure is carried out in the LDI exposure machine, so that the method has the advantages of high exposure speed and strong adaptability, and can improve the production efficiency and quality of PCB manufacture; the exposed PCB is soaked in the developing solution, photoresist in the unexposed area is rapidly removed, an outer layer pattern is displayed, the accuracy of a board surface circuit is improved, the manufactured PCB is more accurate and reliable, the production efficiency is improved, the manufacturing period is shortened, and the developed PCB is cleaned to remove the residual developing solution and the photoresist which are not removed; finally, inspecting the manufactured PCB, ensuring that the printing ink is closely adhered to the drop-off position of the green oil bridge, baking at high temperature, removing residual developing solution, photoresist and surface moisture, and ensuring the drying and cleaning of the surface of the PCB, thereby improving the stability of the quality of the finished PCB.

Further, in the step S1, the alignment hole is selected by using a SET/PNL four-corner hole selection method, including the following steps:

s1.1: the PCB to be reworked is drilled at four corners of the SET board by selecting one position through CAM original data;

s1.2: marking the drilled position of the position corresponding to each laminate, and setting the corresponding position as position data.

In the technical scheme, in order to improve the positioning accuracy of the PCB, balance the stress distribution of the PCB and avoid the deformation of the plate, thereby ensuring the quality and performance of the PCB, the alignment holes are selected by adopting a SET/PNL four-corner hole selection method; firstly, respectively selecting an alignment hole at four corners of the PCB according to CAM original data, wherein the CAM original data comprises various layer data of the PCB, drilling position and aperture information, positions of elements, plate process requirements and the like, the positions of the selected alignment holes can be accurately positioned, the calibration precision is improved, the CAM original data can automatically select the holes, and the cost can be reduced, so that the working efficiency is improved; and then, setting the selected alignment holes as alignment stop points and marking the alignment stop points at the corresponding positions of each layer of plate, and aligning the positions of the layers during positioning to ensure the alignment accuracy between different layers, thereby ensuring the normal operation of subsequent work.

Further, the oil down region includes green oil bridges and land 70 regions between adjacent green oil bridges.

In the above technical scheme, the bonding pad is the junction between the electronic element and the circuit board, has the conductive effect, and in order to ensure that the patched green oil bridge completely covers the surrounding bonding pad, prevent short circuit risk, ensure the normal work of the PCB board, then the oil discharging area except the green oil bridge also comprises the bonding pad area between the adjacent green oil bridges, can also increase the adhesion and the contact area between the patched green oil bridge and the bonding pad, and provide the repair effect, thereby reducing the problem of poor contact or green oil bridge falling which may occur after repair, and further ensuring the quality and the performance of the PCB board after the manufacture is completed.

Further, the screen mesh number of the screen printing plate of the gear point is 48T.

In the technical scheme, the screen printing plate with the screen printing point is manufactured by adopting the 48T screen printing plate when the screen printing is performed, has higher resolution ratio of a wire mesh and density of the screen printing plate, can well copy the circuit pattern on the PCB, improves the quality of the screen printing plate with the screen printing point, has stronger corrosion resistance, and can reduce the penetration of printing ink into other areas, thereby ensuring the quality of a finished product of the PCB.

Further, before the S3 overprinting treatment, the PCB is placed into a cleaning tank for cleaning, and the cleaning liquid of the cleaning tank is 3% -5% sulfuric acid solution.

According to the technical scheme, the PCB after the screen is dried is placed in the cleaning tank for cleaning, so that impurities such as dirt and grease on the surface can be removed, the surface cleaning of the PCB is ensured, the adhesive force of the PCB can be improved, the surface roughness is increased, the guarantee is improved for subsequent oil discharging work, the oil discharging printing times are reduced, the work efficiency is improved, after the screen is manufactured, the residual substances on the surface of the PCB are effectively removed, the influence on the subsequent work is avoided, and the PCB is cleaned by using 3% -5% sulfuric acid solution, so that on one hand, enough corrosive impurities such as surface residual oxides and pollutants can be removed, the surface cleaning of the PCB is ensured, and compared with high-concentration sulfuric acid, the 3% -5% sulfuric acid is easier to process and control, and the operation risk is reduced; on the other hand, the lower concentration is beneficial to prolonging the service life of the sulfuric acid, so that the replacement times are reduced, and the production cost is further reduced.

Further, the overprinting is divided into two modes, wherein the first overprinting mode is overprinting by two sides successively, and the second overprinting mode is overprinting by two sides together.

In the above technical scheme, the overprinting modes of the PCB board are divided into two modes, wherein the first overprinting mode is to print one surface and bake the surface, then print the other surface and bake the surface, and the second overprinting mode is to print the two surfaces together and bake the surface; the two overprinting modes are aimed at two different types of PCB boards, if the PCB board is a SET board, as the SET board has only one side of a printed circuit, the first overprinting mode is adopted, and the printing is performed on the front side and the rear side of the SET board, so that the mutual interference or confusion can be avoided, the printing accuracy can be better controlled, the printing error can be reduced, the printing quality is improved, and the quality and the reliability of a finished product of the PCB board are improved; if the PCB is a PNL board, a second overprinting mode is adopted, the two sides of the PCB are printed together, so that the production period can be shortened, the working efficiency is improved, the consistency of printing can be ensured by the simultaneous printing of the two sides, and the printing difference caused by the change of environmental factors is reduced, thereby influencing the quality of the PCB.

Further, the curing bake temperature was 75 °.

According to the technical scheme, the overprinted ink is quickly and uniformly coated on the surface of the PCB, so that a smooth ink layer is formed, an outer layer circuit is protected, the curing and baking temperature is set to be 75 degrees, and the overprinted ink can be better adhered to the surface of the substrate at the baking temperature of 75 degrees, so that the adhesive force and the durability are improved, and the baking effect and the quality of a finished PCB are further ensured.

Further, the step S4 is performed by using an LDI exposure machine, and includes the following steps:

s4.1: setting information, namely inputting the exposure data into an LDI exposure machine and changing a data format;

s4.2: the alignment reference is carried out, the exposure data is opened in an LDI exposure machine, and the alignment position of the exposure data is confirmed to be consistent with that of the actual PCB;

s4.3: and performing exposure, setting exposure parameters, placing the PCB in an LDI exposure machine, and positioning and calibrating the exposure.

In the above technical scheme, when the LDI exposure machine is used for exposure, the exposure data is firstly input into the LDI exposure machine, and the format of the exposure data is changed into a format matched with the exposure machine, so that the LDI exposure machine can accurately identify and read the exposure data; then opening the exposure data in an exposure machine and performing alignment reference, confirming that the two pairs of loci are consistent with the alignment holes of the PCB in size and position, setting exposure parameters according to normal parameters, placing the PCB on an exposure table, clamping the PCB by adopting a proper clamp, ensuring the flatness and stability of the PCB, avoiding movement and deformation in the exposure process, and ensuring the reliable product quality; the alignment holes on the alignment points and the PCB board are used for positioning calibration and locking the exposure positions, the exposure areas are exposed, so that the mutual collision and damage between the exposed PCB boards are avoided, the flatness is kept, the exposed PCB boards are placed on a multi-layer frame or a common frame, the subsequent work is convenient, the time is further saved, the manufacturing efficiency is improved, the placed PCB board surfaces are prevented from being polluted and scratched, white paper is placed on each layer of the multi-layer frame, and the quality and the reliability of the PCB board are ensured.

Furthermore, the green oil bridge is free from erosion and falling off, and the opposite upper PAD is used as the test standard in the test procedure.

In the technical scheme, in order to ensure that the patterns and the printing ink after the development of the PCB meet the design requirements, the PCB is inspected, and the inspection standards comprise no erosion, no falling and upper PAD of a green oil bridge; the green oil bridge is free of corrosion, so that the green oil bridge after being manufactured is not corroded by the developing solution in the developing process, the integrity of the green oil bridge is maintained, and the reliability and the stability of the PCB are further ensured; the green oil bridge is free from falling, so that the adhesion of the green oil bridge is ensured, and the problem of circuit interruption in the subsequent processing or using process is prevented, thereby influencing the product quality; the upper PAD is opposite to the upper PAD, so that the green oil bridge is prevented from being arranged at the position of the bonding PAD, and the problem of circuit short circuit caused by the green oil bridge on the bonding PAD is prevented, thereby influencing the conductivity of the PCB and further reducing the quality of a finished product of the PCB after the PCB is manufactured.

Further, the baking requirement is that the 3M tape pull test does not fall off.

In the above technical scheme, the high-temperature baking process is a post-inspection process, which can eliminate residual moisture or solvent in the developing process and the inspection process, protect the surface of the PCB board, and further improve the adhesion of the ink; the baking requirement is that the 3M adhesive tape is not fallen off in a tensile test, and can be used as an evaluation standard of the adhesive force of the printing ink, so that the patterns and the printing ink after the development of the PCB can be firmly attached to the PCB, and further the quality and the reliability of a product are ensured.

The anti-drop treatment method for the PCB green oil bridge has the following beneficial effects:

firstly, the working efficiency is high, the LDI exposure machine is used for carrying out local exposure, the LDI exposure machine has the capability of high-speed exposure, the laser beam rapidly completes the whole exposure process under the rapid scanning, the exposure time is saved, the production efficiency is improved, the printing speed can be increased after the baking is carried out, the drying time is reduced, and the production period is shortened;

secondly, the cost is low, the loss of corresponding materials can be reduced by carrying out local printing and exposure on the green oil bridge falling position, and the ink can be prevented from entering other areas and damaging the PCB in the follow-up work during whole-plate printing, so that the rejection rate of products is reduced, and the PCB is automatically calibrated and exposed by using an LDI exposure machine, so that the labor is saved, and the production cost is further saved;

thirdly, the quality of finished products is high, the surface of the PCB is cleaned by using cleaning liquid after the screen printing plate of the shift point is manufactured, the surface residue is removed, the surface is ensured to be clean, the damage to the PCB caused by the residue in the subsequent work is prevented, the printing ink is locally overprinted on the falling position of the green oil bridge, the penetration of the printing ink into other areas can be prevented, the conductivity of the PCB is ensured, and the printing ink is baked after the printing ink is discharged, so that the adhesive force of the green oil bridge is enhanced, and the quality and the durability of the product are improved; in addition, the invention only exposes the green oil bridge position, which can reduce the problem of uneven exposure or excessive exposure possibly occurring in full-board exposure, thereby reducing errors and risks and further improving the quality of the finished PCB.

Drawings

FIG. 1 is a process flow diagram of a PCB green oil bridge anti-drop treatment method of the invention;

FIG. 2 is a diagram showing a distribution of a first set of positioning holes in an embodiment 1 of a method for treating PCB green oil bridge anti-drop according to the present invention;

FIG. 3 is a diagram showing a distribution of a second set of positioning holes in an embodiment 1 of a method for treating PCB green oil bridge anti-drop according to the present invention;

FIG. 4 is a diagram showing a distribution of a first set of positioning holes in an embodiment 2 of a method for treating PCB green oil bridge anti-drop according to the present invention;

FIG. 5 is a diagram showing a distribution of a second set of locating holes in an embodiment 2 of a method for treating PCB green oil bridge anti-drop according to the present invention;

fig. 6 is a schematic diagram of a lower oil area of a method for treating a green oil bridge of a PCB to prevent falling off according to the present invention;

fig. 7 is a schematic diagram of an exposure area of a method for treating a green oil bridge of a PCB according to the present invention.

Reference numerals illustrate:

opening 10, oil drain region 20, positioning hole 30, set plate 40, pnl plate 50, exposure region 60, and pad 70.

Detailed Description

The invention further provides a treatment method for preventing the PCB green oil bridge from falling off by combining specific embodiments with the attached drawings.

Referring to fig. 1 to 5, in a non-limiting embodiment of the present invention, a method for processing a green oil bridge of a PCB to prevent the green oil bridge from falling off, is used for performing a printing reworking process on a green oil bridge falling off position on the PCB, and specifically includes the following steps:

s1: selecting an alignment hole 30 on a PCB to be reworked to be used as an alignment stop point, opening a skylight hole 10 at the green oil bridge falling position to be used as a regional stop point, and designing corresponding exposure data according to the alignment stop point and the regional stop point;

s2: manufacturing a screen printing plate of a gear point, manufacturing the screen printing plate of the gear point according to the area gear point in the step S1, and designing a lower oil area 20 at the drop position of the green oil bridge;

s3: overprinting, namely oiling and curing and baking, wherein the screen printing of the stop point manufactured in the step S2 is mounted on a printing machine, the skylight holes 10 on the screen printing of the stop point are aligned with the green oil bridge falling positions on the PCB through the alignment holes 30, after the alignment, the printing machine is started to print ink on the oiling areas 20 corresponding to the PCB and the stop point screen, and after the printing, the PCB is cured and baked to cure the ink;

s4: a green oil bridge is selected from the oil discharging area 20 to serve as an exposure area 60, LDI exposure data are manufactured according to the exposure data, and after calibration, an LDI exposure machine is used for carrying out local exposure on the exposure area;

s5: developing, namely performing pattern development on the PCB subjected to the exposure in the step S4;

s6: and (3) post-process treatment, namely checking whether the developed green oil bridge is attached to the surface of the PCB, and performing the next process after high-temperature baking.

Example 1

Referring to fig. 1 to 2, in a non-limiting example of the present invention, a method for preventing a green oil bridge of a PCB from falling off is described by taking a SET board 40 as an example:

in the step S1, the alignment hole 30 is selected by using a SET four-corner hole selection method, which specifically includes the following steps:

s1.1: the SET board 40 to be reworked respectively selects one position to drill holes at four corners through CAM original data;

s1.2: the drilled alignment holes 30 are marked at the corresponding positions of each laminate, and the corresponding positions are set as alignment mark data.

In the above steps, in order to improve the positioning accuracy of the SET board 40 and balance the stress distribution of the SET board 40, avoid the deformation of the board, and thereby ensure the quality and performance of the SET board 40, in this embodiment, the SET four-corner hole selection method is adopted to select the alignment holes 30; firstly, respectively selecting an alignment hole 30 at four corners of the SET board 40 according to CAM original data, wherein the CAM original data comprises various image layer data of the SET board 40, drilling position and aperture information, each element position, board process requirements and the like, the position of the selected alignment hole 30 can be accurately positioned, the calibration precision is improved, the CAM original data can automatically select holes, the cost can be reduced, and the working efficiency is improved; then, the selected alignment holes 30 are set as alignment stop points and marked at the corresponding positions of each layer of plates, and are used for aligning the positions of all layers during positioning, so that the alignment accuracy between different layers is ensured, and the normal operation of subsequent work is ensured; in this embodiment, the positions of the alignment holes 30 are not fixed, but four holes with uniform distribution can be selected, including four holes of the SET plate 40 which are parallel and symmetrical or two holes are mutually inclined or vertically symmetrical, or holes with irregular distribution can be selected, the four holes are not symmetrically distributed two by two, but are only distributed at four corners of the SET plate 40, but the selected alignment holes 30 are holes on the SET plate 40, and in order to facilitate more accurate positioning in subsequent work, the selected alignment holes 30 are obviously found on the SET plate 40 and are located in a stable area of the SET plate 40, so that the change of the hole diameter caused by the easy pressure or deformation area is avoided, and thus the accurate positioning cannot be achieved.

Referring to fig. 1, 2 and 5, in a non-limiting embodiment of the present invention, the mesh number of the screen printing plate of the stop point is 48T, in this embodiment, the screen printing plate of the stop point is manufactured by using a 48T screen printing plate, which has a higher line resolution and screen density, can well copy the line pattern on the PCB board, improves the quality of the screen printing plate of the stop point, has a stronger corrosion resistance, and can reduce the penetration of ink into other areas, thereby ensuring the quality of the finished product of the SET board 40; in order to form a solder mask layer in the area of the bonding pad 70, full-screen printing is performed by using a screen with 36T mesh before partial overprinting, the green oil bridge is partially not completely broken and falls off, if the number of the manufactured screen with the grade points is smaller than 36T during overprinting, the quantity of ink in printing can be increased, the thickness of the green oil bridge which does not fall off can be thickened, and the quality of the PCB is affected, so that the screen with 48T mesh in the screen with the grade points manufactured by overprinting can be selected according to the actual manufacturing process, the screen with proper screen mesh including the screen mesh of 64T, 80T mesh and the like, and the screen mesh of the area screen mesh is required to be larger than the screen mesh of the full-screen, and the situation that a gap is left between a part and an IC surface when the height of the green oil bridge exceeds 1.8mil can appear is avoided, and the conductive electrical performance is affected, and the quality of the manufactured SET plate 40 product is affected.

Referring to fig. 1, 2 and 5, in a non-limiting embodiment of the present invention, the overprinting is divided into two ways, the first overprinting way is overprinting by two sides, and the second overprinting way is overprinting by two sides together; in this embodiment, the SET board 40 adopts the overprinting mode of printing one side and baking, and then printing the other side and baking, since only one side of the SET board 40 is printed with a circuit, the first overprinting mode is adopted, and printing is performed on the front side and the rear side of the SET board, so that the SET board can ensure that the SET board is not interfered or confused with each other, can better control the accuracy of printing, is helpful for reducing printing errors, and further provides the quality of printing, and the quality and reliability of the finished product of the SET board 40; in order to quickly and uniformly coat the overprinted ink on the surface of the SET board 40 to form a flat ink layer so as to protect an outer layer circuit, setting the curing and baking temperature to be 75 degrees, and baking the SET board 40 on a multi-layer frame because the surface of the SET board 40 is smaller, wherein the overprinted ink can be better adhered to the surface of a substrate at the baking temperature of 75 degrees, so that the adhesive force and the durability are improved, and further the baking effect and the quality of a finished product of the SET board 40 are ensured; in this embodiment, the curing and baking temperatures of the two sides of the SET board 40 are both 75 °, specifically, the curing and baking time of the first side of the SET board 40 is 15min, the ink on the board surface is primarily cured, and the curing and baking time of the second side is 30min, so that the baking time of the first side does not exceed 45min, on one hand, the SET board 40 is prevented from thermal expansion and deformation caused by long-time baking at high temperature, thereby affecting the quality and reliability of the SET board 40; on the other hand, a long baking time may cause the pattern on the outer layer of the SET plate 40 to be changed, resulting in the subsequent development being not clean.

Referring to fig. 1 to 2, in a non-limiting embodiment of the present invention, the baking requirement is that the 3M adhesive tape is not dropped off in the tensile test, and the high temperature baking process is a post-process of the inspection process, which can eliminate residual moisture or solvent in the developing process and the inspection process, protect the surface of the PCB board, and further improve the adhesion of the ink; the baking requirement is that the 3M adhesive tape is not fallen off in a tensile test, and can be used as an evaluation standard of the adhesive force of the printing ink, so that the patterns and the printing ink after the development of the PCB can be firmly attached to the PCB, and the quality and the reliability of a product are further ensured; in this embodiment, in order to ensure thorough solidification of the developed developer, to avoid adverse effects of the residual developer on the SET board 40, the temperature of high-temperature baking is SET to 150 °, so that evaporation and removal of water on the surface of the SET board 40 can be accelerated, and drying of the surface of the circuit board is ensured; the influence on the circuit pattern on the surface of the circuit board caused by overlong baking time is avoided, and the baking time is set to 45min, so that the performance and the reliability of the circuit board are ensured.

Example 2

Referring to fig. 3 to 5, a non-limiting embodiment of the present invention, a method for preventing a green oil bridge of a PCB from falling off, is substantially the same as embodiment 1, except that the PNL board 50 is taken as an example for illustration in this embodiment:

in the step S1, the alignment hole 30 is selected by adopting a PNL four-corner hole selecting method, and specifically includes the following steps:

s1.1: the PNL board 50 to be reworked respectively selects one position to drill holes at four corners through CAM original data;

s1.2: the drilled alignment holes 30 are marked at the corresponding positions of each laminate, and the corresponding positions are set as alignment mark data.

In the above steps, in order to improve the positioning accuracy of the PNL plate 50 and balance the stress distribution of the PNL plate 50, avoid the deformation of the plate, and thereby ensure the quality and performance of the PNL plate 50, the embodiment adopts the PNL four-corner hole selection method to select the alignment holes 30; firstly, respectively selecting an alignment hole 30 at four corners of the PNL plate 50 according to CAM original data, wherein the CAM original data comprises various layer data of the PNL plate 50, drilling position and aperture information, positions of all elements, plate process requirements and the like, the positions of the selected alignment holes 30 can be accurately positioned, the calibration precision is improved, the CAM original data can automatically select holes, the cost and the cost can be reduced, and the working efficiency is improved; then, the selected alignment holes 30 are set as alignment stop points and marked at the corresponding positions of each layer of plates, and are used for aligning the positions of all layers during positioning, so that the alignment accuracy between different layers is ensured, and the normal operation of subsequent work is ensured; in this embodiment, the positions of the alignment holes 30 are not limited to four holes that are symmetrical or have a special relationship, but four holes that are randomly distributed or not directly associated in the four corners of the PNL board 50 may be used, and for the four selected alignment holes 30, the positions of the four selected alignment holes are to be accurately positioned on the PNL board 50 and are located in a stable area of the PNL board 50, so that the alignment and positioning of the subsequent partial overprinting and exposure processes can be performed, and the hole spacing between the four holes is to be adapted to the appropriate alignment requirements, so that the stability and accuracy of alignment cannot be ensured due to too far or too close distance can be prevented.

Referring to fig. 3 to 5, in a non-limiting embodiment of the present invention, the overprinting is divided into two ways, the first overprinting is performed by overprinting on two sides, and the second overprinting is performed by overprinting on two sides together. The second overprinting mode is that the two sides are printed together and baked; the second overprinting mode of overprinting and baking the two sides is adopted in the embodiment, the PNL board 50 consists of a plurality of circuit boards with small sizes, the production period can be shortened, the working efficiency can be improved by printing the two sides of the PNL board 50 together, the consistency of printing can be ensured by printing the two sides simultaneously, and the printing difference caused by the change of environmental factors is reduced, so that the quality of the PNL board 50 is affected; in order to quickly and uniformly coat the overprinted ink on the surface of the PNL plate 50 to form a flat ink layer so as to protect an outer layer circuit, setting the curing and baking temperature to be 75 degrees, compared with the SET plate 40, the PNL plate 50 is arranged on a common frame in the size of the SET plate 40, and the PNL plate 50 is placed on the common frame to be baked, and the overprinted ink can be better adhered to the surface of a substrate at the baking temperature of 75 degrees, so that the adhesive force and the durability are improved, and further the baking effect and the quality of a finished product of the PNL plate 50 are ensured; in this embodiment, the baking temperature of the PNL board 50 is 75 °, specifically, after the two sides of the PNL board 50 are continuously printed, the PNL board 50 is baked at 75 ° for 45min, and the baking time must not exceed 45min, in general, the baking time of curing and baking should be enough to cure the surface ink, so as to ensure the stability and adhesion of the surface ink, and the excessive time may cause excessive curing, thereby causing the change of the outer layer circuit pattern and the deformation of the board surface, and further affecting the quality and performance of the PNL board 50.

In the description of the present invention, it should be understood that the terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

The above embodiments are merely specific examples of the present invention, which are described in detail and are not to be construed as limiting

And are intended to limit the scope of the invention. It should be noted that modifications and improvements can be made by those skilled in the art without departing from the spirit of the invention, and that these obvious alternatives are intended to be protected by the invention.

Claims (10)

1. A PCB green oil bridge anti-falling treatment method is used for carrying out printing reworking treatment on a green oil bridge falling position on a PCB board and is characterized by comprising the following steps:

s1: selecting an alignment hole (30) on a PCB to be reworked to be set as an alignment stop point, setting a starting window hole (10) at a green oil bridge falling position to be a regional stop point, and designing corresponding exposure data according to the alignment stop point and the regional stop point;

s2: manufacturing a screen printing plate of a gear point, manufacturing the screen printing plate of the gear point according to the area gear point in the step S1, and designing a lower oil area (20) at the drop position of the green oil bridge;

s3: overprinting, namely oiling and curing and baking, wherein the screen printing of the stop point manufactured in the step S2 is mounted on a printing machine, a skylight hole (10) on the screen printing of the stop point is aligned with a green oil bridge falling position on a PCB (printed circuit board) through an alignment hole (30), after the alignment, a printing machine is started to print ink on an oiling area (20) corresponding to the PCB and the screen printing plate, and after the printing, the PCB is cured and baked to cure the ink;

s4: local exposure, namely selecting a green oil bridge from the oil discharging area (20) as an exposure area (60), manufacturing LDI exposure data according to the exposure data, and performing local exposure on the exposure area by using an LDI exposure machine after calibration;

s5: developing, namely performing pattern development on the PCB subjected to the exposure in the step S4;

s6: and (3) post-process treatment, namely checking whether the developed green oil bridge is attached to the surface of the PCB, and performing the next process after high-temperature baking.

2. The method for preventing the PCB green oil bridge from falling off according to claim 1, wherein in the step S1, the alignment holes (30) are selected by adopting a SET/PNL four-corner hole selection method, and the method comprises the following steps:

s1.1: the PCB to be reworked is drilled by selecting one position at each of four corners through CAM original data;

s1.2: the positions of the drilled alignment holes (30) are marked at the corresponding positions of each laminate, and the corresponding positions are set as alignment mark data.

3. The method of claim 1, wherein the oil down area (20) comprises green oil bridges and land (70) areas between adjacent green oil bridges.

4. The method for treating the PCB green oil bridge with the anti-falling effect according to claim 1, wherein the screen mesh number of the screen at the stop point is 48T.

5. The method for treating the PCB green oil bridge with the anti-falling effect according to claim 1, wherein the method further comprises a cleaning process before the S3 overprinting process, wherein the cleaning process is to put the PCB into the cleaning tank for cleaning, and the cleaning liquid in the cleaning tank is 3% -5% sulfuric acid solution.

6. The method for preventing the PCB green oil bridge from falling off according to claim 1, wherein the overprinting is divided into two modes, wherein the first overprinting mode is two-sided overprinting, and the second overprinting mode is two-sided overprinting.

7. The method for treating a green oil bridge of a PCB according to claim 1, wherein the curing baking temperature is 75 °.

8. The method for treating the anti-falling of the green oil bridge of the PCB according to claim 1, wherein the step S4 is performed by using an LDI exposure machine, and comprises the following steps:

s4.1: setting information, namely inputting the exposure data into an LDI exposure machine and changing a data format;

s4.2: the alignment reference is performed, the exposure data is opened in an LDI exposure machine, and the alignment hole (30) of the actual PCB is confirmed to be consistent in position;

s4.3: and performing exposure, setting exposure parameters, placing the PCB in an LDI exposure machine, and positioning and calibrating the exposure.

9. The method for treating the green oil bridge of the PCB with the anti-falling effect according to claim 1, wherein the inspection process uses the green oil bridge with no erosion, no falling and the upper PAD as an inspection standard.

10. The method for treating the green oil bridge of the PCB with the anti-falling effect according to claim 1, wherein the requirement of high-temperature baking is that the 3M adhesive tape is not fallen off in a tensile test.