Method for producing a substrate arrangement, substrate arrangement, and method for connecting a substrate arrangement to an electronic component

Abstract

One aspect relates to a method for manufacturing a substrate assembly for attachment to an electronic component A substrate is provided with a first side and a second side. A contact material layer is applied to the first side of the substrate. A pre-fixing agent is applied at least to sections of a side of the contact material layer facing away from the substrate.

Claims

1. A method for manufacturing a substrate assembly for attachment to an electronic component, the method comprising: providing a substrate with a first side and a second side; applying a contact material layer to the first side of the substrate such that the substrate has a lateral edge on which no contact material is applied; applying a pre-fixing agent at least to sections of a side of the contact material layer facing away from the substrate; positioning the substrate with applied contact material layer and applied pre-fixing agent on a carrier film such that the first side of the substrate is arranged to face the carrier, and wherein the pre-fixing agent is at least adhesively bonded with the carrier; separating the substrate, while applied to the carrier film, into multiple substrate assemblies, including separating from the substrate the lateral edges on which no contact material is applied.

2. The method of claim 1, wherein the substrate is one of a group comprising a metal sheet, a metal band section, a copper sheet, a copper band section, a lead frame, a DCB substrate, and a PCB substrate.

3. The method of claim 1, wherein the substrate or a substrate blank is coated on at least one side with a material comprising one of gold (Au), nickel-gold (NiAu), silver (Ag), nickel-silver (NiAg), nickel-palladium-gold (NiPdAu), by galvanising or chemical plating.

4. The method of claim 1, wherein the contact material layer applied to the substrate has a layer thickness in a range comprising one of from 10-150 m, from 30-100 m, and from 40-80 m.

5. The method of claim 1, wherein after a contact material layer is applied, the substrate has a lateral edge on which no contact material layer has been applied, and wherein the edge has such a width (b.sub.R) that is not more than 20% of the total width (b.sub.S) of the substrate.

6. The method of claim 1, wherein at least sections of a lateral edge of the substrate, in the state in which it is attached to the carrier, are detached and/or the substrate is structured and/or separated, in the state in which it is attached to the carrier.

7. The method of claim 6, wherein the detachment of the lateral edge and/or the structuring of the substrate and/or the separation of the substrate is/are carried out by means of laser.

8. The method of claim 6, wherein at least sections of the contact material layer and/or the pre-fixing agent is/are detached and/or structured and/or separated when the lateral edge is detached and/or when the substrate is structured and/or when the substrate is separated.

9. The method of claim 1, wherein contact material of the contact material layer comprises auxiliary sintering agent and silver particles, and wherein the pre-fixing agent comprises the same auxiliary sintering agent.

10. The method of claim 1, contact material comprising a sintering paste including metal particles and auxiliary sintering agents, the pre-fixing agent being a sintering agent of the sintering paste.

11. The method of claim 10, the auxiliary sintering agents being at least one of organic compounds, fatty acids, and binding agents.

Description

(1) In the following text, the invention and further features thereof will be explained in greater detail with reference to the accompanying schematic drawings based on exemplary embodiments. In the drawings:

(2) FIGS. 1-5: show individual steps of the method for producing a substrate assembly;

(3) FIGS. 6a-8: show individual steps of a method according to the invention for attaching an electronic component to a substrate assembly according to a first embodiment; and

(4) FIGS. 9-11: show individual steps of a method according to the invention for attaching an electronic component to a substrate assembly according to another embodiment.

(5) In the following text, the same reference numbers will be used for identical and functionally equivalent parts.

(6) In FIG. 1, a substrate 11 is represented. Substrate 11 has a first side 12 and a second side 13. Substrate 11 is preferably a copper band section. It is also possible for copper alloys band sections to be used.

(7) It may be provided further that substrate 11 is coated on one or both sides 12 and 13 thereof. The first side 12 and/or the second side 13 is/are preferably coated, particularly galvanised with gold or nickel-gold or silver or nickel-silver or nickel-palladium-gold.

(8) In the example shown, the first side 12 of substrate 11 is designed parallel to the opposite, second side 13 of substrate 11.

(9) FIG. 2 shows that a contact material is applied to side 12 of substrate 10 to form a contact material layer 15. The contact material of contact material layer 15 is preferably a sintering paste, particularly a silver sintering paste. A sintering paste typically consists of auxiliary sintering agents and metal particles. In particular, the metal particles are silver particles. The auxiliary sintering agents are organic compounds and/or fatty acids and/or binding agents.

(10) Contact material layer 15 may be applied to the first side 12 of the substrate 11 with the aid of a pressing process. A contact material layer 15 is preferably applied to the largest possible area of the first side 12 of substrate 11. However, narrow edges 19 may remain on substrate 11 or on the first side 12 of substrate 11 which are not covered with the contact material layer 15 due to the selected application technique, for example in the pressing process.

(11) Edge 19 preferably has such a width b.sub.R, which particularly constitutes not more than 5% of the total width b.sub.S of the substrate 11. As is shown in FIG. 3 a pre-fixing agent 18 is applied to the first side 16 of contact material layer 15. The first side 16 of contact material layer 15 is the side of the contact material layer 15 facing away from substrate 11 or the first side 12 of substrate 11.

(12) Pre-fixing agent 18 is applied to this first side 16 of the contact material layer in the form of droplet-shaped elements or elliptical elements. The pre-fixing agent 18 comprises the same auxiliary sintering agent as the contact material of contact material layer 15. The effect of this is that when the substrate assembly 10 is brought into contact with an electronic component no contaminations or materials of other kinds are introduced into contact material layer 15.

(13) According to FIG. 3, substrate assembly 10 comprises substrate 11, contact material layer 15 and pre-fixing agent 18. The contact material layer 15 applied to the substrate 11 has a layer thickness from 40-80 m.

(14) As is shown in FIG. 4, substrate 11 with the contact material layer 15 applied and the pre-fixing agent 18 applied is positioned on a carrier 20 in such manner that the first side 12 of substrate 11 is arranged to face carrier 20, wherein the pre-fixing agent 18 is at least adhesively bonded with carrier 20. Carrier 20 may be a carrier film. In the example shown, a UV tape is stretched over a wafer frame, so that substrate 11 is applied to this UV tape together with the contact material layer 15 and pre-fixing agent 18. In the representation according to FIG. 4, substrate assembly 10 thus comprises the carrier 20, the substrate 11 as well as the contact material layer 15 and pre-fixing agent 18.

(15) FIG. 5 shows that substrate assembly 10 has been brought into a desired final part geometry. With the aid of a laser, for example, the edges 19 are removed. Substrate 11 in the state in which it is attached to carrier 20 is also detached. Cutouts 25 are introduced into substrate 10, so that the substrate assembly 10 is divided into three individual geometries or three smaller substrate assemblies 10. When the lateral edge 19 was detached and when substrate 11 was separated, at least sections of the contact material layer 15 and the pre-fixing agent 18 were also detached or structured and separated.

(16) As represented in FIG. 6a, a separated substrate assembly 10 is detached from carrier 20 with the aid of a nozzle 40. The separated substrate assembly 10 may be for example the left substrate assembly 10 of FIG. 5. The adhesive bond between the fixing agent 18 and the carrier 20 is removed by the application of a tensile force to substrate assembly 10, so that substrate assembly 10 may be attached to electronic component 30 again with the aid of nozzle 40. Substrate assembly 10 and electronic component 30 are positioned relative to each other in such manner that the first side 12 of substrate 11 is arranged to face electronic component 30.

(17) According to FIG. 7, substrate assembly 10 is pre-fixed to the at least one electronic component 30 by the pre-fixing agent 18 applied to at least sections of the first side 16 of contact material layer 15. Substrate assembly 10 is accordingly pre-fixed on the first side 31 of electronic component 30 with the aid of the pre-fixing agent 18. Pre-fixing may be carried out by the application of light pressure and/or the application of heat. On other hand, in the embodiment shown the second side 32 of electronic component 30 is free of further layers and/or components.

(18) In FIG. 8, the electronic component 30 is represented in the state in which it is attached to the substrate assembly. The pre-fixing agent 18 is dissolved when the substrate assembly 10 is attached to the electronic component 30, particularly when sintering and/or pressing and/or bonding. All that remains is the contact material layer 15. Since the pre-fixing agent 18 comprises the same auxiliary sintering agent as the contact material in contact material layer 15, the contact material layer is not contaminated. In other words, after processing the pre-fixing agent or the pre-applied adhesive is inactive and no longer present.

(19) A second embodiment relating to a method for attaching at least one electronic component to a substrate assembly 10 is represented in FIGS. 9-11. The method steps shown are typically preceded by the method steps represented in FIGS. 1-3, wherein substrate 13 may also be a lead frame, a DCB or a PCB. Accordingly, it is possible to position two electronic components 30 and 30 on a substrate assembly 10, which in the example shown does not comprise a carrier. Electronic components 30 and 30 are positioned in a mounting process. In this context, a pick-and-place process is conceivable.

(20) In the example represented in FIG. 9, heat may also be applied. Electronic components 30 and 30 are each positioned so that the first sides 31 of the electronic components 30 and 30 are facing towards the first side 12 of the substrate 11, so that electronic components 30 and 30 can be pre-fixed on substrate assembly 10 by the pre-fixing agent 18 on the first side 16 of contact material layer 15. As is represented in FIG. 10, electronic components 30 and 30 are secured for further processing by the pre-fixing agent 18 or pre-applied adhesive.

(21) The pre-fixing is followed by the actual attachment of substrate assembly 10 to the electronic components 30 and 30. The term attachment is understood to mean the joining of the substrate assembly 10 to electronic components 30 and 30. The attachment may be carried out by soldering or pressing or sintering or adhesive bonding. In this context it is conceivable that the substrate assembly 10 is sintered together with electronic components 30 and 30 in a process furnace, e.g., a pressure sintering furnace or a sintering press or a reflow furnace or a laminating furnace. Pre-fixing agent 18 is removed almost entirely, particularly burned off and/or melted off during the attachment, preferably sintering. After processing, the pre-applied adhesive is inactive and no longer present.

(22) It should be noted at this point that of the method steps and elements described in the preceding text in connection with the embodiments according to FIGS. 1-11, particularly the details represented in the drawings may be claimed as essential to the invention either alone or in any combination.