Method and device for a thermal treatment

Abstract

The invention relates to a method and a device for a thermal treatment of components, in particular electric components or the like, comprising a batch carrier (10) and at least two component assemblies arranged on the batch carrier. Each component assembly has at least one first component and a second component which is connected or is to be connected to the first component, wherein the batch carrier has at least two carrier units (11), each of which receives a component assembly, and each carrier unit has a carrier (12) and a connection device (13) for interconnecting the carriers. The connection device is made of at least one connection element (14), and the material of the connection element and / or of the carrier is selected such that the connection element and / or the carrier has a thermal expansion in at least one linear direction during a thermal treatment, said thermal expansion corresponding substantially to the thermal expansion of the first component and / or of the second component in the linear direction.

Description

[0001] Method and device for heat treatment

[0002] 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 have at least a first component and a second component to be connected or connected to the first component, wherein the batch carrier has at least two support units, each of which accommodates a component group.

[0003] Electronic components and circuits are regularly manufactured from a plurality of components, wherein the components or groups of components are joined by means of heat treatment to form an electrically conductive connection. In particular, a material-to-material and electrically conductive connection between the components is then created by means of soldering, sintering or the like. It is important that a connecting material is used during soldering or sintering, which is at least partially melted during the heat treatment or in which a material-to-material bond is created by diffusion. For example, conductor tracks of a first component are electrically conductively connected to contacts of a second component, or electrically insulated areas are materially connected to produce a mechanically stable group of components. The heat treatment can be carried out in a variety of ways, for example by local heating orHeating a contact point or by heating entire component groups accordingly. During such a manufacturing step, the component groups or components are held relative to each other in the desired contact position. This positioning of the components is usually achieved using batch carriers into which the components are inserted and which can accommodate a large number of component groups. This makes it possible to perform simultaneous or consecutive heat treatment of these component groups, thus enabling cost-effective production in large quantities.

[0004] A disadvantage of known heat treatment processes and devices is that large temperature differences, combined with different thermal expansion rates, can occur between the components to be joined. This can then lead to distortion of the components, particularly during cooling. For example, cooling of the components or the joined group of components can lead to distortion or warping as a result of shrinkage. Differences in thermal expansion rates between the components have a greater influence on distortion than temperature differences within the components. Heating of the charge carrier can also lead to inaccurate relative positioning of the components to be joined, making it difficult to maintain tight tolerances. Depending on the arrangement or fixing of the components to the charge carrier, undesirable play or relative offset of the components can occur as a result of the heat treatment.Furthermore, the entire batch carrier can deform to the point where the component assemblies 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 joint. As a result, short circuits or other malfunctions can occur in the component assembly.

[0005] The present invention is therefore based on the object of proposing a device and a method for the heat treatment of components with which a more precise production can be carried out economically.

[0006] This object is achieved by a device having the features of claim 1 and a method having the features of claim 14.

[0007] The device according to the invention for the heat treatment of components, in particular electronic components or the like, comprises a charge carrier and at least two component groups arranged on the charge carrier, wherein the component groups each have at least one first component and a second component to be connected or connected to the first component, wherein the charge 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 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 has a thermal expansion in at least one linear direction during a heat treatment,which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction.

[0008] Accordingly, a plurality of component groups with at least two components, which are connected to one another in an electrically or non-electrically conductive manner during the heat treatment, can be arranged on the charge carrier. The component groups are each arranged on a separate support unit of the charge carrier, wherein the support units are formed from the carrier and the connecting device. The charge carrier can have 2 + n support units, i.e. a number of support units that can in principle still be managed with the charge carrier. The connecting device serves to firmly connect the carriers to one another and has at least one connecting element. If the charge carrier is partially or completely heated during heat treatment of the respective components, thermal expansion of the charge carrier and of at least one component or the component group occurs.This thermal expansion occurs here relative to a common coordinate system of the charge carrier and the component group in the same at least one linear direction. A material of the connecting element and / or the carrier is selected such that the connecting element or the carrier experiences thermal expansion during heat treatment which corresponds to a thermal expansion of at least one of the respective components. Thermal expansion is understood here to mean thermal expansion in at least the linear direction, i.e. a change in length. However, the thermal expansion can also be related to an area or a volume and accordingly have an effect in several directions. Since the thermal expansion of the connecting element orIf the carrier's thermal expansion is approximately equal to or equal to the thermal expansion of one of the components in the component group, this thermal expansion of the respective components can be compensated by the charge carrier to such an extent that undesirable relative displacement of the components during heat treatment and / or possible distortion of the components after heat treatment upon cooling are prevented. This makes it possible to produce high-quality component groups economically and maintain tight tolerances during production.

[0009] The supports can be positively connected to the connecting element by means of a fastening device each. In principle, the supports can be separated from one another, i.e. designed as individual components or elements that are then connected to the connecting element. This makes it possible to space the supports apart from one another in such a way that thermal expansion of the supports is not influenced by mutual contact between the supports or propagated via the supports. At the same time, direct heat transfer between the supports can also be prevented. Nevertheless, a relative spacing between the supports can be achieved very precisely through the positive connection with the connecting element. This is particularly advantageous when a relative spacing between the supports is required as part of a serial or parallel heat treatment using a corresponding machine.The fastening device may, for example, comprise a screw, a pin, and / or other fastening means. Furthermore, several connecting elements may be provided.

[0010] The connecting device can be formed from at least two connecting elements, wherein the connecting elements can be parallel profile bars that can connect spaced-apart supports. The profile bars can, for example, be flat profile bars along whose longitudinal extent a number of supports are arranged. The profile bars can preferably be of identical design so that no distortion of the connecting device or the charge carrier occurs during heat treatment. The profile bars can also be connected to the supports on an upper side and / or an underside of the latter, so that the components come into contact with the profile bars when positioned on the charge carrier or are spaced from them.

[0011] The respective support unit can be designed 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 be designed for positioning or receiving further components. Each support unit or only selected support units can be designed with a positioning aid. The positioning aid can, for example, be a pin, a stop, a rail, or the like, which enables the components to be positioned correctly or with a form-fitting fit on the batch carrier. The recess can also be used for such positioning of the components. For example, one of the components or both components can be inserted into the recess completely or in part. Overlapping components can then be connected to one another particularly easily.For example, the first component can be a DBC substrate and the second component a leadframe.

[0012] The connecting element and the supports can be made of different materials. By using different materials for the supports and the at least one connecting element, it is possible to influence the temperature conductivity and thermal expansion of the charge carrier accordingly. The materials can then be selected such that the charge carrier has at least one thermal expansion adapted to the thermal expansion of the component group or to the first and / or second component. Alternatively, the connecting element and the supports can also be made of the same materials.

[0013] Nevertheless, 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 thermal expansions for the respective components or component groups. Alternatively, the first component and the second component can also be made of the same materials.

[0014] The material of the connecting element or the support can match a material of the first component. Accordingly, the material of the connecting element or the support can be selected based on a material of the first component. It is essential that the material of the connecting element or the support and the material of the first component have similar physical properties with regard to thermal expansion, for example, a maximum difference in the thermal expansion coefficients of ± 5 x 10' 6 / K. This makes it particularly easy to adapt the thermal expansion of the connecting element or the support to the thermal expansion of the first component, depending on the geometric design of the connecting element or the support. Matching materials here also include essentially similar materials, such as copper and copper alloys.

[0015] The material of the connecting element or the carrier can be a material with an anisotropic coefficient of thermal expansion. The coefficient of thermal expansion of the material therefore differs depending on the layer of a structure, such as a crystal lattice or reinforcement, of the material. This can cause varying degrees of thermal expansion at the connecting element or the carrier. For example, the connecting element or the carrier can be arranged such that particularly low thermal expansion occurs in a specific linear direction, so that when the charge carrier is heated, there is no or only a slight offset between the components of a component group.

[0016] 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 in particular be made from one of these materials. In particular, graphite or a modification of graphite can have 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 group can be heated particularly quickly via the support, for example with a heating plate. This can significantly reduce cycle times. Likewise, materials with a particularly low thermal conductivity can also be used, for example if only partial heating of the component group is desired.

[0017] Furthermore, the material of the connecting element or the carrier can be a metal, preferably copper or aluminum, or a ceramic. Copper and aluminum have a comparatively high thermal conductivity, so that these metals can also be advantageously used to form the connecting element or the carrier. High thermal conductivity and thus high thermal conductivity are advantageous when rapid supply or removal of heat energy to or from the component group is desired. At the same time, the thermal conductivity can also be used to create the smallest or largest possible temperature gradient within the charge carrier or the connecting element or the carrier, and thus to accelerate or suppress thermal expansion during heating of the charge carrier and the component groups.

[0018] A thermal expansion coefficient ÖM of a material of the connecting element and / or the supports and a thermal expansion coefficient a m of a material of the first component and / or the second component can be < 20 x 10' 6 / K, preferably < 10 x 10' 6 / K, particularly preferably < 5 x 10' 6 / K, differ from one another or be equal. The stated values ​​refer to a temperature of 20°C. Approximately identical or identical thermal expansion coefficients result in uniform thermal expansion of the connecting element and / or the support compared to the first and / or second component or component group. Furthermore, the materials of the connecting element and the support can each have widely differing thermal expansion coefficients, which in turn are adapted to the respective materials of the first component and the second component.

[0019] A thermal conductivity coefficient of a material of the connecting element and / or the carrier can be > 100 W / (mx K), preferably > 200 W / (mx K), particularly preferably > 300 W / (mx K). Such a high thermal conductivity of the material promotes rapid heating or cooling of the material or of the connecting element and / or the carrier. This can significantly accelerate a process for heat treating the component group, since joining or post-treatment of the respective components can then take place quickly. In principle, it can also be provided that the thermal conductivity coefficient of the material of the connecting element and the carrier differ greatly from one another. In this way, good heat conduction can be provided particularly where rapid heating of the component group is desirable.

[0020] A thermal conductivity av, ar of the connecting element and / or the carrier and a thermal conductivity am, a2B of the first component and / or the second component can be < 5 mm 2 / s, preferably < 3 mm 2 / s, particularly preferably < 1 mm 2 / s, differ from one another or be the same. The values ​​given refer to a temperature of 20°C. Thermal conductivity is understood to be thermal conductivity divided by the product of density and specific heat capacity. The connecting element and / or the carrier can be designed in terms of their geometric shape and mass so that the connection of the carrier with the respective material of the connecting element results in a high or low thermal conductivity. This thermal conductivity can in turn be adapted to a thermal conductivity of the respective components or group of components. If the respective heat flows in the connecting element and / or the carriers as well as the respective components can then be distributed simultaneously and evenly, a correspondingly coordinated, parallel thermal expansion of the connecting element and / or the carrier with the respective components can be achieved.Furthermore, high thermal conductivity can reduce the temperature gradient within the charge carrier. This is advantageous because it prevents distortion of the charge carrier and the components to be joined relative to a machine.

[0021] In the method according to the invention 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 region of the first components and the second components a connection material is applied by means of heat treatment orThermal energy from a heating device is used to at least partially melt or diffuse the first components and to bond the second components together, 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 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.

[0022] Using the heating device, a solder can be melted as a joining material, or a metal paste, preferably silver paste or copper paste, can be sintered as a joining material. The heating device can be a hot plate and / or a furnace. The method can then be used, for example, for soldering electronic components using soldering systems or for silver sintering or copper sintering of electronic components using a suitable machine. Soldering and sintering can be carried out using a hot plate of the machine and / or a furnace. The charge carrier can be brought into direct contact with the hot plate, thus heating the component group. The charge carrier can also be heated together with the component group in a furnace.

[0023] During the heat treatment of the first components and the second components, the connecting element and / or the supports, as well as the first components and / or the second components, can be heated or cooled at different rates. A material of the connecting element and / or the supports can be selected such that thermal expansion of the first components and / or the second components occurs uniformly with 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 components and / or the second components or the respective component group, such that simultaneous and uniform thermal expansion occurs.In this way, distortion of the components can be prevented and their connection to the respective support unit can be improved, so that particularly good heat transfer between the support unit and the component group can be ensured.

[0024] During heat treatment, thermal expansion of the first components, the second components, and the supports can occur, whereby the first components, the second components, and the supports can be positioned coplanar relative to one another. Consequently, no change in the position of the components and the support relative to one another occurs during heat treatment.

[0025] During the heat treatment, a temperature gradient of <15 K, preferably <10 K, particularly preferably <5 K, can be formed within the carrier. A low temperature gradient can advantageously be achieved through high thermal conductivity and ensures homogeneous heat distribution within the carrier. Warpage resulting from inhomogeneous heat distribution can thus be avoided. Further advantageous embodiments of the method emerge from the feature descriptions of the subclaims referring back to device claim 1.

[0026] A preferred embodiment of the invention is explained in more detail below with reference to the accompanying drawings.

[0027] They show:

[0028] Fig. 1 is a perspective view of a charge carrier;

[0029] Fig. 2 is a plan view of the charge carrier;

[0030] Fig. 3 is a sectional view of the charge carrier of Fig. 2 along a line III-III;

[0031] Fig. 4 shows a detailed view IV of the charge carrier from Fig. 3.

[0032] A synopsis of Figures 1 to 4 shows a charge carrier 10 which serves to accommodate a plurality of component groups (not shown here), wherein the component groups are fed to a heat treatment together with the charge carrier. The component groups each comprise at least a first component and a second component to be connected to the first component in an electrically or non-electrically conductive and materially bonded manner, wherein a materially bonded, electrically conductive connection between the two components is achieved by at least partial melting or diffusion of connecting material, such as solder or a metal paste, through the heat treatment. It is also possible for only heat treatment of already formed or joined component groups to be provided.

[0033] The batch carrier 10 forms support units 11 in a row arrangement, each of which can accommodate a component group. The support units 11 are each formed from a carrier 12 and a connecting device 13 for connecting the carriers 12. In particular, the connecting device 13 is formed here from two connecting elements 14. The respective connecting element 14 is a profile bar 15 and is made of copper. Alternatively, the profile bar 15 can be made of aluminum. The connecting elements 14 connect the carriers 12, which, in the row arrangement shown here, are spaced apart from one another by a narrow gap 16. The carriers 12 are formed 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.

[0034] The charge carrier 10 further comprises a fastening device 19 for the positive connection of the connecting elements 14 to the supports 12. The fastening device 19 comprises screws 20 and pins 21 formed or molded onto the supports 12, which are inserted into matching through-openings 22 in the connecting elements 14. The interlocking of the pins 21 with the through-openings 22 creates a positive connection between the supports 12 and the connecting elements 14. At the same time, the supports 12 are firmly fixed to the connecting elements 14 with the respective screws 20, both positively and non-positively. In addition, a shoulder 24 is formed on the respective long sides 23 of the supports 12, the depth of which approximately corresponds to a height of the connecting elements 14.The connecting elements 14 are inserted essentially flush into this shoulder 24, wherein the shoulder 24 is designed such that a narrow gap 25, which runs along the longitudinal extent or a longitudinal axis 26 of the charge carrier 10, is also formed between the respective connecting elements 14 and the supports 12.

[0035] The aluminum graphite of the respective carrier 14 has an anisotropic thermal expansion coefficient. A positioning aid 27 for components, formed here by a pin 28, is also provided on the respective connecting elements 14. In particular, a copper sheet or a leadframe (not shown here) can be precisely positioned as a second component, which can be formed with a punching tool, on an upper side 29 of the charge carrier 10. The pins 28 can then, among other things, engage in through-holes in the copper sheet and thus position it correctly.

[0036] A heat treatment can now be carried out in such a way that a heating plate (not shown here) is applied to an underside 30 of the charge carrier 10, which heats the charge carrier 10. This heating takes place up to a temperature by which the connecting material is at least partially melted, whereupon the charge carrier 10 is subsequently cooled again and the connecting material is solidified, so that a materially bonded and electrically conductive connection is formed between the first component and the second component.

[0037] When the charge carrier is heated with the heating plate, the high thermal conductivity of the aluminum graphite of the carrier 12 causes rapid heating of the components in this area. Thermal expansion transverse to the longitudinal axis 26 is low because the expansion coefficient of the aluminum graphite is also small in this direction. In contrast, thermal expansion of the carrier 12 along the longitudinal axis 26 is of minor importance because the carriers 12 are spaced apart by the gap 16. Since the connecting elements 14 have essentially the same expansion coefficient as the stamped copper sheet, thermal expansion of the charge carrier together with the copper sheet along the longitudinal axis 26 is essentially the same. Therefore, there is no undesirable offset of the first component and the second component during heat treatment or any possible deformation during cooling.The same applies to 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 particularly tight tolerances to be maintained during the manufacture of electronic components and advantageously accelerates the manufacturing process.

Claims

Claims: 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 of which accommodates a component group, characterized in that the support units each comprise a carrier (12) and a connecting device (13) for 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. Device according to claim 1, characterized in that the supports (12) are positively connected to the connecting element (14) by means of a fastening device (19) each. Device according to claim 1 or 2, characterized in 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 supports (12) spaced apart from one another. Device according to any one of the preceding claims, characterized in 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. Device according to any one of the preceding claims, characterized in that the connecting element (14) and the supports (12) are made of different materials.Device according to one of the preceding claims, characterized in that the first component and the second component are made of different materials. A device according to any one of the preceding claims, characterized in that the material of the connecting element (14) or the support (12) is the same as the material of the first component. A device according to any one of the preceding claims, characterized in that the material of the connecting element (14) or the support (12) is a material with an anisotropic coefficient of thermal expansion. A device according to any one of the preceding claims, characterized in that the material is a composite material, graphite, preferably aluminum-graphite, or a ceramic, preferably aluminum-silicon carbide. A device according to any one of the preceding claims, characterized in that the material of the connecting element (14) or the support (12) is a metal, preferably copper or aluminum, or a ceramic.Device according to one of the preceding claims, characterized in that a coefficient of thermal expansion (UM) of a material of the connecting element (14) and / or the support (12) and a coefficient of thermal expansion (a. m ) of a material of the first component and / or the second component by < 20 x 10' 6 / K, preferably < 10 x 10' 6 / K, especially preferred < 5 x 10' 6 / K, differ from each other or are the same size. Device according to one of the preceding claims, characterized in that a thermal conductivity (X) 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). Device according to one of the preceding claims, characterized in that a thermal diffusivity (av, ar) of the connecting element (12) and / or the support (14) and a thermal diffusivity (am, 012B) of the first component and / or the second component is < 5 mm 2 / s, preferably < 3 mm 2 / s, especially preferred < 1 mm 2 / s, differs from each other or is of the same size. 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 connected to the first component, wherein in at least one connection area of ​​the first components and the second components a connecting material is at least partially melted or diffused by means of heat treatment by a heating device and the first components are materially bonded to the second components, characterized in that a carrier (12) of the respective support unit and / or at least one connecting element (14) of a connecting device (13), for connecting the carriers to each other,During heat treatment, thermal expansion occurs in at least one linear direction, which essentially corresponds to a thermal expansion of the first component and / or the second component in the linear direction. The method according to claim 14, characterized in 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.A method according to claim 14 or 15, characterized in 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. A method according to any one of claims 14 to 16, characterized in that during the heat treatment, the first components, the second components and the supports (12) undergo thermal expansion, wherein the first components, the second components and the supports are positioned coplanarly relative to one another.Method according to one of claims 14 to 16, characterized in that a [something] is placed within the carrier (12) during the heat treatment. A temperature gradient of < 15 K, preferably < 10 K, particularly preferably < 5 K, is formed.

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