Thermode Selection Guide

Pulse Heated

Theory of Operation:

The resistance of the thermode to the flow of electrical currentproduces the heat required to melt the solder and create the connection. As the electrical energy flows through the thermode, the heat generated is conducted directly to the workpiece. Since most of the electrical current passes through the thermode, there is little chance of electrical damage to the workpiece. After the reflow temperature is reached and the solder has flowedsufficiently, the current is terminated. The thermode remains in contact with the parts just long enough for the solder to solidify.The size and thermal properties of the workpiece directly affectthe amount of heat required. This is why thermodes incorporate a thermocouple which provides temperature data to a closed loop heating system (Uniflow

Thermode Selection

•Wide variety of tip shapes and sizes•Uniform heating •Dimensionally stableMiyachi Unitek offers a variety of thermodes for differentapplications. In order to optimize the transfer of thermalenergy from the thermode to the part, the thermode foot- print should equal or exceed the size of the part. If a partis thermally more conductive than the thermode, the ther-mode may not be able to reach reflow temperature.Thermode life is dependent on set point temperature.Brazed construction offers increased operating life.

® ).The pulse heated control performs the following functionsduring the soldering process:•Detects when the mechanical system (head) has applied theprogrammed pressure of the thermode to the parts.•Rapidly heats the thermode. •Maintains the preset temperature for a precise time to achievea quality joint. •At the end of the cooling period, the control signals the head toretract the thermode from the parts when the joint has solidified.The temperature of a pulse heated thermode will normally beat ambient when it contacts the parts. A quality thermode should be capable of heating itself and the portion of the workpiece it contactsin a very short time. Because of its low thermal mass,the thermode heats and cools rapidly. The amount of energy transferred to the part by the thermode should be of the same order of magnitude as the energy required to reflow the solder.

Reflow Soldering Mounting Blocks forThree-Dimensional Thermodes (TD) Quick Connect Blocks (QCB) for Thermo-Plane Thermodes

This range of thermode mounting blocks will fit on all 80,84and 180 series weld heads and is standard with the 87SA/24, 84SA/24 and 180SA/24.The robust design allows efficient heat dissipation for applications with high repetition rates. The design also facilitates efficient current transfer to the thermode,thus allowing fast heat-up and cool-down,and therefore the shortest process times.A industrial nozzle for cooling air is fitted and a cooling module can be ordered specially to fit to the Uniflow control. This range of thermode QCBs will fit on all Unitek EAPROSH80 and SH500 series weld heads.The QCB and Thermo-Plane Thermode are designed to be used as a set.The set is ground to optimize co-planarity resulting in the best quality of product bonds.The set also enables fast exchange of the Thermode in mid-production without further adjustment.The special shaft design of the QCB guarantees repeatable position of the thermode.
Unitek Eapro QuickConnect Block (QCB) SMALL45mm / 1.77" MEDIUM65mm / 2.56" LARGE 105mm / 4.13"

Miyachi Unitek Mounting Blocks

The SMALL block (P/N:17TDSB177) is standard on the 87SA/24 head.The MEDIUM block (P/N:17TDMB256) is standard on the 84SA/24. The LARGE block (P/N:17TDLB413) is standard on the 180SA/24.