Method for joining two components

Abstract

The invention relates to a method for joining two components (12, 14) by means of a double-sided adhesive tape (20; 20a; 20b; 20c) to form a component assembly (10; 10a; 10b; 10c), in which the two components (12, 14) are pressed against each other in the region of oppositely arranged joining surfaces (13, 15; 52) of the components (12, 14) with the adhesive tape (20; 20a; 20b; 20c) interposed.

Description

Technical area

[0001] The invention relates to a method for joining two components by means of a double-sided adhesive tape to form a component composite, wherein the component composite is characterized by improved or increased shear and creep strength compared to the prior art. State of the art

[0002] From WO 2016 / 023663 A1, the applicant discloses a heat-conducting element arranged in the area of ​​a circuit carrier. This element forms a component assembly consisting of two heat-conducting components that are interconnected with an electrically insulating intermediate element formed as a double-sided adhesive tape. Such a component assembly consisting of two components is produced according to the features of the preamble of claim 1 by pressing the two components against each other in the area of ​​their oppositely arranged joining surfaces with the double-sided adhesive tape interposed. This bonds an adhesive layer of the adhesive tape to the respective joining surface of the component. Disclosure of the invention

[0003] The inventive method for joining two components using a double-sided adhesive tape to form a component assembly, having the features of claim 1, is characterized by increased shear and creep strength compared to the prior art. Within the scope of the invention, shear strength is understood to mean the strength of the adhesive bond of the double-sided adhesive tape between the components when a force is exerted on one or both components in the plane of the adhesive layer. This force leads to what is known as creep of the adhesive layer and to a reduction in shear strength. This creep behavior therefore also leads to a loss of shape and stability of the component assembly. Creep processes in the adhesive or adhesive tape can essentially be explained by the fact that, depending on the degree of crosslinking, the molecular structure / arc width and branching of side chains, fillers, etc.The molecular chains of the adhesive components can unravel under the influence of applied forces and slide past each other. It can also cause the adhesive molecular chains to slide across the joining surfaces. In both cases, this can, in extreme cases, lead to the cohesive failure of the adhesive layer or the failure of its adhesive bond to the surface of a joining part.

[0004] The invention is based on the idea of ​​achieving increased shear strength in the adhesive layer by means of individual measures not previously known from the prior art with regard to increased shear strength or a combination of these measures.

[0005] Against the background of the above explanation, a method according to the invention for joining two components by means of a double-sided adhesive tape to form a component assembly with the features of claim 1 therefore provides that the two components are pressed against one another in the region of oppositely arranged joining surfaces of the components with the adhesive tape interposed. The method according to the invention is characterized in that, to increase the shear strength of the component assembly, either a carrier layer of the adhesive tape and / or at least one of the joining surfaces is provided with a surface structuring before the components are joined with the adhesive tape. Alternatively or additionally, it can be provided that a particularly skeletal support contour is created in the adhesive tape or that the creation of the support contour is prepared.Alternatively or additionally, it can further be provided that fillers are introduced into the adhesive tape to make it more difficult for the molecular chains of an adhesive to move and / or that the polymeric base material of an adhesive is provided with grafted, e.g. hydrocarbon- or siloxane-based side chains on its oligomer chains and / or a distribution of the polymer chain length is adjusted. Finally, it is alternatively or additionally provided that the base material of an adhesive of the adhesive tape is provided with chemically reactive and subsequently activated groups on its polymer chains. With regard to double-sided adhesive tapes, there are two main types: In the first type, two adhesive layers are applied to opposite sides of a carrier material. The carrier material, which is made of plastic, forms an adhesive bond with the respective adhesive layer on the side facing the adhesive layer.Also known are so-called transfer adhesive tapes. These consist of a single layer of adhesive with a protective film on at least one side for handling and storage purposes when stored as an adhesive tape roll. This protective film is removed after the adhesive tape has been applied to a joining surface of the first component and before it is connected to the second component.

[0006] Advantageous further developments of the method according to the invention for connecting two components are listed in the subclaims.

[0007] With regard to the formation of the surface structuring, it should be mentioned that surface structuring in the context of the invention is understood to mean subsequent material processing in the area of ​​the joining surfaces, i.e. after the manufacturing of the joining surfaces of the components. In other words, this means that a surface quality of the component resulting from the manufacturing process is subsequently specifically converted or provided with the surface structuring. The effect of such surface structuring is that when shear forces or shear stresses are introduced at the interface between the adhesive and the joining surface of the component, the shear forces are weakened by force splitting, force redirection and force deflection at the surface structures. This in turn leads to minimal creep effects in the adhesive tape and on the surfaces of the joining parts.

[0008] In a first variant of the process, such surface structuring can be created by removing material from the carrier layer of the adhesive tape and / or the joining surfaces of the components (subtractive structuring). The material removal can be achieved either mechanically, through a chemical or electrochemical process, or through a physical process, for example, using laser radiation. Alternatively, however, it is also possible for the surface structuring to be created by applying an additional material to the carrier layer of the adhesive tape and / or the joining surfaces of the components, for example, through 3D printing or jet processes (additive structuring). The latter process also offers the possibility of forming the surface structuring from a different material than the component in the area of ​​the respective joining surface in order to achieve desired properties.Furthermore, it is also conceivable to create suitable surface structures by forming the surface, for example by embossing rollers.

[0009] Regardless of whether the surface structuring is created by a removal or application process, it can also be advantageous if the surface structuring is post-treated with a physical or chemical process after its formation. Such a process includes, for example, plasma treatment or the application of adhesion promoters or primers to create adhesion-promoting layers, thereby enhancing the effect of the surface structuring.

[0010] A further influence on increasing shear strength can be achieved by creating a surface structure that exhibits different shear strengths in different directions. In other words, this means that the geometry or shape of the surface structure can create, for example, claw effects or similar effects that increase the shear strength in a specific direction determined by the geometry of the surface structure.

[0011] With regard to the creation or preparation of a particularly skeletal support structure in the adhesive tape, it is mentioned that in a first variant, the support contour is created in a carrier layer of the adhesive tape before adhesive layers are applied to the carrier layer. Such support contours can be created in particular using 3D printing, in which the carrier layer of the adhesive tape provided with the support contour is covered with adhesive layers after the support contour has been formed in order to produce the double-sided adhesive tape (with carrier layer). However, if no carrier material is present, i.e. if the double-sided adhesive tape is a so-called transfer tape, the support structure can also be introduced directly into one or both sides of the (single) adhesive layer. The support structure can also be infiltrated or impregnated with the not yet cross-linked pressure-sensitive adhesive.The not yet crosslinked pressure-sensitive adhesive in the support structure is then crosslinked by a crosslinking process, for example by UV radiation or elevated temperatures, and converted into its typical pressure-sensitive adhesive state.

[0012] With regard to a further increase in shear strength when using a support contour, it is also possible to create anisotropic properties in different directions by means of an appropriate shape or geometry of the support contour in the adhesive layer or the adhesive tape.

[0013] However, such support contours as described above do not necessarily have to be fully formed during the production of the adhesive tapes, but can also be created, for example, by introducing reactive additives into the adhesive tape and activating additives into the joined component assembly. Such additives or forming components can be present in liquid, pasty, or solid form in the adhesive tape or adhesive layer. However, it is also conceivable that they are added to the adhesive in a protected encapsulation (e.g. in small hollow beads) in order to prevent premature reaction. The activation of the additives occurs in particular by an increase in temperature, by UV radiation, by mechanical stress, or similar. The reactive additives are released to start the reaction, whereby the interpenetrating skeleton or the support contour is formed.

[0014] To make it difficult for the adhesive's molecular chains to move through fillers, glass, carbon, mineral, metallic and / or polymeric fillers can be used.

[0015] Regarding the possibility of providing the polymer base material of the adhesive with (laterally) grafted side chains, for example, hydrocarbon- or siloxane-based side chains, and / or adjusting a distribution of the polymer chain length, it is mentioned that these side chains may also contain heteroatoms such as oxygen, nitrogen, phosphorus, etc. These can be, for example, tertiary-butyl or ethyl-hexyl side chains.

[0016] Regarding the possibility of providing the base material of the adhesive with chemically reactive and subsequently activatable groups on its polymer chains, it is mentioned that functional A groups and B groups are used as chemically reactive and subsequently activatable groups. These are suitable chemically reactive groups that can react with each other and lead to cross-linking between the oligomer strands. In the broadest sense, this is a two-component reaction concept. For example, the A group / component can be an alcohol group (-OH) and the B group / component a carboxylic acid group (-COOH). These groups form an ester group during a reaction, which then acts as a connecting bridge / link between the polymer chain parts involved.Further examples of suitable A groups / components are isocyanate (-NCO) and B groups / components are alcohol (-OH) or amino groups (-NHR2, -NH2R, etc.). This creates a post-crosslinking mechanism in the adhesive. The material of the adhesive tape carries chemically reactive groups on its polymer chains. As soon as the adhesive tape has been laminated to a component, these groups are exposed or activated, for example, by UV radiation. The second component is then assembled. The intrinsic instant tack of the adhesive enables immediate initial strength of the component bond, while the activation step causes the adhesive material in the pressure-sensitive adhesive bond to crosslink, forming additional links between the polymer strands within the pressure-sensitive adhesive structure. This additional cross-linking orThe additional links contribute / contribute to a reduction in the creep behavior of the adhesive tape under later external shear load.

[0017] The activation of the groups is preferably carried out by thermal treatment or by UV irradiation.

[0018] The invention further comprises a component assembly comprising two components and a double-sided adhesive tape, wherein the two components are connected in the region of oppositely arranged joining surfaces of the components with the adhesive tape interposed, wherein the component assembly was produced by means of the described method.

[0019] It is also possible to use grafted functional A groups with a mixed additive containing a functional B group as chemically reactive and subsequently activatable groups. The additive can, for example, be in the form of hollow spheres, which are released during the curing step.

[0020] Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments of the invention and from the drawings. Short description of the drawings Fig. 1 and Fig. 2 shows a simplified representation of a component assembly before and after the connection of its two components, Fig. 3 and Fig. 4 sections through component assemblies in which the adhesive tape is provided with a structure or a skeletal support contour, Fig. 5 and Fig. 6 differently formed surface structures in the area of ​​a component in longitudinal sections and Fig. 7 a section through another component assembly in which the adhesive tape was treated with an additive to form skeletal structures. Embodiments of the invention

[0021] Identical elements or elements with the same function are provided with the same reference numbers in the figures.

[0022] In the Fig. 1 and Fig. Figure 2 shows a highly simplified representation of sequential steps for producing a component assembly 10. The component assembly 10 comprises a first component 12 with a first joining surface 13 and a second component 14 with a second joining surface 15, which are joined together by pressing the two components 12, 14 against each other with a double-sided adhesive tape 20 in between.

[0023] The two components 12, 14 can be any components that, for example, form a technical unit, such as a housing or the like. For the sake of simplicity, the two components 12, 14 are depicted as plate-shaped or flat components 12, 14, respectively. In addition to thermoplastics, thermosets, or elastomers, metallic or ceramic materials or glass are also generally suitable as materials for the two components 12, 14.

[0024] The two joining surfaces 13, 15 each have surface structures 22, 24, which in the illustrated embodiment are each identically designed and are formed in the form of depressions 26, 28 in the respective joining surface 13, 15. The depressions 26, 28 are in the Fig. 1 and Fig. 2 purely by way of example and not as a limitation, the cross-section is rectangular and of the same size. The formation of the recesses 26, 28 can be achieved mechanically or in another suitable manner in which material from the respective component 12, 14 is removed. The surface structures 22, 24 or the recesses 26, 28 are only created in the joining surface 13, 15 after the actual manufacturing process of the respective component 12, 14. Alternatively, the recesses 26, 28 can also be created during the manufacturing process of the respective component 12, 14 and its surface, for example during the injection molding process of a plastic component in which an injection mold is used whose surface is designed with defined surface structures, which are then reproduced or transferred onto the injection-molded part.In other words, this means that the surface structures 22, 24 are formed in the respective component 12, 14 by an upstream process or a subsequent process or manufacturing step.

[0025] In the illustrated embodiment, the adhesive tape 20 is designed as a so-called transfer adhesive tape 30, consisting of a single adhesive layer 32. One or two protective films bonded to the adhesive layer 32 during storage or handling of the transfer adhesive tape 30 are not shown for the sake of simplicity or were not shown in connection with the Fig. 1 and Fig. 2 already removed.

[0026] The formation or joining of the two components 12, 14 to form the component assembly 10 is achieved by, in a first step, applying the adhesive tape 20 with its adhesive layer 32 to one of the two joining surfaces 13, 15. Subsequently, the two components 12, 14 are pressed against one another by means of a joining force F that runs perpendicular to the two joining surfaces 13, 15. When the two components 12, 14 are pressed against one another, the adhesive layer 32 of the adhesive tape 20 is deformed and penetrates into the recesses 26, 28 of the surface structures 22, 24. The joining process described so far can be accelerated or improved if the component assembly 10 is subjected to heat treatment or radiation treatment in the joined state, as is known per se from the prior art.

[0027] In the Fig. 3 shows an already joined component assembly 10a, in which the adhesive tape 20a is provided as a double-sided adhesive tape 20a with a carrier layer 34 made of plastic or similar material arranged between the two adhesive layers 32a, 32b. Here, too, the two components 12, 14 are each formed with surface structures 22, 24 in the form of depressions 26, 28. However, additionally, recesses 36 with a rectangular cross-section are formed in the carrier material 34 of the adhesive tape 20a as surface structures 38. The two adhesive layers 32a, 32b were applied after the surface structures 38 were formed in the carrier layer 34 by coating the carrier layer 34. After the two components 12, 14 are pressed against each other, the material of the adhesive layers 32a, 32b fills both the recesses 36 in the carrier element 34 and the recesses 26 and 28 in the joining surfaces 13 and 15.

[0028] In addition, it is mentioned that the shape and arrangement of the surface structures 22, 24 or the depressions 26, 28 can be matched to the depressions 36 of the surface structures 38 in such a way that the surface structures 22, 24 of the components 12, 14 mesh with the surface structures 38 of the adhesive tape 20a or penetrate each other (not shown).

[0029] The one in the Fig. The component assembly 10b shown in Figure 4 is characterized by the fact that a skeletal support contour 42 is arranged or formed in the carrier layer 40 of the adhesive tape 20b. This support contour 42 is then bonded or coated with the material of the two adhesive layers 32a, 32b, analogous to the recesses 36.

[0030] In the Fig. 5 illustrates the case where, for example, a component 44 made of a first material has a surface structuring 46, consisting of a material different from the material of the component 44, applied using an additive process. The surface structuring 46 has, in cross-section, rectangular structural elements 48 (made of the other material), which are arranged at an oblique angle α relative to the component 44 and form a joining surface 52. Due to the oblique position of the structural elements 48, the joining surface 52 has a direction in which increased shear forces can be absorbed.

[0031] In the Fig. 6 shows that in analogy to Fig. 5, a surface structuring 46a with structural elements 48a was formed on a component 44a using an additive process. In the illustrated embodiment, the structural elements 48a are triangular in cross-section, so that equal shear forces can be absorbed or transmitted in the direction of the double arrow 54 when the component 44a interacts with a corresponding adhesive layer 32, 32a, 32b.

[0032] Most recently, in the Fig.7 shows a component assembly 10c in which an adhesive tape 20c is used, which either has a carrier layer (not shown) or is designed as a so-called transfer adhesive tape. Two skeletal support contours 60, 62 arranged next to one another are shown by way of example in the adhesive tape 20c, wherein the support contour 60 has elements 64 running rectilinearly or perpendicularly to the plane of the adhesive tape 20c, and the support contour 62 has oval-shaped structural elements 66 arranged at an oblique angle β to the plane of the adhesive tape 20c. While the structural elements 64 absorb equal shear forces in both directions in the plane of the adhesive tape 20c, the structural elements 66 of the support contour 62 can transmit or absorb increased shear forces in the direction of arrow 68.

[0033] The component assemblies 10, 10a to 10c shown so far can be modified or altered in a variety of ways without deviating from the inventive concept. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2016 / 023663 A1

[0002]

Claims

[1] Method for joining two components (12, 14) by means of a double-sided adhesive tape (20; 20a; 20b; 20c) to form a component assembly (10; 10a; 10b; 10c), in which the two components (12, 14) are pressed and / or arranged against one another in the region of oppositely arranged joining surfaces (13, 15; 52) of the components (12, 14) with the adhesive tape (20; 20a; 20b; 20c) interposed, characterized by , that to increase the shear strength of the component assembly (10; 10a; 10b; 10c) either before joining the components (12, 14) with the adhesive tape (20; 20a), a carrier layer (34) of the adhesive tape (20a) and / or at least one of the joining surfaces (13, 15) is provided with a surface structuring (22, 24; 38; 46; 46a), and / or that a, in particular skeletal, support contour (42; 60; 62) is produced in the adhesive tape (20b; 20c) or the production of the support contour (42; 60; 62) is prepared, and / or that fillers which make it difficult for molecular chains of an adhesive to move are introduced into the adhesive tape (20; 20a; 20b; 20c), and / or that the polymeric base material of an adhesive of the adhesive tape (20; 20a; 20b; 20c) is provided with grafted, in particular hydrocarbon- or siloxane-based, side chains on its oligomer chains, and / or that a distribution of polymer chain length is set, and / or that the base material of an adhesive of the adhesive tape (20; 20a; 20b; 20c) is provided with chemically reactive and subsequently activatable groups on its polymer chains. [2] Method according to claim 1, characterized by that the surface structuring (22, 24; 38; 46; 46a) is produced by material removal on the carrier layer (34) of the adhesive tape (20a) and / or the joining surfaces (13, 15; 52) of the components (12, 14). [3] Method according to claim 1, characterized bythat the surface structuring (22, 24; 38; 46; 46a) is produced by applying an additional material to the carrier layer (34) of the adhesive tape (20a) and / or the joining surfaces (13, 15; 52) of the components (12, 14). [4] Method according to claim 2 or 3, characterized by that the surface structuring (22, 24; 38; 46; 46a) is post-treated with a physical or chemical process after its formation. [5] Method according to one of claims 2 to 4, characterized by that a surface structuring (46a) is produced which has different shear strengths in different directions. [6] Method according to one of claims 1 to 5, characterized by that the support contour (42; 60; 62) is produced in a carrier layer (40) of the adhesive tape (20b; 20c) before the application of adhesive layers (32a, 32b) to the carrier layer (40). [7] Method according to one of claims 1 to 5, characterized bythat the support contour (42; 60; 62) is produced in an adhesive layer (32a; 32b) of the adhesive tape (20b; 20c). [8] Method according to claim 5 or 6, characterized by that the support contour (42; 60; 62) is produced by an additive process, in particular a 3D printing process. [9] Method according to one of claims 6 to 8, characterized by that the support contour (42; 60; 62) has anisotropic properties with different shear strengths in different directions. [10] Method according to one of claims 1 to 9, characterized by that the support contour (42; 60; 62) is produced by introducing reactive additives into the adhesive tape (20b; 20c) and activating the additives when the component assembly (10b; 10c) is joined. [11] Method according to one of claims 1 to 10, characterized by that glass, carbon, mineral, metallic and / or polymeric fillers are used as fillers. [12] Method according to one of claims 1 to 10, characterized by that functional A groups and B groups are used as chemically reactive and subsequently activatable groups. [13] Method according to claim 12, characterized by that grafted functional A groups with a mixed additive with functional B group are used as chemically reactive and subsequently activatable groups. [14] Method according to claim 12 or 13, characterized by that the activation of the groups occurs by thermal treatment or by UV irradiation. [15] Component assembly (10; 10a, 10b, 10c) comprising two components (12, 14) and a double-sided adhesive tape (20; 20a; 20b; 20c), wherein the two components (12, 14) are connected in the region of oppositely arranged joining surfaces (13, 15; 52) of the components (12, 14) with the adhesive tape (20; 20a; 20b; 20c) interposed, characterized bythat the component assembly (10; 10a, 10b, 10c) was produced by means of the method according to one of the preceding claims.

Images