Solder bath and method of heating solder contained in the solder bath

Abstract

A solder bath comprises a solder bath main body containing lead-free solder. A heating member heats the solder and is mounted on outer surfaces of a bottom and sides of the solder bath main body. The heating member contains a thermal diffusion member that is made of stainless steel, a porous heat insulator that is mounted on and attached to the thermal diffusion member, and a heating element that is buried in the porous heat insulator. The heating element is also away from the thermal diffusion member. The thermal diffusion member is heated by heat of the heating element to heat the solder bath main body evenly through thermal diffusion from the thermal diffusion member up to a constant range of temperature and the solder contained in the solder bath is heated evenly to a constant range of temperature.

1 . A method of heating solder contained in a solder bath, the method comprising the steps of:
 providing a solder bath apparatus that comprises a solder bath main body and a heating member for heating solder in the solder bath main body, said heating member being mounted on outer surfaces of a bottom and sides of the solder bath main body and comprising a thermal diffusion member that is made of stainless steel and is mounted on the outer surfaces of the bottom and sides of the solder bath main body, a porous heat insulator that is made of ceramic foam and has a three-dimensional network, the porous heat insulator being mounted on and attached to the thermal diffusion member and being formed with a channel toward the thermal diffusion member, and a heating resistive element disposed in the channel, wherein the channel is of a depth that is greater than a thickness dimension of the heating element whereby a gap is provided between the heating element and the thermal diffusion member,   providing lead-free solder in the solder bath main body to a level at or above an upper edge of said thermal diffusion member, and   heating the heating resistive element,   whereby the thermal diffusion member is heated by heat of the heating element to heat the solder bath main body evenly through thermal diffusion from the thermal diffusion member up to a constant range of temperature and the lead-free solder contained in the solder bath is heated evenly by the solder bath main body to a constant range of temperature.   
     
     
         2 . The method according to  claim 1 , comprising circulating the lead-free solder contained in the solder bath main body by a solder-circulating device that is contained in the solder bath main body and has an inlet positioned below the level of the solder contained in the solder bath main body and an outlet positioned above the level of the solder contained in the solder bath main body, and a pump that sends the solder into an interior of the solder-circulating device from the inlet.