Test method for dry film wet press short

Abstract

The application provides a dry film wet pressing short circuit test method, which comprises the following steps: step one, selecting a copper substrate and performing pretreatment; step two, placing the pretreated dry film in an oven and fully preheating the copper substrate; step three, exposing; step four, washing away the unexposed part of the copper substrate with the dry film after exposure, leaving the exposed circuit pattern; step five, etching away the area on the copper plate without dry film protection; step six, washing away the exposed dry film on the copper plate, leaving uniform grooves, i.e. the copper substrate to be used; step seven, using a film press to paste the dry film to be tested on the copper substrate to be used prepared in step six; step eight, exposing; step nine, washing away the unexposed part, leaving the exposed circuit pattern; step ten, if there is a non-exposed area between the circuits but the part that has not been developed is not developed, it is determined that a short circuit phenomenon occurs. Through the above steps, it is effectively identified whether the use of the dry film will have the risk of short circuit, thereby reducing the production failure rate.

Description

Technical Field

[0001] This invention relates to the field of photosensitive dry films, and more particularly to a test method for wet pressure short circuit of dry films. Background Technology

[0002] Photosensitive dry film, also known as photoresist dry film, is a type of film used in various etching, electroplating of copper, nickel, gold, tin, tin / lead, and via masking applications. It is currently a primary material used in circuit board manufacturing. As PCB manufacturing technology matures and many production techniques are continuously optimized, wet lamination has been used in the PCB industry for many years to improve the conformability and adhesion of photosensitive dry film during application. Wet lamination involves passing the copper substrate through a wet roller before application, forming a continuous water film on the substrate. Further lamination at this point effectively improves the flowability of the dry film, reduces gaps, and enhances its ability to fill deep pits. However, wet lamination also increases the risk of short circuits in the dry film. There is currently no effective testing method for detecting short circuits after wet lamination.

[0003] Therefore, it is necessary to develop a method for testing dry film wet pressing short circuits, which can effectively identify whether a short circuit will occur after the dry film is wet pressed and the severity of the short circuit, thus avoiding low yield and scrap caused by using incorrect dry film during production. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a test method for wet short circuit of dry film, comprising the following steps:

[0005] Step 1: Select a copper substrate and perform pretreatment;

[0006] Step 2: Place the pre-treated dry film in the oven and preheat the copper substrate. Then, select a suitable dry film and apply it to the preheated copper substrate using the hot press rollers of the laminating machine.

[0007] Step 3: Expose the copper substrate with the dry film applied in Step 2 after a period of time;

[0008] Step 4: After exposure, the copper substrate with the dry film attached is developed, washed, and dried in a developing machine to remove the unexposed parts, leaving the exposed circuit pattern.

[0009] Step 5: After developing, the copper substrate is etched, washed, and dried by an etching machine. The area on the copper substrate without dry film protection is etched away. The etching depth is controlled by adjusting the speed and pressure of the etching machine.

[0010] Step 6: After the etched copper substrate is stripped, washed with water, and dried, the exposed dry film on the copper substrate is washed away, leaving uniform grooves, which is the copper substrate to be used.

[0011] Step 7: After passing through wet pressing rollers and hot pressing rollers, the dry film to be tested is applied to the copper substrate to be used obtained in Step 6 using a laminating machine;

[0012] Step 8: Expose the copper substrate with the dry film applied in Step 7 for a period of time.

[0013] Step 9: After the exposed copper substrate with dry film is developed, washed, and dried in a developing machine, the unexposed parts are washed away, leaving the exposed circuit pattern.

[0014] Step 10: Use a microscope to observe the exposed circuit pattern. If there are unexposed areas between the circuits that are not developed, it is determined that a short circuit has occurred.

[0015] Preferably, the settings for the laminating machine in step two are: temperature 110℃, pressure 4 kg / cm². 2 The speed is 1.5 m / min.

[0016] Preferably, the exposure pattern used in step three is a straight line pattern with a line width of 100µm and a line spacing of 100µm.

[0017] Preferably, in step four, the developing solution used in the developing machine is 1% Na2CO3, the developing temperature is 30℃, and the developing speed is set to 2m / min.

[0018] Preferably, the etching depths in step five are 8µm, 10µm, and 12µm, respectively.

[0019] Preferably, in step six, the trenches have a depth of 8µm, 10µm, or 12µm, a width of 100µm, and a spacing of 100µm.

[0020] Preferably, the water used for wet pressing in step seven is pure water.

[0021] Preferably, in step eight, the exposure pattern used is a straight line pattern with a line width of 100µm and a line spacing of 100µm. During exposure, the direction of the line pattern must be perpendicular to the direction of the grooves on the copper plate.

[0022] Preferably, the copper substrate pretreatment steps in step one include: acid washing, grinding, water washing, and drying.

[0023] Compared to existing technologies, the beneficial effects of this invention are as follows: This invention relates to a test method for short circuits in dry film wet lamination, comprising the following steps: Step 1: Selecting a copper substrate and performing pretreatment; Step 2: Placing the pretreated dry film in an oven to fully preheat the copper substrate; Step 3: Exposure; Step 4: Washing away the unexposed portions of the exposed copper substrate with the dry film, leaving the exposed circuit pattern; Step 5: Etching away areas on the copper substrate not protected by the dry film; Step 6: Washing away the exposed dry film on the copper substrate, leaving uniform grooves, i.e., the copper substrate to be used; Step 7: Applying the dry film to be tested onto the copper substrate to be used obtained in Step 6 using a laminating machine; Step 8: Exposure; Step 9: Washing away the unexposed portions, leaving the exposed circuit pattern; Step 10: If there are unexposed areas between circuits that are not developed, it is determined that a short circuit has occurred. Through the above steps, the risk of short circuits when using this type of dry film wet lamination is effectively identified, thereby reducing the production defect rate.

[0024] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the preferred embodiments of the present invention are described in detail below. Specific embodiments of the present invention are given in detail in the following examples. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the copper substrate being manufactured. Figure 1 ;

[0026] Figure 2 This is a schematic diagram of the copper substrate being manufactured. Figure 2 ;

[0027] Figure 3 It is an image formed after a dry film is applied to a copper substrate and then developed.

[0028] Figure 4 It is an image formed after the non-exposed areas between the lines are not developed and are not removed by the development process.

[0029] Figure 5 This is the diagram corresponding to no short circuit (Level 1);

[0030] Figure 6 This is the diagram corresponding to short-circuit area accounting for less than 50% of the total area (Level 2);

[0031] Figure 7 This is the diagram corresponding to a short-circuit area that accounts for more than 50% of the total area (Level 3). Detailed Implementation

[0032] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0033] In printed circuit board (PCB) manufacturing, wet lamination is a common method. This involves passing a copper substrate through a wet roller to form a continuous water film on the copper surface, improving the dry film's filling and adhesion. However, wet lamination also increases the risk of short circuits caused by the dry film. Due to the surface roughness and variations of the copper substrate, some areas contain more water than others. Even after a period of rest following lamination, the dry film cannot completely absorb the moisture from these areas. When the laminated copper substrate is then exposed to ultraviolet light (350nm–405nm) from the exposure machine, the light will penetrate the moisture between the dry film and the copper substrate, causing reflection and refraction onto unexposed areas, leading to short circuits. This patent describes a method for testing wet-press short circuits in dry films, capable of detecting different types of dry films and preventing low yields and scrap due to the use of incorrect dry films at the customer's end. Specifically, it includes the following steps:

[0034] Step 1: Select a copper substrate and perform pretreatment; it should be understood that the surface of the copper substrate should be flat and smooth; in some embodiments, a smooth copper plate with a copper thickness of 16um can be specifically selected, with the size of the copper plate being 200mm×125mm and the thickness being 1.6mm.

[0035] Step 2: Place the pre-treated dry film in the oven and preheat the copper substrate. Then, select a suitable dry film and apply it to the preheated copper substrate using the hot press rollers of the laminating machine.

[0036] Specifically, the pretreated dry film is placed in an oven set at 80°C for 10 minutes to fully preheat the copper substrate. Then, a suitable dry film is selected and applied to the preheated copper substrate using the hot press rollers of a laminating machine. The commonly used dry film model is SDKL-1038. The laminating machine is set to 110°C, pressure of 4 kg / cm2, and speed of 1.5 m / min.

[0037] Step 3: Expose the copper substrate with the dry film applied in Step 2 after a period of time;

[0038] Specifically, the copper substrate with the dry film was placed for 30 minutes and then exposed. The exposure machine selected was the Tianzhun TZDI-20 model, and the exposure pattern used was a straight line pattern with a line width of 100um and a line spacing of 100um.

[0039] Step 4: After exposure, the copper substrate with the dry film attached is developed, washed, and dried in a developing machine to remove the unexposed parts, leaving the exposed circuit pattern.

[0040] Specifically, after exposure, the copper substrate with the dry film attached is developed, washed with water, and dried in a developing machine. The unexposed parts are then washed away, leaving the exposed circuit pattern. The developing solution used here can be 1% Na2CO3, the developing temperature is 30℃, and the developing speed is set to 2m / min.

[0041] Step 5: After developing, the copper substrate is etched, washed, and dried by an etching machine. The area on the copper substrate without dry film protection is etched away. The etching depth is controlled by adjusting the speed and pressure of the etching machine.

[0042] Specifically, the copper plate with straight-line patterns of 100µm linewidth and 100µm line spacing, after development, undergoes etching, washing, and drying processes using an etching machine. This process removes areas on the copper plate without dry film protection. The etching depth is controlled by adjusting the speed and pressure of the etching machine, achieving depths of 8µm, 10µm, and 12µm. The etching solution used is a mixture of concentrated sulfuric acid, concentrated hydrochloric acid, and copper ions, at a temperature of 50°C.

[0043] Step 6: After the etched copper substrate is stripped, washed with water, and dried, the exposed dry film on the copper substrate is washed away, leaving uniform grooves, which is the copper substrate to be used.

[0044] Specifically, the etched copper plate undergoes steps such as film removal, washing, and drying to remove the exposed dry film, leaving uniform trenches with depths of 8µm, 10µm, and 12µm, widths of 100µm, and spacings of 100µm, thus obtaining the substrate we need. The film removal solution used here is a 3% NaOH solution at a temperature of 50℃.

[0045] Step 7: After passing through wet pressing rollers and hot pressing rollers, the dry film to be tested is applied to the copper substrate to be used obtained in Step 6 using a laminating machine;

[0046] Specifically, the dry film to be tested is applied to the copper plate prepared above using a laminating machine, passing it through wet pressing rollers and hot pressing rollers. The water used for wet pressing is pure water, and the laminating machine is set to: 100℃, pressure: 4 kg / cm². 2 The speed is 1.0 m / min.

[0047] Step 8: Expose the copper substrate with the dry film applied in Step 7 for a period of time.

[0048] Specifically, the copper substrate with the dry film is placed for 1 hour and then exposed. The exposure pattern is a straight line pattern with a line width of 100um and a line spacing of 100um. During exposure, the direction of the line pattern must be perpendicular to the direction of the grooves on the copper substrate.

[0049] Step 9: After the exposed copper substrate with dry film is developed, washed, and dried in a developing machine, the unexposed parts are washed away, leaving the exposed circuit pattern.

[0050] Step 10: Use a microscope to observe the exposed circuit pattern. If there are unexposed areas between the circuits that are not developed, it is determined that a short circuit has occurred.

[0051] In some embodiments, the settings for the film applicator in step two are: temperature 100℃±5℃, 4.5±0.5kg / cm2, 1.5±0.5m / min.

[0052] In some embodiments, the exposure pattern used in step three is a straight line pattern with a line width of 100µm and a line spacing of 100µm. This shape allows for simple and clear observation of short circuits. If the shape is too complex, it will be difficult to observe. If the line width and line spacing are too large or too small, it will affect the amount of water in the trench, thereby affecting the formation of short circuits.

[0053] In some embodiments, the developing solution used in step four is 1% Na2CO3, the developing temperature is 30°C, and the developing speed is set to 2 m / min.

[0054] It should be understood that other developing solutions that can achieve the developing effect can also be used as the developing solution of this invention.

[0055] In some embodiments, the etching depths in step five are 8µm, 10µm, and 12µm, respectively.

[0056] In some embodiments, the trenches in step six have a depth of 8µm, 10µm, or 12µm, a width of 100µm, and a spacing of 100µm. It should be understood that the trench depth can be adjusted by etching speed and pressure, and is not limited to the aforementioned 8µm, 10µm, or 12µm. Applying the dry film to this type of copper plate using a wet lamination method can help identify whether the wet lamination of this dry film carries a risk of short circuit.

[0057] In some embodiments, the water used for wet pressing in step seven is pure water.

[0058] In some embodiments, the exposure pattern used in step eight is a straight line pattern with a line width of 100µm and a line spacing of 100µm. During exposure, the direction of the line pattern must be perpendicular to the direction of the grooves on the copper plate.

[0059] In some embodiments, in step one, the copper substrate undergoes a series of pretreatment steps such as pickling, grinding, washing, and drying to remove foreign matter, dirt, and other defects from the surface of the copper substrate.

[0060] Since the short-circuit conditions after wet pressing vary depending on the type of dry film, we categorize short circuits into three levels for easy identification. Specifically, as follows: Figure 5-7 As shown.

[0061] Example 1

[0062] Step 1: Select a smooth copper substrate with a thickness of 16µm. The copper substrate should be 200mm × 125mm in size and 1.6mm thick. The surface of the copper substrate should be flat and smooth. Perform a series of pretreatment steps, including acid pickling, grinding, washing, and drying, to remove foreign matter, dirt, and other defects from the surface of the copper substrate.

[0063] Step 2: Place the pretreated dry film in an oven set to 80℃ for 10 minutes to fully preheat the copper substrate. Then, select a suitable dry film and apply it to the preheated copper substrate using the hot press rollers of a laminator. The dry film model used here is SDK-1038, and the laminator settings are: 110℃, pressure: 4 kg / cm². 2 The speed is 1.5 m / min;

[0064] Step 3: Place the copper substrate with the dry film on for 30 minutes and then expose it. Exposure energy: 120mJ (Tianzhun TZDI-20). The exposure pattern is a straight line pattern with a line width of 100um and a line spacing of 100um.

[0065] Step 4: After exposure, the copper plate with the dry film attached is developed, washed with water, and dried in a developing machine. The unexposed parts are then washed away, leaving the exposed circuit pattern. The developing solution used here is 1% Na₂CO₃, the developing temperature is 30℃, and the developing speed is set to 2 m / min.

[0066] Step 5: After development, the copper plate with straight line patterns of 100µm line width and 100µm line spacing is etched, washed, and dried using an etching machine. This process removes areas on the copper plate without dry film protection. The etching depth is controlled by adjusting the speed and pressure of the etching machine, resulting in etching depths of 8µm, 10µm, and 12µm. The etching solution used here is a mixture of concentrated sulfuric acid, concentrated hydrochloric acid, and copper ions, at a temperature of 50℃.

[0067] Step 6: After etching, the copper plate undergoes processes such as film removal, washing, and drying. The exposed dry film on the copper plate is washed away, leaving uniform trenches with a depth of 8µm, a width of 100µm, and a spacing of 100µm, thus obtaining the substrate we need. The film removal solution used here is a 3% NaOH solution at a temperature of 50℃.

[0068] Step 7: Apply the dry film to be tested onto the copper plate prepared above using a laminating machine, passing it through wet pressing rollers and hot pressing rollers. The water used for wet pressing is pure water. The laminating machine settings are: 100℃, pressure: 4 kg / cm². 2 The speed is 1.0 m / min.

[0069] Step 8: Expose the copper plate with the dry film for 1 hour. Use a straight line pattern with a line width of 100um and a line spacing of 100um for exposure. The direction of the line pattern must be perpendicular to the direction of the grooves on the copper plate during exposure.

[0070] Step 9: After exposure, the copper plate with the dry film attached is developed, washed with water, and dried in a developing machine. The unexposed parts are washed away, leaving the exposed circuit pattern.

[0071] Step 10: Use a microscope to observe the exposed circuit pattern and determine the short circuit level as 1.

[0072] Example 2

[0073] The difference from Example 1 is that the dry film type in step 2 is SDK-1038; the exposure energy in step 3 is 120mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is 10um; and the final short circuit level is determined to be 1.

[0074] Example 3

[0075] The difference from Example 1 is that the dry film model in step 2 is SDK-1038; the exposure energy in step 3 is 120mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is 8um; and the final short circuit level is determined to be 1.

[0076] Example 4

[0077] The difference from Example 1 is that the dry film type in step 2 is SDKL-1038; the exposure energy in step 3 is 30mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is 8um; and the final short circuit level is determined to be 1.

[0078] Example 5

[0079] The difference from Example 1 is that the dry film type in step 2 is SDKL-1038; the exposure energy in step 3 is 30mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is 10um; and the final short circuit level is determined to be 1.

[0080] Example 6

[0081] The difference from Example 1 is that the dry film type in step 2 is SDKL-1038; the exposure energy in step 3 is 30mJ (TZDI-20); the copper trench depth in step 6 is 12um; and the final short circuit level is determined to be 1.

[0082] Example 7

[0083] The difference from Example 1 is that the dry film type in step 2 is: other 38um thick dry film (comparative product from another company); the exposure energy in step 3 is: 50mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is: 8um; and the final short circuit level is determined to be: 2.

[0084] Example 8

[0085] The difference from Example 1 is that the dry film type in step 2 is: other 38um thick dry film (comparative product from another company); the exposure energy in step 3 is: 30mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is: 10um; and the final short circuit level is determined to be: 2.

[0086] Example 9

[0087] The difference from Example 1 is that the dry film type in step 2 is: other 38um thick dry film (comparative product from another company); the exposure energy in step 3 is: 30mJ (Tianzhun TZDI-20); the copper plate trench depth in step 6 is: 12um; and the final short circuit level is determined to be: 3.

[0088] Comparative analysis of Examples 1-9 above shows that the risk of short circuit failure is low when using SDK-1038 and SDKL-1038 during wet pressing.

[0089] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown herein.

Claims

1. A test method for wet voltage short circuit of dry film, characterized in that, Includes the following steps: Step 1: Select a copper substrate and perform pretreatment; Step 2: Place the pre-treated dry film in the oven and preheat the copper substrate. Then, select a suitable dry film and apply it to the preheated copper substrate using the hot press rollers of the laminating machine. Step 3: Expose the copper substrate with the dry film applied in Step 2 after a period of time; Step 4: After exposure, the copper substrate with the dry film attached is developed, washed, and dried in a developing machine to remove the unexposed parts, leaving the exposed circuit pattern. Step 5: After developing, the copper substrate is etched, washed, and dried by an etching machine. The areas on the copper substrate without dry film protection are etched away. The etching depth is controlled by adjusting the speed and pressure of the etching machine. Step 6: After the etched copper substrate is stripped, washed with water, and dried, the dry film exposed on the copper substrate is washed away, leaving uniform grooves, which is the copper substrate to be used. Step 7: After passing through wet pressing rollers and hot pressing rollers, the dry film to be tested is applied to the copper substrate to be used obtained in Step 6 using a laminating machine; Step 8: Expose the copper substrate with the dry film applied in Step 7 for a period of time. During exposure in Step 8, the direction of the circuit pattern must be perpendicular to the direction of the grooves on the copper substrate. Step 9: After the exposed copper substrate with dry film is developed, washed, and dried in a developing machine, the unexposed parts are washed away, leaving the exposed circuit pattern. Step 10: Use a microscope to observe the exposed circuit pattern. If there are unexposed areas between the circuits that are not developed, it is determined that a short circuit has occurred.

2. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, The settings for the laminating machine in step two are: temperature 110℃, pressure: 4 kg / cm². 2 The speed is 1.5 m / min.

3. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, The exposure pattern used in step three is a straight line pattern with a line width of 100µm and a line spacing of 100µm.

4. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, In step four, the developing solution used in the developing machine is 1% Na2CO3, the developing temperature is 30℃, and the developing speed is set to 2m / min.

5. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, The etching depths in step five are 8µm, 10µm, and 12µm, respectively.

6. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, In step six, the trenches have depths of 8µm, 10µm, and 12µm, widths of 100µm, and intervals of 100µm.

7. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, The water used for wet pressing in step seven is pure water.

8. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, In step eight, the exposure pattern used is a straight line pattern with a line width of 100µm and a line spacing of 100µm.

9. The test method for dry film wet voltage short circuit as described in claim 1, characterized in that, The copper substrate pretreatment steps in step one include: acid washing, grinding, water washing, and drying.

Images