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The resistance value of a film resistor is defined by its geometric dimensions (length, width, height) and the resistor material. A lateral cut in the resistor material by the laser narrows or lengthens the current flow path and increases the resistance value. The same effect is obtained whether the
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boards are contacted by test probes on the assembly side and trimmed with a laser beam from the resistor side. This trimming method requires no contact points between the resistances, because the fine pitch adapter contacts the component on the opposite side of where the trimming occurs. Therefore,
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chip resistor or chip capacitor, and the potentiometer adjusting screwdriver is replaced by the laser trimming. The achieved accuracy can be higher, the procedure can be automated, and the long-term stability is better than with potentiometers and at least as good as with SOT components. Often the
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but only requires four banks for full operation. During testing, each cache bank is exercised. If a defect is found in one bank, that bank can be disabled by blowing its programming fuse. This built-in redundancy allows higher chip
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Laser-trimmed precision thin-film resistor network from Fluke, used in the
Keithley DMM7510 multimeter. Ceramic backed with glass hermetic seal cover. Laser trim marks are visible in the grey resistive
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Trimmable chip capacitors are built up as multilayer plate capacitors. Vaporizing part of the top layer with a laser decreases the capacitance by reducing the area of the top electrode.
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is the adjustment of a resistor to a given value. If the trimming adjusts the whole circuit output such as output voltage, frequency, or switching threshold, this is called
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than would be possible if all cache banks had to be perfect in every chip. If no bank is defective, a fuse can be blown arbitrarily, leaving just four banks.
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From the top side the chamber is pressurized to 1 to 4 bars, with a controlled exhaust port to achieve air flow through the chamber.
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resistor. The surface-mount resistor is produced with the same technology and may be laser trimmed as well.
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One type of passive trimmer uses a pressure chamber to enable resistor trimming in a single run. The
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Trimming of unlimited number of printed resistors in one step without obstruction from test probes.
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laser for active trimming can be integrated in existing measurement systems by the manufacturer.
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are blown by the laser, enabling or disabling various logic circuits. An example of this is the
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As the resistance material is vaporized, the waste particles are removed in the air flow.
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A similar approach can be used to program digital logic circuits. In this case,
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laser changes a thick-film or a thin-film resistor on a ceramic substrate or an
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One of the most common applications uses a laser to burn away small portions of
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the LTCC can be arranged more compactly and less expensively.
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From the opposite side a rigid probe contacts the circuit.
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microprocessor where the chip contains five banks of
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185:Trimming LTCC resistances in a pressure chamber
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132:is the manufacturing process of using a
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51:adding citations to reliable sources
265:Program from digital logic circuits
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302:Semiconductor device fabrication
252:It is simpler to substitute the
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236:Density up to 280 points/cm².
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225:Advantages of this method:
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107:June 2015
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91:scholar
55:removed
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278:POWER4
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