Drying equipment for drying PCB (Printed Circuit Board) and drying method thereof

Abstract

The invention discloses drying equipment for drying a PCB (Printed Circuit Board) and a drying method thereof, the drying equipment comprises a drying box, the drying box is internally provided with a closable cavity for placing a to-be-dried PCB, the top of the cavity is provided with a far infrared heating device facing a PCB placing area, and the drying box is also provided with a vacuum generation device communicated with the cavity; the drying method comprises the following steps: step 1, placing a PCB to be dried in a cavity and sealing the cavity; 2, starting the vacuum generating device to reduce the air pressure in the cavity; 3, starting a far infrared heating device to irradiate the PCB to heat the PCB; fourthly, after the PCB is dried, the vacuum generating device is controlled to work to restore the air pressure in the cavity to the normal pressure, and the far infrared heating device is controlled to work to gradually restore the PCB to the room temperature; and step 5, taking out the PCB after the interior of the cavity is recovered to room temperature and normal pressure.

Description

Technical Field

[0001] The invention relates to a drying device and a drying method for drying PCB. Background Art

[0002] When using a wet process to process PCBs, the PCBs need to be dried to remove moisture from the PCBs. Currently, the commonly used drying method in the industry is to use a heating wire and a blower to output hot air to the PCBs, thereby drying the PCBs with hot air.

[0003] Although hot air drying can remove moisture from PCBs, there are certain risks. For example, it is difficult to accurately control the temperature, which can easily lead to uneven temperature of the PCB and generate thermal stress that causes the PCB to warp and deform. At the same time, uneven temperature can also lead to incomplete removal of some moisture. This type of defect caused by uneven temperature is particularly obvious on PCBs with a thickness of more than 3mm or on PCBs with a relatively large thickness and diameter. In addition, the heating efficiency of the heating method using a blower and a heating wire to output hot air is also relatively low, which will lead to high energy consumption in the drying process.

[0004] Therefore, how to overcome the above-mentioned defects has become an important issue to be solved urgently by those skilled in the art. Summary of the invention

[0005] The present invention overcomes the deficiencies of the above-mentioned technology and provides a drying device and a drying method for drying PCBs.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A drying device for drying PCBs comprises a drying box 1, wherein a closable cavity 2 for placing PCBs to be dried is provided in the drying box 1, a far-infrared heating device 3 facing the PCB placement area is provided on the top of the cavity 2, and a vacuum generating device 4 connected to the cavity 2 is also provided on the drying box 1.

[0008] Preferably, the drying box 1 is also provided with a temperature and humidity monitoring device 5 for detecting the temperature and humidity in the cavity 2 .

[0009] Preferably, the far-infrared heating device 3 includes a plurality of far-infrared emitting panels 31, and the power of each far-infrared emitting panel 31 can be adjusted individually.

[0010] Preferably, one of the far-infrared emitting plates 31 is located directly above the PCB board, and the remaining far-infrared emitting plates 31 are arranged around the far-infrared emitting plate 31 directly above the PCB board. The far-infrared emitting plate 31 directly above the PCB board faces directly downward on the PCB board, and the remaining far-infrared emitting plates 31 are tilted toward the center and obliquely radiate on the PCB board.

[0011] Preferably, a reflective coating or a reflective plate for reflecting far infrared rays is provided on the wall surface of the cavity 2.

[0012] Preferably, a plurality of support columns 21 extending upwards for supporting the PCB board are provided at the bottom of the cavity 2, and the tops of the support columns 21 are hemispherical.

[0013] A drying method applicable to the above drying equipment comprises the following steps:

[0014] Step 1: Place the PCB to be dried into the cavity 2 and close the cavity 2;

[0015] Step 2: Start the vacuum generating device 4 to reduce the air pressure in the cavity 2;

[0016] Step 3: Start the far infrared heating device 3 to irradiate the PCB to heat it;

[0017] Step 4: After the PCB is dried, the vacuum generating device 4 is controlled to restore the air pressure in the cavity 2 to normal pressure, and the far-infrared heating device 3 is controlled to gradually restore the PCB to room temperature;

[0018] Step 5: After the cavity 2 returns to room temperature and normal pressure, take out the PCB board.

[0019] Preferably, in the step 2, the vacuum generating device 4 reduces the air pressure in the cavity 2 to 1-10 kPa, and in the step 3, the far-infrared heating device 3 heats the PCB board to 45-62°C.

[0020] Preferably, in step 4, the vacuum generating device 4 is first controlled to reduce the power recovery pressure and then the far-infrared heating device 3 is controlled to reduce the power recovery temperature.

[0021] Preferably, the changes in air pressure and temperature in step 4 include the following stages:

[0022] Stage 1: gradually reduce the power of the vacuum generating device 4, and restore the air pressure to 50 kPa at a uniform speed within 20 to 30 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged.

[0023] Stage 2: gradually reduce the power of the vacuum generating device 4 until it stops working, and uniformly restore the air pressure from 50 kPa to normal pressure within 10 to 15 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged.

[0024] Stage 3: gradually reduce the power of the far-infrared heating device 3 until it stops working and restores the temperature of the PCB board to room temperature, with a cooling rate of no more than 5°C / min.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The drying device in this case can effectively reduce the temperature required for drying PCB panels by setting a vacuum generating device to reduce the air pressure in the cavity and thus reduce the boiling point of water, thereby reducing energy consumption. The use of a far-infrared heating device to emit far-infrared rays to irradiate PCB panels can heat the PCB panels in a targeted manner through thermal radiation with a heating accuracy and heating efficiency far higher than hot air drying.

[0027] 2. Different from the traditional hot air drying method, the drying method in this case first creates a low-pressure environment through a vacuum generating device to reduce the boiling point of water, so that the PCB board can be dried at a temperature far below 80°C, thereby greatly reducing the heating power. Then, the far-infrared heating device is used to emit far-infrared rays to heat the PCB board by thermal radiation. In this way, the PCB board can be heated accurately, and the strong penetrability of far-infrared rays can be used to effectively avoid the problem of uneven temperature distribution of the PCB board itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is one of the schematic diagrams of the drying equipment in this case.

[0029] Figure 2 This is the second schematic diagram of the drying equipment in this case.

[0030] Figure 3 This is the third schematic diagram of the drying equipment in this case, in which the PCB board has been placed in the inner cavity.

[0031] Figure 4 It is a schematic diagram of the far-infrared heating device and PCB board, which hides the drying box, vacuum generating device and temperature and humidity monitoring device. DETAILED DESCRIPTION

[0032] The features of the present invention and other related features are further described in detail below through embodiments to facilitate understanding by those skilled in the art:

[0033] like Figures 1 to 4 As shown, a drying device for drying PCBs comprises a drying box 1, wherein the drying box 1 is provided with a closable cavity 2 for placing PCB panels to be dried, a far-infrared heating device 3 is provided on the top of the cavity 2 facing the PCB panel placement area, and the drying box 1 is also provided with a vacuum generating device 4 connected to the cavity 2.

[0034] The drying equipment in this case is provided with a closable cavity 2 and a vacuum generating device 4 for evacuating the cavity 2 in the drying box 1, and a far-infrared heating device 3 for heating the PCB board is provided in the cavity 2. In this way, evacuating the cavity 2 by the vacuum generating device 4 can reduce the air pressure in the cavity 2, and then reduce the boiling point of the water in the cavity 2. The use of the far-infrared heating device 3 can utilize the characteristics of far-infrared rays to heat the PCB board more accurately and efficiently, reducing meaningless energy loss. At the same time, because far-infrared rays have strong penetrability, when heating PCB boards with a thickness of more than 3mm or a large thickness-to-diameter ratio, the use of far-infrared heating can effectively avoid a large temperature difference between the inside and outside of the PCB board itself.

[0035] As described above, the drying device in this case can effectively reduce the temperature required for drying PCB boards by setting up a vacuum generating device 4 to reduce the air pressure in the cavity 2 and thus reduce the boiling point of water, thereby reducing energy consumption. The use of a far-infrared heating device 3 to emit far-infrared rays to irradiate the PCB boards can perform targeted heating of the PCB boards through thermal radiation with a heating accuracy and heating efficiency that is much higher than hot air drying.

[0036] Specifically, the vacuum generating device 4 is selected from vacuum generating devices that are publicly sold on the market and meet the design requirements according to different vacuum degree requirements.

[0037] like Figure 2 and Figure 3 As shown, preferably, the drying box 1 is also provided with a temperature and humidity monitoring device 5 for detecting the temperature and humidity in the cavity 2. In this way, the temperature of the PCB board can be monitored in real time and the drying progress can be judged by the humidity of the cavity 2, thereby promoting the drying process more accurately.

[0038] Specifically, the temperature and humidity monitoring device 5 is a commercially available finished device that can be used to monitor temperature and humidity.

[0039] like Figures 2 to 4 As shown, preferably, the far-infrared heating device 3 includes a plurality of far-infrared emitting panels 31, and the power of each far-infrared emitting panel 31 can be adjusted individually. In this way, the power of the far-infrared emitting panel 31 irradiating the corresponding area can be adjusted according to the heating conditions of different areas of the PCB board, thereby further reducing the problem of thermal deformation or incomplete moisture removal caused by uneven temperature of the PCB board.

[0040] like Figures 2 to 4As shown, preferably, one of the far-infrared emitting plates 31 is located directly above the PCB board, and the remaining far-infrared emitting plates 31 are arranged around the far-infrared emitting plate 31 directly above the PCB board. The far-infrared emitting plate 31 directly above the PCB board directly faces downward to the PCB board, and the remaining far-infrared emitting plates 31 are tilted toward the center and obliquely face the PCB board. In this way, the far-infrared heating device 3 can irradiate the PCB board by emitting far-infrared rays from multiple directions, thereby reducing the shadow effect of thermal radiation and promoting the vaporization of moisture at various locations on the PCB board.

[0041] Preferably, a reflective coating or a reflective plate for reflecting far infrared rays is provided on the wall surface of the cavity 2, so that the far infrared rays irradiated on the cavity 2 can be reflected back onto the PCB board, thereby reducing energy loss and further improving heating efficiency.

[0042] like Figures 2 to 4 As shown, preferably, a plurality of support columns 21 extending upward for jointly supporting the PCB board are provided at the bottom of the cavity 2, and the top ends of the support columns 21 are hemispherical. In this way, the PCB board can be suspended in the cavity 2 by supporting the PCB board by the support columns 21. This ensures that the moisture at the bottom of the PCB board also has space for vaporization, thereby preventing the moisture at the bottom of the PCB board from being unable to be removed. At the same time, the portion of the top end of the support column 21 that contacts the PCB board is hemispherical, thereby effectively preventing the support column 21 from damaging the PCB board.

[0043] like Figures 1 to 4 As shown, a drying method that can be applied to the above drying equipment includes the following steps:

[0044] Step 1: Place the PCB to be dried into the cavity 2 and close the cavity 2;

[0045] Step 2: Start the vacuum generating device 4 to reduce the air pressure in the cavity 2;

[0046] Step 3: Start the far infrared heating device 3 to irradiate the PCB to heat it;

[0047] Step 4: After the PCB is dried, the vacuum generating device 4 is controlled to restore the air pressure in the cavity 2 to normal pressure, and the far-infrared heating device 3 is controlled to gradually restore the PCB to room temperature;

[0048] Step 5: After the cavity 2 returns to room temperature and normal pressure, take out the PCB board.

[0049] When using the drying method of this case to dry the PCB board, first place the PCB board in the cavity 2 and close the cavity 2 to form a closed drying environment, then start the vacuum generator 4 to evacuate the cavity 2, and after the air pressure in the cavity 2 is reduced, start the far-infrared heating device 3 to emit far-infrared rays to the PCB board to heat and dry the PCB board. After the drying is completed, control the vacuum generator 4 and the far-infrared heating device 3 to restore the air pressure and temperature in the cavity 2 to normal and then take out the PCB board. In this way, in the low-pressure environment of the closed cavity 2, the boiling point of water will also be reduced accordingly. At this time, the water can be vaporized at a temperature far below 80°C to complete the drying. The far-infrared heating device 3 emits far-infrared rays to heat the PCB board by thermal radiation, which can better concentrate the energy on the PCB board, avoiding the energy loss caused by the traditional hot air drying solution dispersing heat to the entire cavity 2 due to convection, and the use of far-infrared heating can also more accurately control the temperature of the PCB board to avoid overheating.

[0050] Different from the traditional hot air drying method, the drying method in this case first creates a low-pressure environment through the vacuum generating device 4 to reduce the boiling point of water, so that the PCB board can be dried at a temperature far below 80°C, thereby greatly reducing the heating power, and then the far-infrared heating device 3 is used to emit far-infrared rays to heat the PCB board by thermal radiation. In this way, the PCB board can be heated accurately, and the strong penetrability of far-infrared rays can also be used to effectively avoid the problem of uneven temperature distribution of the PCB board itself.

[0051] Preferably, in the step 2, the vacuum generating device 4 reduces the air pressure in the cavity 2 to 1-10 kPa, and in the step 3, the far-infrared heating device 3 heats the PCB board to 45-62°C. Thus, the boiling point of water at 1-10 kPa will drop to 45-62°C. Accordingly, the drying temperature can be reduced from 80°C of traditional hot air drying to 45-62°C. This can greatly reduce the energy consumption when drying the PCB board, and the reduction in the drying temperature is also conducive to preventing the PCB board from warping and deformation due to thermal stress.

[0052] Preferably, in step 4, the vacuum generating device 4 is first controlled to reduce the power recovery pressure and then the far-infrared heating device 3 is controlled to reduce the power recovery temperature.

[0053] As described above, during the drying process, the moisture in the cavity 2 mainly exists in the form of water vapor. Therefore, restoring the air pressure first and then the temperature can effectively prevent the water vapor from re-condensing into water droplets during the cooling process and attaching to the PCB board to affect the drying effect.

[0054] Preferably, the changes in air pressure and temperature in step 4 include the following stages:

[0055] Stage 1: gradually reduce the power of the vacuum generating device 4, and restore the air pressure to 50 kPa at a uniform speed within 20 to 30 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged.

[0056] Stage 2: gradually reduce the power of the vacuum generating device 4 until it stops working, and uniformly restore the air pressure from 50 kPa to normal pressure within 10 to 15 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged.

[0057] Stage 3: gradually reduce the power of the far-infrared heating device 3 until it stops working and restores the temperature of the PCB board to room temperature, with a cooling rate of no more than 5°C / min.

[0058] As described above, the drying method of this case gradually restores the air pressure and temperature through three stages after drying. Stages one and two gradually restore the air pressure at a uniform speed while maintaining the temperature of the PCB board, and stage three gradually reduces the temperature of the PCB board to room temperature. This way, gradually restoring the air pressure in stages can avoid mechanical deformation of the PCB board caused by the surrounding air pressure. At the same time, maintaining the drying temperature when restoring the air pressure can avoid restoring the air pressure at low temperatures and causing moisture to re-condense. At the same time, slowly restoring the air pressure and temperature through three stages can also effectively avoid stress concentration and deformation of the PCB board caused by rapid changes in the environment, thereby ensuring the structural integrity of the PCB board.

[0059] As mentioned above, this case protects a drying device and a drying method for drying PCBs. All technical solutions that are the same or similar to those in this case should be deemed to fall within the scope of protection of this case.

Claims

1. A drying device for drying PCB, characterized in that The invention comprises a drying box (1), wherein a closable cavity (2) for placing PCB panels to be dried is provided inside the drying box (1), a far-infrared heating device (3) facing the PCB panel placement area is provided on the top of the cavity (2), and a vacuum generating device (4) connected to the cavity (2) is also provided on the drying box (1).

2. A drying device for drying PCB according to claim 1, characterized in that The drying box (1) is also provided with a temperature and humidity monitoring device (5) for detecting the temperature and humidity in the cavity (2).

3. A drying device for drying PCB according to claim 1, characterized in that The far-infrared heating device (3) comprises a plurality of far-infrared emitting panels (31), and the power of each far-infrared emitting panel (31) can be adjusted individually.

4. A drying device for drying PCB according to claim 3, characterized in that One of the far-infrared emitting plates (31) is located directly above the PCB board, and the other far-infrared emitting plates (31) are arranged around the far-infrared emitting plate (31) directly above the PCB board. The far-infrared emitting plate (31) directly above the PCB board directly irradiates the PCB board downward, and the other far-infrared emitting plates (31) are arranged obliquely toward the center to irradiate the PCB board.

5. The drying device for drying PCB according to claim 1, characterized in that A reflective coating or a reflective plate for reflecting far infrared rays is provided on the wall surface of the cavity (2).

6. A drying device for drying PCB according to claim 1, characterized in that The bottom of the cavity (2) is provided with a plurality of support columns (21) extending upwards and used to jointly support the PCB board, and the top ends of the support columns (21) are hemispherical.

7. A drying method applicable to the drying equipment according to any one of claims 1 to 6, characterized in that The following steps are involved: Step 1: placing the PCB to be dried into the cavity (2) and sealing the cavity (2); Step 2: Activate the vacuum generating device (4) to reduce the air pressure in the cavity (2); Step 3: Start the far infrared heating device (3) to irradiate the PCB to heat it; Step 4: After the PCB is dried, the vacuum generating device (4) is controlled to restore the air pressure in the cavity (2) to normal pressure, and the far-infrared heating device (3) is controlled to gradually restore the PCB to room temperature; Step 5: After the cavity (2) returns to room temperature and pressure, remove the PCB.

8. A drying method according to claim 7, characterized in that In the step 2, the vacuum generating device (4) reduces the air pressure in the cavity (2) to 1-10 kPa, and in the step 3, the far-infrared heating device (3) heats the PCB board to 45-62° C.

9. A drying method according to claim 7, characterized in that In the fourth step, the vacuum generating device (4) is first controlled to reduce the power recovery air pressure and then the far infrared heating device (3) is controlled to reduce the power recovery temperature.

10. A drying method according to any one of claims 7 or 9, characterized in that The changes in air pressure and temperature in step 4 include the following stages: Stage 1: gradually reduce the power of the vacuum generating device (4), and restore the air pressure to 50 kPa at a uniform speed within 20 to 30 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged. Stage 2: gradually reduce the power of the vacuum generating device (4) until it stops working, and uniformly restore the air pressure from 50 kPa to normal pressure within 10 to 15 minutes. During this stage, the temperature of the PCB is controlled to remain unchanged. Stage 3: gradually reducing the power of the far-infrared heating device (3) until it stops working and restoring the temperature of the PCB to room temperature, with a cooling rate of no more than 5°C / min.

Images