Leadless welding flux

A lead-free solder, high-quality technology, used in welding/cutting media/materials, welding media, welding equipment, etc., can solve problems such as serious copper leaching, and achieve the effect of improving reliability

Inactive Publication Date: 2004-05-19
SENJU METAL IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, since this Sn-based lead-free solder has a high liquidus temperature, the soldering temperature or the temperature of the molten solder is also high, and copper leaching becomes even more serious
As a result, the effect of these prior art Sn-based lead-free solders is insufficient to achieve a satisfactory degree of prevention of copper leaching at the ends of the coils, especially when the coils are formed with thin copper wires up to 100 μm in diameter.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0031] Solders having the compositions shown in Table 1 were prepared and tested for copper leaching speed and wettability by the following methods.

[0032] Copper leaching speed

[0033] Each solder was heated to 400°C in a metal melting bath to achieve a molten state. A coil of coated copper wire and covered with an inner enamel coating and an outer polyurethane resin coating was used as the test material to be impregnated. After applying rosin flux to the end of the coil along a predetermined length, the end of the coil was dipped in molten solder at 400° C. for 10 seconds, 20 seconds or 30 seconds. The diameter of the copper wire was measured after each immersion period to determine the reduction rate (μm per second) of the diameter of the copper wire caused by copper leaching as the copper leaching rate.

[0034] wettability

[0035] The wettability of each solder was tested with a wetting balance test by the following method: A copper sheet with dimensions of 10 mm x...

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PUM

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Abstract

lead-free solder which is significantly less susceptible to copper leaching when used in a molten state in which coil ends of copper wire are dipped comprises 1.5-8 mass % of Cu, 0.01-2 mass % of Co, optionally 0.01-1 mass % of Ni, and a remainder of Sn and has a liquidus temperature of 420 DEG C. or below. The solder may further comprise at least one oxidation-inhibiting element selected from the group consisting of P, Ge, and Ga in a total amount of 0.001-0.5 mass %, and / or Ag in an amount of 0.05-2 mass % as a wettability-improving element.

Description

technical field [0001] The present invention relates to a lead-free solder, which is classified as a high-temperature solder, and more particularly, to a lead-free tin-based solder suitable for use in soldering and pre-coating coil ends. Background technique [0002] Various coils are used in electronic equipment such as computers. For example, coils are incorporated into transformers in electronic equipment or into motors for disk drives or fans for cooling. The ends of these coils are typically soldered to electrical contacts to form an electrical connection. [0003] Typically, the coils are formed from copper wire covered with an insulating coating, typically consisting of an enamel coating on the inside and a polyurethane resin coating on the outside. Therefore, in order to solder the ends of the coils to the electrical terminals, both the enamel coating on the inside and the polyester resin coating on the outside of the coil ends of copper wire (hereinafter both coat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K1/20B23K35/26C22C13/00C23C2/04
CPCB23K35/262C23C2/04C22C13/00
Inventor 大西司
Owner SENJU METAL IND CO LTD
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