Heating unit

Abstract

To provide a heating unit that can reduce power consumption. [Solution] A heating unit comprising a heater plate 2 having a first surface 21 and a heat transfer plate 8 having a joining surface 81 with the first surface, wherein the heater plate comprises a first layer containing a heating element 6 inside and a second layer laminated on the first layer so as to include the first surface, and the joining surface includes irregularities, with the second layer fitted into the irregularities.

Description

Technical Field

[0001] This disclosure relates to a heating unit.

Background Art

[0002] Patent Document 1 discloses a substrate heating unit including a surface plate, a flat plate, a planar heater, and a ceramics plate. Hereinafter, the substrate heating unit is simply referred to as a heating unit. The planar heater is configured by sandwiching a thin heater circuit between two polyimide plates. The planar heater is disposed between the flat plate and the ceramics plate. The flat plate, the planar heater, and the ceramics plate are coupled by screws. The surface plate is placed on the flat plate. The substrate to be heated is placed on the surface plate.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology of Patent Document 1, since the planar heater is sandwiched between the flat plate and the ceramics plate, the total thickness of the substrate heating unit tends to be large. The larger the total thickness of the substrate heating unit, the larger the heat capacity. When the heat capacity is large, the heating time becomes long and the power consumption is large.

[0005] One of the objectives of this disclosure is to provide a heating unit that can reduce power consumption.

Means for Solving the Problems

[0006] The heating unit of this disclosure comprises a heater plate having a first surface and a heat transfer plate having a bonding surface with the first surface. The heater plate comprises a first layer containing a heating element inside and a second layer laminated on the first layer so as to include the first surface. The bonding surface includes irregularities. The second layer is fitted into the irregularities. [Effects of the Invention]

[0007] The heating unit of this disclosure can reduce power consumption. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic plan view illustrating the configuration of the heating unit in the embodiment. [Figure 2] Figure 2 is a schematic cross-sectional view showing the heating unit of the embodiment. [Figure 3] Figure 3 is a schematic cross-sectional view showing an enlarged view of region III in Figure 2. [Figure 4] Figure 4 is a schematic plan view showing an example of a heater plate provided in the heating unit of the embodiment. [Figure 5] Figure 5 is a schematic plan view showing another example of a heater plate provided in the heating unit of the embodiment. [Figure 6] Figure 6 is a schematic diagram illustrating the arrangement of the circuit pattern formed by the heating element in the heating unit of the embodiment. [Figure 7] Figure 7 is a schematic diagram illustrating the manufacturing method of the heating unit according to the embodiment. [Figure 8] Figure 8 is a schematic diagram illustrating the peel test performed in the example test. [Modes for carrying out the invention]

[0009] [Description of Embodiments in this Disclosure] First, the embodiments of this disclosure will be listed and described.

[0010] (1) A heating unit according to one aspect of the present disclosure comprises a heater plate having a first surface and a heat transfer plate having a bonding surface with the first surface. The heater plate comprises a first layer containing a heating element inside and a second layer laminated on the first layer so as to include the first surface. The bonding surface includes irregularities. The second layer is fitted into the irregularities.

[0011] The second layer of the heater plate fits into the irregularities of the heat transfer plate, resulting in a strong bond between the heater plate and the heat transfer plate. Because the two plates, the heater plate and the heat transfer plate, are bonded to each other, there is no need to provide the ceramic plate that was previously required. Therefore, the total thickness of the heating unit can be made thinner than before. The thinner total thickness of the heating unit allows for a smaller heat capacity compared to before. A smaller heat capacity of the heating unit allows for a shorter heating time for the object to be heated, and thus reduces the power consumption of the heating unit.

[0012] (2) In the heating unit described in (1) above, the surface roughness of the bonding surface may be 1.0 μm or more in terms of arithmetic mean roughness Ra.

[0013] If the bonding surface of the heat transfer plate is rough, the surface roughness is determined by the irregularities that make up the rough surface. If the surface roughness of the bonding surface is 1.0 μm or more in terms of arithmetic mean roughness Ra, the heater plate and the heat transfer plate can be firmly bonded together by the second layer.

[0014] (3) In the heating unit described in (1) or (2) above, the surface roughness of the bonding surface may be 10.0 μm or less in terms of arithmetic mean roughness Ra.

[0015] If the surface roughness of the bonding surface is 10.0 μm or less in terms of arithmetic mean roughness Ra, the second layer will easily fit into the irregularities.

[0016] (4) In any of the heating units described in (1) to (3) above, the thickness of the heater plate may be 0.025 mm or more and 1.0 mm or less.

[0017] When the thickness of the heater plate is 0.025 mm or more, it is easy to contain the heating element inside. When the heater plate is 1.0 mm or less, it is easy to miniaturize the heating unit.

[0018] (5) In any of the heating units from (1) to (4) above, the thickness of the second layer may be 1.0 μm or more and 10.0 μm or less.

[0019] When the thickness of the second layer is 1.0 μm or more, the heater plate and the heat transfer plate are likely to be firmly adhered. When the thickness of the second layer is 10.0 μm or less, it is easy to miniaturize the heating unit. When the thickness of the second layer is 10.0 μm or less, heat conduction from the heating element to the heat transfer plate can be efficiently performed.

[0020] (6) In any of the heating units from (1) to (5) above, the first layer is formed of a polyimide resin, and the second layer may be formed of an adhesive containing a polyimide resin or a thermoplastic polyimide resin.

[0021] The heater plate formed of a polyimide resin has sufficient heat resistance and is easy to make thin. When the second layer is formed of an adhesive containing a polyimide resin or a thermoplastic polyimide resin, by thermally pressing the second layer onto the bonding surface of the heat transfer plate, the second layer is likely to fit into the unevenness of the heat transfer plate, and the heater plate and the heat transfer plate are likely to be firmly adhered.

[0022] (7) In any of the heating units from (1) to (6) above, the heater plate may include a first sheet and a second sheet arranged to sandwich the heating element. The first sheet may include the second layer.

[0023] If the heating element can be arranged between the first sheet and the second sheet, the heating element is likely to be arranged at a specific location inside the heater plate.

[0024] (8) In the heating unit of (7) above, the first sheet and the second sheet are made of polyimide resin, and at least the second layer may be made of thermoplastic polyimide resin.

[0025] The first and second sheets, formed from polyimide resin, possess sufficient heat resistance and allow for a thin heater plate. When the second layer is made of thermoplastic polyimide resin, heat pressing the second layer onto the bonding surface of the heat transfer plate allows it to easily fit into the irregularities of the heat transfer plate, resulting in a strong bond between the heater plate and the heat transfer plate.

[0026] (9) In any of the heating units described in (1) to (8) above, the heat transfer plate may be made of ceramics or a composite material including ceramics.

[0027] Heat transfer plates made of ceramics or ceramic-containing composites have excellent thermal conductivity and heat resistance. Heat transfer plates made of ceramics or ceramic-containing composites have higher rigidity for the same thickness compared to those made of metal alone.

[0028] (10) In any of the heating units described in (1) to (9) above, the heater plate may be provided with a plurality of slits that divide the heater plate into a plurality of segments in a direction along the first surface.

[0029] If the difference in thermal expansion coefficients between the heater plate and the heat transfer plate is large, the heater plate is likely to detach from the heat transfer plate. For example, in the case of a heater plate made of polyimide resin and a heat transfer plate made of ceramics, the difference in thermal expansion between the polyimide resin and the ceramics may cause the heater plate to detach from the heat transfer plate depending on the operating temperature. By providing multiple slits in the heater plate, the heater plate is less likely to detach from the heat transfer plate even if the difference in thermal expansion coefficients between the heater plate and the heat transfer plate is large.

[0030] (11) In the heating unit of (10) above, the longest length of the plurality of segments may be less than or equal to the value obtained by 300 × 10 / (α2 - α1). α1 is the thermal expansion coefficient of the heat transfer plate, and its unit is ppm / °C. α2 is the thermal expansion coefficient of the heater plate, and its unit is ppm / °C.

[0031] If the maximum length of the segment is less than or equal to the value obtained by the above formula, the heater plate will not easily detach from the heat transfer plate, even if there is a large difference in the coefficient of thermal expansion between the heater plate and the heat transfer plate.

[0032] (12) In any of the heating units described in (1) to (11) above, the heater plate has a circuit pattern formed by the heating element, and the heat transfer plate has an upper surface on which the object to be heated is placed, and the first distance may be less than or equal to the second distance. The first distance is the distance between adjacent heating elements in the circuit pattern. The second distance is the distance from the upper surface to the heating element.

[0033] By shaping the circuit pattern so that the first distance is less than or equal to the second distance, the uniformity of the heating unit is improved.

[0034] [Details of the embodiments of this disclosure] Specific examples of the heating units of this disclosure will be described with reference to the drawings. Identical reference numerals in the drawings indicate the same or corresponding parts. In each drawing, some parts of the configuration may be exaggerated or simplified for ease of explanation. The dimensional ratios of parts in the drawings may also differ from those of the actual components. However, the present invention is not limited to these examples and is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended.

[0035] <Heating Unit> ≪Overview≫ The heating unit 1 of the embodiment will be described with reference to Figures 1 to 6. As shown in Figure 2, the heating unit 1 comprises a heater plate 2 and a heat transfer plate 8. One of the features of the heating unit 1 of the embodiment is that, as shown in Figure 3, the heater plate 2 comprises a first layer 3 and a second layer 4, and the joining surface 81 of the heat transfer plate 8 includes irregularities 810, in which the second layer 4 fits.

[0036] ≪Heater Plate≫ The heater plate 2 is a component that heats the heat transfer plate 8. As shown in Figure 2, the heater plate 2 is positioned below the heat transfer plate 8. The heater plate 2 is equipped with a heating element 6. Figure 1 shows the heating unit 1 viewed from the direction in which the heater plate 2 and the heat transfer plate 8 are stacked, so that the relative positions of the heater plate 2, the heating element 6, and the heat transfer plate 8 can be seen. Hereafter, the direction in which the heater plate 2 and the heat transfer plate 8 are stacked may be referred to as the first direction. In Figure 1, the outer shape of the heater plate 2 and the heating element 6 are shown by dashed lines. In Figure 1, for clarity, the size of the heater plate 2 is shown to be slightly smaller than the size of the heat transfer plate 8. When the heating unit 1 is viewed from the first direction, the heater plate 2 may be smaller than the size of the heat transfer plate 8, or it may be the same size as the heat transfer plate 8.

[0037] As shown in Figure 2, the heater plate 2 has a first surface 21 and a second surface 22. The first surface 21 is the surface that is joined to the heat transfer plate 8. The second surface 22 is the surface facing away from the first surface 21. The heating unit 1 in this example does not include the ceramic plate disclosed in Patent Document 1.

[0038] As shown in Figure 3, the heater plate 2 comprises a first layer 3 and a second layer 4. In Figure 3, for clarity, the boundary between the first layer 3 and the second layer 4 is shown as a straight line with a dashed dot. In the heater plate 2, the layer containing the first surface 21 that is joined to the heat transfer plate 8 is the second layer 4. In the heater plate 2, the layers other than the second layer 4 are the first layer 3. The first layer 3 may include layers made of the same material as the second layer 4. Even if the first layer 3 includes layers made of the same material as the second layer 4, if it does not include the first surface 21, that layer is considered to be the first layer 3. The interface between the first layer 3 and the second layer 4 can be determined by SEM (scanning electron microscope).

[0039] The third layer constitutes the main part of the heater plate 2. The third layer contains the heating element 6 shown in Figures 1 and 2. The heating element 6 is positioned in a plane perpendicular to the first direction, between the first surface 21 and the second surface 22. In Figures 2 and 6, a part of the heating element 6 is shown in a simplified manner for ease of explanation, and its dimensions and pattern differ from the heating element 6 in Figure 1. The heating element 6 will be described later.

[0040] The second layer 4 is laminated on the first layer 3 so as to include the first surface 21. The heater plate 2 and the heat transfer plate 8 are bonded together by the second layer 4.

[0041] The first layer 3 is made of a heat-resistant resin material that can withstand the heat pressing between the heater plate 2 and the heat transfer plate 8. The second layer 4 is made of a thermoplastic resin. The second layer 4 softens at temperatures above its glass transition point, so that during heat pressing, the second layer 4 fits into the irregularities 810 of the heat transfer plate 8.

[0042] The thickness of the heater plate 2 is, for example, 0.025 mm or more and 1.0 mm or less. The thickness of the heater plate 2 is the average distance between the first surface 21 and the second surface 22 in the portion where the heating element 6 is not placed. The first surface 21 has irregularities following the irregularities 810 of the joint surface 81. The thickness of the heater plate 2 is the above average distance including these irregularities. If the thickness of the heater plate 2 is 0.025 mm or more, it is easier to enclose the heating element 6 inside. The thickness of the heater plate 2 is, for example, more than twice the thickness of the heating element 6. If the thickness of the heater plate 2 is 1.0 mm or less, it is easier to miniaturize the heating unit 1. The thickness of the heater plate 2 may also be 0.050 mm or more and 0.20 mm or less, or 0.10 mm or more and 0.15 mm or less.

[0043] The thickness of the heater plate 2 is determined as follows: Observe a cross-section of the heating unit 1 parallel to the first direction using an SEM (scanning electron microscope) and obtain an observation image. The observation image includes the cross-section of the heater plate 2. In this observation image, calculate the average distance for multiple measurement points measured within a 1 mm range along a direction perpendicular to the first direction. The number of measurement points can be any number that allows the above average distance to be calculated. For example, the number of measurement points can be three or more.

[0044] The thickness of the first layer 3 is, for example, between 0.015 mm and 0.990 mm. The thickness of the first layer 3 is the average distance from the interface between the first layer 3 and the second layer 4 to the second surface 22 in the portion where the heating element 6 is not placed. In other words, the thickness of the first layer 3 is the thickness of the heater plate 2 minus the thickness of the second layer 4. If the thickness of the first layer 3 is 0.015 mm or more, it is easier to include the heating element 6 inside. If the thickness of the first layer 3 is 0.990 mm or less, it is easier to miniaturize the heating unit 1. The thickness of the first layer 3 may also be between 0.040 mm and 0.190 mm, or between 0.090 mm and 0.150 mm. The thickness of the first layer 3 is determined by calculating the average distance above for multiple measurement points measured within a 1 mm range along a direction perpendicular to the first direction in the observation image, similar to the thickness of the heater plate 2.

[0045] The thickness of the second layer 4 is, for example, between 1.0 μm and 10.0 μm. The thickness of the second layer 4 is the average distance from the interface between the first layer 3 and the second layer 4 to the first surface 21. As described above, the first surface 21 has irregularities following the irregularities 810 of the bonding surface 81. The thickness of the second layer 4 is the average distance including these irregularities. If the thickness of the second layer 4 is 1.0 μm or more, the heater plate 2 and the heat transfer plate 8 are easily firmly bonded. If the thickness of the second layer 4 is 10.0 μm or less, the heating unit 1 can be easily miniaturized. If the thickness of the second layer 4 is 10.0 μm or less, heat conduction from the heating element 6 to the heat transfer plate 8 can be performed efficiently. The thickness of the second layer 4 may also be, for example, between 2.0 μm and 8.0 μm, or between 2.5 μm and 5.0 μm. The thickness of the second layer 4 is determined by calculating the average distance from multiple measurement points within a 1 mm range along a direction perpendicular to the first direction in the observation image, similar to the thickness of the heater plate 2.

[0046] It is sufficient that at least a portion of the second layer 4 fits into the irregularities 810 of the joint surface 81. The entire second layer 4 may fit into the irregularities 810, or a portion of the second layer 4 may fit into the irregularities 810. The tips of some of the protrusions of the irregularities 810 may extend into the first layer 3.

[0047] The first layer 3 and the second layer 4 are formed of, for example, polyimide resin. When the first layer 3, which constitutes the main part of the heater plate 2, is made of polyimide resin, it provides sufficient heat resistance and makes it easy to reduce the thickness of the heater plate 2.

[0048] The second layer 4 is formed of, for example, a thermoplastic polyimide resin. When the second layer 4 is formed of a thermoplastic polyimide resin, by heat-pressing the second layer 4 onto the joint surface 81 of the heat transfer plate 8, the second layer 4 easily fits into the irregularities 810 of the joint surface 81 (described later), and the heater plate 2 and the heat transfer plate 8 are easily bonded together. The second layer 4 may be formed not only of a thermoplastic polyimide resin, but also of an adhesive capable of bonding the heater plate 2 and the heat transfer plate 8. By using an adhesive containing polyimide resin, or an adhesive sheet containing thermosetting polyimide resin, as the second layer 4, the coefficient of thermal expansion of the second layer 4 tends to be close to that of the first layer 3.

[0049] The third layer may be made of a thermoplastic polyimide resin or a thermosetting polyimide resin.

[0050] The first layer 3 and the second layer 4 may be integrally molded. For example, if the first layer 3 and the second layer 4 are integrally molded from polyimide resin, then, as described above, the second layer 4 is made of thermoplastic polyimide resin. The first layer 3 and the second layer 4 may be separate components. For example, the second layer 4, which is made of adhesive, may be laminated onto the first layer 3. A polyimide film having a thermoplastic polyimide layer on one or both sides of a heat-resistant polyimide layer can also be made using commercially available films.

[0051] The heater plate 2 may include a first sheet 2A and a second sheet 2B arranged to sandwich the heating element 6, as shown in Figure 2. In Figure 2, the boundary between the first sheet 2A and the second sheet 2B is shown by a dashed line. The first sheet 2A and the second sheet 2B are formed of, for example, polyimide resin. The first layer 3 shown in Figure 3 is formed by the first sheet 2A and the second sheet 2B sandwiching the heating element 6. The first sheet 2A includes the second layer 4 shown in Figure 3. If the heating element 6 can be placed between the first sheet 2A and the second sheet 2B, it is easier to position the heating element 6 at a specific location inside the heater plate 2.

[0052] The heater plate 2 may have multiple slits 52 that divide the heater plate 2 into multiple segments 5 in a direction along the first surface 21, as shown in Figure 4 or Figure 5. In Figures 4 and 5, the positions of the slits 52 are shown by lines for clarity. In reality, there are gaps between adjacent segments 5. If the difference in thermal expansion coefficients between the heater plate 2 and the heat transfer plate 8 is large, the heater plate 2 is likely to peel off the heat transfer plate 8. For example, in the case of a heater plate 2 made of polyimide resin and a heat transfer plate 8 made of ceramics, the difference in thermal expansion between the polyimide resin and the ceramics causes the polyimide resin to stretch, making it easy for the heater plate 2 to peel off the heat transfer plate 8. By providing multiple slits 52 in the heater plate 2, the difference in thermal expansion can be reduced, making it difficult for the heater plate 2 to peel off the heat transfer plate 8. The slits 52 can be formed, for example, by punching out the heater plate 2.

[0053] In Figures 4 and 5, the position of the slit 52 is shown by a continuous line, but the slit 52 may be formed so that adjacent segments 5 are locally connected. In other words, adjacent segments 5 may be locally connected by a connecting portion (not shown). The connecting portion is part of the heater plate 2. If a connecting portion is provided, the heater plate 2 can be treated as a single unit even if it is divided into multiple segments 5.

[0054] As shown in Figures 4 and 5, the heater plate 2 in this example is a disc. The slits 52 may include, for example, a circular slit formed along a circle concentric with the heater plate 2, two straight slits formed in a cross shape within the circle, and four straight slits formed at equal intervals around the central axis 50 of the heater plate 2 so as to connect the outer edge of the heater plate 2 with the circular slit, as shown in Figure 4. The heater plate 2 shown in Figure 4 is divided into eight segments 5. The segments 5 shown in Figure 4 consist of four sector-shaped segments formed by dividing a circle into four equal parts, and four arc-shaped segments formed by dividing a ring surrounding the outer circumference of a circle formed by combining four sectors into four equal parts.

[0055] The slit 52 may include a plurality of straight slits extending radially from the central axis 50 of the heater plate 2 to the outer edge of the heater plate 2, as shown in Figure 5, for example. These radially extending linear slits may be formed at equal intervals around the central axis 50 of the heater plate 2. The heater plate 2 shown in Figure 5 is divided into eight segments 5. The segments 5 shown in Figure 5 are sector-shaped segments obtained by dividing a circle into eight equal parts.

[0056] The longest length of each segment 5 separated by the slit 52 is less than or equal to the value obtained by, for example, 300 × 10 / (α2 - α1). The longest length of each segment 5 is the length of the longest straight line connecting any two points on the contour line of each segment 5. In the case of the heater plate 2 shown in Figure 4, each segment 5 has an arc, and the longest length is the length of the chord connecting the two ends of that arc. In the case of the heater plate 2 shown in Figure 5, it is the length of the straight line connecting the central axis 50 and the outer edge of the heater plate 2. In the above formula, α1 is the thermal expansion coefficient of the heat transfer plate 8, and its unit is ppm / °C. In the above formula, α2 is the thermal expansion coefficient of the heater plate 2, and its unit is ppm / °C. For example, if the difference between the thermal expansion coefficient α1 of the heat transfer plate 8 and the thermal expansion coefficient α2 of the heater plate 2 is 10, the heat transfer plate 8 and the heater plate 2 are easily bonded in the region where the longest length of segment 5 is 300 mm or less. If the maximum length of segment 5 is less than or equal to the value obtained by the above formula, the heater plate 2 will not easily detach from the heat transfer plate 8, even if there is a large difference in the coefficient of thermal expansion between the heater plate 2 and the heat transfer plate 8. The slits 52 should be provided so that the maximum length of each segment 5 is less than or equal to the value obtained by the above formula.

[0057] ≪Heat Transfer Plate≫ The heat transfer plate 8 is a component on which a heating object (not shown) is placed. The heat transfer plate 8 transfers heat from the heater plate 2 to the heating object. As shown in Figure 2, the heat transfer plate 8 has a bonding surface 81 and an upper surface 82. The bonding surface 81 is bonded to the first surface 21 of the heater plate 2. The heating object is placed on the upper surface 82. The heating object is, for example, a wafer. The wafer, which is the heating object, may be placed directly on the upper surface 82, or it may be placed on a support member positioned on the upper surface 82. The support member positioned on the upper surface 82 is also a heating object.

[0058] The joint surface 81 includes irregularities 810, as shown in Figure 3. The second layer 4 of the heater plate 2 is fitted into the irregularities 810. The irregularities 810 may be random irregularities corresponding to the surface roughness of the joint surface 81, or they may be regularly formed irregularities.

[0059] As an indicator of the unevenness 810, the surface roughness of the bonding surface 81 is, for example, 1.0 μm or more in terms of arithmetic mean roughness Ra. If the surface roughness of the bonding surface 81 is 1.0 μm or more in terms of arithmetic mean roughness Ra, the heater plate 2 and the heat transfer plate 8 can be firmly bonded by the second layer 4. The arithmetic mean roughness Ra is measured in accordance with JIS B 0601:2013.

[0060] The greater the surface roughness, the more firmly the heater plate 2 and the heat transfer plate 8 are bonded together due to the anchoring effect of the second layer 4 penetrating into the recesses in the uneven surface 810. The surface roughness of the bonding surface 81 may be 1.3 μm or more, 2.0 μm or more, 3.0 μm or more, or 5.0 μm or more in terms of arithmetic mean roughness Ra.

[0061] The surface roughness of the bonding surface 81 may be 10.0 μm or less in terms of arithmetic mean roughness Ra, considering the formation of the irregularities 810. When the surface roughness of the bonding surface 81 is 10.0 μm or less in terms of arithmetic mean roughness Ra, the second layer 4 fits more easily into the irregularities 810. The surface roughness of the bonding surface 81 may also be 1.0 μm or more and 10.0 μm or less, 1.3 μm or more and 10.0 μm or less, or 3.0 μm or more and 5.0 μm or less in terms of arithmetic mean roughness Ra.

[0062] The heat transfer plate 8 is formed of, for example, ceramics or a composite containing ceramics. The heat transfer plate 8 formed of ceramics or a composite containing ceramics has excellent thermal conductivity and heat resistance. The heat transfer plate 8 formed of ceramics or a composite containing ceramics has higher rigidity for the same thickness compared to the case where it is formed of metal only. Examples of ceramics are silicon carbide (SiC), aluminum nitride, aluminum oxide, or silicon nitride. Examples of composites containing ceramics are a composite of silicon (Si) and silicon carbide, a composite of aluminum (Al) and silicon carbide, or a composite of aluminum, silicon, and silicon carbide.

[0063] The thickness of the heat transfer plate 8 is, for example, 2 mm to 12 mm. The thickness of the heat transfer plate 8 is the average distance between the top surface 82 and the joint surface 81. The thickness of the heat transfer plate 8 is the above average distance including the irregularities 810 of the joint surface 81. If the thickness of the heat transfer plate 8 is 2 mm or more, it is less likely to crack even when subjected to heat cycles. If the thickness of the heat transfer plate 8 is 12 mm or less, the thermal responsiveness when heating the object to be heated is good. The thickness of the heat transfer plate 8 may be 2 mm to 5 mm, or 2 mm to 4 mm. The thickness of the heat transfer plate 8 is determined by calculating the above average distance for multiple measurement points measured within a 1 mm range along a direction perpendicular to the first direction in the observation image, similar to the thickness of the heater plate 2.

[0064] ≪Heating element≫ The heating element 6 is positioned in a plane perpendicular to the first direction, between the first surface 21 and the second surface 22. The heating element 6 is formed of, for example, a thin metal film that generates heat when an electric current is passed through it. The heating element 6 is formed, for example, by partially etching a stainless steel foil. The heat generated by the heating element 6 is transferred from the heater plate 2 to the heat transfer plate 8. A heating object (not shown) is placed on the upper surface 82 of the heat transfer plate 8. The heating object, such as a wafer, is heated by the heat transferred to the heat transfer plate 8.

[0065] As shown in Figure 6, a circuit pattern 60 is formed by the heating elements 6. The circuit pattern 60 is appropriately selected according to the heating temperature and the desired temperature distribution. The circuit pattern 60 is formed such that, for example, the first distance L1 is less than or equal to the second distance L2. The first distance L1 is the distance between adjacent heating elements 6 in the circuit pattern 60. The first distance L1 is the distance between adjacent heating elements 6. The second distance L2 is the distance from the upper surface 82 of the heat transfer plate 8 to the heating element 6. The second distance L2 is the shortest distance from the upper surface 82 to the surface of the heating element 6. However, in places such as between segments with through holes or slits, the first distance L1 may be greater than the second distance L2.

[0066] Figure 6 schematically shows how heat is transferred from the heating elements 6 using dashed-dotted hatching. The hatching in Figure 6 shows the heat transfer region from each heating element 6 as an inverted isosceles trapezoid. If the first distance L1 is too long, there is a risk that cool spots will be formed on the upper surface 82 of the heat transfer plate 8 where heat is not substantially transferred. By setting the first distance L1 and the second distance L2 so that the heat transfer regions formed by each adjacent heating element 6 overlap on the upper surface 82, the formation of cool spots is less likely to occur. The uniformity of the heating unit 1 is improved by having fewer or no cool spots. The first distance L1 is longer than the length that allows for electrical insulation between adjacent heating elements 6 in the circuit pattern 60.

[0067] The thickness of the heating element 6 is, for example, 0.01 mm or more and 0.10 mm or less, or 0.02 mm or more and 0.05 mm or less. The width of the circuit pattern 60 formed by the heating element 6 is, for example, 0.2 mm or more and 4.0 mm or less, or 0.4 mm or more and 1.0 mm or less.

[0068] <Manufacturing method for heating units> Referring to Figure 7, an example of a manufacturing method for the heating unit 1 described above will be explained. This manufacturing method comprises a first step of preparing a heat transfer plate 8, a first resin film 91, and a second resin film 92; a second step of forming a circuit pattern 60 consisting of a heating element 6 on the first resin film 91; and a third step of stacking the heat transfer plate 8, the first resin film 91, and the second resin film 92 and heat pressing them together.

[0069] The heat transfer plate 8 prepared in the first step is the heat transfer plate 8 of the heating unit 1 described above. The joint surface 81 of the heat transfer plate 8 includes irregularities 810. The surface roughness of the joint surface 81 is, for example, 1.0 μm or more in terms of arithmetic mean roughness Ra. The irregularities 810 of the joint surface 81 can be formed, for example, by blasting.

[0070] The first resin film 91 and the second resin film 92 prepared in the first step are made of the same material. The first resin film 91 and the second resin film 92 may have the same thickness or different thicknesses. The first resin film 91 comprises a core layer 911 and two adhesive layers 912 and 913 laminated so as to sandwich the core layer 911. The first resin film 91 has a three-layer structure. The core layer 911 and the adhesive layers 912 and 913 are made of polyimide resin. The adhesive layers 912 and 913 are made of thermoplastic polyimide resin. The core layer 911 may be made of thermoplastic polyimide resin or thermosetting polyimide resin. The glass transition temperature of the adhesive layers 912 and 913 is below the glass transition temperature of the core layer 911. Similarly, the second resin film 92 comprises a core layer 921 and two adhesive layers 922 and 923 laminated so as to sandwich the core layer 921. The second resin film 92 has a three-layer structure. The core layer 921 and the adhesive layers 922 and 923 are made of polyimide resin. The adhesive layers 922 and 923 are made of thermoplastic polyimide resin. The core layer 921 may be made of thermoplastic polyimide resin or thermosetting polyimide resin. The glass transition temperatures of the adhesive layers 922 and 923 are below the glass transition temperature of the core layer 921.

[0071] In the second step, the material film of the heating element 6 is integrated onto the adhesive layer 913 of the first resin film 91, and the material film is processed into a predetermined shape by etching to form a circuit pattern 60 consisting of the heating element 6. The material film is, for example, stainless steel foil.

[0072] In the third step, the first resin film 91 and the second resin film 92 are stacked so as to sandwich the heating element 6, and the heat transfer plate 8 is placed on top of the first resin film 91 and heat-pressed. The heat pressing should be performed at a temperature and pressure such that the adhesive layer 913 of the first resin film 91 and the adhesive layer 922 of the second resin film 92 are heat-fused to each other, and the adhesive layer 912 of the first resin film 91 fits into the irregularities 810 of the heat transfer plate 8. The first resin film 91 and the second resin film 92 joined by heat pressing constitute the heater plate 2 shown in Figure 2. The adhesive layer 912 fitted into the irregularities 810 of the heat transfer plate 8 constitutes the second layer 4 shown in Figure 3. The laminate of core layers 911, 921 and adhesive layers 913, 922, 923 as a whole constitutes the first layer 3 shown in Figure 3. The second layer 4 is laminated with the first layer 3, and the heating element 6 is contained within the first layer 3.

[0073] In this manufacturing method, the second layer 4 of the heater plate 2 fits into the grooves 810 of the heat transfer plate 8 by heat pressing, thereby bonding the heater plate 2 and the heat transfer plate 8 together. Because the two plates, the heater plate 2 and the heat transfer plate 8, can be bonded to each other, the total thickness of the heating unit 1 can be made thinner than in conventional designs. A thinner total thickness of the heating unit 1 allows for a smaller heat capacity compared to conventional designs. A smaller heat capacity of the heating unit 1 allows for a shorter heating time for the object to be heated, thus reducing the power consumption of the heating unit 1.

[0074] [Example Test] In the test example, a heating unit was simulated in which irregularities were formed on the joint surface of the heat transfer plate, and the second layer of the heater plate was fitted into these irregularities to bond the heater plate and the heat transfer plate together. The degree of adhesion between the heater plate and the heat transfer plate was then investigated.

[0075] <Description of the test specimen> Four test specimens were prepared: specimen A, specimen B, specimen C, and specimen D. The four specimens differed in the surface roughness of the heat transfer plate joints, but all other conditions were the same.

[0076] For each test specimen, a first resin film and a second resin film were prepared to fabricate a heater plate. Each of the first and second resin films had a three-layer structure made of polyimide resin, with adhesive layers made of thermoplastic polyimide resin on both sides. The thickness of each of the first and second resin films was 0.05 mm. The thickness of each adhesive layer was 5 μm. A circuit pattern consisting of heating elements was formed on one side of the first resin film. The thickness of the heating elements was 0.02 mm. The circuit pattern was formed such that the distance between adjacent heating elements in the circuit pattern was smaller than the distance from the top surface of the heat transfer plate to the heating elements.

[0077] In all test specimens, the heat transfer plate is made of ceramic. The thickness of the heat transfer plate is 3.0 mm. The surface roughness of the joint surface of the heat transfer plate in each test specimen, expressed as an arithmetic mean roughness Ra, is as follows: Test specimen A: 0.3 μm; Test specimen B: 1.5 μm; Test specimen C: 2.0 μm; Test specimen D: 3.0 μm.

[0078] In each test specimen, a first resin film and a second resin film were layered so as to sandwich the heating element, and a heat transfer plate was placed on top of the first resin film and heat-pressed. At this time, as shown in Figure 8, a portion of the test piece 10, consisting of the first and second resin films, was placed on the joint surface 81 of the heat transfer plate 8. Figure 8 shows a cross-section of the test piece 10 with a portion placed on the joint surface 81. The size of the test piece 10 was 85 mm in length and 25 mm in width. The heat pressing was performed at a temperature and pressure such that the adhesive layer of the first resin film and the adhesive layer of the second resin film were heat-fused to each other, and the adhesive layer of the first resin film was fitted into the irregularities 810 of the heat transfer plate 8. The adhesive layer fitted into the irregularities 810 of the heat transfer plate 8 is the second layer of the heater plate. The test piece 10 has an adhesive region 11 and a non-adhesive region 12. The adhesive region 11 is bonded to the joint surface 81. The non-adhesive region 12 is not adhered to the bonding surface 81 and extends beyond the outer edge of the heat transfer plate 81.

[0079] <Peel test> In each test specimen, as shown in Figure 8, the end of the non-adhesive region 12 of the test piece 10 was pulled up from the bottom to the top of Figure 8, and the adhesive region 11 was peeled away from the heat transfer plate 10. In each test specimen, the end of the non-adhesive region 12 was pulled up with a force of 1 kN and a speed of 100 mm / min, and the test piece 10 was peeled away from the heat transfer plate 8. The adhesive portion was visually inspected in the state before peeling, the dimensions of the adhesive portion were measured, and the adhesive area relative to the joint surface 81 was calculated.

[0080] The results of the peel test are as follows: Test specimen A did not adhere. The adhesion area of ​​test specimen B was 65%. The adhesion area of ​​test specimen C was 94%. The adhesion area of ​​test specimen D was 99%. These results show that the greater the surface roughness of the bonding surface, the stronger the bond between the heater plate and the heat transfer plate. It is thought that the greater the surface roughness of the bonding surface, the more securely the adhesive layer fits into the irregularities of the heat transfer plate, resulting in a stronger bond between the heater plate and the heat transfer plate. [Explanation of Symbols]

[0081] 1 Heating unit 2 Heater Plates 21 Front page 22 Second side 2A First Seat 2B Second seat 3 First layer 4 Second layer 5 segments 50 center axis 52 slits 6. Heating element 60 circuit patterns 8 Heat transfer plate 81 Joint surface 810 Unevenness 82 Top surface 91 Daiichi Resin Film 911 Core Layer 912,913 Adhesive layer 92 Second resin film 921 Core Layer 922,923 Adhesive layer L1 first distance L2 second distance 10 test specimens 11 Adhesion area 12 Non-adhesive area

Claims

1. A heater plate having a first surface, A heat transfer plate having a bonding surface with the first surface, The aforementioned heater plate is The first layer contains a heating element inside, A second layer is laminated on the first layer so as to include the first surface, The aforementioned joining surface includes irregularities, The second layer is fitted into the aforementioned irregularities. Heating unit.

2. The heating unit according to claim 1, wherein the surface roughness of the bonding surface is 1.0 μm or more in terms of arithmetic mean roughness Ra.

3. The heating unit according to claim 2, wherein the surface roughness of the bonding surface is 10.0 μm or less in terms of arithmetic mean roughness Ra.

4. The heating unit according to claim 1 or claim 2, wherein the thickness of the heater plate is 0.025 mm or more and 1.0 mm or less.

5. The heating unit according to claim 1 or claim 2, wherein the thickness of the second layer is 1.0 μm or more and 10.0 μm or less.

6. The aforementioned layer is formed of polyimide resin, The heating unit according to claim 1 or claim 2, wherein the second layer is formed of an adhesive containing a polyimide resin or a thermoplastic polyimide resin.

7. The heater plate comprises a first sheet and a second sheet arranged to sandwich the heating element, The heating unit according to claim 1 or claim 2, wherein the first sheet comprises the second layer.

8. The first sheet and the second sheet are formed of polyimide resin. The heating unit according to claim 7, wherein at least the second layer is made of a thermoplastic polyimide resin.

9. The heating unit according to claim 1 or 2, wherein the heat transfer plate is formed of ceramics or a composite containing ceramics.

10. The heating unit according to claim 1 or claim 2, wherein the heater plate is provided with a plurality of slits that divide the heater plate into a plurality of segments in a direction along the first surface.

11. The heating unit according to claim 10, wherein the longest length of the plurality of segments is less than or equal to the value obtained by 300 × 10 / (α2 - α1). α1 is the thermal expansion coefficient of the heat transfer plate, and its unit is ppm / °C. α2 is the thermal expansion coefficient of the heater plate, and its unit is ppm / °C.

12. The heater plate is provided with a circuit pattern formed by the heating element, The heat transfer plate has an upper surface on which the object to be heated is placed, The first distance is less than or equal to the second distance. The first distance is the distance between adjacent heating elements in the circuit pattern. The heating unit according to claim 1 or claim 2, wherein the second distance is the distance from the upper surface to the heating element.

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