JP4404195B2 - Whisker suppression method and electronic component manufacturing method - Google Patents

Description

  The present invention relates to a method for suppressing generation of contact pressure whiskers from a tin or tin alloy film and a method for manufacturing an electronic component in which generation of contact pressure whiskers is suppressed.

It is known that tin and tin alloy plating films generate whiskers when the film has internal stress, and this whisker causes problems such as short circuit.
For this reason, various methods for reducing the internal stress of tin and tin alloy plating films have been proposed, such as improving the plating solution. However, even if the internal stress is reduced and the member itself is difficult to generate a whisker, a contact pressure whisker is generated when stress is applied to the member from the outside. Here, the contact pressure refers to, for example, an external load applied to a contacted tin or tin alloy film in an electronic component such as a connector when a flexible board is fitted to a contact insertion portion, such as tin or tin. It is an external load applied to tin or tin alloy film when other members are pressure-fixed to the alloy film, and Sn, Sn-Cu, Sn-Ag are applied as surface treatments to fitting parts and contact parts of electronic parts. Although plating of Sn-Bi or the like has been performed, a contact pressure whisker is generated at a pressure contact portion such as a fitting portion or a contact portion.

FIG. 1 shows an example of a fitting state between one member a and another member b, and a portion c in the figure is a contact pressure portion.
Specifically, the connector 1 shown in FIG. 2 is subjected to tin or tin alloy plating on the connector pin 2. In this case, in the state where the lead 3 is not inserted as shown in FIG. 2, the connector pin 2 has been subjected to heat treatment or improvement of the plating solution so as to relieve internal stress. Whisker does not occur. However, when the lead 3 having the pattern 5 insulated and separated so as not to contact each other by the polyimide 4 is inserted into the connector 1, an external load is applied to the connector pin 2. If it does so, it will be in the same state as the internal stress in the tin or tin alloy plating film of the connector pin 2, and a whisker (contact pressure whisker) will generate | occur | produce. Thereby, the insulation of the lead 3 by the polyimide 4 is inhibited, and there is a possibility that the pattern 5 is short-circuited.

In the crystal oscillator shown in FIG. 3, tin or tin alloy plating is applied to the inner and outer surfaces of the container 6, and the crystal oscillator 7 is press-fitted into the container 6. Here, 8 is a crystalline lens, 9 is a lead terminal, and 10 is a lead terminal cover made of silicone resin for covering and protecting the lead terminal. By the above press-fitting, an external load is applied to the container 6 plating film in the portion X in FIG. As described above, the oscillator is provided with the lead terminal cover for the purpose of preventing the lead from being short-circuited, but the contact pressure whisker W grows in the lead terminal cover 10 from the tin or tin alloy plating film of the container 6. There is a risk of short circuit by contact with the lead terminal 9.
However, the present condition is that the effective method which suppresses generation | occurrence | production of a contact pressure whisker is not discovered conventionally.

  The present invention has been made in view of the above circumstances, and provides a method for suppressing the generation of contact pressure whiskers from a tin or tin alloy film, and a method for manufacturing an electronic component in which the generation of such contact pressure whiskers is suppressed. For the purpose.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors have applied an external load equal to or greater than that to the portion where the contact pressure whisker may be generated due to the other members being pressed and fixed. It has been found that the generation of contact pressure whiskers can be effectively suppressed by heat treatment, and the present invention has been made.

Therefore, according to the present invention, with respect to one member in which tin or a tin alloy film is formed on the surface on which the other member is pressure-fixed, the pressure-contact force is applied to at least a portion of the one member where the other member is pressure-fixed in it from the tin or tin alloy film of one element, characterized in that 5 0-400 heat treatment for 3 hours to 1 minute at ℃ while applying a more external load load of 3-5 kg / mm ² A method for suppressing the occurrence of contact pressure whiskers is provided. In addition, the present invention provides a first electronic member having a conductive portion isolated by an insulating portion as a second electronic member in which a tin or tin alloy film is formed on a surface to which the first electronic member is pressure-bonded. In the method of manufacturing an electronic component to be fixed by crimping, both the electronic members are crimped and fixed with a pressing force of 3 to 5 kg / mm ² and then subjected to heat treatment at 50 to 400 ° C. for 3 hours to 1 minute , or both the electronic members Before the crimping and fixing, at least the first electronic member of the second electronic member is pressed and fixed to the external portion with a load of 3 to 5 kg / mm ² or more which is the pressing force of the fitting portion when using the connector Heat treatment is performed at 50 to 400 ° C. for 3 hours to 1 minute in a state where a load is applied, and then both the electronic members are crimped and fixed, and the generation of contact pressure whiskers from the tin or tin alloy film is suppressed. A method for manufacturing a manufactured electronic component is provided. The heat treatment is preferably performed at 150 to 400 ° C. for 3 hours to 10 minutes.

  According to the present invention, even when an external load is applied to the tin or tin alloy film, the generation of whiskers is suppressed.

  The method for suppressing a contact pressure whisker according to the present invention is a portion in which at least the other member of the one member is pressed and fixed to one member having a tin or tin alloy film formed on the surface on which the other member is pressed and fixed. Heat treatment is performed with an external load applied.

  In this case, the tin or tin alloy film is usually formed by a plating method. The plating may be an electroplating method or an electroless plating method, and a vapor phase plating method such as vacuum deposition may be employed. The film thickness is appropriately selected depending on the type of member, purpose of use, etc., but is usually 0.5 to 15 μm, preferably 1.5 to 6 μm. Examples of the tin alloy film include Sn—Cu, Sn—Ag, and Sn—Bi. The tin content in the tin alloy is 50% by mass or more, more preferably 60% by mass or more, and further preferably 70% by mass. The above is preferable.

  Further, the external load applied to one member is preferably a load that is equal to or greater than the load applied by pressure-contact fixing of the other member. If the applied load is smaller than the pressure-fixing load, a contact pressure whisker may be generated. As a method of applying an external load to one member, another member may be press-fixed to one member, and a heat treatment may be performed in a state where a component is obtained. It is possible to employ a method in which at least a portion of the member where the other member is pressure-fixed is pressed with a load equal to or greater than the pressure-fixing load and heat treatment is performed in this state.

Incidentally, the contact pressure of the other member applied to members of the one, in the fitting point of time of connector used Ru 3-5 kg / mm ² der. Further, the upper limit of the load equal to or greater than the pressure contact force (load) is selected as appropriate, and is possible as long as one member is not mechanically broken.

The heat treatment conditions, Ru heating time der 3 hours 1 minute at 50 to 400 ° C.. At this time, it is preferable to perform the heat treatment at a low temperature for a long time and at a high temperature for a short time. Under heat treatment conditions outside the above ranges, contact pressure whiskers may occur, particularly at low temperatures and low times.

  The combination of the one member and the other member includes a connector (connector pin) and a lead frame as shown in FIGS. 2 and 3, a container and a crystal oscillator, etc. It is not limited.

The above combination is a combination of electronic members, but when an electronic component is manufactured by combining such electronic members, as described above, the first electronic member in which the conductive portion is isolated by the insulating portion, When manufacturing an electronic component to be crimped and fixed to a second electronic member having a tin or tin alloy film formed on the surface to which the first electronic member is crimped and fixed, heat treatment is performed after the above-mentioned electronic members are crimped and fixed. Or at least a portion of the second electronic member to which the first electronic member is crimped and fixed, preferably more than a load applied by crimping and fixing the first electronic member before the electronic member is crimped and fixed. It is preferable that the heat treatment is performed with an external load applied, and then both the electronic members are crimped and fixed.
In addition, the said crimping | fixing fixation aspect and heat processing conditions are as having mentioned above.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not restrict | limited to the following Example.
In the following examples, the following contact pressure clip method was used as a method for measuring the generation of contact pressure whiskers.

Pressure contact clip method A double-sided adhesive tape is applied to one side of the pin 12 of the eyeball clip 11 (65 mm width) shown in FIG. 4, and three stainless steel balls (SUS balls) 13 having a diameter of 1 mm are arranged on the inner surface at approximately equal intervals. They are bonded together in parallel, and an Sn—Cu alloy electroplating film (Cu content: 2.) on one side of a Ni—Fe (42 alloy) alloy plate having a size of 0.3 mm thickness × 15 mm width × 20 mm length. 0 wt%) with a film thickness of 5.7 μm was sandwiched so that the plating film was in contact with the central SUS sphere 13, and the sample was removed after a certain period of time (1-10 days) in this loaded state. The whisker was observed with a scanning electron microscope (SEM), the contact pressure whisker was counted from the SEM image, and the result of the number of whisker generation was quantitatively converted into data. In addition, according to this eyeball clip system, it is possible to examine the occurrence state of the contact pressure whisker in a short period (1 to 3 days).

[Example 1, Comparative Example 1]
An Sn—Cu alloy electroplating film (Cu content 2.0 wt%) was formed to a thickness of 5.7 μm on one side of a 0.3 mm thick × 15 mm wide × 20 mm long Ni—Fe (42 alloy) alloy plate. A state in which a load is applied to this sample with a load of 750 g (24 kg / mm ² ) (Example 1) by the above-mentioned contact pressure clip method, and a state in which the above-mentioned contact pressure clip method is not employed (no load is applied) ( In Comparative Example 1), heat treatment was performed at 200 ° C. for 1 hour. The sample of Example 1 was not removed from the eyeball clip as it was, and the sample of Comparative Example 1 was heated and brought into the same contact pressure state as in Example 1 by the above-mentioned contact pressure clip method, and left in the atmosphere at room temperature for 3 days. The sample was observed for the occurrence of whiskers. The observation results are shown in Table 1 below.

[Examples 2 and 3, Comparative Examples 2 and 3]
An Sn—Cu alloy electroplating film (Cu content 2.0 wt%) was formed to a thickness of 5.7 μm on one side of a 0.3 mm thick × 15 mm wide × 20 mm long Ni—Fe (42 alloy) alloy plate. A state in which a load was applied to this sample at 24 kg / mm ² (Example 2), 26 kg / mm ² (Example 3), and 22 kg / mm ² (Comparative Example 2), and a state in which no load was applied (Comparative Example 3) And heat-treated at 200 ° C. for 1 hour. After heating, each load was not applied once and left in the atmosphere at room temperature for 1 day. Each sample left for 1 day was allowed to stand in the atmosphere for 3 days at room temperature with a contact pressure (pressure contact force) of 750 g (24 kg / mm ² ) applied by the contact pressure clip method. The presence or absence of occurrence was observed. The observation results are shown in Table 2 below.

[Example 4]
In the above contact pressure clip method, the contact pressure (pressure contact force) applied to the sample when the sample is sandwiched is a load of 750 g (24 kg / mm ² ). The whisker state was examined by leaving it at room temperature for 3 days under a contact pressure of 750 g (24 kg / mm ² ). The results showing the relationship between the heat treatment time and the number of whiskers generated are shown in FIG. FIG. 5 shows that when heat treatment is performed at 150 ° C., the whisker is not generated even in the contact pressure state by increasing the treatment time.

[Example 5]
In the above contact pressure clip method, the contact pressure (pressure contact force) applied to the sample when the sample is sandwiched is a load of 750 g (24 kg / mm ² ). After heat treatment at a predetermined temperature for 1 hour in the sample pressure contact state, the load is also 750 g. The whiskers were examined by leaving them at room temperature for 3 days under a contact pressure of (24 kg / mm ² ). The results showing the relationship between the heat treatment temperature and the number of whiskers generated are shown in FIG. In Example 5, when performing the heat processing for 1 hour like FIG. 6, if a heating temperature is 200 degreeC, even if it is a contact pressure state, it turns out that a whisker does not generate | occur | produce.

It is the figure which showed an example of the fitting state of one member and other members in this invention. It is the figure which showed one specific example of one member in this invention, and another member. It is the figure which showed the other specific example of the one member and other member in this invention, Comprising: (B) is an enlarged view of the X section of (A). It is a figure for demonstrating the contact pressure clip method used for generation | occurrence | production measurement of the contact pressure whisker in the Example of this invention. It is the figure which showed the relationship between the heat processing time in Example 1 of this invention, and the number of whisker generation | occurrence | production. It is the figure which showed the relationship between the heat processing temperature in Example 2 of this invention, and the number of whisker generation | occurrence | production.

Explanation of symbols

1 Connector 2 Connector Pin 3 Lead 4 Polyimide 5 Pattern a, b Member c Contact Pressure Location W Contact Pressure Whisker

Claims (7)

With respect to one member in which tin or a tin alloy film is formed on the surface on which the other member is pressure-fixed, at least a portion of this one member where the other member is pressure-fixed is 3-5 kg / Suppressing generation of contact pressure whiskers from the above-mentioned tin or tin alloy film of one member, wherein heat treatment is performed at 50 to 400 ° C. for 3 hours to 1 minute with an external load of mm ² or more applied how to. The method for suppressing the generation of contact pressure whiskers according to claim 1, wherein the heat treatment is performed at 150 to 400 ° C for 3 hours to 10 minutes. 3. The method for suppressing generation of a contact pressure whisker according to claim 1, wherein the other member is a lead, and the one member is a connector pin. An electronic component for crimping and fixing a first electronic member having a conductive portion isolated by an insulating portion to a second electronic member having a tin or tin alloy film formed on a surface to which the first electronic member is crimped and fixed. In the manufacturing method, the both electronic members are subjected to heat treatment at 50 to 400 ° C. for 3 hours to 1 minute after being crimped and fixed with a pressing force of 3 to 5 kg / mm ² . A method of manufacturing an electronic component in which generation of contact pressure whiskers is suppressed. An electronic component for crimping and fixing a first electronic member having a conductive portion isolated by an insulating portion to a second electronic member having a tin or tin alloy film formed on a surface to which the first electronic member is crimped and fixed. In the manufacturing method, before crimping and fixing the two electronic members, at least a first electronic member of the second electronic member is pressed and fixed to a portion 3 to 5 kg / From the above tin or tin alloy film, heat treatment is performed at 50 to 400 ° C. for 3 hours to 1 minute with an external load of mm ² or more applied, and then both the electronic members are crimped and fixed. A method of manufacturing an electronic component in which generation of contact pressure whiskers is suppressed. The method of manufacturing an electronic component according to claim 4 or 5, wherein by performing 3 hours to 10 minutes to heat treatment at 0.99 to 400 ° C.. 7. The method of manufacturing an electronic component according to claim 4, wherein the first electronic member is a lead and the second electronic member is a connector pin.

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