Electrode assembly for the removal of surface oxides by electron attachment

A technology of oxides and components, applied in the direction of electrical components, electrical solid devices, printed circuits assembled with electrical components, etc., can solve problems such as changing electric fields and hindering precise control

Active Publication Date: 2007-05-16
AIR PROD & CHEM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this insulating shield collects surface charges that can alter the electric field and prevent precise control
The method described is for melting the base metal surface only

Method used

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  • Electrode assembly for the removal of surface oxides by electron attachment
  • Electrode assembly for the removal of surface oxides by electron attachment
  • Electrode assembly for the removal of surface oxides by electron attachment

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083] A first experiment was performed using a laboratory scale furnace. The sample used was a fluxless tin-lead solder preform (melting point 183°C) on a grounded copper sheet (positive terminal) at N 2 5% H in 2 Under air flow, it was loaded into a furnace and heated to 250°C. When the sample temperature was in equilibrium, a DC voltage was applied between the negative electrode (cathode) and the grounded sample (positive pole), and the voltage was gradually increased to about -2 kV with a current of 0.3 mA. The distance between the two electrodes is about 1 cm. Pressure is ambient air pressure. It was found that the solder on the copper surface was indeed very wet. At such low temperatures, without the application of voltage, good fluxless solder wetting cannot be obtained on copper surfaces, even in pure H 2 in, because pure H is used on tin-based solder 2 The effective temperature for tin oxide removal is above 350°C. Therefore, this result indicates that in promo...

Embodiment 2

[0085] Using the same setup as in Example 1 and utilizing the field emission mechanism, several cathode electrode materials for hydrogen-promoted electron attachment fluxless soldering were investigated. The results of the study are listed in Table I.

[0086] As shown in Table I, the best results were obtained by using a Ni / Cr cathode, which provided the highest fluxing efficiency, resulting in the shortest wetting time. It is believed that the Ni / Cr cathode produces a relatively larger amount of electrons and a suitable electron energy level compared to other negative electrode materials.

[0087] Table I: 250°C and 20% H 2 Next, the effect of cathode material on wetting time

[0088] Tip cathode rod material (1 / 16" diameter)

[0089] aluminum

Embodiment 3

[0091]This example was carried out to investigate the efficiency of the thermal-field emission method of generating electrons. A large 3 mm diameter graphite rod protruding from the rod surface with a 1 mm long machined end served as the cathode, and its geometry was similar to the rod described in Fig. 2i. Each protruding machined end has a tip taper angle of 25 degrees. Resistance heating using AC energy, at 5% H 2 and 95%N 2 The graphite rod is heated to about 400 to 500°C in a gas mixture. A DC voltage source of 5KV was applied between graphite cathodes at 1.5cm intervals and copper sheets as anodes. All endpoints on the graphite are illuminated, indicating that electrons can be generated uniformly from distributed ends of the graphite rod. Without heating the graphite rod, there is no electron emission from the cathode, or a breakdown occurs between one end and the anode sheet. This indicates that the combination of using a cathode with a large number of endpoints an...

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PUM

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Abstract

An apparatus and a method comprising same for removing metal oxides from a substrate surface are disclosed herein. In one particular embodiment, the apparatus comprises an electrode assembly that has a housing that is at least partially comprised of an insulating material and having an internal volume and at least one fluid inlet that is in fluid communication with the internal volume; a conductive base connected to the housing comprising a plurality of conductive tips that extend therefrom into a target area and a plurality of perforations that extend therethrough and are in fluid communication with the internal volume to allow for a passage of a gas mixture comprising a reducing gas.

Description

[0001] Related Applications Cited by Reference [0002] This application is a continuation-in-part of US Patent Application Serial No. 10 / 425,405, filed April 28, 2003, the entire disclosure of which is incorporated herein by reference. technical field [0003] Disclosed herein is a flux-free method and device for removing metal oxides on the surface of a substrate. More specifically, disclosed herein is a method and apparatus for fluxless reflow of solder on a substrate surface, particularly for wafer bump applications. Background technique [0004] Wafer bumping is a method of producing thick metal bumps on the die pads for internal lead bonding. Usually by depositing solder on the chip pad, and then reflow (referring to the first reflow here) to carry out alloying treatment and change the shape of the solder bump from mushroom shape to hemisphere shape. Chips with primary reflow bumps are "bumped" to conform to the footprint of the solder-wettable end on the substrate,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L21/60H05K3/34H05H1/00B23K1/20B23K35/38C23G5/00C25F1/02B23K1/008B23K35/26H01J37/32H01L21/00H01L21/304H01L21/3063H01L21/3065H01L21/311
CPCH01L2924/0002B23K35/38B23K1/206B23K35/268C23G5/00H01L21/31116H01L2924/00H01L21/3065
Inventor C·C·董W·T·麦德莫特A·施瓦尔兹G·K·阿斯拉尼安R·E·帕特里克G·A·奥贝克D·A·小塞科贝
Owner AIR PROD & CHEM INC
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