CN102858091B - A kind of method removing mixed pressure shaping pcb board resin gummosis - Google Patents

Abstract

The embodiment of the present invention relates to the field of PCB board molding, and in particular to a method for removing resin flow from mixed-pressure molding PCB boards, which is used to solve the problem that it is difficult to completely remove overflow in the chip stacking mixed-pressure molding process existing in the prior art. Resin flow problem. The method for removing the resin flow of mixed pressure molded PCB boards provided by the embodiments of the present invention includes: coating the solder resist on the surface of at least one outer core board, and coating the solder resist on the visible surface of the components to be mixed and pressed, so that the pressing The overflowing resin flow glue adheres to the surface of the solder resist after the treatment; the solder resist on the surface of the outer core board and the visible surface of the component to be mixed and pressed is washed off with an alkaline solution.

Description

A method for removing resin flow glue of mixed pressure forming PCB board

technical field

The invention relates to the field of PCB board molding, in particular to a method for removing resin flow from mixed pressure molding PCB boards.

Background technique

PCB boards (Printed Circuit Board, printed circuit boards) are generally laminated, and PCB boards generally have two stacking methods before lamination: one is copper foil lamination (FOIL-LAM), which consists of one or more layers Core board, prepreg and copper foil; the other is core board lamination (CORE-LAM), which is composed of one or more layers of core board and prepreg.

In the production of circuit boards, when it is necessary to press sub-boards or metal components in the multi-layer core board of the PCB board, local mixed pressure is required. The so-called local mixed pressure refers to the PCB sub-boards of different materials (such as high-frequency low-loss special boards, conventional FR4 material boards, etc.), or metal components (such as copper blocks, etc.) The local position of the core board, press and bond each layer of core boards, prepregs, PCB sub-boards or metal components of different materials together by heating and pressing; manufacture PCB boards with special functions at the lowest possible cost, such as High-frequency high-speed board, high-frequency cooling board, etc.

However, during the pressing process, the resin flow glue of the prepreg between the core boards of each layer will flow, which will not only fill the gap between the sub-board and the core board, or between the metal component and the core board, but also part of the resin flow. Glue overflows to the sub-board, or metal components, or the surface of the PCB board. The spilled resin flow glue needs to be removed in time, otherwise it will affect the subsequent processing and performance of the PCB board. At present, the resin flow glue overflowed from the PCB board is usually removed by a ceramic or abrasive belt grinder. Due to the height difference between the local mixed pressure position and the board surface, and the warpage of the board, the ceramic or abrasive belt grinder cannot completely remove the resin flow. It can be seen that in the existing mixed pressure molding process of PCB boards, it is difficult to completely remove the spilled resin flow glue.

Contents of the invention

Embodiments of the present invention provide a method for removing resin flow from mixed-pressure molding PCB boards, which is used to solve the problem in the prior art that it is difficult to completely remove overflowing resin flow in the chip stacking mixed-pressure molding process.

An embodiment of the present invention provides a method for removing resin flow on a mixed-pressure formed PCB board, the method comprising the following steps:

Coating green oil on the surface of at least one outer core plate, and coating green oil on the visible surface of the component to be mixed and compressed;

Curing the outer core plate coated with the green oil on the surface, and curing the components to be mixed and pressed that are visible on the surface coated with the green oil, so that the overflowing resin flow glue adheres to the Oil-green surface, wherein the curing temperature is 160°C, and the curing treatment time is 50 minutes;

The solder resist on the surface of the outer core board and the visible surface of the component to be mixed and pressed is washed away with an alkaline solution. Preferably, the solder resist on the surface of the outer core board and the visible surface of the component to be mixed and pressed is washed off and pressed with an alkaline solution, specifically:

The temperature of the alkaline solution is 80°C.

Preferably, the alkaline solution adopts an 8% NaOH solution, and the washing time is 40 minutes.

Preferably, the green oil is solder resist ink.

Preferably, the thickness of the green oil is 5-10 μm.

In the embodiment of the present invention, before the pressing treatment, the surface of the outer core plate and the visible surface of the components to be mixed and pressed are coated with an anti-adhesive layer, so that the resin flow glue overflowing during the pressing process will remain on the surface of the anti-adhesive layer, and It will not remain on the surface of the outer core board or the component to be mixed, and then remove the anti-adhesive layer after the pressing process, so that the spilled resin flow glue can be completely removed by removing the anti-adhesive layer, thus solving the problem in the prior art Existence is difficult to thoroughly remove the problem of overflowing resin flow glue.

Description of drawings

Fig. 1 is the flow chart of the method for clearing mixed pressure molding PCB board resin flow glue in the embodiment of the present invention;

Fig. 2 is the flow chart of the method for removing the resin flow glue of mixed pressure molding PCB board in the embodiment of the present invention, in which the component to be mixed pressure can be seen on one side;

Fig. 2A is a schematic structural view before mixed pressure treatment in the embodiment of the single-sided visible component to be mixed pressure of the present invention;

Fig. 2B is a schematic structural view of the mixed pressure treatment in the embodiment of the single-sided visible component to be mixed pressure of the present invention;

Fig. 2C is a schematic structural view of the embodiment of the component to be mixed-pressed that can be seen on one side of the present invention after removing the resin flow glue treatment;

Fig. 3 is the flow chart of the method for clearing the resin flow glue of the mixed pressure molding PCB board in the embodiment of the double-sided visible components to be mixed pressure of the present invention;

Fig. 3A is a schematic structural view before mixed pressure treatment in the embodiment of the double-sided visible component to be mixed pressure of the present invention;

Fig. 3B is a schematic structural view of the mixed pressure treatment in the embodiment of the double-sided visible component to be mixed pressure of the present invention;

FIG. 3C is a schematic structural view of the embodiment of the double-sided visible component to be mixed and pressed after the resin flow removal treatment in the embodiment.

Detailed ways

In the embodiment of the present invention, before the pressing treatment, the surface of the outer core plate and the visible surface of the components to be mixed and pressed are coated with an anti-adhesive layer, so that the resin flow glue overflowing during the pressing process will remain on the surface of the anti-adhesive layer, and It will not remain on the surface of the outer core board or the component to be mixed, and then remove the anti-adhesive layer after the pressing process, so that the spilled resin flow glue can be completely removed by removing the anti-adhesive layer, thus solving the problem in the prior art Existence is difficult to thoroughly remove the problem of overflowing resin flow glue.

As shown in FIG. 1 , it is a flowchart of a method for removing resin flow on a mixed pressure molded PCB board in an embodiment of the present invention. A method for removing the resin flow of mixed-pressure formed PCB board provided by the embodiment of the present invention includes the following steps:

Step 101, coating an anti-adhesive layer on the surface of at least one outer core plate, and coating an anti-adhesive layer on the visible surface of the component to be mixed and pressed, so that the overflowing resin flow glue adheres to the surface of the anti-adhesive layer after the pressing process;

Step 102 , removing the anti-adhesive layer on the surface of the outer core plate and the visible surface of the component to be mixed and pressed after the pressing treatment.

Preferably, before step 101, it also includes:

Provide the core boards (CORE) of the PCB board and the components to be mixed and pressed. Among them, the core boards of each layer are laminated according to the production requirements, and the core boards of each layer are bonded with prepreg.

The upper surface and/or the lower surface of the core board can be a copper foil layer, and the middle is a resin and glass fiber layer, that is, the core board is formed by laminating a copper foil layer and a PP (Polypropylene, polypropylene) layer.

Specifically, in step 101, an anti-adhesive layer may be coated on the surface of one or two outer core boards according to the production requirements of the PCB board and the shape of the components to be mixed and pressed. For example, if you only need to embed the components to be mixed and compressed at the upper end, you can choose to coat the upper surface of the upper outer core plate with an anti-adhesive layer; The upper surface of the layer core board and the lower surface of the outer layer core board at the lower end are coated with an anti-adhesive layer.

The purpose of coating the anti-adhesive layer is to make the resin flow glue attached to it easy to remove with the removal of the anti-adhesive layer, so the anti-adhesive layer has the characteristics of high temperature resistance of 200 ° C and above and easy removal. According to For these characteristics, it is recommended to use solder resist to achieve the effect of easy removal of resin flow.

Among the commonly used solder resists, green oil, namely liquid photo-solder resist, is often used in the manufacture of printed circuit boards to coat the circuits and substrates of printed circuit boards that do not need to be soldered to play a role The function of protecting the formed line graphics. In a preferred embodiment of the present invention, green oil is used to coat the surface of the outer core board and the corresponding surface of the components to be mixed and pressed, so as to prevent the spilled resin flow glue from adhering to the surface of the pressed PCB board, so as to achieve the cleaning of spilled The role of resin flow glue.

Preferably, the applied anti-sticking layer is solder resist.

Preferably, the solder resist is green oil. If the solder resist is green oil, the green oil can be coated by silk screen printing (ie screen printing).

Preferably, the thickness of the green oil coated on the surface of the outer core plate may range from 5 μm to 10 μm.

Specifically, in step 101, an anti-adhesive layer is coated on the visible surface of the component to be mixed and compressed, wherein the visible surface means that the component to be mixed and compressed can still be seen after the compression treatment of the component to be mixed and pressed and the multi-layer core board. surface; generally the upper surface and/or the lower surface; it should be noted that when coating the anti-adhesive layer, try not to apply it on the invisible surface of the component to be mixed (that is, the component to be mixed and the multi-layer core board after the compression treatment) Finally, the part to be mixed and pressed is in contact with the multi-layer core board due to pressing, so the position that cannot be seen) is coated with an anti-adhesive layer, so as not to affect the bonding effect between the core board and the mixed and pressed member.

Preferably, silk screen printing (ie screen printing) can also be used to coat the visible surface of the component to be mixed and pressed with green oil.

Preferably, the thickness of the green oil coated on the visible surface of the component to be mixed and pressed is in the range of 5-10 μm.

Preferably, after the visible surface of the outer core plate and the component to be mixed and pressed is coated with green oil, and before the pressing treatment, the step further includes:

Curing the outer core plate coated with green oil;

The component to be mixed and pressed with the visible surface coated with green oil is cured.

The preferred curing temperature in this embodiment is 160°C, and the curing time is 50 minutes, but it is not limited thereto, and the temperature within the error range of ±10% can achieve the desired effect; the curing time can be determined according to the green The curing of the oil is shortened or prolonged, and generally 50 minutes can achieve the desired effect; in the embodiment of the present invention, since the temperature of the curing treatment is 160°C, and the time is set to 50 minutes, there is no need to perform exposure and post-curing treatment after the curing treatment. This simplifies the curing process.

During implementation, after the curing treatment and before the pressing treatment, the following steps are also included:

According to the shape of the component to be mixed and pressed, grooves are made on the pre-compressed position of the outer core plate.

Among them, the pre-pressing position is set according to the production needs of the PCB board; according to the production needs of the laminated PCB board, slots can be made at the outer core board at the upper end and/or at the outer core board at the lower end; According to the production of the PCB board, it is necessary to open multiple slots to press the multiple components to be mixed with multiple core boards to obtain the required PCB board; in addition, according to the shape of the components to be mixed, one or more The core board and the prepreg are slotted.

In practice, the step of making grooves on the pre-compressed position of the outer core plate according to the shape of the component to be mixed and compressed can also be performed before step 101, that is, the pre-compressed position of the outer core plate according to the shape of the component to be mixed and compressed Grooves are made at the position, and an anti-adhesive layer is coated on the surface of at least one outer core plate and the visible surface of the component to be mixed and compressed.

It should be noted that when coating the anti-adhesive layer, try not to apply it on the inner wall of the groove and the invisible surface of the component to be mixed (that is, after the component to be mixed and the multi-layer core board are pressed, the component to be mixed and the multi-layer The core plate is in contact due to pressing, so the part that cannot be seen) is coated with an anti-adhesive layer, so as not to affect the bonding effect between the core plate and the components to be mixed and pressed.

After step 101, the multi-layer core board and the components to be mixed and pressed are pressed together to obtain the required PCB board; during the pressing process, the resin flow glue in the prepreg is not only filled with the components to be mixed and pressed and each core board There will be gaps between them, and part of the resin flow glue will overflow the surface of the anti-adhesive layer, and will not directly remain on the outer core board of the PCB board and the surface of the components to be mixed and pressed.

Preferably, in step 102, if the applied anti-sticking layer is solder resist, the solder resist on the surface of the outer core board and the visible surface of the components to be mixed and pressed may be washed off with an alkaline solution.

The alkaline solution used in this embodiment is a NaOH solution with a temperature of 80° C. and a concentration of 8%, and the washing time is 40 minutes, but it is not limited thereto.

It should be noted that the preferred embodiments of the embodiments of the present invention are given above, and the NaOH solution with temperature and concentration errors within the range of ±10% can achieve the expected effect; the fading time can be shortened according to the removal of the solder resist Or extended; the alkaline solution can also use Na ₂ CO ₃ , NaHCO ₃ and other solutions, but the dewashing effect is not as significant as NaOH solution.

Preferably, after washing the solder resist on the surface of the outer core board and the visible surface of the component to be mixed and pressed with an alkaline solution, it can also be washed with high-pressure water to more thoroughly remove the solder resist on the surface; While removing the solder resist, the resin flow glue attached to the solder resist is also completely removed.

It should be noted that, according to the preparation requirements of the PCB board, the component to be mixed-pressed can be a sub-board; it can also be a metal component, but it is not limited to this, and the component to be mixed-pressed needs to be determined according to the preparation requirement of the PCB board.

Specifically, according to the different preparation requirements of the PCB board, when the mixed pressure component is a sub-board, the material of the sub-board can be a functional board made of other materials in the prior art that are different from the material of the core board, and its function is to provide To achieve some special functions or needs of the PCB board, it is embedded in the PCB board; the material of the sub-board can also be the same as that of the core board, such as the mixed pressure of boards with different layers of the same board.

Specifically, for the mixed pressing process, the mixed pressing of boards with different layers of the same type of board, the high-number boards are partially pressed into the low-layer boards, and during the mixed-press molding process, around the surface of the high-layer boards and the outer low-layer boards Coating the anti-adhesive layer, after curing treatment, and then performing pressing treatment, and then removing the anti-adhesive layer to achieve the purpose of removing the spilled resin flow glue, and then performing post-processing according to the methods of the prior art, and finally forming PCB boards with outer graphics and circuits; among them, post-processing includes drilling, deburring templates, copper plating, outer graphics transfer and other processes.

It should be noted that, in the embodiments of the present invention, the method of stacking core boards is used as an example for illustration, but it is not limited thereto. The embodiment of the present invention is also applicable to the PCB board adopting the copper foil lamination method. Since the copper foil lamination only has more copper foil layers than the core board lamination, the resin flow glue removal method of the PCB board adopting the copper foil lamination method is the same as that of the core board. The cleaning method of the stacked PCB board is similar, and will not be repeated here.

Preferably, the green oil in the embodiment of the present invention can be solder resist ink.

Further, the green oil in the embodiment of the present invention can be commonly used solder resist ink for making PCB boards, such as TAIYO PSR-4000 GHP3X, PSR-4000 G23K, PSR-4000 MP HF, PSR-2000CE823HF, PROBIMER 77/72101 CL, etc.

Specifically, the green oil in the embodiment of the present invention can be a solder resist ink filtered by a white screen such as 36T, 51T, 77T (such as TAIYO PSR-4000 GHP3X, etc.).

Preferably, the embodiment of the present invention adopts the method of solder resist ink filtered by 77T white screen, which not only makes it easy to control the thickness of the coating, but also makes the time for subsequent fading treatment shorter.

Since the green oil is a commonly used material in the PCB manufacturing process, the cost is lower compared with the existing technology; in addition, all the silk screen green oil in the local area can ensure the uniformity of the board surface and avoid the unevenness of the board surface, so that it can be more It is best to ensure the flatness of the board surface in the local mixed pressure area.

The following takes the component 3A, which is visible on one side to be mixed-pressed, as an example to illustrate the method of removing the resin flow glue of the PCB board that is mixed-pressed and formed by laminating the core board. The anti-sticking layer coated in this embodiment takes green oil as an example, and other The anti-adhesive layer of the material is similar to the green oil and will not be repeated here. As shown in Figure 2, the method for removing the resin flow of the mixed-pressed PCB board in the embodiment of the embodiment of the present invention in which the component to be mixed-pressed is visible on one side includes the following steps:

Step 201, provide a plurality of core boards 1, prepreg 2, and components 3A to be mixed and pressed; among them, 1A is the upper outer core board, 1B is the lower outer core board, and the rest are inner core boards, and multiple core boards 1 are pressed The production requires lamination, the prepreg 2 is arranged between a plurality of core boards 1, and the prepreg 2 is bonded between each core board 1, as shown in Figure 2A;

Step 202, screen-print green oil 4 on the upper surface of the upper outer core board 1A, and perform curing treatment, as shown in FIG. 2A;

Step 203, according to the shape of the component 3A to be mixed and pressed, make a groove on the pre-pressed position of the outer chip 1A, and the shape and size of the groove 5A correspond to the component 3A to be mixed and pressed, as shown in Figure 2A;

Step 204, on the visible surface of the component 3A to be mixed pressure (in this embodiment, the visible surface of the component 3A to be mixed pressure is the single visible surface, that is, the upper surface of the component 3A to be mixed pressure, and the single visible surface is after the mixed pressure treatment, to be Only one surface of the mixed-pressure component can be seen), and the green oil 4 is silk-screened and cured, as shown in Figure 2A;

Step 205, put the component 3A to be mixed and pressed into the groove 5A, and carry out the pressing process to obtain the required PCB board, as shown in Figure 2B, it can be seen that after the pressing process, the resin flow glue is not only full of the mixed pressure The gap between the component 3A and each core board 1, and part of the resin flow glue 6 also overflows the gap and adheres to the surface of the green oil 4;

Step 206: Wash the green oil 4 on the upper surface of the upper outer core plate 1A and the visible surface of the component to be mixed and pressed 3A with an alkaline solution. After 40 minutes of washing, rinse with high-pressure water to remove it more thoroughly. Green oil 4, the PCB board after cleaning is shown in Figure 2C;

Step 207 , perform post-processing; after the subsequent deburring and grinding process, the overflowing resin flow glue 6 on the surface of the PCB can be completely removed.

The order of the above step 204 is not limited to be after the step 203, and may also be before the step 203 and the step 202.

The sequence of the above-mentioned step 203 is not limited to after step 202, but can also be before step 202, that is, according to the shape of the component to be mixed and pressed, slots are made on the pre-pressed position of the outer chip, and then the upper surface of the outer core board is silk-screened in green. Oil.

It should be noted that the pre-pressing position is set according to the production needs of the PCB board; according to the production needs of the laminated PCB board, slots can be made at the upper outer core board 1A and/or the lower outer core board 1B; A plurality of slots can be opened according to the production needs of the PCB board, so that multiple components 3 to be mixed and pressed and multiple core boards 1 can be pressed together to obtain the required PCB board; in addition, according to the shape of the components to be mixed and pressed, a Or multiple core boards and prepregs for slotting.

In addition, when coating the green oil 4, the inner wall of the groove 5A and the invisible surface of the component 3A to be mixed and pressed (in this embodiment, the invisible surface of the component 3A to be mixed and pressed is its side and lower surface) cannot be coated with green oil 4, so as not to affect the bonding effect between the core plate 1 and the component to be mixed and pressed 3A.

The following is an example of the double-sided visible component 3B to be mixed-pressed to illustrate the method of removing the resin flow glue of the PCB board that is mixed-pressed and molded by core board lamination. The anti-adhesive layer coated in this embodiment takes green oil as an example, other The anti-adhesive layer of the material is similar to the green oil and will not be repeated here. As shown in FIG. 3 , the method for removing the resin flow of the mixed-pressed PCB board in the embodiment of the embodiment of the present invention in which the components to be mixed-pressed can be seen on both sides includes the following steps:

Step 301, providing multiple core boards 1, prepreg 2, and components 3B to be mixed and pressed; among them, 1A is the upper outer core board, 1B is the lower outer core board, and the rest are inner core boards; multiple core boards 1 are pressed The production requires lamination, the prepreg 2 is arranged between multiple core boards 1, and the prepregs are bonded between the core boards 1 of each layer, as shown in Figure 3A;

Step 302, screen-print green oil 4 on the upper surface of the upper outer core board 1A and the lower surface of the lower outer core board 1B, and perform curing treatment, as shown in FIG. 3A ;

Step 303, open a groove on the pre-pressed position of the outer chip 1A or outer chip 1B according to the shape of the component to be mixed and pressed 3, and the shape and size of the groove 5B correspond to the component to be mixed and pressed 3B, as shown in Figure 3A;

Step 304, on the visible surface of the component 3B to be mixed and pressed (in this embodiment, the visible surface of the component to be mixed and pressed 3B is a double visible surface, that is, the upper surface and the lower surface of the component to be mixed and pressed 3B, and the double visible surface is the mixed and pressed component 3B. After the pressure treatment, the green oil 4 is screen-printed on both surfaces of the mixed-pressure component to be seen), and is cured, as shown in Figure 3A;

Step 305, put the component 3B to be mixed and pressed into the groove 5B, and carry out the pressing process to obtain the required PCB board, as shown in Figure 3B, it can be seen that after the pressing process, the resin flow glue is not only full of the mixed pressure The space between the component 3B and each core plate 1, and part of the resin flow glue 6 also overflows the space and adheres to the surface of the green oil 4;

Step 306: Wash the upper surface of the upper outer core plate 1A, the lower surface of the lower outer core plate 1B, and the visible surface of the component to be mixed and pressed 3B (in this embodiment, the upper surface of the to be mixed and pressed component 3B) with an alkaline solution The green oil 4 on the surface and the lower surface) can be rinsed with high-pressure water after 40 minutes of fading to remove the green oil 4 more thoroughly. The PCB board after cleaning is shown in Figure 3C;

Step 307 , perform post-processing; after the subsequent deburring and grinding process, the overflowing resin flow glue 6 on the surface of the PCB can be completely removed.

The order of the above step 304 is not limited to be after step 303, and may also be before step 303 and step 302.

The sequence of the above step 303 is not limited to after step 302, it can also be before step 302, that is, according to the shape of the components to be mixed and pressed, slots are made on the pre-pressed position of the outer chip, and then green oil is silk-screened on the surface of the outer core board .

It should be noted that the pre-pressing position is set according to the production needs of the PCB board; according to the production needs of the laminated PCB board, slots can be made at the outer core board at the upper end and/or at the outer core board at the lower end ; It is also possible to open a plurality of slots according to the production needs of the PCB board, so as to carry out the pressing process with a plurality of components to be mixed and pressed with a plurality of core boards 1 to obtain the required PCB board; in addition, according to the shape of the components to be mixed and pressed One or more cores and prepregs are slotted.

In addition, when applying green oil, try not to apply green oil 4 on the inner wall of the tank and the invisible surface of the component to be mixed and pressed (in this embodiment, the invisible surface of the mixed and pressed component 3B is its side), so as not to affect the core plate 1 and the bonding effect between the component to be mixed and pressed 3B.

In the embodiment of the present invention, before the pressing treatment, the surface of the outer core plate and the visible surface of the components to be mixed and pressed are coated with an anti-adhesive layer, so that the resin flow glue overflowing during the pressing process will remain on the surface of the anti-adhesive layer, and It will not remain on the surface of the outer core board or the component to be mixed, and then remove the anti-adhesive layer after the pressing process, so that the spilled resin flow glue can be completely removed by removing the anti-adhesive layer, thus solving the problem in the prior art There is a problem that it is difficult to completely remove the overflowed resin flow. The method of the embodiment of the present invention can not only completely remove the overflowed resin flow during the mixed pressure molding process, but also has low cost, simple and convenient operation.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (5)

1. remove a method for mixed pressure shaping pcb board resin gummosis, it is characterized in that, the method comprises:

At the surface-coated green oil of at least one outer central layer, and treating the visible surface coating green oil of mixed pressure component;

The outer central layer of green oil described in surface-coated is cured process, and visible surface applied described green oil treat that mixed pressure component is cured process, the resin gummosis overflowed after making pressing process is attached to described green oil surface, wherein, described curing temperature is 160 DEG C, and the described solidification processing time is 50min;

After adopting alkaline solution to take off to wash pressing process outer central layer surface and treat the described green oil of visible surface of mixed pressure component.

2. the method for claim 1, is characterized in that, after described employing alkaline solution takes off and washes pressing process outer central layer surface and treat the described green oil of visible surface of mixed pressure component, described method is specially:

The temperature of described alkaline solution is 80 DEG C.

3. method as claimed in claim 2, is characterized in that, described alkaline solution adopts concentration to be the NaOH solution of 8%, and taking off the time of washing is 40min.

4. method as claimed in claim 1 or 2, it is characterized in that, described green oil is solder mask.

5. method as claimed in claim 1 or 2, it is characterized in that, the thickness of described green oil is 5 ~ 10 μm.