Apparatus and method for removal of surface oxides via fluxless technique involving electron attachment

An electron and electron emission technology used in chemical instruments and methods, auxiliary devices, cleaning methods and utensils, etc.

Active Publication Date: 2013-02-06
AIR PROD & CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Furthermore, a further problem exists in the art to provide a flux-free soldering process that does not involve one or more combustible gases

Method used

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  • Apparatus and method for removal of surface oxides via fluxless technique involving electron attachment
  • Apparatus and method for removal of surface oxides via fluxless technique involving electron attachment
  • Apparatus and method for removal of surface oxides via fluxless technique involving electron attachment

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0078] The field emission device used in this embodiment, such as figure 2 As shown, it contains 5 stainless steel cathode needles, each of which is tightly inserted into the dielectric material, which constitutes an alumina ceramic tube (inner diameter (I.D.) 0.46 mm, outer diameter (O.D) 1.2 mm), which is mounted on a ceramic board. The spacing between the cathode pins is 5 mm. The tip of each cathode needle protruded about 1.0 mm outside the corresponding alumina ceramic tube. An anode wire is wrapped around each of the 5 tubes and electrically grounded. The surrounding anode wire is spaced 10 mm from the end of the tube towards the tip side of the cathode needle. Place the thus prepared structure at room temperature in a 2 N 2 Purged quartz tube furnace. When the pulsed (10KV) negative voltage potential applied to the 5 cathode needles was increased to -3.7KV, all 5 needle tips started emitting electrons. When electron emission starts on the needle, due to the gas ...

Embodiment 2

[0080] test as image 3 Field emission device structure constructed as shown, containing two stainless steel cathode pins, each inserted into a ceramic (alumina) tube or dielectric material, mounted on a die resting on a copper plate Secure both sides of the sample. Die-mounted samples are conductive and grounded. The distance between the tip of each needle and the edge of the sample is 5.5 mm. The tip of each cathode needle extended 1.0 mm outside the corresponding dielectric tube. An anode wire is wrapped around each of the two dielectric materials or tubes and is electrically grounded. The surrounding anode wire is spaced 10 mm from the end of the tube towards the needle tip side. Place the thus prepared structure at room temperature in a bath containing 4 vol% H 2 N 2 Purged quartz tube furnace. When the pulsed (10KV) negative voltage potential applied to the 2 needles increases to -1.9KV, the 2 needle tips light up blue, indicating electron emission. When the samp...

Embodiment 3

[0082] and figure 2 and image 3 The same field emission device structure and sample arrangement described in 2 N 2 Tested in a purged quartz tube furnace. The die-attach sample consisted of a flux-free gold / tin solder pellet (melting point 280°C) sandwiched between gold / nickel-coated ceramic and gold / nickel-coated copper to simulate a die-attach device. The 3 die-mounted samples each had the same dimensions: 3 mm × 6 mm. To demonstrate electron attachment (EA) activation at N 2 H in 2 For fluxless die attach feasibility, a pulsed (10KV) negative voltage potential was applied to the 2 pins at room temperature. When the applied voltage was increased to -1.8KV, the 2 needle tips lit up blue, indicating electron emission. The current received on the sample was -0.45 mA. The samples were then heated to 290°C with a ramp time of 2 minutes, soaked at 290°C for 1 minute, and then cooled. Electron attachment (EA) is maintained during temperature ramping and holding. It was ...

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Abstract

Described herein is a method and apparatus for removing metal oxides on a surface of a component via electron attachment. In one embodiment, there is provided a field emission apparatus (10, 500), wherein the electrons attach to at least a portion of the reducing gas to form a negatively charged atomic ions which removes metal oxides comprising: a cathode (20, 520) comprising an electrically conductive and comprising at least one or more protrusions having an angled edge or high curvature surface, wherein the cathode is surrounded by a dielectric material (30, 530) which is then surrounded by an electrically conductive anode (40, 540) wherein the cathode (20, 520) and anode (40, 540) are each connected to an electrical voltage source (60, 560), and the dielectric material (30, 530) between the cathode (20, 520) and anode (40, 540) is polarized, intensifying the electrical field strength and accumulating electrons at the apex of the cathode to promote field emission of electrons from the cathode.

Description

[0001] [0002] Cross References to Related Applications [0003] This application claims priority to the following US provisional application numbers: 61 / 514,615, filed August 3, 2011; and 61 / 563,112, filed November 23, 2011. This application is a continuation of US Application No. 13 / 364,925, filed February 2, 2012, which claims priority to US Provisional Application No. 61 / 441,053, filed February 9, 2011. All of the above applications are incorporated herein by reference in their entirety. Background of the invention [0004] The present invention generally relates to a flux-free process for removing surface oxides. More particularly, the present invention relates to an apparatus and method comprising the above process for flux-free reflow and soldering involving electron attachment and field emission under ambient (eg, non-vacuum) pressure. [0005] In electronic component assembly, reflow and soldering are important process steps for making solder joints. As used here...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01J37/32B23K3/08
CPCH01J37/06B23K1/20C23G5/024B23K35/38B23K1/206C23G5/00B01J19/088C25F1/00C11D11/0005B08B7/04H05K3/00
Inventor 董春R.A.西明斯基
Owner AIR PROD & CHEM INC
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