KR100420470B1 - Method of Soldering for Making a PTC Device - Google Patents

Abstract

The present invention relates to a soldering process for coupling between a metal electrode and a metal lead in the manufacture of a conductive composite device having a constant temperature characteristic, in particular a constant temperature characteristic device excellent in mechanical and electrical coupling, and almost no change in performance It relates to a soldering method for manufacturing.

The above object is in the constant temperature characteristic device manufacturing process for maintaining the inherent physical properties between the metal lead and the electrode of the conductive composite after the soldering process between the metal lead and the conductive electrode for the production of the constant temperature characteristic device,

The soldering process is achieved by the soldering method for manufacturing a positive temperature characteristic device, characterized in that the following conditions are satisfied.

(1) Maximum temperature condition: 180 ~ 250 ℃

Sn (63w%) Pb (37w%) selected as solder is the temperature of melting in the range of 180 ℃ to 250 ℃.

(2) Movement speed condition: 0.10 or more but less than 1.00 m / min

(3) Temperature rise / cooling condition: 0.5 ~ 2 ℃ / min

Description

Method for Soldering for Making a PTC Device

The present invention relates to a soldering process for coupling between a metal electrode and a metal lead in the manufacture of a conductive composite device having a constant temperature characteristic, in particular a constant temperature characteristic device excellent in mechanical and electrical coupling, and almost no change in performance It relates to a soldering method for manufacturing.

In general, a conductive composite device (PTC device) having a PTC (Positive Temperature Coefficient) characteristic has a property that a resistance value increases as the temperature increases. By using these characteristics, it is widely used as a safety device for overcurrent blocking such as a battery.

In order to actually use the conductive composite, a composite of a polymer having carbon properties and carbon, a metal electrode, and a metal lead for mounting on a battery are required.

In this case, a soldering process that is generally widely used is introduced as a method of coupling the metal electrode and the metal lead.

However, since the positive temperature element contains a polymer, it is very sensitive to heat.

For this reason, high temperature soldering processes require temperature conditions to have an effective bond at the lowest possible temperature. In addition, the use of a solder that is too low temperature is a problem below the operating temperature range of the PTC device.

Therefore, the present invention selects a solder of a suitable material for the effective bonding of the metal electrode and the metal lead of the conductive composite, which is a heat sensitive device, to provide a soldering process excellent in mechanical and electrical coupling after soldering, and hardly changes in performance. Has its purpose.

The purpose is to maintain the inherent characteristics even after soldering by the factors such as the reflow moving speed, the temperature of the highest point in the process where the heat is transferred by hot air using the reflow type heat transfer furnace as an example. It is achieved by the manufacturing process of the composite.

1 is a diagram showing the temperature-time relationship in reflow.

2 is a cross-sectional view of a positive temperature characteristic element.

[Description of Symbols for Main Parts of Drawing]

a: Maximum temperature point in reflow b: Reflow discharge point

c: metal lead d: solder joint

e: metal electrode f: conductive composite

Hereinafter, the present invention will be described in more detail with reference to Examples.

In general, a method of melting and joining a non-ferrous metal material to be bonded for bonding a metal to a metal is called brazing. This nonferrous metal is called a brazing material. A melting point of 450 ° C. or higher is used for brazing, and 450 ° C. or lower is a lead, and a method used for joining metals at 450 ° C. or lower is generally called a solder. Soldering methods can be divided into iron soldering using iron, dip soldering which is immersed in lead bath and soldering several devices at the same time, furnace soldering using electric furnace and infrared (IR). have. The soldering method applied to the present invention adopts a reflow soldering method capable of soldering by flowing a hot air section heated at a constant speed by using a heat transfer furnace.

In the present invention, a soldering technique widely used to develop a device having a constant temperature characteristic is developed, and it is not merely interested in joining and bonding metal electrodes and metal leads, but includes sensitive devices capable of being modified by heat. The present invention relates to a soldering process that combines the external metal foil of a composite with a metal lead necessary for practical application while maintaining the inherent properties of the conductive composite inside the device.

That is, a coupling technique between metals such as soldering may be applied to couple the metal electrode forming the conductive composite surface of the positive temperature characteristic device with the metal lead required for mounting. Because of the thermal sensitivity of the conductive composite inside the device, the minimum operating temperature, temperature rise method and minimum time required for possible metal-to-metal bonding in the soldering process are factors that significantly affect performance. In addition, the conductive composite has an electrical short-circuit action in which resistance increases rapidly with temperature rise due to overcurrent or the like.

Therefore, the soldering joint material should be in the range above the operating temperature because sufficient mechanical bonding properties must be maintained at this operating temperature.

The process temperature required for soldering has a melting point of 150 ℃ or higher considering the operating temperature, and SnPb-based material (melting point approximately 183 ℃) is selected as a material having excellent mechanical bonding and electrical conductivity.

Therefore, the temperature required for soldering was set at a temperature of 180 ° C. to 250 ° C. and a temperature and a speed (time) so as to have good mechanical and electrical coupling at a low temperature if possible.

In addition, the temperature rising method of the reflow required for soldering is, for example, a temperature curve that does not undergo a preheating step, which is the most widely used heating method as shown in FIG. 1, and has a moving speed of 0.10 to 1.00 m / min. Caught in the range.

The configuration of the positive temperature characteristic element is shown in FIG.

The conductive composite (f) is composed of HDPE (high density polyethylene) and carbon black, and was crosslinked with peroxide.

-HDPE has a density of 0.95 ~ 0.965g / cm³ and melt index 3 ~ 6.

-Carbon black accounts for 30 ~ 40w% by mass ratio of conductive composite.

Peroxide crosslinker is 0.2wt%.

Nickel-plated copper foil without fine roughness was used as the metal electrode (e), and metal lead (c) was used with nickel or nickel alloy. As the solder cream (d), Sn (63w%) Pb (37w%)-based material was used.

The following examples summarize the resistivity values and mechanical coupling characteristics, which are electrical coupling characteristics when soldering is performed by varying the moving speed and the peak temperature (a).

Example Reflow Movement Speed (m / min) Peak temperature (℃) Electrical resistivity of positive temperature device after soldering (ohm cm) Adhesiveness A 0.10 210 0.833 Good B 0.10 230 0.956 Good C 0.10 250 1.032 Good D 0.66 230 0.656 Good E 0.66 250 0.656 Good F 0.66 210 0.614 Good G 1.00 250 0.651 Bad H 1.00 210 0.649 Bad I 1.00 230 0.642 Bad

Experimental results Example F is the best characteristic, the temperature-time relationship at that time is shown in FIG.

Of course, Examples D and E also showed good characteristics.

Example C showed a poor result with a specific resistance of 1 kPa or more, and Examples A and B exhibited a relatively high specific resistance.

On the other hand, as in Examples G, H, and I, when the reflow speed is as fast as 1.00 m / min, the coupling between the lead and the electrode is weak and poor adhesion is not suitable.

The present invention, which is a process as described above, selects a solder of a suitable material for the effective bonding of a metal electrode and a metal lead of a thermally sensitive constant temperature characteristic device, and has excellent mechanical and electrical coupling after soldering, and almost no change in performance. It is effective to lose.

Claims (4)

In the constant temperature characteristic device manufacturing process for maintaining the inherent physical properties between the metal lead and the electrode of the conductive composite after the soldering process between the metal lead and the conductive metal electrode for the production of a constant temperature characteristic device, The soldering process is to be by reflow soldering, the soldering process is a soldering method for manufacturing a positive temperature characteristic device, characterized in that the following conditions are satisfied. (1) Maximum temperature condition: 180 ~ 250 ℃ (2) Movement speed condition: 0.10 or more but less than 1.00 m / min (3) Temperature rise / cooling condition: 0.5 ~ 2 ℃ / min The method of claim 1, (1) The maximum temperature condition is 210 ~ 250 ℃, (2) The moving speed condition is 0.66m / min, (3) Temperature rising / cooling conditions: Soldering method for manufacturing a positive temperature characteristic device, characterized in that 0.5 ~ 2 ℃ / min. The method of claim 2, (1) The maximum temperature condition is 210 ℃, (2) The moving speed condition is 0.66m / min, (3) Temperature rising / cooling conditions: Soldering method for manufacturing a positive temperature characteristic device, characterized in that 0.5 ~ 2 ℃ / min. The soldering process according to any one of claims 1 to 3, wherein Soldering method for manufacturing a constant temperature characteristic device, characterized in that using a heat source in an electric furnace or infrared furnace.