Method of patterned metallization of substrate surfaces

• US 5,593,739 A
• Filed: 02/14/1996
• Issued: 01/14/1997
• Est. Priority Date: 02/14/1995
• Status: Expired due to Fees

• Current Assignee: LPKF Laser & Electronics AG
• Original Assignee: LPKF Cad/Cam Systeme GmbH
• Inventors: Kickelhain, Joerg
• Primary Examiner(s): PIANALTO, BERNARD D
• Application Number:
  US08/601,120
• Time in Patent Office: 335 Days
• Field of Search: 427/96, 427/98, 427/123, 427/258, 427/264, 427/265, 427/271, 427/272, 427/282, 427/385.5, 427/404, 427/407.1, 427/429, 427/421, 427/430.1, 427/555, 427/558, 427/559
• US Class Current: 427/555
• CPC Class Codes: B05D 3/00 Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials successively applying liquids or other fluent materials B05D1/36; drying ovens F26B
• CPC Class Codes: C23C 18/1605 by masking
• CPC Class Codes: C23C 18/1653 Two or more layers with at least one layer obtained by electroless plating and one layer obtained by electroplating
• CPC Class Codes: C23C 18/2066 Use of organic or inorganic compounds other than metals, e.g. activation, sensitisation with polymers
• CPC Class Codes: C23C 18/30 Activating or accelerating or sensitising with palladium or other noble metal
• CPC Class Codes: H05K 3/185 by making a catalytic pattern by photo-imaging

Abstract

A method for patterned metallization of substrate surfaces, especially circuit boards, even three-dimensional ones, by using electromagnetic UV radiation, particularly from an excimer laser. In the method a primer layer is applied to the full substrate surface in the area of a metal layer that is subsequently applied; insulating channels then are made in the primer layer by complete removal of the primer in certain areas by the action of electromagnetic radiation in the UV range; and afterward the remaining patterned primer layer is provided with the metal layer to form conductor strips. The method makes it possible to create insulating channels with extremely sharp contours in the primer layer on the surface of even three-dimensional, electronic circuit media.

Claims

1. A method for patterned metallization of a substrate surface comprising the steps of:

applying a layer of primer to entirely cover a substrate surface in an area where a metallized pattern is to be formed;

selectively ablating portions of the primer layer from the substrate by exposing said portions to the action of electromagnetic ultraviolet radiation to completely remove the primer from the exposed portions so that a patterned primer layer with primer-free insulating channels formed therein remains on the substrate surface; and

thereafter depositing a metal layer on the remaining patterned primer layer to form conducting paths.

2. A method according to claim 1, wherein the substrate surface has a three-dimensional configuration.

3. A method according to claim 1, wherein the substrate is an electronic circuit board.

4. A method according to claim 1, wherein the electromagnetic UV radiation is applied by means of an excimer laser.

5. A method according to claim 4, wherein the laser is a krypton-fluoride excimer laser with a wavelength of 248 nm.

6. A method according to claim 1, wherein the insulating channels in the primer layer are wider by twice the thickness of the deposited metal layer than is necessary for insulation between the conducting paths, such that deposition of the metal layer on flanks of the patterned primer layer leaves sufficiently wide insulating channels between adjacent conductive paths.

7. A method according to claim 1, wherein the insulating channels and conductive paths have widths in the range from 5 μ

m to 200 μ

m.

8. A method according to claim 7, wherein the insulating channels and conductive paths have widths in the range from 10 μ

m to 100 μ

m.

9. A method according to claim 1, wherein portions of the primer layer are ablated from the substrate by exposing the primer layer to an ultraviolet radiation image corresponding to the insulating channels.

10. A method according to claim 9, wherein the primer layer is exposed to radiation from an excimer laser through a mask interposed between the laser and the primer layer.

11. A method according to claim 1, wherein portions of the primer layer are ablated by exposing the primer layer to a focused excimer laser beam which scans a pattern corresponding to the insulating channels.

12. A method according to claim 1, wherein the primer layer is applied to the substrate by a method selected from the group consisting of brushing, spraying, printing, dipping or precipitation.

13. A method according to claim 1, wherein the primer is a non-conductive paste comprising a catalytic activator for non-electrical metallization.

14. A method according to claim 1, wherein the metal layer is deposited on the remaining patterned primer layer to form conducting paths by non-electrical deposition from a non-electrical metallization bath.

15. A method according to claim 1, further comprising the additional step of galvanically applying additional metal onto the deposited metal layer to increase the thickness of the conducting paths.