Method and apparatus for heat treatment

Abstract

Device for the heat treatment of components, in particular electronic components or the like, comprising a batch carrier (10) and at least two component groups arranged on the batch carrier, wherein the component groups each comprise at least one first component and a second component to be connected to or connected with the first component, wherein the batch carrier comprises at least two support units (11) each receiving a component group, characterized in that the support units each comprise a carrier (12) and a connecting device (13) for firmly connecting the carriers to one another, wherein the connecting device is formed from at least one connecting element (14), wherein a material of the connecting element and / or the carrier is selected such that the connecting element and / or the carrier exhibits thermal expansion in at least one linear direction during heat treatment.which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction.

Description

[0001] The invention relates to a method and a device for the heat treatment of components, in particular electronic components or the like, with a batch carrier and at least two component groups arranged on the batch carrier, wherein the component groups each comprise at least a first component and a second component to be connected to or connected with the first component, wherein the batch carrier has at least two support units, each of which accommodates a component group.

[0002] Electronic components and circuits are typically manufactured from a multitude of components, with the components or groups of components being joined using heat treatment to create an electrically conductive connection. Specifically, a metallurgical and electrically conductive bond between the components is created by soldering, sintering, or similar processes. Crucially, soldering or sintering requires a bonding material that is at least partially melted during the heat treatment or where a metallurgical bond is formed through diffusion. For example, conductive traces of one component are electrically connected to contacts of a second component, or electrically insulated areas are metallurgically bonded to create a mechanically stable component group. The heat treatment can be carried out in various ways, such as through local heating or...Heating of a contact point or entire component groups is achieved through this process. During such a manufacturing step, the component groups or individual components are held in the desired contact position relative to each other. This positioning is typically accomplished using batch carriers into which the components are placed, and which can accommodate a large number of component groups. This allows for simultaneous or consecutive heat treatment of these component groups, thus enabling economical mass production.

[0003] US 6,581,278 B2 and US 2015 / 0257280 A1 also describe a device for the heat treatment of electronic components, comprising a batch carrier and at least two component groups arranged on the batch carrier. Each component group includes at least one first component and a second component to be connected to the first component, with the batch carrier having at least two support units, each accommodating one component group.

[0004] AT 007 038 U1 discloses a device for connecting electronic circuits, for example chips and / or their contact tracks, to a substrate, such as a wafer, a printed circuit board, or the like, which includes a heating chamber. This document further discloses that the pressure plate, the cushion layer, the intermediate plate, the heating surface, and the electronic circuits or the substrates have approximately the same coefficient of thermal expansion.

[0005] A disadvantage of known heat treatment methods and devices is that large temperature differences, combined with differing thermal expansions, can occur in the components being joined. This can lead to distortion of the components, particularly during cooling. For example, cooling of the components or the joined component group can result in distortion or warping due to shrinkage. Differences in thermal expansion of the components have a greater influence on distortion than temperature differences within the components themselves. Heating of the batch carrier can also lead to inaccurate relative positioning of the components being joined, making it difficult to maintain tight tolerances. Depending on the arrangement or fixation of the components on the batch carrier, undesirable play or relative misalignment of the components can occur as a result of the heat treatment.Furthermore, the entire batch carrier can deform in such a way that the component groups are no longer arranged in the desired position relative to a machine that, for example, uses an actuator to press the components together at a connection point. As a result, short circuits or other malfunctions can occur in the component group.

[0006] The present invention is therefore based on the objective of proposing a device and a method for the heat treatment of components, with which more precise manufacturing can be carried out economically.

[0007] This problem is solved by a device having the features of claim 1 and a method having the features of claim 14.

[0008] The device according to the invention for the heat treatment of components, in particular electronic components or the like, comprises a batch carrier and at least two component groups arranged on the batch carrier, wherein the component groups each have at least a first component and a second component to be connected to or connected with the first component, wherein the batch carrier has at least two support units, each of which accommodates a component group, wherein the support units each have a carrier and a connecting device for firmly connecting the carriers to one another, wherein the connecting device is formed from at least one connecting element, wherein a material of the connecting element and / or the carrier is selected such that the connecting element and / or the carrier exhibits thermal expansion in at least one linear direction during heat treatment.which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction.

[0009] The batch carrier can therefore accommodate multiple component groups, each consisting of at least two components that are electrically or non-electrically connected during heat treatment. Each component group is arranged on its own support unit of the batch carrier, with the support units comprising the carrier and the connecting device. The batch carrier can have 2 + n support units, meaning a number of support units that is still manageable with the batch carrier. The connecting device serves to firmly connect the carriers to one another and includes at least one connecting element. If the batch carrier is partially or completely heated during the heat treatment of the respective components, thermal expansion of the batch carrier and at least one component or component group occurs.This thermal expansion occurs here relative to a common coordinate system of the batch carrier and the component assembly in at least one linear direction. The material of the connecting element and / or the carrier is selected such that the connecting element or the carrier undergoes thermal expansion during heat treatment that corresponds to the thermal expansion of at least one of the respective components. Thermal expansion here is understood as a thermal expansion in at least the linear direction, i.e., a change in length. However, thermal expansion can also be related to an area or a volume and thus have an effect in several directions. Since the thermal expansion of the connecting element or...If the carrier's thermal expansion is approximately equal to or the same as that of one of the components within the assembly, this thermal expansion of the components in question can be compensated for by the carrier to such an extent that undesirable relative displacement of the components during heat treatment and / or any distortion of the components after heat treatment during cooling are prevented. This then makes it possible to produce high-quality assembly groups economically and to maintain tight manufacturing tolerances.

[0010] The beams can be positively connected to the connecting element by means of a fastening device. The beams can, in principle, be separate from one another, meaning they can be designed as individual components or elements that are then connected by the connecting element. This makes it possible to space the beams apart in such a way that thermal expansion is not influenced by or transmitted through mutual contact between the beams. At the same time, direct heat transfer between the beams is prevented. Nevertheless, the relative distance between the beams can be very precisely defined by the positive connection with the connecting element. This is particularly advantageous when a relative distance between the beams is required during serial or parallel heat treatment using a suitable machine.The fastening device can include, for example, a screw, a pin, and / or other fasteners. Furthermore, multiple connecting elements can be provided.

[0011] The connecting device can be formed from at least two connecting elements, which can be parallel profile bars that connect spaced-apart supports. The profile bars can, for example, be flat profile bars along whose longitudinal extent a number of supports are arranged. Preferably, the profile bars can be of the same type so that distortion of the connecting device or the batch carrier does not occur during heat treatment. The profile bars can also be connected to the supports on a top and / or bottom surface, so that the components come into contact with the profile bars or are spaced apart from them when positioned on the batch carrier.

[0012] Each support unit can be equipped with at least one positioning aid and / or a recess for receiving and positioning the first component and / or the second component. The support unit can also be designed to position or receive additional components. Each support unit, or only selected support units, can be equipped with a positioning aid. The positioning aid can be, for example, a pin, a stop, a rail, or the like, which enables the components to be positioned correctly or securely on the batch carrier. The recess can also be used for this type of component positioning. For example, one or both components can be inserted fully or partially into the recess. Overlapping components can then be joined together particularly easily.The first component could be, for example, a DBC substrate and the second component a leadframe.

[0013] The connecting element and the carriers can be made of different materials. Using different materials for the carriers and at least one connecting element makes it possible to influence the thermal conductivity and thermal expansion of the batch carrier in different ways. The materials can then be selected so that the batch carrier exhibits a thermal expansion adapted to the thermal expansion of the component group or to the first and / or the second component. Alternatively, the connecting element and the carriers can also be made of the same materials.

[0014] However, the first component and the second component can be made of different materials. In principle, it is also possible for the components themselves to be made of different materials. This can then result in different thermal conductivities and coefficients of thermal expansion for the respective components or component groups. Alternatively, the first component and the second component can also be made of the same materials.

[0015] The material of the fastener or support can be the same as that of the first component. Therefore, the material of the fastener or support can be selected based on the material of the first component. It is essential that the material of the fastener or support and the material of the first component have similar physical properties with respect to thermal expansion, for example, a maximum difference in the coefficients of thermal expansion of ± 5 × 10⁻⁶. -6 / K. This makes it possible, depending on the geometric design of the connecting element or the support, to easily adapt the thermal expansion of the connecting element or the support to the thermal expansion of the first component. "Matching materials" here also refers to essentially similar materials, such as copper and copper alloys.

[0016] The material of the connecting element or the support can be a material with an anisotropic coefficient of thermal expansion. Consequently, the coefficient of thermal expansion of the material differs depending on the position of a structure, such as a crystal lattice or reinforcement. This can result in varying degrees of thermal expansion at the connecting element or support. For example, the connecting element or support can be arranged so that thermal expansion is particularly low in a specific linear direction, so that when the batch carrier is heated, there is no or only minimal displacement of the components within a component group relative to each other.

[0017] The material can be a composite material, graphite (preferably aluminum graphite), or ceramic (preferably aluminum silicon carbide). The connecting element and / or the supports can be made of one of these materials. In particular, graphite or a graphite modification can exhibit an anisotropic coefficient of thermal expansion. Furthermore, aluminum graphite has a particularly high thermal conductivity. If the support is made of aluminum graphite, the component assembly can be heated very quickly via the support, for example, with a heating plate. This significantly reduces cycle times. Likewise, materials with particularly low thermal conductivity can also be used, for example, if only partial heating of the component assembly is desired.

[0018] Furthermore, the material of the connecting element or the support can be a metal, preferably copper or aluminum, or a ceramic. Copper and aluminum exhibit comparatively high thermal conductivity, making these metals advantageously suited for the design of the connecting element or the support. High thermal conductivity, and thus high thermal diffusivity, is advantageous when rapid transfer of heat energy to or from the component assembly is desired. Simultaneously, thermal diffusivity can also be used to create the smallest or largest possible temperature gradient within the batch carrier, the connecting element, or the support, thereby accelerating or suppressing thermal expansion during the heating of the batch carrier and the component assemblies.

[0019] A coefficient of thermal expansion α Ma material of the connecting element and / or the support and a coefficient of thermal expansion α m The material of the first component and / or the second component can be reduced by ≤ 20 × 10 -6 / K, preferably ≤ 10 × 10 -6 / K, especially preferred ≤ 5 × 10 -6 The coefficients of thermal expansion (CET) of the connecting element and the supporting element can differ significantly or be the same. The values ​​given refer to a temperature of 20°C. Approximately equal or equal coefficients of thermal expansion result in uniform thermal expansion of the connecting element and / or the supporting element compared to the first and / or the second component or component group. Furthermore, the materials of the connecting element and the supporting element can each have significantly different coefficients of thermal expansion, which in turn are adapted to the respective materials of the first and second components.

[0020] The thermal conductivity λ of the material of the connecting element and / or the support can be ≥ 100 W / (m × K), preferably ≥ 200 W / (m × K), and particularly preferably ≥ 300 W / (m × K). Such a high thermal conductivity of the material promotes rapid heating or cooling of the material or the connecting element and / or the support. This significantly accelerates the heat treatment process of the component assembly, as joining or post-treatment of the individual components can then be carried out quickly. In principle, it is also possible for the thermal conductivity of the connecting element material and the support to differ significantly from each other. This allows for good thermal conductivity, particularly where rapid heating of the component assembly is desirable.

[0021] A thermal diffusivity α V , α T of the connecting element and / or the support and a thermal conductivity α 1B , α2B of the first component and / or the second component can be adjusted by ≤ 5 mm 2 / s, preferably ≤ 3 mm 2 / s, especially preferred ≤ 1 mm 2The thermal diffusivity values ​​may differ from each other or be the same. The values ​​mentioned refer to a temperature of 20°C. Thermal diffusivity is defined as thermal conductivity divided by the product of density and specific heat capacity. The connecting element and / or the support can be designed with regard to its geometric shape and mass such that the connection of the support with the respective material of the connecting element results in a high or low thermal diffusivity. This thermal diffusivity can, in turn, be adapted to the thermal diffusivity of the respective components or component group. If the respective heat flows in the connecting element and / or the supports and the respective components can then be distributed simultaneously and uniformly, a correspondingly coordinated, parallel thermal expansion of the connecting element and / or support with the respective components can also be achieved.Furthermore, high thermal conductivity can reduce temperature gradients within the batch carrier. This is advantageous because it prevents distortion of the batch carrier and the components being joined relative to the machine.

[0022] In the inventive method for the heat treatment of components, in particular electronic components or the like, at least two component groups are arranged on at least two support units of a batch carrier, wherein the support units each accommodate a component group, wherein the component groups are each formed from at least one first component and a second component to be connected to the first component, wherein in at least one connection area of ​​the first components and the second components a connecting material is applied by means of heat treatment orThermal energy from a heating device is at least partially melted or diffused, and the first components are materially bonded to the second components, wherein a support of the respective support unit and / or at least one connecting element of a connecting device for connecting the supports to one another undergoes thermal expansion in at least one linear direction during the heat treatment, which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction. For the advantages of the method according to the invention, reference is made to the description of advantages of the device according to the invention.

[0023] Using the heating device, a solder can be melted as a bonding material, or a metal paste, preferably silver or copper, can be sintered as a bonding material. The heating device can be a heating plate and / or an oven. The process can then be used, for example, for soldering electronic components with soldering equipment or for silver or copper sintering of electronic components with a suitable machine. Soldering and sintering can be carried out using a heating plate of the machine and / or an oven. The batch carrier can be in direct contact with the heating plate, thus heating the component group. Alternatively, the batch carrier can be heated together with the component group in an oven.

[0024] During the heat treatment of the first and second components, the connecting element and / or the supports, as well as the first and / or second components, can be heated or cooled at different rates. The material of the connecting element and / or the supports can be selected such that the thermal expansion of the first and / or second components is uniform with the thermal expansion of the connecting element and / or the supports. Consequently, the thermal expansion of the connecting element and / or the supports can compensate for the thermal expansion of the first and / or second components, or the respective component group, resulting in simultaneous and uniform thermal expansion.This prevents distortion of the components and improves their contact with the respective support unit, ensuring particularly good heat transfer between the support unit and the component group.

[0025] During heat treatment, the first components, the second components, and the support can undergo thermal expansion, whereby the first components, the second components, and the support can be positioned coplanarly relative to each other. Consequently, no change in the position of the components and the support relative to each other occurs during the heat treatment.

[0026] Within the substrate, a temperature gradient of ≤ 15 K, preferably ≤ 10 K, and particularly preferably ≤ 5 K, can be established during heat treatment. A low temperature gradient can advantageously be achieved by high thermal conductivity and ensures a homogeneous heat distribution within the substrate. This prevents distortion resulting from an inhomogeneous heat distribution.

[0027] Further advantageous embodiments of the method result from the feature descriptions of the dependent claims relating back to device claim 1.

[0028] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0029] They show: Fig. 1 a perspective view of a batch carrier; Fig. 2 a top view of the batch carrier; Fig. 3 a sectional view of the batch carrier made of Fig. 2 along a line III-III; Fig. 4 a detailed view IV of the batch carrier from Fig. 3.

[0030] A summary of Fig.Figures 1 to 4 show a batch carrier 10 that serves to hold a plurality of component groups (not shown here), wherein the component groups are subjected to heat treatment together with the batch carrier. Each component group comprises at least a first component and a second component to be electrically or non-electrically conductively and materially bonded to the first component. A materially bonded, electrically conductive connection between the two components is achieved by at least partial melting or diffusion of the bonding material, such as solder or a metal paste, during the heat treatment. Alternatively, heat treatment may be performed only on already formed or joined component groups.

[0031] The batch carrier 10 forms support units 11 in a row arrangement, each capable of holding a component group. The support units 11 each consist of a support 12 and a connecting device 13 for joining the supports 12. Specifically, the connecting device 13 is formed from two connecting elements 14. Each connecting element 14 is a profile bar 15 made of copper. Alternatively, the profile bar 15 can be made of aluminum. The connecting elements 14 connect the supports 12, which, in the row arrangement shown here, are spaced apart from each other by a narrow gap 16. The supports 12 are designed with a recess 17 for receiving a first component of the component group (not shown here). The first component can be a DCB substrate.The recess 17 is designed such that the first component can be inserted into it and positioned or fixed in a desired position by a contour 18 of the recess 17. The supports 12 are made of aluminum graphite.

[0032] The batch carrier 10 further comprises a fastening device 19 for the positive-locking connection of the connecting elements 14 to the supports 12. The fastening device 19 includes screws 20 and pins 21 formed or molded onto the supports 12, which are inserted into matching through-holes 22 in the connecting elements 14. The engagement of the pins 21 with the through-holes 22 creates a positive-locking connection between the supports 12 and the connecting elements 14. Simultaneously, the supports 12 are firmly, positively, and force-lockedly fixed to the connecting elements 14 by the respective screws 20. Furthermore, a shoulder 24 is formed on the respective longitudinal sides 23 of the supports 12, the depth of which corresponds approximately to the height of the connecting elements 14.The connecting elements 14 are essentially flush with this paragraph 24, the paragraph 24 being designed such that a narrow gap 25, which runs along the longitudinal extent or a longitudinal axis 26 of the batch carrier 10, is also formed between the respective connecting elements 14 and the carriers 12.

[0033] The aluminum-graphite of the respective carrier 14 exhibits an anisotropic coefficient of thermal expansion. Each connecting element 14 also features a positioning aid 27 for components, formed here by a pin 28. In particular, a copper sheet (not shown) or a leadframe (which may be formed using a stamping tool) can thus be precisely positioned on a top surface 29 of the batch carrier 10. The pins 28 can then engage in through-holes in the copper sheet, among other things, and thus position it correctly.

[0034] Heat treatment can now be carried out by placing a heating plate (not shown) on the underside 30 of the batch carrier 10, which heats the batch carrier 10. This heating continues until the temperature at which the bonding material is at least partially melted, whereupon the batch carrier 10 is subsequently cooled again and the bonding material solidifies, so that a material-bonded and electrically conductive connection is formed between the first component and the second component.

[0035] When the batch carrier is heated with the heating plate, the high thermal conductivity of the aluminum graphite of the carriers 12 leads to rapid heating of the components in this area. Thermal expansion perpendicular to the longitudinal axis 26 is minimal, as the coefficient of expansion of the aluminum graphite is also low in this direction. Thermal expansion of the carriers 12 along the longitudinal axis 26 is negligible, however, because the carriers 12 are spaced apart by the gap 16. Since the connecting elements 14 have essentially the same coefficient of expansion as the stamped copper sheet, the thermal expansion of the batch carrier together with the copper sheet along the longitudinal axis 26 is essentially the same. Therefore, no undesirable misalignment of the first and second components occurs during heat treatment, nor does any deformation occur during cooling.The same applies to the thermal expansion of the respective carriers 12 and the first components inserted into the recesses 17. Here, too, the thermal expansion of the carriers 12 is dimensioned such that the first components rest against the contour 18 and are not displaced. This allows for particularly tight tolerances to be maintained in the manufacture of electronic components and advantageously accelerates the manufacturing process.

Claims

[1] Device for the heat treatment of components, in particular electronic components or the like, comprising a batch carrier (10) and at least two component groups arranged on the batch carrier, wherein the component groups each comprise at least a first component and a second component to be connected or connected to the first component, wherein the batch carrier comprises at least two support units (11) each receiving a component group, characterized by, that the support units each have a support (12) and a connecting device (13) for firmly connecting the supports to each other, wherein the connecting device is formed from at least one connecting element (14), wherein a material of the connecting element and / or the support is selected such that the connecting element and / or the support exhibits thermal expansion in at least one linear direction during heat treatment, which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction. [2] Device according to claim 1, characterized by that the supports (12) are positively connected to the connecting element (14) by means of a fastening device (19) each. [3] Device according to claim 1 or 2, characterized by, that the connecting device (13) is formed from at least two connecting elements (14), wherein the connecting elements are parallel profile bars (15) that connect spaced-apart supports (12). [4] Device according to any one of the preceding claims, characterized by , that the respective support unit (11) is designed with at least one positioning aid (27) and / or a recess (17) for receiving and positioning the first component and / or the second component. [5] Device according to any of the preceding claims, characterized by , that the connecting element (14) and the supports (12) are made of different materials. [6] Device according to one of the preceding claims, characterized by that the first component and the second component are made of different materials. [7] Device according to one of the preceding claims, characterized by, that the material of the connecting element (14) or the support (12) matches a material of the first component. [8] Device according to any of the preceding claims, characterized by , that the material of the connecting element (14) or the support (12) is a material with an anisotropic coefficient of thermal expansion. [9] Device according to any of the preceding claims, characterized by that the material is a composite material, graphite, preferably aluminium graphite or ceramic, preferably aluminium silicon carbide. [10] Device according to any one of the preceding claims, characterized by that the material of the connecting element (14) or the support (12) is a metal, preferably copper or aluminium, or a ceramic. [11] Device according to any of the preceding claims, characterized by , that a coefficient of thermal expansion (α M) of a material of the connecting element (14) and / or the support (12) and a coefficient of thermal expansion (α m ) of a material of the first component and / or the second component by ≤ 20 × 10 -6 / K, preferably ≤ 10 × 10 -6 / K, especially preferred ≤ 5 × 10 -6 / K, differ from each other or are the same size. [12] Device according to any of the preceding claims, characterized by , that a thermal conductivity coefficient (λ) of a material of the connecting element (14) and / or the support (12) is ≥ 100 W / (m × K), preferably ≥ 200 W / (m × K), particularly preferably ≥ 300 W / (m × K). [13] Device according to any of the preceding claims, characterized by , that a thermal diffusivity (α V , α T ) of the connecting element (14) and / or the support (12) and a thermal diffusivity (α 1B , α 2B ) of the first component and / or the second component by ≤ 5 mm 2 / s, preferably ≤ 3 mm 2 / s, especially preferred ≤ 1 mm 2 / s, differ from each other or are the same size. [14] Method for the heat treatment of components, in particular electronic components or the like, wherein at least two component groups are arranged on at least two support units (11) of a batch carrier (10), wherein the support units each accommodate a component group, wherein the component groups are each formed from at least one first component and a second component to be joined to the first component, wherein in at least one connection area of ​​the first components and the second components a joining material is at least partially melted or diffused by means of heat treatment of a heating device and the first components are joined to the second components in a metallurgical bond, characterized by, that a support (12) of the respective support unit and / or at least a connecting element (14) of a connecting device (13), for the fixed connection of the supports to each other, undergoes thermal expansion in at least one linear direction during heat treatment, which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction. [15] Method according to claim 14, characterized by , that a solder is melted as a bonding material or a metal paste, preferably silver paste or copper paste, is sintered as a bonding material by means of the heating device, wherein the heating device is a heating plate and / or an oven. [16] Method according to claim 14 or 15, characterized by, that during the heat treatment of the first components and the second components, the connecting element (14) and / or the supports (12) as well as the first components and / or the second components are heated or cooled at different rates, wherein a material of the connecting element and / or the supports is selected such that the thermal expansion of the first components and / or the second components is uniform with the thermal expansion of the connecting element and / or the supports. [17] Method according to any one of claims 14 to 16, characterized by , that during the heat treatment a thermal expansion of the first components, the second components and the support (12) takes place, wherein the first components, the second components and the support are positioned coplanarly relative to each other. [18] Method according to any one of claims 14 to 16, characterized by, that within the support (12) a temperature gradient of ≤ 15 K, preferably ≤ 10 K, particularly preferably ≤ 5 K, is formed during the heat treatment.

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