Method of forming a soldered electrical connection
AssigneeThe Boeing Company
InventorsBoon Wong, Robert E. Silhavy, Jennifer Shinno
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Abstract
A reliable, long-lived soldered electrical connection is made to a ceramic substrate having a thick-film metallization thereon, over which is deposited a joint-structure-stabilizing thin-film metallization. The thin-film metallization is a multilayered structure having an adhesion layer overlying and in contact with the thick-film metallization, a readily wettable base-metal layer overlying and in contact with the adhesion layer, and an oxidation-prevention layer overlying and in contact with the base-metal layer. An electrical conductor is soldered to the thin-film metallization of the ceramic substrate. The electrical conductor may be a bonding pad of a flip chip having a solder bump thereon.
Claims20
A method of forming a soldered electrical connection, comprising the steps of
- providing a ceramic substrate having a thick-film metallization thereon;
- depositing a thin-film metallization overlying the thick-film metallization, the thin-film metallization comprising:
- an adhesion layer overlying and in contact with the thick-film metallization,
- a base-metal layer overlying and in contact with the adhesion layer, and
- an oxidation-prevention layer overlying and in contact with the base-metal layer;
- providing an electrical conductor;
- and
- soldering the electrical conductor to the thin-film metallization of the ceramic substrate.
A metallized ceramic substrate, comprising:
- a ceramic substrate having a thick-film metallization thereon;
- a thin-film metallization overlying the thick-film metallization, the thin-film metallization comprising:
- an adhesion layer overlying and in contact with the thick-film metallization,
- a base-metal layer overlying and in contact with the adhesion layer, and
- an oxidation-prevention layer overlying and in contact with the base-metal layer.
A method of forming a soldered electrical connection, comprising the steps of
- providing a ceramic substrate having a thick-film metallization thereon;
- depositing a thin-film metallization overlying the thick-film metallization, the thin-film metallization including:
- an adhesion layer overlying and in contact with the thick-film metallization,
- a base-metal layer overlying and in contact with the adhesion layer, and
- an oxidation-prevention layer overlying and in contact with the base-metal layer;
- providing an electrical conductor, wherein the electrical conductor is a bonding pad of a flip chip having a solder bump and
- soldering the electrical conductor to the thin-film metallization of the ceramic substrate, wherein the step of soldering includes the steps of
- placing the bonding pad having the solder bump thereon in contact with the thin-film metallization, and
- heating the solder bump to a temperature greater than its liquidus temperature.
A method of forming a soldered electrical connection, comprising the steps of
- providing a ceramic substrate having a thick-film metallization thereon, wherein the thick-film metallization comprises a precious metal selected from the group consisting of gold, platinum, palladium, and combinations thereof;
- depositing a thin-film metallization overlying the thick-film metallization, the thin-film metallization comprising:
- an adhesion layer overlying and in contact with the thick-film metallization, wherein the adhesion layer is a metal selected from the group consisting of titanium, titanium-tungsten, and chromium, and wherein the adhesion layer has a thickness of from about 25 nanometers to about 100 nanometers,
- a base-metal layer overlying and in contact with the adhesion layer, wherein the base-metal layer is a metal selected from the group consisting of copper, nickel, and alloys thereof, and wherein the base-metal layer has a thickness of from about 0.15 micrometers to about 5 micrometers, and
- an oxidation-prevention layer overlying and in contact with the base-metal layer the oxidation-prevention layer is a metal selected from the group consisting of gold and silver, and wherein the oxidation-prevention layer has a thickness of from about 70 nanometers to about 600 nanometers;
- providing a flip chip having a bonding pad with a solder bump thereon;
- placing the bonding pad having the solder bump thereon in contact with the thin-film metallization, and
- heating the solder bump to a temperature greater than its liquidus temperature to solder the bonding pad to the thin-film metallization.
Dependencies are inferred from the claim text.