KR950004236B1 - Method for coating a tin by the pulse current - Google Patents

Method for coating a tin by the pulse current Download PDF

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Publication number
KR950004236B1
KR950004236B1 KR1019920023036A KR920023036A KR950004236B1 KR 950004236 B1 KR950004236 B1 KR 950004236B1 KR 1019920023036 A KR1019920023036 A KR 1019920023036A KR 920023036 A KR920023036 A KR 920023036A KR 950004236 B1 KR950004236 B1 KR 950004236B1
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South Korea
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tin
duty cycle
pulse
plating
pulse period
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KR1019920023036A
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Korean (ko)
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KR940014917A (en
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김창하
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한국전기통신공사
이해욱
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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/18—Electroplating using modulated, pulsed or reversing current
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/30—Electroplating: Baths therefor from solutions of tin
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
    • C25D5/60—Electroplating characterised by the structure or texture of the layers
    • C25D5/605—Surface topography of the layers, e.g. rough, dendritic or nodular layers
    • C25D5/611—Smooth layers

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

The tin plating method increases the surface hardness of plated layer by controlling pulse plating variables like pulse period and duty cycle. The method comprises (A) preparing electroplating solution containg Na2SnO3 90 g/l, NaOH 7.5 g/l, NaC2H3O2 15 g/l: (B) dipping spring phosphor bronze into the electroplating solution; (C) applying pulse current with average current density 15 mA/cm2, pulse period 20 to 40 milisecond, and duty cycle 10 to 40%.

Description

펄스전류에 의한 주석도금방법Tin Plating Method by Pulse Current

제1도는 듀티사이클과 펄스주기에 따른 표면경도를 나타내는 그래프.1 is a graph showing surface hardness according to duty cycle and pulse period.

본 발명은 펄스전류에 의한 주석도금방법에 관한 것으로, 특히, 펄스주기와 듀티사이클 등의 펄스도금변수를 조정하여 표면경도를 향상시킬 수 있는 펄스전류에 의한 주석도금방법에 관한 것이다.The present invention relates to a tin plating method using a pulse current, and more particularly, to a tin plating method using a pulse current that can improve surface hardness by adjusting pulse plating variables such as pulse period and duty cycle.

일반적으로, 동합금 표면에 도금되는 주석은 우수한 대기부식 저항성과 정착성으로 인하여, 주석-주석이접합할 때 완전한 결합과 접촉면적 증대가 이루어지고, 동일 용도로 사용되는 금에 비하여 가격면에서 저렴하기 때문에, 통신 커넥터용 도금에 많이 사용되고 있다.In general, tin plated on the surface of the copper alloy is due to excellent atmospheric corrosion resistance and fixing properties, complete bonding and contact area increase when the tin-tin is bonded, and is inexpensive compared to the gold used for the same purpose It is widely used for plating for communication connectors.

그러나, 현재 많이 사용되고 있는 직류도금 방식으로 주석을 도금하면, 치밀한 도금이 이루어지지 못하므로, 도금층의 표면경도가 낮아지게 된다. 따라서, 도금층이 다른 소재와 접촉할 때, 도금층이 너무 쉽게 제거되어, 접촉부의 일부에서는 지지(구리합금) 사이에서 접촉이 발생하여, 전체적인 접점 특성이 멀어지는 문제점이 있었다.However, when tin is plated by DC plating, which is currently widely used, it is impossible to perform dense plating, and the surface hardness of the plating layer is lowered. Therefore, when the plating layer is in contact with another material, the plating layer is removed too easily, so that contact occurs between the supports (copper alloy) in a part of the contact portion, and there is a problem in that the overall contact characteristic is far from.

본 발명은 상술한 문제점을 제거하여 표면경도가 향상된 주석도금층을 형성하는 것을 목적으로 한다.It is an object of the present invention to form a tin plated layer having an improved surface hardness by eliminating the above problems.

상기 목적을 달성하기 위해 본 발명은 펄스주기를 20 내지 40msec로 하고, 듀티사이클을 l0 내지 40%영역으로 하여, 주석도금을 하는 것을 그 특징으로 한다.In order to achieve the above object, the present invention is characterized by tin plating with a pulse period of 20 to 40 msec and a duty cycle of 10% to 40%.

이하, 첨부된 도면으로 본 발명을 더욱 상세하게 설명하기로 한다.Hereinafter, the present invention will be described in detail with the accompanying drawings.

제1도는 듀티 사이클과 펄스주기에 따른 표면경도를 나타내는 그래프로서, 주석산나트륨(sodiumstannate) 90g/L, 가성 소자(sodium hydroxide) 7.5g/L, 아세트산나트륨(∞dium acetate) 1.5g/L를 함유한 60℃의 전기도금용 용액에 스테인레스 스틸을 양극으로 하여 상용스프링용 인청동을 침지시켜 듀티사이클과 펄스주기를 변화시키면서, 상기 상용스프링용 인청동상에 주석을 도금하였을 때, 주석표면의 경도변화를 나타내고 있다.1 is a graph showing the surface hardness according to the duty cycle and the pulse cycle, containing 90 g / L of sodium stannate, 7.5 g / L of sodium hydroxide, and 1.5 g / L of sodium acetate. When the tin plated on the commercial spring phosphor bronze, while changing the duty cycle and pulse period by immersing the commercial spring phosphor bronze with stainless steel as an anode in a solution for electroplating at 60 ℃, the hardness change of the surface of the tin It is shown.

펄스전류를 인가하여 인청동 상에 주석을 도금하는데 있어서, 펄스주기와 듀티사이클의 조정은 조정인자이다. 여기서 펄스주기는 펄스전류의 한 사이클에 해당하는 시간이며 전류가 인가되는 시간(on-time)과 전류가 인가되지 않는 시간(off-time)으로 구성된다. 그리고 듀티사이클은 펄스주기에 대한 전류가 인가되는 시간의 비로써 나타낼 수 있으며, 펄스주기가 40msec이고 전류가 인가되는 시간과 전류가 인가되지 않는 시간이 각각 20msec일 때 듀티사이클은 50%가 된다. 예로써 듀티사이클이 100%라 하는 것은 지속적으로 전류가 흐르는 경우이므로 직류도금에 해당한다.In plating tin on phosphor bronze by applying a pulse current, adjustment of the pulse period and duty cycle is an adjustment factor. Here, the pulse period is a time corresponding to one cycle of the pulse current, and is composed of an on-time and an off-time. The duty cycle may be expressed as a ratio of the time when the current is applied to the pulse period, and the duty cycle becomes 50% when the pulse period is 40 msec, the time when the current is applied and the time when the current is not applied is 20 msec. For example, a duty cycle of 100% corresponds to direct current plating because current flows continuously.

상술한 조건에서, 직류도금을 하여, 전자 현미경으로 주석도금의 표면을 관찰하면, 다수의 기공이 관찰되어, 약한 외부충격에도 도금층이 벗겨지는 문제가 있다 즉, 펄스주기가 너무 작으면 직류도금과 거의 같은 조건이 되어 치밀한 도금층이 형성되지 못한다 반면에 필스주기가 너무 크면, 전류가 인가되는 시간(on-time)동안 결정립 성장이 촉진되므로 오히려 표면경도가 떨어지게 된다.Under the above-described conditions, when the surface of tin plating is observed with an electron microscope by direct current plating, a number of pores are observed, and there is a problem in that the plating layer is peeled off even at a weak external impact. On the other hand, a dense plating layer is not formed at almost the same conditions. On the other hand, if the fill period is too large, grain growth is accelerated during the on-time of application of current, thereby decreasing the surface hardness.

즉, 본 발명에서 가장 중요한 조정인자 중에 하나인 펄스주기를 조정하면서 주석도금을 하는 경우, 도시된 바와같이, 펄스주기가 10msec에서는 표면경도가 45 이하가 되어, 치밀한 도금층이 이루어기지 못하며, 펄스주기 20msec 내지 40msec에서 표면경로가 상승하며, 펄스주기가 60msec 및 80msec에서는 결정립 성장이 촉진되어 오히려 경도가 떨어지게 된다.That is, when tin plating is performed while adjusting the pulse period, which is one of the most important adjustment factors in the present invention, as shown, when the pulse period is 10msec, the surface hardness is 45 or less, and a dense plating layer is not formed, and the pulse period is performed. The surface path is increased at 20 msec to 40 msec, and the grain growth is promoted at 60 msec and 80 msec, and the hardness decreases.

따라서, 펄스주기 20msec 내지 40msec 영역이 가장 적합하게 된다. 또한 듀티사이클을 조정하는 경우, l0% 미만에서는 스파크현상이 발생하여 치밀한 도금층이 형성되지 못하며, 50% 이상에서는 직류도금 조건과 유사하게 전류가 인가되는 동안 결정립 성장이 촉진됨으로 인하여 도금층의 경도가 크게 떨어진다.Therefore, the pulse period 20 msec to 40 msec region is most suitable. In addition, when the duty cycle is adjusted, a spark phenomenon occurs at less than l0% to prevent the formation of a dense plated layer, and at 50% or more, the hardness of the plated layer is greatly increased due to the promotion of grain growth during application of current, similar to the DC plating conditions. Falls.

따라서, 듀티사이클은 10에서 40% 영역이 가장 적합함을 알 수 있다.Thus, it can be seen that the duty cycle is most suitable for the 10 to 40% region.

하기의 표1은 듀티사이클을 60%로 고정시켰을 때, 각각의 펄스주기에 따른 경도의 변화를 나타내고 있는데, 펄스주기가 20 내지 10msec에서 경도값이 최고치인 것을 알 수 있다.Table 1 below shows the change in hardness according to each pulse period when the duty cycle is fixed at 60%. It can be seen that the hardness value is the highest at the pulse period of 20 to 10 msec.

하기의 표2는 펄스주기를 40msec로 고정시켰을 때 각각의 듀티사이클에 대한 경도의 변화를 나타내고 있는데, 듀티사이클 10내지 40% 영역에서 최고의 경도값을 나타냄을 알 수 있다.Table 2 below shows the change in hardness for each duty cycle when the pulse period is fixed at 40 msec. It can be seen that the maximum hardness value is shown in the duty cycle of 10 to 40%.

다음의 표3은 듀티사이클을 40%로 고정시켰을 경우, 각각의 펄스주기에 따른 경도를 나타내고 있다. 다음의 표3에 있어서, 펄스주기가 20 내지 40msec에서 경도값이 65 내지 77VHN으로 최고치인 것을 알 수있다.Table 3 below shows the hardness of each pulse period when the duty cycle is fixed at 40%. In the following Table 3, it can be seen that the hardness value is the highest value of 65 to 77 VHN when the pulse period is 20 to 40 msec.

다음의 표4은 듀티사이클을 10%로 고정시겼을 경우, 각각의 펄스주기에 따른 경도를 나타내고 있다. 다음의 표4에 있어서, 펄스주기가 20 내지 40msec에서 경도값이 77 내지 84VHN으로 최고치인 것을 알 수있다.Table 4 below shows the hardness of each pulse period when the duty cycle is fixed at 10%. In the following Table 4, it can be seen that the hardness value is the highest value of 77 to 84 VHN when the pulse period is 20 to 40 msec.

이상에서 살펴본 바와같이, 상용스프링 인청동에 주석도금을 할때, 펄수주기는 20 내지 40msec로 하고, 듀티사이클은 10 내지 40%로 하여 도금할 때, 도금층의 표면경도가 최대가 됨을 알 수 있다.As described above, when tin-plating the commercial spring phosphor bronze, the pearl number period is 20 to 40msec, the duty cycle is 10 to 40% when plating, it can be seen that the surface hardness of the plating layer is the maximum.

Claims (1)

주석산나트륨 90g/L, 수산화나트륨7.5g/L, 아세트산나트륨 15g/L를 함유한 전기도금용 용액에 상용스프링 인청동을 침지시켜 평균전류밀도 15mA/㎠로 가하여 펄스전류에 의하여 주석을 도금하는 방법에 있어서, 펄스주기는 20 내지 40msec로 듀티사이클은 10 내지 40%로 하는 것을 특징으로 하는 펄스전류에 의한 주석도금방법.In the method of plating tin by pulse current by immersing commercial spring phosphor bronze in an electroplating solution containing 90g / L sodium hydrate, 7.5g / L sodium hydroxide and 15g / L sodium acetate The tin plating method according to the pulse current, characterized in that the pulse period is 20 to 40msec and the duty cycle is 10 to 40%.
KR1019920023036A 1992-12-02 1992-12-02 Method for coating a tin by the pulse current KR950004236B1 (en)

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KR950004236B1 true KR950004236B1 (en) 1995-04-27

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825281A1 (en) * 1996-08-21 1998-02-25 Lucent Technologies Inc. Tin electroplating process

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0825281A1 (en) * 1996-08-21 1998-02-25 Lucent Technologies Inc. Tin electroplating process

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KR940014917A (en) 1994-07-19

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