Method for electroplating metals of tin and bismuth

A technology for electroplating tin, bismuth and bismuth metal, which is applied in the field of electroplating composite metal layers on the outer lead pins of integrated circuits, can solve the problems of low manufacturing cost and fast electroplating speed, and achieve high production efficiency, fast electroplating speed, and dense crystallization.

Inactive Publication Date: 2009-09-23
WUXI WELNEW MICRO ELECTRONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention studies and improves the above-mentioned inhomogeneity problem of the tin-bismuth electroplating layer in the prior art, and provides a method for electroplating a tin-bismuth metal layer. The tin-bismuth metal layer electroplated by the method can meet the uniformity requirement, and the process is simple , Low manufacturing cost, fast plating speed

Method used

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  • Method for electroplating metals of tin and bismuth
  • Method for electroplating metals of tin and bismuth
  • Method for electroplating metals of tin and bismuth

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Take 50 products to be electroplated (TSOP48 integrated circuit package shell and its outer leads), such as figure 2 Attach and fix on the cathode transmission steel belt with a spring clip, and the distance between the steel belt and the two anode plates is equal, both are 100mm. The material of the anode plate is a tin plate, and the dimensions are: length 500 mm, width 30 mm, height 100 mm.

[0038] Cathode conveying steel belt speed: 4.5m / min.

[0039] The formula of electroplating solution, electroplating process steps and process conditions are as follows.

[0040]

[0041]

[0042] The additive SNB31 in the electroplating solution formula in the above table can avoid the oxidation of divalent tin and prevent the substitution reaction between bismuth and anode tin; the additive SNB14 can make the coating bright and crystallized.

[0043] Take 10 lead electroplating samples of the integrated circuit casing in the middle of the hanging basket, test the thic...

Embodiment 2

[0049] Cathode conveying steel belt speed: 5m / min.

[0050] The formula, electroplating process steps and process conditions of the electroplating solution are as follows, and other process descriptions are the same as in Example 1.

[0051]

[0052]

[0053] Its measurement data are as follows:

[0054]

Embodiment 3

[0056] Cathode conveying steel belt speed: 5.5m / min.

[0057] The formula, electroplating process steps and process conditions of the electroplating solution are as follows, and other process descriptions are the same as in Example 1.

[0058]

[0059] Its measurement data are as follows:

[0060]

[0061]

[0062] It can be seen from the data of the above examples that the plating layer of the product electroplated by the method of the present invention has a uniform thickness and a uniform bismuth content.

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Abstract

The invention relates to a method for electroplating metals of tin and bismuth, which is characterized by comprising 40-80g / l of tin methane-sulfonate and 1-3g / l of bismuth methane-sulfonate in terms of volume mass ratio, and also comprising 100-280ml / l of methylsulfonic acid, 30-100ml / l of additive SNB31 produced by Dr. Ing Max Schlotter GmbH & Co. KG, 5-15ml / l of additive SNB14 produced by Dr. Ing Max Schlotter GmbH & Co. KG, and the balanced water in terms of volume ratio; and the electroplate liquid is used for electroplating for 1.5-2.5min with a current density of 10-20 ampere / square decimeter and at a temperature of 35-65 DEG C. The cathode plate of the plating tank containing the electroplate liquid is a conveying steel belt, and the distances between an electroplating part and two anode plates are the same. The tin and bismuth metal layers electroplated by the invention have uniform thickness and even distribution of bismuth, and tin and bismuth metal layers have good weldability.

Description

Technical field: [0001] The technology relates to a method for electroplating a compound metal layer, in particular to a method for electroplating a compound metal layer for an integrated circuit outer lead pin. Background technique: [0002] Tin-bismuth electroplating technology is widely used in the electroplating of PCB boards (printed circuit boards) and the outer leads of integrated circuits. Compared with tin-lead electroplating, tin-bismuth electroplating has the characteristics of non-toxicity, low corrosion, bright coating, good solderability, and simple wastewater treatment. It is a green and environmentally friendly electroplating system that countries around the world are currently committed to promoting and using. The bismuth component in the tin-bismuth electroplating layer is 1-3%, and the uniformity of the coating thickness is an important index affecting product quality, including the uniformity of the coating thickness and the uniformity of the bismuth comp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C25D3/60C25D7/06
Inventor 薛永健涂利彬
Owner WUXI WELNEW MICRO ELECTRONICS
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