JP4896391B2 - Plating contact and contact plating method - Google Patents

Description

  The present invention relates to contacts used for various terminals such as connectors as electronic components, and more particularly to a plated contact subjected to a plating process such as gold or tin, and a method for plating the contact.

  The contact is mainly fitted in a connector provided for connection between the mating connector and the printed wiring board, and a terminal portion for electrical contact with the mating connector is provided on one end side and a terminal portion is provided on the other end side. It has a contact portion for mounting and connecting to a printed wiring board by soldering.

The contact is subjected to nickel or nickel alloy plating (simply referred to as “nickel-based plating”) as a base plating over the entire surface of a contact material made of a copper alloy or the like. In order to improve the characteristics, for example, contact plating such as gold or gold alloy (simply referred to as “gold plating”) is applied.
On the other hand, in order to improve the affinity for the solder at the contact portion, for example, solder plating of tin or tin alloy (simply referred to as “tin-based plating”) is performed on the contact portion.

In such a contact with two types of plating, a so-called “solder up” occurs in which the molten solder at the contact portion crawls up or sucks up to the terminal portion side during mounting.
Accordingly, the molten solder on the contact portion reaches the terminal portion side, that is, solder rise occurs, and the solder adheres on the gold plating of the terminal portion, so that the contact electrical characteristics in the terminal portion are extremely deteriorated. In order to prevent this, it is necessary to form a barrier region in the connecting portion between the contact portion and the terminal portion.

  Conventionally, as a well-known technique in this type of contact, for example, an extremely thin alloy layer of tin and nickel with low solder wettability (simply referred to as “ultra thin alloy layer”) is provided on the connecting portion using a masking belt. Thus, a contact using this as a barrier region (see Patent Document 1) can be mentioned.

Patent Document 1 shows an example of a contact having a barrier region in a continuous portion for the purpose of preventing solder rise. The continuous portion has an ultra-thin alloy layer adjacent to a tin-based plating, and this is used as a barrier region. It is characterized by that.
In the above example, a plating method using a masking belt, a so-called “drum method” is employed as a plating manufacturing method. However, in this manufacturing method, the gold-based plating solution enters from the masking portion during the gold-based plating production, so that an extremely thin “gold smear” occurs in the connecting portion, and the solder rise is assisted as it is.

Here, the ultra-thin alloy layer is formed by performing a reflow process on the ultra-thin tin-based plating layer plated on the nickel-based plating layer. For example, even if a gold bleed has reached the ultrathin tin plating layer before the reflow process and an ultrathin gold plating layer is formed, the ultrathin gold plating layer dissolves in the ultrathin tin plating layer at the same time as the reflow process. An ultrathin alloy layer having extremely deteriorated wettability with respect to the solder is formed up to the surface, which functions as a barrier region.
JP 2003-342882 PR

However, in the configuration of Patent Document 1, the step of eliminating the gold bleeding problem on the ultrathin tin-based plating layer by the formation process of the ultrathin alloy layer and forming the barrier region has at least a gold bleeding ultrathin alloy layer. It contains uncertain elements such as remaining on top.
In addition, the above process requires maintenance and management of an apparatus such as a masking belt that requires high technology, which is used to form an ultrathin tin-based plating layer, and the plating manufacturing process is complicated and expensive. is there.

  Therefore, the present invention provides a plating that can easily and inexpensively form a barrier region necessary for preventing solder rise in a contact subjected to plating treatment such as gold plating or tin plating. It is an object of the present invention to provide a contact and a plating method for the contact.

In order to solve the above problem, the first invention is a contact in which a terminal portion is formed on one end side and a contact portion is formed on the other end side,
Nickel base plating applied to the outer surface of this contact;
Gold plating that is applied to the base plating from the one end side and has an inclined surface that gradually decreases in thickness as it approaches the end,
A tin-based plating which is applied from the other end side on the base plating, is thicker than the gold-based plating, and has an inclined surface whose thickness gradually decreases as it approaches the terminal end;
An alloy layer of nickel plating and tin plating formed between the tin plating and the nickel base plating and formed on the inclined surface of the gold plating is provided. ,
The alloy layer is exposed from between the end of the inclined surface of the tin plating and the inclined surface of the gold plating .

As a result, the alloy layer of nickel-based plating and tin-based plating rides on the inclined surface reaching the end of the gold-based plating, so that the alloy layer formed during the reflow process reaches the surface of the tin-based plating. And the surface is not covered by the gold-based plating. Therefore, the alloy layer having low wettability with respect to the molten solder is sufficiently formed on the inclined surface reaching the end of the tin-based plating until reaching the surface, thereby reliably preventing the solder from rising. Can do.

It second invention is a plated contacts of the first invention, wherein the thickness of the gold-plated is 0.03～0.1Myu m, the thickness of the tin-based plating is 1～4Myu m It is characterized by.

  Thereby, the thickness of the gold-based plating is set to 1/10 to 10/10 of the thickness of the tin-based plating, so that the gold-based plating can be formed with respect to the formation of the alloy layer in the riding-up portion during the reflow process. To prevent it from affecting.

The third invention is a plated contacts of the second aspect of the invention, wherein the thickness of the gold-plated at the end of the tin-based plating is characterized in that less than 0.04μ m.

Thus, the thickness of the gold-plated at the end of the tin-based plating by less 0.04Myu m, the alloy layer having a low wettability with respect to molten solder reaches the end of the tin-plated By being more sufficiently formed on the inclined surface, it is possible to more reliably prevent the solder from rising.

  4th invention is a plating contact of 1st invention or 2nd invention, Comprising: The said terminal part is formed facing a pair of terminal piece, The said boundary part is formed in the root of the said terminal piece. It is characterized by that.

  Thus, by minimizing the boundary that requires the barrier region, it is possible to more reliably prevent the solder from rising from the contact portion to the terminal portion.

A fifth invention is a plating method using a contact row in which a large number of contact bodies each having a terminal portion formed at one end and a contact portion formed at the other end are connected to a holding portion at the end on the contact portion side. And
A step of immersing the entire contact row in a nickel plating bath, and applying a nickel base plating to the entire contact row;
The contact row is immersed in a metal plating bath from the terminal side, and gold plating is applied to the base plating partway from the one end side to the contact portion , and the thickness gradually approaches the end. Forming a thin inclined surface;
The contact line is immersed in a tin plating bath from the holding portion side, and tin plating is applied on the base plating until reaching the gold plating, and the inclined surface gradually decreases in thickness as it approaches the end. And a step of causing the end face of the tin-based plating to ride on the end face of the gold-based plating, and
The nickel-based base plating and the tin-based plating are thermally diffused by a reflow process, so that the inclined surface of the gold-based plating layer and the reflow process are between the nickel-based base plating and the tin-based plating after the reflow process. And a step of forming an alloy layer of the nickel-based base plating and the tin-based plating exposed from the end of the inclined surface of the subsequent tin-based plating layer .

Thereby, the structure that the alloy layer of the nickel-based undercoat and the tin-based plating runs on the inclined surface reaching the end of the gold-based plating can be easily and reliably formed. Therefore, the alloy layer having low wettability with respect to the molten solder is not covered with the gold plating, and the inclined surface of the gold plating layer and the tin-based plating layer after the reflow treatment are formed. by being formed sufficiently between the end of the inclined surface, it is possible to reliably prevent solder uplink.

  As described above, the plated contact and the contact plating method of the present invention are tin-plated so as to ride on the end of the gold-plated layer in the contact that has been plated such as gold-plated or tin-plated. By forming the layer, the alloy layer of the underlying nickel-based plating layer and tin-based plating layer is formed in a state of being surely exposed to the surface of the tin-based plating layer. By simply controlling the liquid level in the tank, the barrier region can be formed more easily and at low cost. Further, the present invention is effective for either pre-plating or post-plating.

  Hereinafter, embodiments of a plating contact and a plating method thereof according to the present invention will be described with reference to the drawings.

First, the configuration of the plating contact will be described with reference to FIGS.
In FIG. 1, a plating contact 1 is formed by applying predetermined plating to the outer periphery of a main body 2 having a predetermined shape.
The main body 2 is processed into a predetermined shape by press forming a metal plate made of a copper alloy such as brass or phosphor bronze. The plated main body 2 extends from one end side and achieves electrical connection, a terminal portion 3 that is located on the other end side, a contact portion 4 that is soldered to the substrate, and a terminal portion 3. It consists of the continuous part 5 between the contact parts 4.
The terminal portion 3 has a U-shape in which a pair of terminal pieces 3a and 3b composed of a movable terminal piece 3a and a fixed terminal piece 3b are opposed to each other. The contact portion 4 is L-shaped so that it can be easily soldered to the substrate.
A gold plating layer 12 is formed from one end side of the terminal portion 3, and a tin plating layer 13 is formed from the other end side of the contact portion 4. A boundary portion 14 between the gold-based plating 12 and the tin-based plating 13 is formed at the base portion of the terminal pieces 3a and 3b.

The structure of the plating on the main body 2 will be further described with reference to FIG. 2 which is a cross-sectional view taken along the line AA in FIG. 1 and FIG. First, the nickel base plating layer 11 is formed on the outer periphery of the main body 2. Nickel-based plating is plating with nickel or a nickel alloy. Nickel primer plating layer 11 has a thickness of usually 1~2μ m.
A gold-based plating layer 12 is formed on the nickel-based base plating layer 11 from the terminal portion side (one end side) of the main body 2. Gold-based plating is plating with gold or a gold alloy. The gold-plated layer 12 has a thickness of 0.03~0.1μ m.
A tin-based plating layer 13 is formed on the nickel-based base plating layer 11 from the contact portion side (the other end side) of the main body 2. The tin-based plating layer 13 is plating with tin or a tin alloy. The tin-based plating layer 13 has a thickness of 1～4Myu m, and has a 10 to 100 times the thickness of the gold-plated layer 12. An alloy layer 15 of tin and nickel is formed inside the tin-based plating layer 13. The alloy layer 15 is formed by thermal diffusion between nickel-based plating and tin-based plating by a reflow process at a high temperature of 350 ° C. or higher.

The vicinity of the boundary portion 14 between the gold-based plating layer 12 and the tin-based plating layer 13 will be further described with reference to FIG. The end of the gold-based plating layer 12 is an inclined surface 12b that gradually decreases in thickness until reaching the end 12a. The end of the tin-based plating layer 13 is also an inclined surface 13b that gradually decreases in thickness until reaching the terminal end 13a. The end portion 13 a of the tin-based plating layer 13 rides on the inclined surface 12 b of the gold-based plating layer 12, so that the riding portion 16 is formed. The height of the extended part 16 is preferably not more than 0.04μ m. Then, it is preferable that a valley-like depression is formed at the terminal end 13 a of the tin-based plating layer 13.
An alloy layer 15 of nickel and tin is formed in an exposed state on the inclined surface 13 b reaching the terminal end 13 a of the tin-based plating layer 13 and the riding-up portion 16. The tin-based metal remains exposed on the surface layer of the tin-based plating layer 13 other than the inclined surface 13b.

  The tin-based metal of the tin-based plating layer 13 has wettability with respect to the molten solder material. The gold-based metal of the gold-based plating 12 is also wettable with the molten solder material. However, the alloy of nickel and tin forming the alloy layer 15 has no wettability with respect to the molten solder material and has an action of preventing the rise of the molten solder. Therefore, as shown in FIG. 4, the sucking up phenomenon of the molten solder 17 when soldering to the substrate, that is, the solder rising, stops near the boundary portion 14 or on the contact portion 4 side and before the boundary portion 14. It will be.

  Such a plating contact 1 is suitably used for a connector 31 for a printed circuit board as shown in FIG. A large number of plating contacts 1 are fitted and fixed in the connector 31 and the housing 32, and the slide housing 33 is slidably mounted in the housing 32. The connector 31 is installed on the printed board 35 and soldered to the board at the contact portion 4 of the plating contact 1. When the flat cable 36 is inserted into the housing 32 and the slide housing 33 is pushed in, the flat cable 36 is electrically connected to the terminal piece 3 a of the terminal portion 3 of the plating contact 1. At this time, even if there is solder rise from the contact portion 4 in the plating contact 1, the solder rise stops near the boundary portion 14 or on the contact portion 4 side and before the boundary portion 14. Solder that degrades electrical characteristics does not adhere.

According to the plating contact 1 of the above-mentioned configuration, the thickness of the gold-plated 12 is thin and 0.03～0.1Myu m, and since having an inclined surface 12b that leads to the termination 12a, end 13a of the tin-plated 13 It is possible to reduce the thickness of the gold-based plating on the part to be ridden.
Further, since the thickness of the tin-plated 13 is formed with 1～4Myu m, 10 to 100 times the thickness of the gold-plated 12, the inclined surface 13b leading to the end 13a of the tin-plated 13 is formed in a wide range The Therefore, the alloy layer 15 of the tin plating 13 and the nickel base plating 11 is also formed over a wide range.
Further, since the gold plating 12 under the riding portion 16 of the tin plating 13 is thin and slight, the gold plating 12 hardly interferes with the formation of the alloy layer 15 reaching the riding portion 16.

  Thus, since the alloy layer 15 serving as a barrier against solder rise is formed in a wide range regardless of the presence of the gold-based plating 12, the barrier function against solder rise effectively acts.

Next, the plating method for the plating contact described above will be described with reference to FIG.
(Contact line press molding)
First, by press-molding a metal plate made of a copper alloy such as brass or phosphor bronze, many of the main bodies 2 shown in FIG. The contact row 22 is processed.
Each of the multiple connected main bodies 2 has a terminal portion 3 on one end side and a contact portion 4 on the other end side.
A large number of the main bodies 2 are connected in the holding portion 21 provided at the end on the contact portion 4 side. Therefore, a large number of the main bodies 2 can be plated at the same condition at the same time, so that the productivity is high.

(Nickel base plating process)
Next, the entire nickel base plating layer is immersed in the nickel plating bath so that the nickel base plating layer has a thickness of 1 to 2 μ over the outer periphery of the contact base 22, that is, the main body 2. 11 is applied.

(Gold plating process)
Next, from the direction a in FIG. 6, the contact row 22 is immersed in a gold plating tank from the terminal portion 3 side, and on the nickel-based plating layer 11 on the way from the one end side to the contact portion 4. Until the base of the terminal pieces 3a and 3b of the terminal portion 3, the gold plating 12 is applied so that the thickness of the gold plating layer is 0.03 to 0.1 μm. At this time, the liquid level of the gold plating tank is controlled so that the thickness reaching the terminal end 12a of the gold-based plating 12 becomes an inclined surface 12b.

(Tin-based plating construction and its riding part formation process)
Next, from the direction b of FIG. 6, the contact row 22 is dipped in a tin plating tank from the contact portion 4 side to the nickel plating layer 11 and from the other end side to the gold plating 12. The tin-based plating 13 is applied so that the thickness of the tin-based plating layer is 1 to 4 μm. At this time, the thickness of the tin-based plating 13 reaches the end surface 13b of the tin-based plating 13 and the inclined surface 12b of the gold-based plating 12 reaches the end surface 13b. The liquid surface of the tin-based plating tank is managed so that the riding-up portion 16 on which the inclined surface 13b rides is formed. By this liquid level management, the height of the ride-up portion 16, that is, the thickness of the gold-based plating layer 12 at the end 13 a of the tin-based plating 13 is 0.04 μ or less, and the end of the tin-based plating 13 is further reduced. A valley-like depression is formed in 13a.

(Reflow treatment and alloy layer formation process)
Next, by reflowing the contact row 22 at a high temperature of 350 ° C. or higher, the nickel-based plating 11 and the tin-based plating 13 are formed on the inclined surface 13 b including the riding-up portion 16 and reaching the terminal end 13 a of the tin-based plating layer 13. And are thermally diffused. As a result, the inclined surface 13b including the riding-up portion 16 is exposed to the surface, and the alloy layer 15 of tin and nickel is formed.
Here, the thickness of the tin-based plating layer 13 is 10 to 100 times larger than the thickness of the gold-based plating layer 12, and the inclined surface 13b reaching the terminal end 13a of the tin-based plating layer 13 is the gold-based plating. and that it is formed rides on the inclined surface 12b leading to the end 12a of the layer 12, and the thickness of the gold-plated layer 12 at the end 13a of the tin-plated layer 13 is less 0.04Myu m, by The alloy layer 15 is more reliably formed on the inclined surface 13b including the riding-up portion 16 in an exposed state reaching the surface.

(Separation process from contact line)
Next, the desired plated contact 1 can be obtained by separating the plated main body 2 from the contact row 22. Here, the main body 2 is exposed at the cut surface of the plated contact 1 at the above-mentioned cut position as seen at the right end of FIG. 2, but the function of the plated contact 1 is not affected.

  According to the above plating method, first, a thin gold plating 12 having an inclined surface reaching the end is formed, and then the thin surface of the inclined surface 12b reaching the end 12a of the gold plating 12 is thinned by a liquid level management method. In order to allow the tin-based plating 13 with a certain thickness to ride, the position of the terminal end 13a of the thick tin-based plating 13 can be controlled to easily and reliably form the plating structure as shown in FIG.

  In the above embodiment, the barrier region, that is, the alloy layer 15 is formed on the contact as shown in FIG. 1 based on the tin-based plating layer 13 plated so as to run on the gold-based plating layer 12. However, the present invention is not limited to this, and can be freely designed without departing from the technical idea of the present invention.

  There are various contact shapes to which this plating is applied. For example, the present invention can be applied to a strip-like long and thin linear contact having a terminal portion formed at one end and a contact portion formed at the other end. Further, the present invention can also be applied to a contact that is bent in an L shape, in which a terminal portion is formed on one end side and a contact portion is formed on the other end portion.

The following experiment was conducted in order to demonstrate the effect of the present invention.
In this experiment, a contact 1 having the shape shown in FIG. 1 is manufactured by press working from a connector press material having a thickness (T) of 0.12 to 0.2 mm and used as a spring phosphor bronze. Nickel plating as a base plating was applied so that the thickness was 1 μm or more.
Then, the terminal unit 3 of the contact 1, the inclined surface its end is gradually thinner, thickness was plated with gold is contact for plating 0.03~0.1μ m.

Then, from the contact portion 4 of the contacts 1, an inclined surface that its end is gradually thinner, and, while managing liquid surface so its end rides on the end of the gold plating, the thickness is in 1～4Myu m Thus, tin plating with good solder wettability was performed.

At this time, the end of the tin plating, i.e., those gold plating thickness at the place where the thickness is zero, 0.01μ m, 0.02μ m, 0.03μ m, 0.04μ m, the 0.05 .mu.m m Were prepared as Inventive Examples 1, 2, 3, 4, and 5, respectively.

  A reflow process was performed on the contact row 22 thus manufactured. At that time, the material temperature of the contact row 22 was about 400 ° C.

In Comparative Example 1, the entire surface of the nickel undercoat plating thickness such that the 0.03～0.1Myu m, was created which plated with gold is contact for plating. However, in Comparative Example 1, tin-based plating is not applied.

Further, as Comparative Example 2, over the entire surface of the nickel undercoat plating, to a thickness of 1～4Myu m, subjected to good tinned solder wettability, those subjected to reflow treatment at about 400 ° C. Created. However, in Comparative Example 2, no gold plating is applied.

Using the contacts 1 to 5 of the present invention and the contacts 1 according to Comparative Examples 1 and 2 obtained as described above, a simulation test of a solder mounting test was performed. That is, using the contact portion 4 of the contact 1 as a general electronic substrate, solder of 96.5% tin (Sn) 3% silver (Ag) 0.5% copper (Cu), nitrogen (N ₂ ), etc. The reflow mounting was performed in the atmosphere (about 100 to 260 ° C., 2 to 3 minutes), and the adhesion state of the solder was observed. The results are shown in Table 1.

(Experimental result)

From Table 1, when the gold plating thickness at the end of the tin plating is less than 0.04Myu m, that is, when the present invention examples 1 to 4, the solder up from the contact portion 4, the boundary portion 14 near or in contact portion 4 side And it stops before the boundary part 14.

On the other hand, if the gold plating thickness at the end of the tin plating is 0.05 .mu.m m, that is, when the present invention Example 5, the solder up from the contact portion 4, the boundary portion 14 near or a contact portion 4 side boundary portion It does not always stop before 14 but may cross the boundary 14.
However, in the case of Example 5 of the present invention, even if the solder rise from the contact portion 4 exceeds the boundary portion 14, it reaches the contact portion where the terminal portion 3 is in electrical contact with the mating connector. There is no.

Accordingly, the thinner the gold plating thickness at the end of the tin plating, preferably the thickness is more thinner there than 0.04Myu m, it can be seen that the solder uplink stopped more reliably.

  Further, in Comparative Examples 1 and 2 in which gold plating or tin plating was performed over the entire surface of the plating contact 1, since no barrier region was provided, solder rising was confirmed over the entire surface of the plating contact 1. .

  In particular, FIG. 7 shows the result of measuring the thickness of each plating layer in the vicinity of the boundary portion 14 in Example 3 of the present invention. Moreover, the situation of the solder rise in Example 3 of the present invention is schematically shown in FIG.

  In the case of Example 3 of the present invention, it can be seen that the solder rise stops in the vicinity of the boundary portion 14.

It is the side of a plating contact. It is the sectional view on the AA line of FIG. It is an expanded sectional view which shows the boundary part of a plating contact. It is an expanded sectional view showing typically stop of the solder rise in the boundary part of a plating contact. It is sectional drawing of the side surface of the connector with which the plating contact was mounted | worn. It is a top view of a contact row in which contacts are arranged. It is a graph which shows the result of having measured each plating thickness in the boundary part 14 vicinity of the example 3 of this invention. It is a schematic diagram which shows the stop state of the solder rise of the example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plating contact 2 Main body 3 Terminal part 3a Terminal piece 3b Terminal piece 4 Contact part 5 Connection part 11 Nickel-type base plating layer 12 Gold-type plating layer 12a Termination 12b Inclined surface 13 Tin-type plating layer 13a Termination 13b Inclined surface 14 Boundary part DESCRIPTION OF SYMBOLS 15 Alloy layer 16 Riding part 17 Molten solder 21 Holding part 22 Contact line 31 Connector 32 Housing 33 Slide housing 35 Printed circuit board 36 Flat cable

Claims (5)

A main body in which a terminal portion is formed on one end side and a contact portion is formed on the other end side, a nickel-based base plating applied to the outer surface of the main body, and applied on the base plating from the one end side, The gold-based plating which is an inclined surface whose thickness gradually decreases as it approaches the end, and is applied on the base plating from the other end side and is thicker than the gold-based plating, and the thickness becomes closer to the end Is formed between the tin-based plating and the nickel-based undercoat, and the nickel-based plating is formed so as to ride on the inclined surface of the gold-based plating. With an alloy layer of tin-based plating and tin-based plating,
The plating contact, wherein the alloy layer is exposed from between an end of the inclined surface of the tin plating and the inclined surface of the gold plating . The thickness of the gold-plated is 0.03～0.1Myu m, plated contacts according to claim 1, wherein the thickness of the tin-based plating is 1~4μ m. The thickness of the gold-plated at the end of the tin-based plating is plated contacts according to claim 2, wherein at most 0.04μ m.   The plated contact according to claim 1, wherein the terminal portion is formed by facing a pair of terminal pieces, and the riding-up portion is formed at a base of the terminal piece. A plating method using a contact row in which a large number of contact bodies each having a terminal portion formed at one end and a contact portion formed at the other end side are connected to a holding portion at an end on the contact portion side. A step of immersing the whole in a nickel-based plating tank, and applying a nickel-based undercoat to the entire contact row, and dipping the contact row in a gold-based plating bath from the terminal side, and the one end side on the undercoat A step of forming a gold-based plating partway from the contact portion to the contact portion and forming an inclined surface whose thickness gradually decreases as the end thereof is approached, and the contact row from the holding portion side to the tin-based plating tank the pickled, this on the underlying plating subjected to tin plating up to the gold-plated, thereby forming an inclined surface having a thickness gradually thinner as it approaches its end, the end of the gold-plated A step to make rides the inclined surface of the end of the tin plating on the inclined surface of, by thermal diffusion and said nickel undercoat plating and tin-based plating by a reflow process, a nickel-based base after the reflow treatment Between the plating and the tin plating, the nickel base plating and the tin plating exposed from between the inclined surface of the gold plating layer and the end of the inclined surface of the tin plating layer after the reflow treatment. Forming an alloy layer with a contact plating method.

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