Most mounting questions concern the TO-220AB and TO-247AC package styles used to house diodes, MOSFETs, and IGBTs, and the three methods used to make electrical connections to the die within these packages: wire bonding, soldering, and compression mounting. Each method has its own advantages and disadvantages.

Wire bonding, shown in Figure 23, uses a small diameter (typically <=20 mils) wire that is ultrasonically bonded (melted) at each connection point. Advantages: wire bonding is quick and easy, and can be completely automated. Disadvantages: increased voltage drop due to the small wires, low fusing current, expensive equipment required.

Solder mounting shown in Figure 24 below is typically used in smaller diodes (< 10A), mostly the familar axial-leaded diode.

Some smaller IR Schottky diodes (SMB and SMC) also use this technique. Advantages: both the voltage drop, and fusing current are improved. For example, the 30BQ015 Schottky diode is rated at 3 amps and 15 volts, but the surge rating is 650 amps because the die is soldered directly to the leadframe. Disadvantage: both sides of the die must be solderable.

Compression bonding (Figure 25 above) is used in devices where power cycling capability is required, typically high power diodes and SCRs. Advantage: in these applications, compression bonding makes a much better connection because there is no fixed (soldered) interface to fatigue, and the fusing current is very high. Disadvantage: compression bonding is more expensive, and requires physically rugged die. All IR hockey puks are compression bonded. Some stud mounted diodes and SCRs, and some diode and SCR modules are also compression bonded.