Method for manufacturing printed circuit boards

• US 9,648,720 B2
• Filed: 07/22/2013
• Issued: 05/09/2017
• Est. Priority Date: 02/19/2007
• Status: Active Grant

• Current Assignee: HzO, Inc.
• Original Assignee: Semblant Global Limited
• Inventors: Ferdinandi, Frank, Smith, Rodney Edward, Humphries, Mark Robson
• Primary Examiner(s): Vo, Peter DungBa
• Assistant Examiner(s): Carley, Jeffrey T
• Application Number:
  US13/947,525
• Publication Number:
  US 20130334292A1
• Time in Patent Office: 1,387 Days
• CPC Class Codes: H01L 2224/43848 Thermal treatments, e.g. annealing, controlled cooling
• CPC Class Codes: H01L 2224/45124 Aluminium (Al) as principal constituent
• CPC Class Codes: H01L 2224/45144 Gold (Au) as principal constituent
• CPC Class Codes: H01L 2224/45147 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/45686 with a principal constituent of the material being a non metallic, non metalloid inorganic material
• CPC Class Codes: H01L 2224/4569 with a principal constituent of the material being a polymer, e.g. polyester, phenolic based polymer, epoxy
• CPC Class Codes: H01L 2224/48225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48245 the item being metallic
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48647 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48747 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/48847 Copper (Cu) as principal constituent
• CPC Class Codes: H01L 2224/81024 Applying flux to the bonding area
• CPC Class Codes: H01L 2224/81395 having an external coating, e.g. protective bond-through coating
• CPC Class Codes: H01L 2224/81815 Reflow soldering
• CPC Class Codes: H01L 2224/83024 Applying flux to the bonding area
• CPC Class Codes: H01L 2224/83205 Ultrasonic bonding
• CPC Class Codes: H01L 2224/83395 having an external coating, e.g. protective bond-through coating
• CPC Class Codes: H01L 2224/83815 Reflow soldering
• CPC Class Codes: H01L 2224/85203 : Thermocompression bonding
• CPC Class Codes: H01L 2224/85207 : Thermosonic bonding
• CPC Class Codes: H01L 2224/85395 : having an external coating, e.g. protective bond-through coating
• CPC Class Codes: H01L 2224/85447 : Copper (Cu) as principal constituent
• CPC Class Codes: H01L 24/45 : of an individual wire connector
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/85 : using a wire connector wire bonding in general B23K20/004
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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: H01L 2924/12042 : LASER
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/181 : Encapsulation
• CPC Class Codes: H05K 1/02 : Details
• CPC Class Codes: H05K 2201/015 : Fluoropolymer, e.g. polytetrafluoroethylene [PTFE]
• CPC Class Codes: H05K 2201/0179 : Thin film deposited insulating layer, e.g. inorganic layer for printed capacitor
• CPC Class Codes: H05K 2203/092 : Particle beam, e.g. using an electron beam or an ion beam
• CPC Class Codes: H05K 2203/107 : Using laser light shaping a substrate by laser ablation H05K3/0026
• CPC Class Codes: H05K 2203/1338 : Chemical vapour deposition
• CPC Class Codes: H05K 2203/1366 : Spraying coating apparatus for coating printed circuit boards using liquid non-metallic coating compositions H05K3/0091
• CPC Class Codes: H05K 2203/1372 : Coating by using a liquid wave solder dip coating H05K2203/04
• CPC Class Codes: H05K 2203/1383 : Temporary protective insulating layer
• CPC Class Codes: H05K 3/00 : Apparatus or processes for manufacturing printed circuits
• CPC Class Codes: H05K 3/282 : for inhibiting the corrosion of the circuit, e.g. for preserving the solderability
• CPC Class Codes: H05K 3/285 : Permanent coating compositions
• CPC Class Codes: H05K 3/288 : Removal of non-metallic coatings, e.g. for repairing
• CPC Class Codes: H05K 3/3485 : Applying solder paste, slurry or powder thick film methods for applying conductive paste or ink patterns H05K3/12
• CPC Class Codes: H05K 3/3489 : Composition of fluxes; Methods of application thereof; Other methods of activating the contact surfaces
• CPC Class Codes: H05K 3/3494 : Heating methods for reflowing of solder using integral heating means H05K1/0212

Abstract

A method including: attaching a plurality of conductive tracks to at least one surface of a substrate, depositing a coating comprising at least one halo-hydrocarbon polymer on the at least one surface of the substrate, and soldering through the coating.

Claims

1. A method, comprising:

attaching a plurality of conductive tracks to at least one surface of a substrate comprising an insulating material;

depositing a coating on the at least one surface of the substrate, the coating covering at least a portion of the plurality of conductive tracks, the coating comprising at least one halo-hydrocarbon polymer; and

after depositing the coating, soldering through the coating to form a solder joint between an electrical component and at least one conductive track attached to the substrate, the solder joint abutting the coating; and

wherein;

the coating is deposited as a substantially continuous layer on the at least one surface of the substrate;

the solder joint is formed at a particular region of the substrate; and

the soldering removes the coating from the particular region of the substrate without removing the coating from other regions of the substrate.

2. The method of claim 1, wherein the coating has a thickness from 1 nanometer to 10 micrometers.

3. The method of claim 1, wherein the coating has a thickness from 10 nanometers to 100 nanometers.

4. The method of claim 1, wherein the coating is deposited directly on the plurality of conductive tracks such that there is essentially no solder between the coating and the plurality of conductive tracks.

5. The method of claim 1, wherein the at least one halo-hydrocarbon polymer comprises one or more fluoro-hydrocarbons.

6. The method of claim 1, wherein less than five percent of the total number of atoms in the at least one halo-hydrocarbon polymer are heteroatoms.

7. The method of claim 6, wherein:

the at least one halo-hydrocarbon polymer has a straight or branched chain structure;

the at least one halo-hydrocarbon polymer comprises at least one heteroatom; and

the at least one heteroatom comprises at least one of;

nitrogen;

sulfur; and

oxygen.

8. The method of claim 1, wherein depositing the coating comprises:

forming a first layer directly on the plurality of conductive tracks, the first layer comprising a metal halide; and

forming a second layer on the first layer, the second layer comprising at least one halo-hydrocarbon polymer.

9. The method of claim 8, wherein the first layer comprising a metal halide allows self fluxing during soldering of the at least one electrical component.

10. The method of claim 1, wherein depositing the coating comprises:

forming a first layer directly on the plurality of conductive tracks, the first layer comprising a metal halide that protects the plurality of conductive tracks from oxidation; and

forming a second layer on the first layer, the second layer comprising one or more halo-hydrocarbon polymers that protect the plurality of conductive tracks from corrosion.

11. The method of claim 1, wherein depositing the coating comprises:

forming a first layer directly on the plurality of conductive tracks, the first layer comprising a metal fluoride and having a thickness from 3 angstroms to 5 nanometers; and

forming a second layer comprising one or more halo-hydrocarbon polymers, the second layer in direct contact with the first layer, the second layer having a thickness from 1 nanometer to 10 micrometers.

12. The method of claim 1, wherein the coating has a variable thickness such that a portion of the coating on a first region of the substrate has a different thickness than another portion of the coating on a second region of the substrate, wherein the first region of the substrate comprises a region that is distinct from the second region of the substrate.

13. The method of claim 1, wherein:

the plurality of conductive tracks are copper tracks; and

the at least one halo-hydrocarbon polymer comprises a PTFE type material.

14. The method of claim 1, wherein the coating is deposited by plasma deposition using one or more precursor compounds comprising at least one of:

a perfluoroalkane;

a perfluoroalkene;

a perfluoroalkyne;

a fluoroalkane;

a fluoroalkene;

a fluoroalkyne;

a fluorochloroalkane;

a fluorochloroalkene; and

a fluorochloroalkyne.

15. The method of claim 14, wherein the one or more precursor compounds have a straight chain or branched chain structure.

16. The method of claim 1, wherein soldering through the coating comprises heating a flux at a particular region of the substrate, the heated flux dissolving the coating from the particular region without removing the coating from other regions of the substrate.

17. The method of claim 1, wherein soldering through the coating comprises heating a flux at a particular region of the substrate, the heated flux removing the coating from the particular region without removing the coating from other regions of the substrate.

18. The method of claim 1, wherein the coating is configured to withstand multiple heat cycles.

19. The method of claim 1, wherein the coating is deposited by at least one of:

plasma deposition;

chemical vapor deposition;

metallo-organic-chemical vapor deposition;

molecular beam epitaxy;

spray coating;

sputtering; and

spin coating.

20. The method of claim 1, further comprising, after depositing the coating and prior to forming the solder joint, storing the substrate for a substantial period of time, wherein the coating protects the plurality of conductive tracks from oxidation during storage.

21. The method of claim 1, further comprising, after forming the solder joint, storing the substrate for a substantial period of time, wherein the coating protects the plurality of conductive tracks from oxidation during storage.

22. The method of claim 1, further comprising wire bonding a particular electrical component to at least one conductive track, wherein:

the particular electrical component is wire bonded with at least one wire that is coated with the coating; and

the wire bond is formed without first removing the coating from the wire.