Application of electrical conductors to an electrically insulating substrate

Patent metadata

Field	Value
Publication number	US-10645815-B2
Application number	US-201916258851-A
Country	US
Kind code	B2
Filing date	Jan 28, 2019
Priority date	Jul 28, 2016
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A method is disclosed for applying an electrical conductor to an electrically insulating substrate, which comprises providing a flexible membrane with a pattern of groove formed on a first surface thereof, and loading the grooves with a composition comprising conductive particles. The composition is, or may be made, electrically conductive. Once the membrane is loaded, the grooved first surface of the membrane is brought into contact with a front or/and back of the substrate. A pressure is then applied between the substrate and the membrane(s) so that the composition loaded to the grooves adheres to the substrate. The membrane(s) and the substrate are separated and the composition in the groove is left on the surface of the electrically insulating substrate. The electrically conductive particles in the composition are then sintered to form a pattern of electrical conductors on the substrate, the pattern corresponding to the pattern formed in the membrane(s).

First claim

The invention claimed is:

1. A method of applying a pattern of composition to an electrically insulating substrate, which method comprises:
a) providing a flexible membrane, wherein a first surface of the membrane has a pattern of grooves formed therein, the pattern of grooves corresponding at least partially to a desired pattern of electrical conductors for the electrically insulating substrate, and wherein a distance between facing edges for at least one pair of adjacent grooves in the pattern of grooves is less than 15 μm;
b) loading into the grooves of the first surface of the membrane a composition that includes, as composition components, electrically conductive particles and an adhesive, said loading being performed in one or more filling cycle(s) such that on completion of loading the composition substantially fills the grooves, level with the first surface of the membrane, and parts of the first surface between the grooves are substantially devoid of the composition;
c) contacting the membrane with the electrically insulating substrate with the first surface of the membrane facing the electrically insulating substrate;
d) applying pressure to the membrane to cause the composition loaded into the grooves in the first surface of the membrane to adhere to the electrically insulating substrate; and,
e) separating the membrane from the substrate to transfer the composition from the grooves in the first surface of the membrane to the electrically insulating substrate, thereby applying a pattern of composition to the electrically insulated substrate that corresponds at least partially to the desired pattern of electrical conductors for the electrically insulated substrate.

2. The method of claim 1 , wherein the composition loaded into the grooves comprises, as an additional composition component, a liquid carrier to form a wet composition, and wherein each filling cycle includes the steps of:
(i) applying an excess of the wet composition to the whole of the first surface of the membrane;
(ii) removing excess wet composition from the first surface to leave the wet composition substantially only within the grooves in the first surface of the membrane; and
(iii) substantially drying the wet composition within the grooves by removing the liquid carrier to leave dried composition.

3. The method of claim 2 , wherein the relative proportions of the components of the composition applied during different filling cycles differ from one another.

4. The method of claim 1 , wherein a release coating is applied to the grooves of the membrane and dried thereon, prior to loading of the composition into the grooves.

5. The method of claim 1 , wherein prior to contacting said membrane with said substrate according to step c), an adhesive coating is applied to at least one of the first surface of the membrane and the substrate so as to coat any composition present in the grooves and said adhesive coating is dried, a thickness of said dried adhesive coating not exceeding 2 μm.

6. The method of claim 1 , wherein the grooves of the pattern of grooves are substantially identical with one another.

7. The method of claim 1 , wherein at least two grooves in the pattern of grooves, or two different segments of the same groove, have different cross-sectional dimensions.

8. The method of claim 1 , wherein the flexible membrane is selected from a preformed membrane of plastics polymer and a cast plastics polymer.

9. The method of claim 8 , wherein the plastics polymer is a thermoplastic polymer, selected from the group consisting of cyclic olefin copolymer (COC), polyethylene (PE), cast polypropylene (CPP), and other type of polypropylene (PP), thermoplastic polyurethane (TPU), and combinations thereof.

10. The method of claim 1 , wherein the first surface of the flexible membrane has a mean roughness Rz of 1 μm or less.

11. The method of claim 1 , wherein the particles of electrically conductive material are made of compounds selected from the group consisting of metals, alloys, organo-metals, conductive polymers, conductive polymers precursors and salts thereof and combinations thereof.

12. The method of claim 1 , wherein the adhesive includes at least one of (i) an organic binder, (ii) an organic adhesive that is a pressure and/or heat sensitive adhesive, and (iii) a glass frit.

13. The method of claim 1 , wherein the step of providing a flexible membrane having a pattern of grooves formed in a first surface thereof comprises advancing a continuous membrane between a die roller and a counter die, the die roller having protruding rules complementary to the pattern of grooves to be formed on the membrane.

14. The method of claim 1 , wherein the pattern formed in step a) is a first pattern, and the composition of step b) is a first composition, the method further comprising the steps of:
g) forming a second pattern of grooves in the first surface of the membrane, the second pattern of grooves corresponding to a second desired pattern for the electrically insulating substrate;
h) loading the grooves of the second pattern at least once with a second composition while leaving spaces between the grooves of the second pattern of grooves essentially devoid of the second composition;

wherein steps g) and h) are performed after step b) and prior to step c).

15. The method of claim 14 , wherein the second composition is devoid of electrically conductive particles.

16. The method of claim 14 , wherein the second composition comprises ferromagnetic particles and an adhesive.

17. The method of claim 1 , wherein the electrically insulating substrate is non-planar.

18. The method of claim 1 , wherein the distance between the facing edges of the at least one pair of adjacent grooves in the pattern of grooves is at least 7.5 μm and is no more than 12.5 μm.

19. The method of claim 1 , further comprising: applying sufficient energy to sinter the electrically conductive particles wherein, following the application of sufficient energy, electrical conductors of the desired pattern consist of sintered electrically conductive particles and of voids between said sintered electrically conductive particles, the voids being present in at least 1% by area in a cross-section of the electrical conductors.

20. The method of claim 1 , further comprising following step d), cooling the membrane and electrically insulating substrate down to a predetermined temperature.

21. The method of claim 1 , wherein the pattern of composition spans over an area larger than a field of view of lithographic equipment, the pattern of composition having at least one of a width and a length of 70 cm or more.

22. The method of claim 1 , wherein if subsequent to said separating, the composition transferred to the electrically insulating substrate is not electrically conductive, then the method further comprises: rendering the composition electrically conductive, thereby providing electrical conductors of the desired pattern.

23. An electrically insulating substrate, wherein a pattern of composition is applied to the electrically insulating substrate by a method comprising:
a) providing a flexible membrane, wherein a first surface of the membrane has a pattern of grooves formed therein, the pattern of grooves corresponding at least partially to a desired pattern of electrical conductors for the electrically insulating substrate, and wherein a distance between facing edges for at least one pair of adjacent grooves in the pattern of g

Assignees

• Landa Labs 2012 Ltd

Inventors

• Landa Benzion
• Elfassy Naomi
• Thygelbaum Stanislav

Classifications

• H05K2201/0338

  Layered conductor, e.g. layered metal substrate, layered finish layer or layered thin film adhesion layer · CPC title

• H05K3/386

  by the use of an organic polymeric bonding layer, e.g. adhesive · CPC title

• H05K2201/0195

  Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure · CPC title

• H05K3/207 Primary

  using a prefabricated paste pattern, ink pattern or powder pattern · CPC title

• H05K2201/10098

  Components for radio transmission, e.g. radio frequency identification [RFID] tag, printed or non-printed antennas · CPC title