JPS61253802A - Trimming of resistor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a so-called resistor trimming method for adjusting the resistance value of a resistor to a desired resistance value. especially,
The present invention relates to a method for trimming resistors on a substrate such as a hybrid IC (hereinafter referred to as HIC) in which a large number of resistors are scattered on the substrate.

BACKGROUND OF THE INVENTION In recent years, electronic devices are becoming smaller and lighter. The circuits used in these electronic devices require high-density packaging of microcomponents. One of the high-density packaging methods is so-called HIC, in which a circuit block consisting of an IC and IC peripheral components is combined into one module. I (The manufacturing method of IC is generally 9,
After forming a wiring pattern on a ceramic substrate, a resistor is formed by printing, and other components (IC, capacitor, etc.) are mounted.

Here, the resistance value of the resistor formed by printing is:

An error of ±10% to ±20% usually occurs due to resistor material preparation conditions, firing conditions, variations in resistor film thickness, etc.

Therefore, it is essential to adjust the resistance value by trimming the resistor. Lasers are mostly used for trimming resistors due to the demand for smaller resistors and higher speeds, and in order to reduce the cost of HIC, it is necessary to increase the throughput of expensive laser trimming equipment. be.

Conventionally, trimming of a resistor involves pressing a probe onto the electrode of the resistor, then moving the focal point of the laser in a direction that blocks the current flowing through the resistor to burn out the resistor.
This is done by measuring the change in resistance value obtained through the probe with a resistance value measuring circuit, and stopping laser irradiation when the resistance value reaches a desired resistance value. In a board where a large number of resistors are arranged and mounted on the board.

Currently, the trimming method described above is performed by applying a probe to the electrodes of all resistors in advance and sequentially trimming them using a scanner while combining the resistors with a resistance value measurement circuit (for example, [Nikkei Electronics J19g1, May 25, No. 166-188, "Electronic Materials" Vol. 33, No. 5, No. 92-98).

Problems that the invention attempts to solveHowever, with the conventional trimming method as described above,
When a large number (usually several tens) of microresistance elements are mounted on a board in a high-density and scattered manner, such as in a HIC,
It is impossible to simultaneously apply a probe to all resistor electrodes without contacting other probes and without blocking the laser beam.

Therefore, it is possible to divide the resistor on the board into several blocks, provide a probe head for each block, and perform trimming by mechanically switching the probe heads, or prepare a laser trimmer for each probe head and use multiple laser trimmers. It was being trimmed. Therefore, the former method reduces trimming speed, and the latter method results in high equipment costs, both of which have their own problems.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a method for trimming a resistor that can be performed at high speed and at low cost.

Means for Solving the Problems The resistor trimming method of the present invention calculates the trimming amount for the target trim ratio of the resistor from a trim ratio change characteristic table for the resistor trimming amount determined in advance, and calculates the trimming amount for the resistor trimming amount determined in advance. It is characterized by performing amount trimming.

Effect: With this configuration, during trimming, it is only necessary to control the laser beam by the amount of trimming, which eliminates the need for a resistance measurement circuit and measurement probe, allowing for faster trimming of all resistors on the board at once. .

EXAMPLE Hereinafter, the trimming method of the present invention will be explained based on a specific example.

FIG. 1 is a block diagram of a laser trimming device that implements the trimming method of the present invention, in which 1 is a HIC substrate, 2.3 is a printed resistor, and 4.5.6.7 is an electrode part of resistors 2 and 3. Pressed probe, 8 is initial resistance value R1 of resistors 2 and 3
jR11 in order, and 9 is a trimming target resistance value Rt1.jR11 for trimming to a desired resistance value. A target resistance value storage means 10 stores Rt2 and a target trim ratio (Rt1) from the initial resistance value RtR2 and the trimming target resistance value Rtz, Rt2.
/R engineering), (Rt, z/R2), 11 is a trim ratio change characteristic table that stores trim ratio change characteristics with respect to the trimming amounts of the resistors 2 and 3, and 12 is a trim ratio change characteristic table for calculating the target trim. Ratio (Rt1/R,), (Rt,
/R2) trimming amount calculating means for calculating the trimming amount A from the trim ratio change characteristic table 11; , a2 to trim the resistors 2 and 3. Furthermore, the broken line section A in FIG. 1 is a positioning stage during initial resistance value measurement, and the broken line section B is a positioning stage during trimming.

In the trimming process, first, the HIC substrate 1 is positioned on the positioning stage A for initial resistance value measurement, and the probe 4.
Press 5.6.7 to the electrode parts of resistors 2 and 3, and
, 3 (i=1, 2) is measured by the initial resistance value measuring means 8. Next, remove the probe 4.5.6゜7 and move to the positioning stage B when trimming the HIC board 1.
Move to position. On the other hand, trim ratio calculation means 10
The trimming target resistance value Rti (i=1.2) stored in the target resistance value storage means 9 and the initial resistance value Rx
b=1y 2), (hereinafter C1, 2), the target trim ratio (
Rti/Ri), the trimming amount calculation means 1
In step 2, the trimming value for the target trim ratio (Rti/Ri) is determined from the trim ratio change characteristic table 11.

The trimming means 13 trims the determined trimming amount j of the laser condensing point 15 from the resistor edge portions of the resistors 2 and 3 by 21. Trimming is completed by moving ζ2.

Figure 2 shows the resistor after trimming, resistors 2 and 3.
The edges □ and q2 are trimmed from the edge portions 16 and 17, respectively.

Next, the trimming amount calculation means 12 and the trim ratio change characteristic table 11 will be explained using FIG. 3. FIG. 3 is a diagram showing trim ratio change characteristics with respect to trimming amount q, and H is shown in the trim ratio change characteristics table ll.
It is stored in correspondence with each resistor in the IC board. The trimming amount calculation means 12 calculates the trimming rate for the target trim ratio (Rt/R) as shown by the broken line in FIG. The trim ratio change characteristic table 11 can be easily created by measuring the resistance value while trimming each resistor by unit length and calculating the ratio with the initial resistance value.

As described above, according to this embodiment, there is no need to measure the resistance value of the resistor during trimming, so a measurement probe and a resistance value measurement circuit are not required.

As described in the prior art section, the resistance value of the resistor varies by ±1 depending on the compounding conditions of the resistor material, firing conditions, resistor film thickness, etc.
．． There is a variation of 0 to 20%.

Resistance variation in resistors of the same size within the same manufacturing lot is due to variation in resistor film thickness (usually 12 μm ± 2 μm).
A lot depends on the degree). However, when trimming the same amount of resistors of the same size with different resistor film thicknesses,
Although the initial resistance value and the resistance value after trimming are different, the trim ratio is almost the same. Therefore, trimming can be performed by determining in advance the trim ratio change characteristic with respect to the trimming amount.

Note that the amount of trimming for the trim ratio stored in the trim ratio change characteristic table 11 of this embodiment may be obtained by calculation from the dimensions of the resistor and the trim ratio.

As described in the detailed description of the invention, in the resistor trimming method of the present invention, the trimming amount for the target trim ratio of the resistor is determined from a trim ratio change characteristic table for the resistor trimming amount determined in advance. During trimming, it is no longer necessary to measure resistance using a probe, which eliminates conventional problems caused by probes, such as reduced trimming speed due to changing probe beds and high equipment costs due to the use of multiple laser trimmers for each probe head. It is possible to eliminate the problem and perform trimming at high speed and at low cost, which has a great effect on productivity.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of a device that implements the trimming method of the present invention, Fig. 2 is a plan view of a resistor after trimming, and Fig. 3 is a first trim ratio conversion characteristic table and trimming. It is an explanatory diagram of operation of quantity calculation means. l... HIC board, 2, 3... printed resistor, 10.
... Target trim ratio calculation means, 11 ... Trim ratio conversion characteristic table, 12 ... Trimming amount calculation means agent Yoshihiro Morimoto Figure 1 Figure 2

Claims (1)

[Claims] 1. A resistor trimming method in which the trimming amount for a target trim ratio of the resistor is determined from a trim ratio change characteristic table for the trimming amount of the resistor determined in advance, and trimming is performed to the determined trimming amount.