CN114786352A

CN114786352A - Manufacturing method of anti-warping circuit board

Info

Publication number: CN114786352A
Application number: CN202210257664.0A
Authority: CN
Inventors: 潘自锋; 王港生; 杨立发; 李伟荣; 张亚琳; 詹世景; 张静; 杨仕德
Original assignee: Zhuhai Zhongjing Yuansheng Electronic Technology Co ltd
Current assignee: Zhuhai Zhongjing Yuansheng Electronic Technology Co ltd
Priority date: 2022-03-16
Filing date: 2022-03-16
Publication date: 2022-07-22
Anticipated expiration: 2042-03-16
Also published as: CN114786352B

Abstract

The invention discloses and provides a manufacturing method of an anti-warping circuit board, which is reasonable in process and capable of effectively preventing the warping problem of a single panel from occurring. The manufacturing method of the anti-warping circuit board comprises the following steps: selecting materials, RTR sending materials, RTR bearing film pasting, RAR dry film pasting, RTR exposure developing, RTR etching demoulding, RTR projection punching, slicing, acid cleaning passivation, top pasting CVL, top pressing CVL, solidifying I, sand blasting/gold depositing, lower bearing film, bottom pasting CVL, bottom pressing CVL, character printing/solidifying II, first shape punching, packaging film pasting, second shape punching and packaging. The invention is applied to the technical field of circuit board manufacturing.

Description

Manufacturing method of anti-warping circuit board

Technical Field

The invention relates to the technical field of circuit board manufacturing, in particular to a manufacturing method of an anti-warping circuit board.

Background

With the increasing popularity of electronic products, electronic products such as PCs, PADs, smart phones, smart wearing and the like play more and more important roles in life and work. However, electronic products are developing in a lighter and thinner direction, integrated circuits are rapidly developing under the push of the requirements, the use requirements of single-panel, double-panel and multi-layer boards are greatly increased under the background of times, and the flexible circuit board conforms to the requirements of the development direction of electronic products by virtue of the advantages of lightness, thinness and foldability.

In the manufacturing method of the flexible printed circuit board, because the manufacturing method has a long process, for example, the process is not properly managed, various abnormalities are likely to occur in the process, thereby reducing the yield of the product. At present, in the manufacture of a single-face plate, because the thickness of a product is extremely thin, the minimum thickness of a covering membrane plate can reach about 45 micrometers, and because of the characteristics of the single-face plate, the problems of indentation, crease and the like are easily generated in the actual production process, and the most serious problem is the problem of warping deformation of the product, which influences the use of a client machine. Therefore, the problem of warpage of the single-sided board needs to be solved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides the manufacturing method of the anti-warping circuit board, which has reasonable flow and can effectively prevent the warping problem of the single panel.

The technical scheme adopted by the invention is as follows: the manufacturing method of the invention comprises the following steps:

step A: selecting materials, wherein the materials comprise roll materials such as a base material, a dry film, a carrier film and the like, a covering film and a packaging film, the base material is made of a PI film and a copper foil layer, and the covering film is a high-overflow glue covering film;

and B, step B: RTR material sending, namely taking the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film from a warehouse and putting the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film into a yellow room workshop for preparation of production; and C: RTR (room temperature resistance) bearing film pasting, roll-to-roll bearing film pasting, aligning the base material roll material and the bearing film roll material, and performing roll-to-roll synchronous film pasting;

step D: c, pasting a dry film by RAR, pasting the dry film in a roll-to-roll manner, aligning the dry film roll with the new roll pasted in the step C, and pasting the film in a synchronous rolling manner;

step E: d, performing RTR exposure and development, performing roll-to-roll exposure and development, and performing exposure and development on the new roll material which is attached in the step D, wherein the exposure and development acts on the dry film;

step F: RTR etching stripping, reel-to-reel stripping of a dry film and etching of a circuit, stripping of the exposed and developed part of the dry film, and etching of the circuit to obtain a product circuit;

g: RTR projection punching is carried out, positioning holes are punched roll to roll, and the positioning holes are punched in a product coil stock after the circuit manufacturing is finished by using a punching machine;

step H: cutting into pieces, and cutting the punched product roll into independent single products by using a shearing machine;

step I: pickling and passivating, and cleaning the copper surface of the product;

step J: sticking a top CVL, sticking a covering film, sticking the covering film with the size consistent with the size of the product on the upper end face of the product, and protecting the product circuit;

step K: pressing the top CVL, pressing the covering film, and pressing the product by using a hard pressing auxiliary material through a press;

step L: curing the covering film, and baking the product at 165 ℃ for 1 hour;

step M: performing sand blasting/gold deposition, namely performing sand blasting on the product to clean the copper surface of the product, and performing gold deposition on the product finger short to ensure that the product obtains conductivity;

and step N: the lower bearing film is used for removing the bearing film on the lower end face of the product;

step O: pasting a bottom CVL, pasting a covering film, and pasting a new covering film with the size consistent with that of the product on the lower end face of the product, so that the hardness of the product is increased, and the finger flatness of the product is kept;

and (P): pressing the bottom CVL, pressing the covering film, and pressing the product by using a hard pressing auxiliary material through a press;

step Q: printing characters/curing, namely printing the characters on the product by a screen printer, and baking the product at the baking temperature of 165 ℃ for 1 hour after printing;

step R: punching the first shape, punching a design outline of a single product through a punch, and punching a positioning hole required by secondary punching;

step S: sticking a packaging film, wherein the packaging film is stuck to a single product, and the viscosity of the packaging film is 15-20 g;

and T: punching the shape II, punching the single product into a single finished product through a punch, ensuring the size of the finished product through a positioning hole, cutting off the product after punching, and not cutting off the packaging film;

step U: and packaging, taking off the finished product from the packaging film after the finished product is inspected and viewed, loading by using a special tray, and packaging and delivering after confirming the warping degree and the flatness of the product.

Further, in the step A, the glue overflow amount of the covering film is 0.18mm at the upper limit value.

Further, in the step C, the temperature is 70 ℃, the bonding pressure is 5KG, and the bonding speed is 2.5 m/min.

Further, in the step D, the temperature for bonding the dry film is 100 ℃, and the bonding speed is 2.0 m/min.

Further, in step E, the exposure energy is of 5-7 levels, the vacuum value is-75 kpa-95 kpa, the vacuum time is 3S, and the developing speed is 2.8 m/min.

Further, in step F, the etching rate was 3.0 m/min.

Further, in the step K and the step P, the flatness of the press table is kept, the temperature uniformity of the press table is +/-5 ℃, the pressure is 100KG, the pressing time is 120S, the pressing auxiliary material comprises a silicon aluminum foil, a first release film, an FPC (flexible printed circuit), a second release film, Teflon and a silicon steel plate, and the pressing structure is formed by stacking the silicon aluminum foil, the first release film, the FPC, the second release film, the Teflon and the silicon steel plate from bottom to top.

Further, from step A to step U, the time taken for the whole process is less than 168 hours.

The beneficial effects of the invention are: the whole manufacturing process is reasonable in design, the baking times and the baking time are accurately controlled, the phenomenon that products are irregular in thermal expansion is avoided, meanwhile, the cover film is a high-glue-overflow cover film with a proper glue overflow amount, and a special pressing structure is adopted during the pressing process, so that the influence of poor warping can be reduced, and the problem of warping of a single panel can be effectively prevented.

Drawings

FIG. 1 is a diagram of a fishbone analysis used in the analysis of the present invention;

FIG. 2 is a diagram of a standard practice for verifying warpage of a single panel;

FIG. 3 is a schematic diagram illustrating a warpage defect distribution when the effect of the pressing parameters on warpage is verified;

FIG. 4 is a graph of quality score master effects in verifying the effect of material and press stack on warpage;

FIG. 5 is a diagram of a test scenario in verifying the effect of reinforcement design on warpage;

FIG. 6 is a graph of test results demonstrating the effect of reinforcement design on warpage;

FIG. 7 is a diagram of a test protocol in verifying the effect of product design on warpage;

fig. 8 is a flow chart of a manufacturing process of the present invention.

Detailed Description

Before describing the embodiments of the present invention in detail, the cause of the warpage of the circuit board is analyzed, and then a test is performed based on the analysis to determine a coping process.

The cause of the warpage: the warping problem is caused mainly because the thermal expansion coefficients of different materials are different, and after the materials are pressed together, because the thermal expansion coefficients of the materials are different, stress exists among the materials after pressing, so that the materials warp. As shown in the attached figure 1, a fishbone diagram analysis method is adopted to judge factors which may influence the warping of a product, and the factors which influence the warping have the factors of unreasonable pressing parameters, pressed overlapping, excessive glue amount of an encapsulating material, thickness of a base material PI and the like through analysis.

Criteria for warpage: as shown in the attached figure 2, the golden finger is placed downwards on the horizontal plane of the marble, the vertical distance between the highest point and the lowest point of the warping is measured by using a millimeter scale, and the standard requirement of the warping is less than or equal to 1.0 mm.

The various factors of warpage generation were tested for verification:

1. verifying the influence of the pressing parameters on warping:

the experimental protocol is shown in table 1 below:

table 1;

the test results are shown in table 2 below:

table 2;

and (4) test conclusion: through analysis of test results, the warpage defect distribution is as shown in figure 3, and the defect distribution can find that when the pressing parameters are regularly changed, the warpage defect does not have corresponding change, and meanwhile, whether the increase of baking does not obviously improve the warpage defect.

2. Verify the effect of the material and the press stack on warpage:

according to the characteristic factor analysis result, the following 3 factors are mainly considered in combination with the actual situation of production control: a (base material thickness: PI/Cu thickness), B (cover film glue overflow amount) and C (press lamination), and a comparison test is carried out through 3 factors 3 levels, wherein the comparison test is specifically shown in the following table 3:

table 3;

the DOE test data are shown in table 4 below:

table 4;

and (3) data analysis:

the quality score master effect graph is shown in fig. 4. From DOE test data and a quality scoring main effect diagram, the extremely poor difference of the mean values of the glue overflow amount is the largest and is a first influence factor, the second press stacking is the second influence factor, and the thickness influence of the substrate PI is smaller and is a secondary factor;

and (4) analyzing the comprehensive DOE test data, wherein the optimal scheme is A2B3C 2.

3. Verifying the influence of the reinforcing design mode on the warping:

the test protocol was as follows:

the experimental protocol is shown in figure 5;

and (3) test results:

the test results are shown in FIG. 6;

and (4) test conclusion:

according to the test result, the poor warping of the product can be improved to a certain extent by different reinforcement designs.

4. Verifying the influence of product design on warpage:

the test protocol was as follows:

the experimental protocol is shown in figure 7;

the test results are shown in table 5 below:

table 5;

and (4) test conclusion:

as a result of the test, it was confirmed that the larger the design angle a, the less the warpage failure.

Summary of the test:

1. the adverse influence of pressing parameters on warping is small;

2. the adhesive overflow amount of the cover film has the largest adverse effect on warping, and the adhesive overflow amount needs to be controlled to be more than 0.15 mm;

3. the pressfitting is folded and is constructed great to the warpage harmful effects, adopts through testing pressfitting folding: the mode of the silicon aluminum foil, the release film, the FPC, the release film, the Teflon and the silicon steel plate is optimal;

4. the adverse effect of the thickness of the base material PI on the warping is small, and an 12/20 rolled material is preferably selected;

5. the warping is poor and the reinforcing design mode has certain influence, wherein the reinforcing and supporting effect added at the two ends of the edge of the product is optimal;

6. the poor warping has certain influence on the product design angle, the greater the angle between the inclined edge and the horizontal direction is, the less warping is easy to generate, and the square design is preferably adopted;

the verification tests are integrated:

the control of the glue overflow amount is more than 0.15mm, the pressing and stacking structure adopts silicon aluminum foil, a release film, FPC, a release film, Teflon and a silicon steel plate, reinforcing supports are added at two ends of the edge of a product, and batch import verification is carried out, so that poor warping can be 100 percent solved; the control of the glue overflow amount is more than 0.15mm, and the laminated structure adopts silicon aluminum foil, a release film, FPC, the release film, Teflon and a silicon steel plate, and the poor warping of 90 percent can be solved by batch import verification.

According to the analysis result, the manufacturing method adopted by the invention can effectively prevent the single-sided board from warping.

As shown in fig. 8, in the present embodiment, the manufacturing method of the present invention includes the steps of:

step A: selecting materials, wherein the materials comprise roll materials such as a base material, a dry film, a carrier film and the like, a covering film and a packaging film, the base material is made of a PI film and a copper foil layer, the covering film is a high-glue-overflow covering film, and the glue overflow amount of the covering film is 0.18 mm;

and B: the RTR material sending step of taking the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film from a warehouse and putting the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film into a yellow workshop for preparation production; and C: carrying a layer of carrier film on the back before manufacturing, aligning the base material coil stock and the carrier film coil stock, and carrying out coil synchronous film pasting, wherein the temperature is 70 ℃ when the carrier film is pasted, the pasting pressure is 5KG, the pasting speed is 2.5m/min, and carrying out whole roll back pasting of the carrier film;

step D: c, adhering dry films to RAR, adhering dry films roll to roll, wherein the product needs to be manufactured with a circuit, and therefore the dry films need to be adhered, aligning the dry film coil with the new coil material adhered in the step C, and adhering the films synchronously in a rolling mode, wherein the temperature is 100 ℃ during adhering the dry films, and the adhering speed is 2.0 m/min;

step E: d, performing RTR exposure development, performing roll-to-roll exposure development, performing exposure development on the new roll material attached in the step D, wherein the exposure development acts on the dry film, the exposure energy is 5-7 levels, the vacuum value is-75-95 kpa, the vacuum time is 3S, and the development speed is 2.8 m/min;

step F: RTR etching stripping, reel-to-reel stripping of a dry film and an etching line, stripping of the exposed and developed part of the dry film, and line etching at an etching speed of 3.0m/min to obtain a product line;

step G: RTR projection punching is carried out, positioning holes are punched roll to roll, and the positioning holes are punched in a product coil stock after the circuit manufacturing is finished by using a punching machine; the product is produced by using positioning holes in the processes of laminating, punching and character, so that 2.0 positioning holes of the product are punched out by using a punching machine behind the circuit;

step H: cutting into sheets, and cutting the punched product roll into independent single products by using a shearing machine; the products are roll-to-roll products before punching, but at the beginning of the sticking and packaging process, the equipment cannot use roll-to-roll production, so a shearing machine is used after punching to shear the products into single sheets for production;

step I: pickling and passivating, and cleaning the copper surface of the product; after the product comes out of the dust-free room of the yellow house, the copper surface of the product is oxidized and polluted by air, so the copper surface is cleaned before a covering film is attached;

step J: sticking a cover film on the top CVL, sticking the cover film with the size consistent with that of the product on the upper end face of the product, and protecting the product circuit; the back of the product needs to be conducted, so that the circuit needs to be protected by a covering film in the manufacturing process, and the covering film is attached to the product circuit through equipment and manpower and then is pressed;

step K: pressing a top CVL, pressing a covering film, keeping the flatness of a press table, keeping the temperature uniformity of the table at +/-5 ℃, keeping the pressure at 100KG and keeping the pressing time at 120S, and pressing a product by using a pressing structure of a press formed by hard pressing auxiliary materials; the single-sided board is characterized by being thin and asymmetrical, and hard pressing auxiliary materials are needed to be used for pressing during pressing, so that the phenomenon that a product is pressed unevenly after pressing due to the fact that a softer buffer material is used is avoided;

step L: curing, namely curing a covering film, and baking the product at 165 ℃ for 1 hour;

step M: performing sand blasting/gold immersion, namely performing sand blasting on the product to clean the copper surface of the product, and performing gold immersion on the product finger short to ensure that the product obtains conductivity;

step O: sticking a bottom CVL, sticking a covering film, sticking a new covering film with the size consistent with that of the product on the lower end surface of the product, increasing the hardness of the product and keeping the finger flatness of the product;

step P: pressing a bottom CVL, pressing a covering film, keeping the flatness of a press table, keeping the temperature uniformity of the table at +/-5 ℃, keeping the pressure at 100KG and keeping the pressing time at 120S, and pressing a product by using a pressing structure of a press formed by hard pressing auxiliary materials;

step Q: printing characters/curing II, printing the characters on the product by a screen printer, and baking the product at the baking temperature of 165 ℃ for 1 hour after printing;

and step R: punching the first shape, punching a design outline of a single product through a punch, and punching a positioning hole required by secondary punching;

step S: sticking a packaging film, wherein the packaging film is stuck to a single product, and the viscosity of the packaging film is 15-20 g; the product is small and delivered in single piece, so that the product is prevented from scattering after the single piece is punched, the film is pasted before the single piece is punched, and the product is stuck to prevent the single piece from scattering;

and step T: punching the shape II, namely punching the single product into a single finished product through a punch press, ensuring the size of the finished product through a positioning hole, cutting off the product after punching, and not cutting off the packaging film;

step U: and packaging, taking off the finished product from the packaging film after the finished product is inspected and viewed, loading by using a special tray, and packaging and delivering by confirming the warping degree and the flatness of the product.

In this embodiment, in step K and step P, the pressing auxiliary material includes a silicon aluminum foil, a first release film, an FPC, a second release film, teflon, and a silicon steel plate, and the press-fit structure is formed by stacking the silicon aluminum foil, the first release film, the FPC, the second release film, the teflon, and the silicon steel plate from bottom to top.

In this embodiment, in step T, after the single product is cut into single finished products, the wrapping PI is attached to both ends of the cut edges of the finished products as a reinforcing support.

In the present market example, the in-line placement process ensures timeliness, the time from the cutting to the use is not allowed to exceed 7 days, and the time from step A to step U is less than 168 hours.

While the embodiments of the invention have been described in terms of practical embodiments, they are not to be construed as limiting the invention, and modifications of the embodiments and combinations with other embodiments will be apparent to those skilled in the art in light of the present disclosure.

Claims

1. A manufacturing method of an anti-warping circuit board is characterized in that: the manufacturing method comprises the following steps:

and B, step B: the RTR material sending step of taking the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film from a warehouse and putting the base material coil stock, the bearing film coil stock, the dry film coil stock and the cover film into a yellow workshop for preparation production; and C: RTR (real time production) pasting a bearing film, pasting the bearing film in a roll-to-roll manner, aligning the base material roll with the bearing film roll, and synchronously pasting the film in a roll manner;

step D: c, pasting a dry film by RAR, pasting a dry film roll to roll, aligning the dry film roll with the new roll pasted in the step C, and pasting the film in a synchronous rolling manner;

step H: cutting into sheets, and cutting the punched product roll into independent single products by using a shearing machine;

step J: sticking a cover film on the top CVL, sticking the cover film with the size consistent with that of the product on the upper end face of the product, and protecting the product circuit;

step K: pressing the top CVL, pressing the covering film, and pressing the product by using a pressing structure of a press formed by hard pressing auxiliary materials;

step P: pressing the base CVL, pressing the covering film, and pressing the product by using a pressing structure of a press formed by hard pressing auxiliary materials;

and step R: punching a first shape, namely punching a design outline of a single product through a punch press, and punching a positioning hole required by secondary shape punching;

2. The method of claim 1, wherein the step of forming the anti-warping circuit board comprises the steps of: in the step A, the glue overflow amount of the covering film is 0.18mm at the upper limit value.

3. The method for manufacturing a warpage preventing circuit board according to claim 1, wherein: in the step C, the temperature is 70 ℃ when the carrier film is attached, the attaching pressure is 5KG, and the attaching speed is 2.5 m/min.

4. The method for manufacturing a warpage preventing circuit board according to claim 1, wherein: in the step D, the temperature for bonding the dry film is 100 ℃, and the bonding speed is 2.0 m/min.

5. The method of claim 1, wherein the step of forming the anti-warping circuit board comprises the steps of: in the step E, the exposure energy is 5-7 grades, the vacuum value is-75 kpa-95 kpa, the vacuum time is 3S, and the developing speed is 2.8 m/min.

6. The method for manufacturing a warpage preventing circuit board according to claim 1, wherein: in step F, the etching rate was 3.0 m/min.

7. The method for manufacturing a warpage preventing circuit board according to claim 1, wherein: in the step K and the step P, the flatness of the press table surface is kept, the temperature uniformity of the table surface is +/-5 ℃, the pressure is 100KG, the pressing time is 120S, the pressing auxiliary material comprises a silicon aluminum foil, a first release film, an FPC (flexible printed circuit), a second release film, Teflon and a silicon steel plate, and the pressing structure is formed by stacking the silicon aluminum foil, the first release film, the FPC, the second release film, the Teflon and the silicon steel plate from bottom to top.

8. The method for manufacturing a warpage preventing circuit board according to claim 1, wherein: and step T, after the single product is cut into single finished products, attaching and encapsulating PI at two ends of the edge of the cut finished product to be used as a reinforcing support.

9. The method of claim 1, wherein the step of forming the anti-warping circuit board comprises the steps of: from step A to step U, the time taken for the whole process is less than 168 hours.