Magnetic microcontactor and manufacturing method thereof

• US 5,605,614 A
• Filed: 06/14/1995
• Issued: 02/25/1997
• Est. Priority Date: 06/17/1994
• Status: Expired due to Term

• Current Assignee: Asulab SA (The Swatch Group AG)
• Original Assignee: Asulab SA (The Swatch Group AG)
• Inventors: Bornand, Etienne
• Primary Examiner(s): Gorgos, Kathryn
• Assistant Examiner(s): Mee, Brendan
• Application Number:
  US08/490,546
• Time in Patent Office: 622 Days
• Field of Search: 205/122, 205/90, 205/178, 335/38, 335/154
• US Class Current: 205/50
• CPC Class Codes: H01H 1/0036 Switches making use of microelectromechanical systems [MEMS] for electromagnetic relays H01H50/005; for electrostatic relays H01H59/0009
• CPC Class Codes: H01H 1/66 Contacts sealed in an evacuated or gas-filled envelope, e.g. magnetic dry-reed contacts
• CPC Class Codes: H01H 2036/0093 Micromechanical switches actuated by a change of the magnetic field

Abstract

Microcontactor able to be activated by a magnet comprising a flexible beam (5) in one or more conducting materials (13, 14, 15), having one end (4) attached to an insulating substrate (1) via the intermediary of a foot (3), and one free distal end (6) positioned above a contact stud (2) arranged on said substrate (1), said foot (3) and stud (2) being composed of conducting materials and provided with connecting means (7, 8, 9, 10) to an external electronic circuit, and said beam (5) being at least partly composed of a ferromagnetic material in which the beam (5), the foot (3) and the stud (2) are elements formed by electrodeposition of conducting materials from two areas (9, 10) of the substrate, said electrodeposition being carried out through a succession of masks (20, 30, 40) which are subsequently removed.

Claims

1. Method of manufacturing a magnetic microcontactor comprising a flexible beam in one or more conducting materials, having one end attached to an insulating substrate via the intermediary of a foot, and a free distal end disposed above a contact stud arranged on said substrate, said feet and stud being composed of conducting materials and provided with connecting means to an external electronic circuit, and said beam being at least partly composed of a ferromagnetic material activated by a magnet enabling distal end to move towards or away from the contact stud to establish or to break an electrical contact, consisting in the successive steps of:

a) forming two separate conducting areas each comprising a gripping metallization layer and a layer of a non oxidizable metal on the substrate;

b) forming a first mask by depositing a layer of photoresist and configuring the latter, so as to form at least two windows disposed above a conducting area in the vicinity of their facing edges, said windows having substantially vertical walls;

c) growing by electrodeposition, inside the windows, a conducting material in order to obtain studs until said material is flush with the photoresist surface;

d) forming a second mask by depositing a layer of photoresist and configuring, over its entire thickness, a window above a single stud, said window having tapered walls;

e) depositing an intermediate metallization layer over the whole surface of the photoresist, walls and the bottom of the window formed in step d);

f) forming a third mask by depositing a thick layer of photoresist and configuring, over its entire thickness, a channel extending between the farthest edges of the studs disposed on the edges facing the conducting areas;

g) growing by electrodeposition a ferromagnetic material, to form the beam;

h) growing by electrodeposition a compressive material;

i) removing, in one or more steps, the photoresist layers and the intermediate metallization layer either chemically and mechanically, or solely chemically.

2. Method of manufacturing a magnetic microcontactor according to claim 1, wherein the ferromagnetic material is a iron-nickel alloy in a proportion of 20/80 respectively.

3. Method of making a magnetic microcontactor according to claim 1, wherein the compressive material is chromium.

4. Method of making a magnetic contactor according to claim 1 wherein step (g) is preceded by the electrodeposition of a small thickness of a non magnetic material to improve the contact.

5. Method of making a magnetic microcontactor according to claim 4, wherein the material to improve the contact is gold.

6. Magnetic microcontactor obtained by carrying out steps a) to g) and i) of the method according to claim 1, wherein, in the absence of a magnetic field, a free space exists between the distal end of the beam and the contact stud after removal of the masks by step i).

7. Magnetic microcontactor obtained by carrying out steps a) to i) of the method according to claim 1, wherein, in the absence of a magnetic field, the distal end of the beam is in contact with the contact stud after removal of the masks by step i).