TWI862901B - Heating plate - Google Patents

Abstract

A heating plate is provided. The heating plate is used to manufacture a laminator of a printed circuit board. The heating plate includes a substrate, a heating layer and a shield layer. The heating layer is disposed on the substrate. The heating layer include an auxiliary thermal resistance strip. The auxiliary thermal resistance strip is connected to the power supply to use the current to generate heat. The shield layer covers the surface of the substrate for protecting the auxiliary thermal resistance strip. The auxiliary thermal resistance strip is configured to a preset shape and arranged on the substrate. The resistance distribution density of the auxiliary thermal resistance strips in the central region of the substrate is less than the resistance distribution density of the auxiliary thermal resistance strips in the peripheral region of the substrate. The heating plate can balance the uneven heat radiation, so that the temperature of each area of the heating plate is consistent.

Description

Heating plate

The present invention relates to the field of circuit board manufacturing technology, and in particular to a heating plate used in a laminating press.

Printed circuit board, abbreviated as circuit board, is generally composed of copper foil, semi-cured film, inner layer and other components. It can also be called printed circuit board, printed circuit board, abbreviated as PCB (printed circuit board) in English. Among them, copper foil is a cathodic electrolytic material, a thin, continuous metal foil deposited on the base layer of the circuit board, which serves as the conductor of the PCB. It is easy to adhere to the insulating layer, accept the printed protective layer, and form a circuit pattern after corrosion.

The main manufacturing equipment for printed circuit boards is a laminating press, also known as a circuit board press. When manufacturing circuit boards, a heating and pressurizing process is required. The inner core boards and copper foils are bonded together under high temperature and high pressure using semi-cured adhesive sheets. During the lamination process of multi-layer circuit boards, the semi-cured film undergoes a solid-liquid-solid transformation process under high temperature and high pressure. During this process, the resin in the film undergoes complex physical changes such as flow and shrinkage. If the temperature of each area is uneven during the lamination process, the semi-cured film will be inconsistent in thickness, and the copper foil will be tightly attached to the film. The difference in the deformation coefficients of the two will be inconsistent, which will lead to uneven copper foil, poor quality of the circuit board, and even scrap. Especially when the copper foil used on the outside is relatively thin, it is more likely to produce wrinkles during the lamination process.

In view of the shortcomings of the above-mentioned technologies, the present invention provides a heating plate capable of uniform heating.

The technical solution adopted by the present invention to solve the technical problem is: a heating plate, used for manufacturing a laminating press for printed circuit boards, the heating plate comprising: a substrate; a heating layer, laid on the substrate, the heating layer comprising an auxiliary heating resistor strip, the auxiliary heating resistor strip is used to connect to a power source to generate heat using the flowing current; a shield layer, covering the surface of the substrate on which the auxiliary heating resistor strip is laid, used to protect the auxiliary heating resistor strip; the auxiliary heating resistor strip is structured to be laid on the substrate in a preset shape and direction, and the resistance distribution density of the auxiliary heating resistor strip located in the middle area of the substrate is less than the resistance distribution density of the auxiliary heating resistor strip located in the peripheral area of the substrate.

In one embodiment, the cross-sectional area of the auxiliary thermal resistor strip located in the middle region of the substrate is larger than the cross-sectional area of the auxiliary thermal resistor strip located in the peripheral region of the substrate.

In one embodiment, the auxiliary heating resistor strip has uniform dimensions in the thickness direction of the heating plate, and the width of the auxiliary heating resistor strip located in the middle area of the substrate is greater than the width of the auxiliary heating resistor strip located in the peripheral area of the substrate.

In one embodiment, the spacing of the auxiliary thermal resistor strips located in the middle area of the substrate is greater than the spacing of the auxiliary thermal resistor strips located in the peripheral area.

In one embodiment, the spacing of the auxiliary thermal resistor strips located in the middle area of the substrate is greater than the spacing of the auxiliary thermal resistor strips located in the peripheral area, and the cross-sectional areas of the auxiliary thermal resistor strips are consistent at all locations.

In one embodiment, a mounting groove having the same shape as the preset shape of the auxiliary heating resistor strip is provided on the substrate, and the auxiliary heating resistor strip is embedded in the mounting groove.

In one embodiment, the preset shape direction includes a serpentine direction, a U-shaped direction or a zigzag direction.

In one embodiment, the number of the heating layers is two, namely the first heating layer and the second heating layer, the first heating layer and the second heating layer are respectively laid on the two plate surfaces of the substrate, the number of the shield layers is two, namely the first shield layer and the second shield layer, and the assembly order of the heating plate is the first shield layer, the first heating layer, the substrate, the second heating layer and the second shield layer.

In one embodiment, the substrate is square, and the auxiliary thermal resistor strip includes a plurality of strips connected end to end and parallel to each other, and the plurality of strips are arranged parallel to one side of the substrate.

In one embodiment, the auxiliary thermal resistor strip is an integral component.

In one embodiment, a cooling structure for quickly cooling the heating plate is also provided on the substrate.

In one embodiment, the cooling structure includes a pipeline connected to a refrigerant. When the heating plate stops heating after compression, the pipeline passes the refrigerant to quickly cool the circuit board. The pipeline is formed in the substrate, and the refrigerant is cooling water or cooling oil.

Compared with the prior art, the invention has the following beneficial effects: the heating layer of the heating plate provided by the invention has an auxiliary heating resistor strip with a preset shape and direction, and the resistance distribution density of the auxiliary heating resistor strip located in the middle area of the substrate is less than the resistance distribution density of the auxiliary heating resistor strip located in the peripheral area of the substrate, thereby effectively compensating for the temperature unevenness caused by the uneven heat radiation in the middle area and the peripheral area of the heating plate, improving the consistency of the temperature of each area of the heating plate, and ensuring the processing quality of the printed circuit board. In order to make the above features and advantages of the invention more obvious and easy to understand, the following is a preferred embodiment, and is described in detail with the attached drawings.

100: Heating plate

10: First protective layer

11: First heating layer

111: Auxiliary thermal resistor strip

112: Negative electrode

113: Temperature measurement unit

114: Positive electrode

12: Substrate

22: Insulation layer

122: Pipeline

13: Second heating layer

14: Second protective layer

200: Hydraulic unit

210: Hydraulic cylinder

220: Hydraulic control device

300: Main controller

400: Total incoming line

403: Transformer

500:Layer press

510: Main control box

520: Rack body

Figure 1 is a three-dimensional exploded structural schematic diagram of the heating plate of the present invention; Figure 2 is a cross-sectional structural schematic diagram of the heating plate shown in Figure 1; Figure 3 is a top view schematic diagram of the heating layer of the heating plate in another embodiment of the present invention; Figure 4 is a top view schematic diagram of the heating layer of the heating plate in another embodiment of the present invention; Figure 5 is a module structural schematic diagram of a layer press provided in an embodiment of the present invention.

Figure 6 is a schematic diagram of the three-dimensional structure of the laminating press shown in Figure 5.

Figure 7 is a nine-point temperature test diagram of the heating plate shown in Figure 3.

Figure 8 is the nine-point temperature test data of the heating plate shown in Figure 7.

Figure 9 is a graph drawn based on the nine-point temperature data of the heating plate shown in Figure 7.

Figure 10 is the nine-point temperature test data of the heating plate in the prior art.

Figure 11 is a graph drawn based on the nine-point temperature data of the heating plate shown in Figure 10.

In order to make the above-mentioned purposes, features and advantages of the present invention more clearly understandable, the specific implementation of the present invention is described in detail below in conjunction with the attached drawings. It is understandable that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. It should also be noted that, for the convenience of description, the attached drawings only show the parts related to the present invention, not all structures. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative labor are within the scope of protection of the present invention.

The terms "including" and "having" and any variations thereof in the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally also include unlisted steps or units, or may optionally also include other steps or units inherent to these processes, methods, products or devices.

Reference to "embodiments" herein means that the pre-set features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

The present invention is further described below in detail with reference to the attached figures, so that those skilled in the art can implement the invention according to the text of the specification.

As shown in FIG. 1 and FIG. 2, the present invention provides a heating plate 100 for use in a laminating press for manufacturing printed circuit boards. In an embodiment of the present invention, the heating plate 100 includes a shield layer (10, 14), a heating layer (11, 13) and a substrate 12. The heating layer (11, 13) is laid on the surface of the substrate, and the shield layer (10, 14) is placed on the outermost layer of the heating plate 100, covering the surface of the substrate on which the heating layer (11, 13) is laid, for protecting the heating layer (11, 13). After the heating plate 100 is assembled, the heating layer (11, 13) is placed between the substrate 12 and the shield layer 10.

In one embodiment, the number of heating layers is one, and the heating plate includes a substrate 12, a shield layer 10, and a heating layer 11 disposed between the substrate 12 and the shield layer 10. In the scenario of application to a layer press, the number of heating plates is at least two, and the two heating plates are stacked on each other, with a multi-layer core plate for manufacturing a circuit board sandwiched in between, wherein the substrate 12 of the heating plate is located on the outside, the shield layer 10 faces the multi-layer core plate, and the multi-layer core plate is heated by the heating layer 11.

In another embodiment, the heating plate 100 may also include two heating layers, namely, a first heating layer 11 and a second heating layer 13 disposed on the upper and lower plate surfaces of the substrate 12. The outermost layer of the heating layers (11, 13) is a shield layer (10, 14), and the number of shield layers is two, namely, a first shield layer 10 and a second shield layer 14. The heating plate 100 is composed of the first shield layer 10, the first heating layer 11, the substrate 12, the second heating layer 13, and the second shield layer 14 in the order of composition. The upper and lower surfaces of the heating plate 100 provided in this embodiment can both be used for heating. In the specific scenario of application in a layer press, the heating plate 100 provided in this embodiment can be used as an intermediate plate, arranged in the middle of the upper and lower heating plates, forming a gap between the two adjacent heating plates for sandwiching a multi-layer core plate. The number of centrally arranged heating plates can be one or more. The double-heating layer heating plate provided in this embodiment can be used in combination with the single-heating layer heating plate provided in the above embodiment. The single-heating layer heating plate is arranged at the upper and lower ends of the heating plate stack, and the double-heating layer heating plate is arranged in the middle. A multi-layer core plate is sandwiched between adjacent heating plates, and each multi-layer core plate is heated on both the upper and lower sides by two adjacent heating plates.

The first heating layer 11 and the second heating layer 13 have the same structure. For the sake of simplicity, only the first heating layer 11 is used as an example for explanation. Please refer to Figure 3. The first heating layer 11 includes an auxiliary heating resistor bar 111. The two ends of the auxiliary heating resistor bar 111 are connected to the power supply. After the power supply is turned on, there is a current flowing in the auxiliary heating resistor bar 111. The current thermal effect causes the auxiliary heating resistor bar 111 to generate heat, thereby increasing the temperature of the heating plate 100. The auxiliary heating resistor bar 11 is configured to be laid on the substrate 12 in a preset shape. The resistance distribution density of the auxiliary heating resistor bar 11 located in the middle area of the substrate 12 is less than the resistance distribution density of the auxiliary heating resistor bar 111 located in the peripheral area of the substrate 12. With such arrangement, when the current is the same, the average heat generated per unit area by the auxiliary heating resistor bar 111 in the middle area is lower than the average heat generated per unit area by the auxiliary heating resistor bar 111 in the peripheral area, which can balance the situation that the peripheral area loses more heat and drops more temperature due to more heat exchange between the peripheral area of the heating plate and the surrounding environment, thereby improving the uniformity of the temperature of each area of the heating plate. On the contrary, if the auxiliary heating resistor strips 111 are evenly distributed on the substrate 12, when the heating heat is equal, the heat exchange between the peripheral area of the substrate 12 and the surrounding environment is more active, and the heat loss of the substrate 12 in the middle area is slower, resulting in a higher temperature rise than the peripheral area, and the temperature of the peripheral area is lower than the middle area, resulting in uneven temperature of the heating plate 100, poor quality or even scrap of the produced printed circuit board. Here, the resistance distribution density is understood as the total resistance value within a unit area of the substrate 12 board surface, that is, the resistance distribution density is equal to the resistance value of the corresponding area/the area of the corresponding area. It is understandable that the greater the resistance distribution density, the greater the heat generated by the thermal effect of the current per unit area when the same current flows.

For the convenience of manufacturing and temperature control, in this embodiment, the auxiliary heating resistor strip 111 of the first heating layer 11 is a continuous strip conductor, and the two ends of the auxiliary heating resistor strip 111 are used to connect to the power supply. After the power supply is connected, the current at any position of the auxiliary heating resistor strip 111 is the same. Specifically, the auxiliary heating resistor strip 111 is an integrally manufactured part.

Furthermore, since the auxiliary heating resistor strip 111 is a conductor and generates heat by using the flowing current, in order to avoid leakage, an insulating layer 22 is also provided between the heating layer (11, 13) and the adjacent substrate 12 and shield layer (10, 14), thereby effectively avoiding leakage or series current between the heating layer and the adjacent layers. Specifically, the first heating layer 11 is insulated from the first shield layer 10, the first heating layer 11 is also insulated from the substrate 12, the second heating layer 13 is insulated from the substrate 12, and the second heating layer 13 is insulated from the second shield layer 14. The insulating layer 22 includes an insulating structure coated on the auxiliary thermal resistor bar 111, that is, the surface of the auxiliary thermal resistor bar 111 is covered by the insulating structure, so that the auxiliary thermal resistor bar 111 is insulated from the outside. The optional insulating structure is an insulating ceramic sintered on the outer periphery of the auxiliary thermal resistor bar 111. In order to further enhance the reliability of insulation, the shield layer is also insulating. In one embodiment, the shield layer itself can be made of insulating material. In another embodiment, the surface of the shield layer facing the heating layer can also be coated with an insulating protective layer, such as aluminum oxide, to form two layers of insulating protection, thereby improving the safety and reliability of the insulating protection. In another embodiment, the insulating layer 22 can also be provided on the substrate 12 and the shield layers 10 and 14. Since the structure and material of the first shield layer 10 and the second shield layer 14 can be consistent, only one of them is specifically described in this article. Similarly, only one of the first heating layer 11 or the second heating layer 13 is described in this article.

The heating plate 100 provided by the present invention controls the heating amount in different areas of the substrate 12 through the auxiliary heating resistor strip 111 of preset shape and direction, thereby balancing the temperature unevenness caused by uneven heat radiation in different areas, and can improve the temperature uniformity and consistency of the heating plate, ensuring the production quality and yield rate of the printed circuit board.

The following describes how to process printed circuit boards using heating plates. Printed circuit boards are mainly made of copper foils, semi-cured adhesive sheets, inner layers and other core boards stacked in order. A layer of semi-cured adhesive sheets is placed between adjacent copper foils. The semi-cured adhesive sheets undergo a phase change under the action of temperature, thereby bonding multiple layers of copper foil together. The heating plate 100 includes at least two, with multiple layers of core boards to be pressed in the middle. Of course, there can also be multiple heating plates stacked on each other, with multiple layers of core boards laid between adjacent heating plates 100, so that multiple printed circuit boards can be pressed at a high temperature. The centrally arranged heating plate 100 is provided with two heating layers 11, 13 for heating the multi-layer core panels on both sides.

When the heating plate stops heating after the pressing is completed, in order to reduce the temperature as quickly as possible, so as to facilitate the disassembly of the printed circuit board. In one embodiment, the substrate 12 is also provided with a cooling structure for quickly cooling the heating plate 100. The cooling structure includes a pipeline 122. Specifically, the pipeline 122 is formed in the substrate 12. In FIG. 1 and FIG. 2, for the sake of simplicity, only one of the pipelines is labeled 122. The pipeline 122 can accommodate cooling water or cooling oil, and the cooling water or cooling oil is used to effectively cool the heating plate, thereby further reducing the temperature of the circuit board. Since the peripheral area of the substrate 12 is in contact with the external environment, the heat dissipation is faster and the temperature drops faster, while the central area has weaker exchange with the outside world and the temperature drops slower. In order to balance the uneven heat loss. Preferably, the number of pipes in the central area of the pipeline 122 in the substrate 12 is greater than the number of pipes in the peripheral area, thereby accelerating the heat dissipation of the heating plate 100 in the central area, so that the temperature of the heating plate is more uniform during the cooling process, and preventing the quality problems of the printed circuit board caused by the uneven temperature of the substrate during the cooling process. Preferably, the pipeline 122 is formed in the substrate 12, and the pipeline 122 can also be set separately. The substrate 12 is an aluminum substrate. Effective use of aluminum is not only beneficial for heat dissipation but also lightweight.

Continuing to refer to FIG3 , the first heating layer 11 includes a positive electrode 114 and a negative electrode 112, and one end of the auxiliary heating resistor bar 111 is connected to the positive electrode 114, and the other end is connected to the negative electrode 112. In a specific application process, the positive electrode 114 and the negative electrode 112 are connected to the power supply, and the current flows in the auxiliary heating resistor bar 111, and heat energy is generated due to the heat effect of the resistance. The type of power supply can be a direct current power supply or an alternating current power supply, preferably a direct current power supply. After the auxiliary heating resistor bar 111 is powered on, heat energy will be generated. The power-on control method of the auxiliary heating resistor bar 111 can specifically be to change the current value or voltage value of the power-on, or to control the power-on time period. The material of the auxiliary thermal resistor strip 111 can be a material with a higher thermal resistance value, such as iron, steel, chromium, manganese, ceramics, etc.

In the embodiment shown in FIG3 , the spacing between the auxiliary heating resistor bars 111 of the preset shape and direction laid in the middle area of the substrate 12 is greater than the spacing between the auxiliary heating resistor bars 111 of the preset shape and direction laid in the peripheral area of the substrate 12. In this embodiment, the auxiliary heating resistor bars 111 have uniformly distributed resistance, wherein the uniformly distributed resistance is understood to mean that the resistance value of the auxiliary heating resistor bars 111 of any unit length is the same. In a specific embodiment, the cross-sectional area of the auxiliary heating resistor bars 111 is consistent everywhere. The substrate 12 is square, such as a rectangle or a square. The peripheral area and the middle area of the substrate 12 are understood to be along an extension direction of the substrate, such as the length (width) direction. The two ends in the length direction (width) are the peripheral areas, and the middle part between the two ends is the middle area.

In this embodiment, the default shape of the auxiliary heating resistor strip 111 is a serpentine shape, which can also be called a "bow" shape. Please refer to Figure 3. In this embodiment, the substrate 12 is square, which can be a rectangular or square. The auxiliary heating resistor strip 111 includes a plurality of strips that are connected to each other and parallel to each other. The plurality of strips are arranged parallel to one side of the substrate 12. The spacing between the strips in the middle area is greater than the spacing between the strips in the peripheral area. The substrate 12 has two adjacent edges parallel to each other and adjacent to the above-mentioned side edges. Along the extension direction of the adjacent edges, the substrate 12 is sequentially divided into a peripheral region, a middle region, and a peripheral region. The peripheral regions at the two ends are symmetrical to each other. In the extension direction of the adjacent edge length, the width of the middle region accounts for 30%-60% of the adjacent edge length. The peripheral region and the middle region are understood to be along an extension direction of the substrate 12, such as the length (width) direction, the two ends located in the length direction (width) are the peripheral regions, and the portion between the two ends is the middle region. The peripheral region and the middle region are sequentially arranged along the length direction. If the entire area of the substrate 12 is set to 100%, the proportion of the central area ranges from 30% to 60%, and the proportion of each peripheral area on the left and right sides of the central area ranges from 35% to 20%. Further, please refer to Figure 3, the connection between adjacent strips is in an arc shape, thereby reducing the temperature concentration caused by the transition of the sharp corners of the strips.

The inventors of the present invention have found through experimental simulation that if the auxiliary heating resistor strips 111 are evenly arranged, the temperature on the board surface of the substrate 12 is measured to be a hilly mesh temperature line with high temperature in the middle and low temperature on both sides. The temperature in the middle is significantly higher than the temperature at the periphery, and the temperature changes in a roughly parabolic manner. In order to achieve more accurate temperature consistency in each area of the substrate 12, the strips in the middle area are further arranged along the length extension direction of the adjacent edges: the spacing between the strips in the middle area changes in a progressive manner first and then in a progressive manner, and the amplitudes of the progressive and progressive changes are the same, that is, the progressively changing strips are symmetrical to the progressively changing strips, and the optional progressive and progressive amplitudes are 0.2cm, 0.3cm, 0.4cm, 0.5cm, and 0.8cm. When the progressive distance is selected as 0.5cm, the temperature changes at various locations of the heating plate tend to be consistent, and the temperature of each area is more uniform.

In other embodiments, please refer to FIG. 4 , the default shape of the auxiliary heating resistor strip 111 ' may also be a U-shaped direction. The difference between this embodiment and the previous embodiment is only that the default shape of the auxiliary heating resistor strip is different. The same structure uses the same number and will not be repeated. Specifically, the substrate 12 is square, and the U-shaped auxiliary heating resistor strip 111 ' can also be called a coiled auxiliary heating resistor strip, including multiple circles of square ring-shaped belts connected at the first position, and each square ring-shaped belt is an open U-shaped belt. Specifically, the auxiliary thermal resistor strip 111' is laid along the outer contour of the substrate in a first circle at a constant distance, roughly around a circle but not closed, and the second circle is laid at a constant distance from the first circle, and then the third circle is laid in the same way until the middle of the substrate 12. The power supply can be directly led out from the middle, or it can continue to be laid from the middle of the substrate 12 to the peripheral area in circles until it is laid to the edge of the substrate 12, so as to facilitate the power supply from the outside. Each circle of auxiliary thermal resistor strips is continuous, and the spacing between adjacent auxiliary thermal resistor strips is not completely consistent. The spacing between the auxiliary thermal resistor strips in the middle area is greater than the spacing between the auxiliary thermal resistor strips in the peripheral area. In this embodiment, the middle area refers to the area within a preset distance range from the geometric center of the substrate, and the peripheral area refers to the circumferential edge of the substrate, which is a roughly annular area. Specifically, the middle area is a square area centered on the geometric center of the substrate 12, and the outer contour of the square area is similar to the outer contour of the substrate 12. The area of the middle area accounts for 30%-50% of the area of the substrate 12. Preferably, the spacing of the auxiliary thermal resistor strips, along the direction from the geometric center of the substrate to the outer contour of the substrate, the distance between adjacent square ring-shaped bands changes in a decreasing manner, and the amplitude of the decrease gradually decreases. The decreasing amplitude of the distance between the square ring-shaped bands in the middle area is 2mm-10mm, and the decreasing amplitude of the distance between the square ring-shaped bands in the peripheral area is 0.1mm-0.5mm. Furthermore, the intersection of the two edges of the auxiliary heating resistor strip adopts a rounded transition to avoid temperature accumulation caused by right angles. The auxiliary heating resistor strip with a U-shaped direction can be laid with auxiliary heating resistor strips of different densities according to the distance between the substrate and the surrounding environment, which can more effectively compensate for the problem of high temperature in the middle of the substrate and low temperature in the periphery caused by more heat exchange between the peripheral area of the heating plate and the environment. In another embodiment, the auxiliary heating resistor strip 111 can also be set to a zigzag direction.

In another embodiment, the resistance of the auxiliary heating resistor strip 111 is uneven at various locations, and the cross-sectional area of the auxiliary heating resistor strip located in the middle area of the substrate 12 is larger than the cross-sectional area of the auxiliary heating resistor strip 111 located in the peripheral area of the substrate 12. It can be understood that the thicker the auxiliary heating resistor strip 111, the smaller its resistance and the smaller the thermal effect of the current. The resistor strip 111 in the middle area is set to be thicker than the auxiliary heating resistor strip 111 in the peripheral area, so that the same current generates less heat in the middle area, which can balance the uneven temperature of the heating plate caused by the uneven heat radiation in the peripheral area and the middle area of the heating plate.

In a specific embodiment, the cross-section of the auxiliary heating resistor bar 111 is square, and the dimensions of the auxiliary heating resistor bar 111 in the thickness direction of the substrate 12 are consistent. The width of the auxiliary heating resistor bar 111 located in the middle area of the substrate 12 is greater than the width of the auxiliary heating resistor bar 111 located in the peripheral area of the substrate 12, so that the unit length of the auxiliary heating resistor bar 111 covers a larger area of the board surface of the substrate 12 in the middle area, and the area heated by direct contact between the substrate 12 and the auxiliary heating resistor bar 111 is increased, thereby suppressing the temperature fluctuation on the board surface of the substrate 12 caused by the spacing of the auxiliary heating resistor bars 111. Moreover, the heating structure formed by laying the auxiliary heating resistor strip 111 is in the form of a sheet as a whole, with uniform thickness, and the contact area with the substrate 12 is used for direct conduction heating, further improving the uniformity of the heating temperature. Furthermore, the resistance of the auxiliary heating resistor strip 111 per unit length in the middle area is less than the resistance of the auxiliary heating resistor strip 111 per unit length in the peripheral area, which can reduce the heat generated by the auxiliary heating resistor strip 111 per unit length in the middle area, further balancing the situation where the heat loss in the middle area is less.

During the heating process, since the substrate 12 is an aluminum plate with good thermal conductivity, the heat generated in the peripheral area is bound to radiate to the central area. Therefore, the temperature of the central area is also affected by the heat generated by the auxiliary heating resistor strips 111 in the peripheral area and rises. Therefore, it is necessary to consider not only the different heat exchanges between the peripheral area and the central area and the external environment, but also the mutual heat auxiliary heating effect between the peripheral area and the central area of the substrate 12. Considering the above problems, this embodiment further sets the spacing between the auxiliary heating resistor strips 111 located in the central area of the substrate 12 to be greater than the spacing between the auxiliary heating resistor strips 111 in the peripheral area of the substrate 12. It is also possible to further increase the spacing between the auxiliary heating resistor strips 111 in the middle region on the basis of using an auxiliary heating resistor strip with a cross-sectional area smaller than that in the peripheral region. In this way, the spacing between adjacent strips of the auxiliary heating resistor strips 111 in the middle region is enlarged, which can balance the effect of the thermal auxiliary heating in the peripheral region on the temperature of the substrate 12 in the middle region.

The substrate 12 is provided with a mounting groove that is consistent with the preset shape of the auxiliary heating resistor bar 111. The auxiliary heating resistor bar 111 is embedded in the mounting groove and covered with a protective cover 10 (or 14). In order to facilitate processing and manufacturing. The auxiliary heating resistor bar 111 has uniform dimensions in the thickness direction of the heating plate 100, and the width of the auxiliary heating resistor bar 111 located in the middle area of the substrate is greater than the width of the auxiliary heating resistor bar 111 located in the peripheral area of the substrate 12. Correspondingly, the depth of the mounting groove is consistent at all places, and the width of the mounting groove located in the middle area of the substrate 12 is greater than the width of the mounting groove located in the peripheral area of the substrate 12. Therefore, when opening the mounting groove on the substrate 12, it is only necessary to control the width of the mounting groove (the width of the auxiliary thermal resistor strip), which is convenient for processing and manufacturing.

The heating layer of the heating plate 100 provided by the present invention is an auxiliary heating resistor strip with a preset shape and direction. The direction of the auxiliary heating resistor strip or the distance between the directions can be adaptively arranged according to the size of the heating plate, thereby effectively reducing the risk of uneven temperature caused by uneven heat loss in the central area and the peripheral area of the heating plate, and further improving the temperature consistency of various parts of the heating plate 100 during the heating process.

Continuing to refer to FIG. 3 , the heating plate 100 further includes a temperature measuring unit 113. The temperature measuring unit 113 is used to measure the temperature of the heating plate 100 , thereby feeding back the temperature to the main controller 300 of the laminating machine 500 , so that the main controller 300 can form a closed-loop control of heating according to the temperature of the heating plate 100 .

The heating plate 100 provided by the present invention can be used for the manufacture of printed circuit boards, including flexible circuit boards and traditional rigid circuit boards. The total resistance value of the auxiliary heating resistor strip 111 is between 0.1Ω and 10Ω, preferably 1.5Ω and 2.5Ω.

In order to further illustrate the effect of more uniform heating temperature of the heating plate provided by the present invention, the present invention also provides nine-point temperature test data of the heating plate shown in FIG3. FIG7 shows a nine-point temperature test diagram of the heating plate. Specifically, 9 different points are used to detect temperature data, and the heating surface of the heating plate is divided into nine grids, and the 9 temperature detection points are respectively set in each grid. The temperature of the heating process is collected. After experiments, the temperature data is shown in FIG8. The data shown in FIG8 is plotted to obtain the temperature data curve shown in FIG9. From the fitted temperature data curve in Figure 9, it can be seen that the temperatures of the nine points at the same moment are basically the same, and the temperature curves of the nine points are almost overlapping. Therefore, it can be intuitively concluded that the temperature of each area of the heating plate is uniform during the heating process.

As a control group, Figures 10 and 11 show the temperature data of the existing heating plate. As a control group, the heating layer of the existing heating plate adopts uniformly distributed heating rods, the spacing between each heating rod is the same, and the heating rods are roughly cylindrical. The same 9-point temperature test is adopted to obtain the temperature test data shown in Figure 10. The data shown in Figure 10 is plotted to obtain the temperature data curve shown in Figure 11. It can be seen from Figure 11 that the temperature difference of the 9 temperature test points of the heating plate increases with the passage of heating time, the degree of dispersion increases, and the temperature uniformity consistency is poor. Therefore, the heating plate provided by the present invention has a more consistent heating temperature.

As shown in Fig. 5 and Fig. 6, a laminating press 500 using the above-mentioned heating plate is shown. The laminating press 500 can be applied to the production of printed circuit boards. In this embodiment, the laminating press 500 includes a frame body 520, a hydraulic unit 200, a main control box 510, a main controller 300 and a plurality of heating plates 100. Among them, the main controller 300 is arranged in the main control box 510, and the main controller 300 is used to control the hydraulic pressure signal of the laminating press 500 and the heating signal of the laminating press 500. A plurality of heating plates 100 are stacked on each other, and there is space between adjacent heating plates 100 for placing a multi-layer core board for manufacturing printed circuit boards. In a specific application, the main controller 300 can adopt a traditional PC. The hydraulic unit 200 includes a hydraulic cylinder 210 and a hydraulic control device 220 for controlling the hydraulic cylinder 210. The hydraulic control device 220 is used to receive the hydraulic pressure signal of the main controller 300 and control the movement of the hydraulic cylinder 210 according to the hydraulic pressure signal. The hydraulic cylinder 210 is a hydraulic oil cylinder. The heating plate 100 is a heating plate described in any of the above embodiments of this article, which is used to receive the heating signal of the main controller 300 and control the heating of the heating plate 100 according to the heating signal. The heating signal is a heating current.

The specific heating process of the laminar press 500 is as follows: the main incoming line 400 provides a reliable power signal to the transformer 403, and the transformer 403 converts the input voltage signal into the voltage signal required by the hydraulic unit 200 and provides it to the hydraulic control device 220. The main controller 300 can output the specific control method or control curve of heating to the heating plate 100. According to the change of current or voltage, the heating plate 100 can be heated according to the control method or temperature curve. Preferably, the temperature measuring unit 113 can feed back the real-time temperature of the heating plate 100 to the main controller 300, and the main controller 300 adjusts the control method or control curve according to the real-time temperature, thereby forming a closed-loop control of the heating plate 100.

Since the resistance value of the auxiliary heating resistor 111 is relatively small, approximately between 0.1Ω and 10Ω, in order to prevent a short circuit caused by excessive voltage, the transformer 403 includes a step-down circuit for reducing the voltage to a safe range to prevent excessive current flowing through the auxiliary heating resistor 111 from causing a short circuit.

In a specific embodiment, the main controller 300 adjusts the temperature curve of the heating plate 100 by controlling the on-off of the current. The heating plate 100 has a target temperature curve, which first rises and then stabilizes at a set temperature value, including a rising temperature section and a stable temperature section. The main controller 300 controls the temperature of the heating plate 100 to rise along the target temperature curve by controlling the on-off of the current. When the temperature is higher than the target temperature curve, the current of the auxiliary heating resistor strip 111 is cut off. When the temperature is detected to be lower than the target temperature curve, the auxiliary heating resistor strip 111 is turned on and the auxiliary heating resistor strip 111 is energized, thereby heating and heating.

In another embodiment, the main controller 300 adjusts the temperature of the heating plate by controlling the current. Specifically, when the temperature of the heating plate is higher than the optimal target temperature curve, the current of the auxiliary heating resistor strip 111 is reduced, thereby reducing the heat generated by the auxiliary heating resistor strip 111. The heat loss of the heating plate is greater than the heating heat of the auxiliary heating resistor strip 111, so the temperature drops and gradually approaches the target temperature curve. When the temperature is detected to be lower than the target temperature curve, the current flowing in the auxiliary heating resistor strip 111 is increased, thereby heating and raising the temperature of the heating plate to gradually rise to the target temperature curve.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone with common knowledge in the relevant technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

100: Heating plate

10: First protective layer

11: First heating layer

12: Substrate

122: Pipeline

13: Second heating layer

14: Second protective layer

Claims (10)

A heating plate is used for a laminating press for manufacturing circuit boards. The heating plate comprises: a base plate, comprising a plurality of pipes, the pipes are located in the base plate and are used to contain cooling water or cooling oil; a heating layer, which is laid on the base plate, the heating layer comprises an auxiliary heating resistor bar, the auxiliary heating resistor bar is used to be connected to a power source to generate heat by using the flowing current; a shield layer, which covers the surface of the base plate on which the auxiliary heating resistor bar is laid, and is used to To protect the auxiliary heating resistor strip; the auxiliary heating resistor strip is constructed to be laid on the substrate in a preset shape and direction, the resistance distribution density of the auxiliary heating resistor strip located in the middle area of the substrate is less than the resistance distribution density of the auxiliary heating resistor strip located in the peripheral area of the substrate, and the preset shape and direction are in a U-shaped direction; wherein the number of pipes in the middle area of the pipeline in the substrate is greater than the number of pipes in the peripheral area. The heating plate as described in claim 1, wherein the cross-sectional area of the auxiliary heating resistor strip located in the middle area of the substrate is larger than the cross-sectional area of the auxiliary heating resistor strip located in the peripheral area of the substrate. As described in claim 2, the auxiliary heating resistor strip has uniform dimensions in the thickness direction of the heating plate, and the width of the auxiliary heating resistor strip located in the middle area of the substrate is greater than the width of the auxiliary heating resistor strip located in the peripheral area of the substrate. A heating plate as described in any one of claim 1 to claim 3, wherein the spacing of the auxiliary heating resistor strips located in the middle area of the substrate is greater than the spacing of the auxiliary heating resistor strips located in the peripheral area. As described in claim 1, the spacing of the auxiliary heating resistor strips located in the middle area of the substrate is greater than the spacing of the auxiliary heating resistor strips located in the peripheral area, and the cross-sectional areas of the auxiliary heating resistor strips are consistent at all locations. As described in claim 1, the heating plate, wherein the substrate is provided with a mounting groove that is consistent with the preset shape of the auxiliary heating resistor strip, and the auxiliary heating resistor strip is embedded in the mounting groove. The heating plate as claimed in claim 1, wherein the number of the heating layers is two, namely the first heating layer and the second heating layer, the first heating layer and the second heating layer are respectively laid on the two plate surfaces of the substrate, the number of the shielding layers is two, namely the first shielding layer and the second shielding layer, and the assembly order of the heating plate is the first shielding layer, the first heating layer, the substrate, the second heating layer and the second shielding layer. The heating plate as described in claim 1, wherein the auxiliary heating resistor strip is an integral part. The heating plate as described in claim 1 also includes a temperature measuring unit, which is used to measure the temperature of the heating plate, thereby feeding back the temperature to a main controller of a layer press, so that the main controller can form a closed-loop control of heating according to the temperature. The heating plate as described in claim 1, wherein an insulating layer is provided between the heating layer and the adjacent substrate.

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