Method for manufacturing a MID circuit carrier and MID circuit carrier

Abstract

Method for manufacturing a MID circuit carrier (1), comprising at least the following steps: injection molding technique formation of a one-piece injection molded body (3) having a substrate (7) and a contact area (2), structuring of a circuit surface area (4a) on the substrate (7) and a contact flag surface area (2a) on the contact area (2) by activating metal nuclei (16), wherein conductor track areas (105) are structured on the circuit surface area (4a) extending to the contact flag surface area (2a) of the contact area (2), applying a first metal layer (21) without external current to the structured circuit surface area (4a) and the contact flag surface area (2a) such that at least two conductor tracks (6) extend from the circuit surface area (4a) to at least one conductor junction (12) formed on the contact flag surface area (2a), wherein the conductor tracks (6) are contacted with each other via the at least one conductor junction (12), electrochemical formation of a second metal layer (18) on or with the first metal layer (21) by applying an electrical potential (V) to the conductor junction (12), and Remove at least the conductor joining (12) and electrically disconnect the conductor tracks (6).

Description

[0001] The invention relates to a method for manufacturing a MID circuit carrier and such a MID circuit carrier. State of the art

[0002] MID (Molded Interconnect Devices) circuit carriers are injection-molded circuit carriers that feature a substrate with a three-dimensional shape and metallic conductive traces formed on at least one surface area of ​​the substrate. This allows for a largely free, three-dimensional shaping of the substrate, or the integration of the conductive traces into the surface of a body that can be designed largely freely in three dimensions.

[0003] Various MID manufacturing processes are known, such as two-component injection molding and laser MID processes like laser direct structuring (LDS). In LDS, metallic nuclei, e.g., small metal particles, are incorporated into the plastic material, which is then shaped using the injection molding process. Subsequently, structuring is performed using a laser, exposing the metal nuclei in the surface area to be structured. The surface area or the entire injection-molded part is then subjected to passive electroplating in a galvanizing bath, e.g., in a solution containing copper ions. This results in chemical electroplating due to the potential difference between the metal nuclei and the copper ions in the solution, forming an initial metallization layer, generally consisting of unalloyed copper.

[0004] Passive electroplating can be continued to create thicker conductor tracks; however, the conductor tracks also grow in lateral width, so that with a fine pitch or grid spacing (i.e., small lateral distances between the conductor track centers), short circuits can occur after a certain process duration. Furthermore, during passive electroplating, contaminants can be incorporated into the structure via the solution, thus limiting the material properties, especially ductility. An advantage of passive electroplating is therefore that a fine grid spacing or small conductor track widths can initially be achieved, but the conductor track thickness and material quality are limited.

[0005] Following the formation of the first metal layer in passive electroplating, active electroplating can be carried out by applying an electrical potential, i.e., an electrical voltage, to the individual conductive tracks relative to a suitable electroplating bath. Active electroplating is faster from a process engineering perspective and allows the use of specific materials, e.g., for the formation of a gold-nickel alloy, with higher ductility and improved material properties.

[0006] However, when forming a conductor track structure with small lateral conductor track widths and a fine grid spacing of, for example, less than 150 µm, or even less than 100 µm, contacting the individual conductor tracks for active electroplating is sometimes difficult.

[0007] Document EP 0 968 631 A1 describes a method for forming metallic conductor patterns with solderable and / or bondable connection areas on electrically insulating substrates.

[0008] Document US 2007 / 0148420A1 describes a process for manufacturing printed circuit boards in which vias and conductor tracks are defined by laser activation of a thin layer and subsequently built up by electroless copper deposition.

[0009] Document WO 2013 / 055786 A1 describes a process for electroless copper deposition on laser-direct structured plastic substrates.

[0010] Document EP 0 277 118 B1 describes a process in which a removable busbar on a printed circuit board electrically connects the contact surfaces to be electroplated, these surfaces are electroplated and the busbar is then removed from the substrate.

[0011] Document WO 2008 / 120147 A1 describes a process in which a textile substrate is first provided with a continuous electrode, which is then electroplated and subsequently converted into a conductor track pattern for connecting electronic components by means of cutouts. Disclosure of the invention

[0012] According to the invention, a MID method is provided in which the injection-molded body is formed with a contact area, e.g. a contact flag, on which at least one conductor junction is provided that contacts at least two conductor tracks.

[0013] In particular, only a single conductor junction, i.e., a central conductor junction for contacting all conductor tracks, may be provided; however, in principle, the formation of several conductor junctions, e.g., several contact areas, each with a conductor junction, is also possible.

[0014] The formation of the conductor junction in the MID manufacturing process is carried out for an active electrolytic application of a second metal layer, i.e., active electroplating under the application of a voltage; however, the conductor junction is subsequently removed, so that the conductor tracks are separated from each other. According to the invention, several advantages are achieved:

[0015] By actively applying a voltage to the electroplating process, suitable materials can be selected, resulting in favorable material properties, particularly high ductility and thus high mechanical strength. This active electrolytic deposition can be carried out under defined conditions, with the layer thickness determined by the amount of charge applied and therefore the electric current. Furthermore, lateral growth of the conductive traces, and thus the risk of a short circuit, can be avoided or at least reduced.

[0016] Small lateral conductor track widths and fine pitches, e.g., with conductor track widths of less than 60 µm and a pitch of less than 150 µm (e.g., less than 100 µm), can be achieved because the conductor junction or a connection contact associated with the conductor junction can be designed with a larger lateral width and thus easily electrically contacted. Therefore, the lateral width of the conductor tracks and the pitch are not fundamentally limited by the electrolytic process.

[0017] The conductor tracks are contacted with each other via the common conductor junction - or several conductor junctions - whereby the conductor junction is only intended for the step of active electrolytic application or active electroplating, but is subsequently removed again so that the conductor tracks serve separate functions in the usual way, e.g. enabling different contacts of electrical components.

[0018] The removal of the conductor junction can advantageously be achieved by removing the entire contact area, which can thus be designed, for example, as a thin contact flag that is only temporarily formed as part of the injection-molded body, but is then removed.

[0019] For this purpose, the contact area or contact tab can be designed with a predetermined separation point, at which it is subsequently separated. Thus, the individual conductor tracks extend across the predetermined separation point to the at least one conductor junction provided in the contact area, so that the separation or galvanic isolation of the individual conductor tracks already occurs when cutting along the predetermined separation point. The predetermined separation point can also be formed by mechanical thinning, i.e., in particular as a predetermined breaking point, so that a mechanical breaking process occurs, for example, by bending or mechanical cutting. Furthermore, the predetermined separation point can also be separated by laser cutting or laser ablation. This enables further advantages:

[0020] It is simply a matter of structuring and electroplating a larger surface area, which, in addition to the circuit surface area of ​​the substrate, has a contact flag surface area for the conductor joining and, if necessary, the connection contact; however, this does not lead to any process delay.

[0021] By separating the contact area, a galvanic isolation or singulation of the individual conductor tracks is achieved with a high degree of certainty.

[0022] Thus, the inventive method allows for high process reliability with very little additional effort, with significant advantages, such as in particular the improvement of the electroplating process and material selection, as well as fast process control.

[0023] Instead of completely removing the contact area, only the conductor junction and, if applicable, the additional connection contact can be removed from the contact area, e.g., by laser ablation. This allows the contact area to be used subsequently, e.g., for positioning or handling the MID circuit carrier.

[0024] The conductor junction can be linear, especially if, for example, the intended separation point is designed as a predetermined breaking point for directly breaking or cutting off the contact area. However, non-linear or non-straight conductor junctions are also possible, allowing for separation by cutting or punching, or even the laser ablation described above. Brief description of the drawings Fig. Figure 1 shows a MID circuit carrier according to an embodiment of the invention before the contact tab is cut off, with a detail magnification; Fig. 2 to 6 successive steps of a method for manufacturing the MID circuit carrier according to an embodiment of the invention. Description of the embodiments

[0025] According to Fig. 1 is a three-dimensional injection-molded body 3 made of a plastic material or mold material. A conductor track structure 5 with several individual conductor tracks 6 is formed on at least one surface area 4 of the injection-molded body 3. According to the embodiment shown in the figures, the surface area 4 structured with the conductor tracks 6 is essentially planar or flat; however, conductor tracks 6 can also be formed on curved or three-dimensionally shaped surfaces, e.g., in the one shown in Fig. 1 cylindrical area shown further below.

[0026] The one-piece injection-molded body 3 has as sub-areas a substrate 7 and a contact tab 2, which are connected via a predetermined breaking point 8, wherein the predetermined breaking point 8 is e.g. as a thinning, e.g. as in Fig. 1 shown by a cut 9, a depression or notch. The structured surface area 4 extends from the substrate across the predetermined breaking point 8 to the contact tab 2; thus, a circuit surface area 4a is formed on the substrate 7 and a contact tab surface area 2a is formed on the contact tab 2, which are formed by one or more common continuous metallization layers extending across the predetermined breaking point 8.

[0027] The individual conductor tracks 6 extend across a terminal strip 10, which is angled at a right angle here, and from the terminal strip 10 via the predetermined breaking point 8 to a common conductor junction 12 formed on the contact flag surface area 2a, which is thus electrically contacted with all conductor tracks 6, the conductor junction 12 transitioning into or being connected to a terminal contact 14 formed on the contact flag surface area 2a. The central terminal strip 10 can, for example, also extend completely across the contact flag 2, although such a design is more complex and expensive.

[0028] The substrate 7 with the circuit surface area 4a forms a MID circuit carrier 1 up to the predetermined breaking point 8, wherein the several conductor tracks 6 of the circuit surface area 4a are initially electrically connected or short-circuited via the conductor junction 12.

[0029] Alternatively to the embodiment of Fig. 1 can also be configured as a MID circuit carrier 1 with several contact lugs 2, so that the central terminal strip 10 of each contact lug 2 is then contacted with a part of the lines 6.

[0030] The production of the MID circuit carrier 1 is in the Fig. Sections 2 to 6 describe one embodiment. In principle, MID circuit carriers 1 can be manufactured using different MID manufacturing processes. Laser direct structuring (LDS) is described below in particular, without limiting the generality of the method.

[0031] First, according to Fig. 2 the injection molded body 3 is formed from a plastic material containing additives or mold material in an injection molding process.

[0032] In this process, the injection-molded body 3 can be formed in a single step, or the substrate 7 is formed first and the contact flag 2 is injected.

[0033] The following will be discussed in the Fig. 3 to 5 of the surface area 4 is structured; this can be achieved in particular by laser direct structuring (LDS) using a laser beam 13 indicated here, but other MID processes are also possible. Through laser direct structuring in Fig. 3 will therefore initially be - in Fig. Three indicated metal nuclei 16 are exposed and thus activated. This exposes, firstly, conductor track areas 106 of the later conductor tracks 6, then a merging area 112 at the location of the later conductor merging 12, and a connection contact area 114 at the location of the later connection contact 14.

[0034] The following will be according to Fig. 4 a short external current-free metal layer 21, in particular a copper (Cu) layer 21 as a conductive material is applied.

[0035] Thus, in the step of Fig. 4. Chemical electroplating through potential difference, without applying an external voltage. The step of Fig. 4 is thus carried out by immersion in a suitable bath 13, in particular a solution with copper ions which have a higher voltage potential than the metal nuclei 16.

[0036] The following will be according to Fig. 5. The injection-molded body 3 is actively electrolytically coated. For this purpose, the injection-molded body 3 is generally placed in a suitable electrolyte bath containing suitable metal ions, e.g., copper, nickel, and gold ions (Cu, Ni, Au), and a suitable potential V is applied to the terminal contact 14 of the contact tab 2 and thus to the central terminal strip 10, generally with a negative potential V at the terminal contact 14 relative to another electrode 20 immersed in the electrolyte bath. By applying the voltage U, the terminal contact 14, together with the central terminal strip 10 and all conductor tracks 6, is thus placed at a common negative potential relative to the bath or the other electrode 20 in the electrolyte bath 17. This forms the metal layer 18, which, according to the structure, forms the conductor track structure 5 with the conductor tracks 6, the conductor junction 12, and the terminal contact 14. Fig. 1.

[0037] The following is done in accordance with Fig. 6. The separation of the contact tab 2. This can be achieved, in particular, by mechanical separation through breaking off the contact tab 2, i.e., by bending, since a controlled break forms at the predetermined breaking point 8. Because the individual conductor tracks 6 extend over the predetermined breaking point 8, the conductor tracks 6 are no longer connected to each other after removal of the contact tab 2 and the central conductor junction 12, but can be individually connected at the terminal block 10.

[0038] Instead of mechanical breaking, the contact strip 2 can also be separated by laser cutting or mechanical cutting; furthermore, other disruptive separation methods are also possible.

[0039] In a opposite Fig. In the modified embodiment 6, the contact flag 2 is retained; accordingly, the predetermined breaking point 8 is also generally not required and is advantageously not present in this embodiment. The following are described in the Fig. In the following step, the conductor tracks 6 are electrically separated from each other by selectively removing at least the central conductor junction 12, e.g., also the connection contact 14, e.g., by laser ablation. The contact tab 2 can then subsequently serve to position the MID circuit carrier 1.

[0040] But also in the design of the Fig. Steps 2 to 6 can be the step of separating from Fig. 6 after assembly, so that the contact flag 2 can subsequently be used to position the MID circuit carrier 1.

[0041] The conductor flag configuration 5 can have a high number, e.g. more than ten conductor tracks 6, wherein the individual conductor tracks 6 have, e.g. conductor track widths L less than 60 µm, and a pitch distance d less than 100 µm (distance between the individual conductor tracks 6 or the conductor track centers).

Claims

[1] Method for manufacturing a MID circuit carrier (1), comprising at least the following steps: injection molding technique formation of a one-piece injection molded body (3) having a substrate (7) and a contact area (2), structuring of a circuit surface area (4a) on the substrate (7) and a contact flag surface area (2a) on the contact area (2) by activating metal nuclei (16), wherein conductor track areas (105) are structured on the circuit surface area (4a) extending to the contact flag surface area (2a) of the contact area (2), applying a first metal layer (21) without external current to the structured circuit surface area (4a) and the contact flag surface area (2a) such that at least two conductor tracks (6) extend from the circuit surface area (4a) to at least one conductor junction (12) formed on the contact flag surface area (2a), wherein the conductor tracks (6) are contacted with each other via the at least one conductor junction (12), electrochemical formation of a second metal layer (18) on or with the first metal layer (21) by applying an electrical potential (V) to the conductor junction (12), and Remove at least the conductor joining (12) and electrically disconnect the conductor tracks (6). [2] Method according to claim 1, characterized by , that a predetermined separation point (8) is formed between the substrate (7) and the contact area (2), wherein the multiple conductor tracks (6) extend from the circuit surface area (4a) via the predetermined separation point (8) to the conductor junction (12), and When removing the conductor joining (12), the contact area (2) is separated from the substrate (7) along the intended separation point (8) and the conductor tracks (6) are separated. [3] Method according to claim 2, characterized by , that the intended separation point (8) is designed as a predetermined breaking point (8) with a material thinning, e.g. a notch (9) and the contact area (2) with that of the line joining (12) is mechanically separated, e.g. by bending and breaking. [4] Method according to claim 2, characterized by , that the contact area (2) at the intended separation point (8) is separated by laser cutting. [5] Method according to claim 1 or 2, characterized by , that at least one conductor joining (12) is removed without separating the contact area (2), e.g. by laser ablation. [6] Method according to any one of the preceding claims, characterized by , that the first metal layer (21) is formed in a first bath (13), in particular with copper ions, and the second metal layer (18) is formed in a second bath (17), in particular with gold ions, wherein an electrical voltage (U) is applied between an electrode (20) placed in the second bath (17) and the first metal layer (21). [7] Method according to any of the preceding claims, characterized by, that on the contact area (2) a connecting contact (14) is contacted with the at least one conductor junction (12), wherein the connecting contact (14) has a larger lateral width (a) than the individual conductor tracks (6) and is provided for making an electrical contact for the electrolytic application of the second metal layer (18). [8] Method according to any one of the preceding claims, characterized by , that the plastic material has metal nuclei (16) which are exposed during structuring by laser structuring, in particular by laser direct structuring, and are provided for the formation of the conductor tracks (6), the at least one conductor junction (12) and preferably the terminal contact (14). [9] MID circuit carrier (1) that can be manufactured by a method according to any of the preceding claims. [10] MID circuit carrier (1) according to claim 9, characterized by, that the conductor tracks (6) have a first metal layer (21) and a second metal layer (18) formed by active electrolytic galvanizing, wherein the conductor tracks (6) have a spacing (d) of less than 150 µm, e.g. less than 100 µm. [11] MID circuit carrier (1) according to claim 10, characterized by , that the conductor tracks (6) have conductor track widths (L) that are less than 60 µm.

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