Method of laser welding a flexible circuit board with a metal contact

• US 6,919,529 B2
• Filed: 01/28/2003
• Issued: 07/19/2005
• Est. Priority Date: 07/28/2000
• Status: Expired due to Fees

• Current Assignee: Continental Automotive GmbH (Continental AG)
• Original Assignee: Siemens AG
• Inventors: Franzen, Frank, Haupt, Detlef, Loibl, Josef
• Primary Examiner(s): Evans, Geoffrey S.
• Application Number:
  US10/352,497
• Publication Number:
  US 20030114022A1
• Time in Patent Office: 903 Days
• Field of Search: 219/121.63, 219/121.64, 439/876
• US Class Current: 219/121.64
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01R 12/592 connections to contact elements
• CPC Class Codes: H01R 43/0221 Laser welding H01R43/0228 takes precedence
• CPC Class Codes: H05K 1/118 specially for flexible printed circuits, e.g. using folded portions
• CPC Class Codes: H05K 1/189 characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 2203/107 Using laser light shaping a substrate by laser ablation H05K3/0026
• CPC Class Codes: H05K 3/328 by welding
• CPC Class Codes: H05K 3/3447 Lead-in-hole components H05K3/3415 takes precedence

Abstract

A method for producing an electrical circuit between a flexible circuit board (1) is described, with single-sided access and a metallic contact partner (8), such that the contact partner (8) reaches the metallic conductor strip (4) of the circuit board (1) through an access opening (6) in the unit. The circuit board (1) is thus irradiated with laser light (9) in a region opposite the access opening (6) causing a welded connection between the contact partner (8) and the conductor strip (4) to be formed.

Claims

1. A method for producing an electrical connection between a flexible circuit board with single-sided access and a metallic contact partner, comprising the steps of:

providing the flexible circuit board, comprising two insulating layers and at least one metallic conductor strip running in between, wherein in the first insulating layer of which there is formed an access opening exposing the conductor strip;

bringing the metallic contact partner and the circuit board toward each other in such a way that the metallic contact partner is brought to bear against the metallic conductor strip through the access opening; and

irradiating the second insulating layer with laser light at a location lying opposite the access opening, wherein a welded connection being formed between the contact partner and the conductor strip.

2. The method as claimed in claim 1, wherein

the irradiation is carried out without instantaneously melting the contact partner.

3. The method as claimed in claim 1, wherein

the welding operation is carried out in such a way that a melting depth of the surface of the contact partner of between 0.5 and 1 mm is obtained by the laser light irradiation.

4. The method as claimed in claim 1, wherein an Nd:

YAG laser is used as the laser light source and is operated at an average power in the range from 30 to 500 W.

5. The method as claimed in claim 1, wherein

a light spot with a diameter of between 0.3 and 0.6 mm is produced on the second insulating layer by means of an optical system lying in the beam of the laser.

6. The method as claimed in claim 1, wherein

a welding energy of from 7 to 11 J is applied during a welding period of from 3 to 10 ms.

7. The method as claimed in claim 1, wherein

a pulsed Nd:

YAG laser with a pulse power of 1 to 3 kW is used.

8. The method as claimed in claim 1, wherein

a number of laser light pulses applied to the second insulating layer in a positionally offset manner are used for creating the welded connection.

9. The method as claimed in claim 1, wherein

the contact partner has a silvered bearing surface.