JPH0787259B2 - Function trimming method for hybrid integrated circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is directed to a hybrid integrated circuit formed by mounting various circuit components including a resistance element on a wiring board, and the function of a resistor for adjusting the circuit characteristics thereof. Regarding trimming method.

[Conventional technology]

In this type of hybrid integrated circuit, desired electrical characteristics may not be obtained due to variations in characteristics of individual elements. In this case, a function trimming method is generally carried out in which the hybrid integrated circuit is assembled and the electrical characteristics of the circuit are measured while adjusting the resistance value of the resistance element so that the circuit characteristic becomes a desired value. .

Such functional trimming is performed by a sand trimmer in a state where various electronic components are mounted on a wiring board and a hybrid integrated circuit is assembled.
This is carried out by a method of directly trimming the resistance element by a trimming device such as a laser trimmer.

Next, referring to FIG. 8 to FIG. 10, the conventional function trimming method will be described with reference to a hybrid integrated circuit in which an insulating metal substrate is used as a wiring substrate and a chip resistor is mounted as a resistance element on the substrate. explain. First, FIG. 8 shows an example of the case where a normal chip resistor whose structure is shown in FIG. 9 is used. In FIG. 1, 1 is a wiring substrate as an insulating metal substrate in which a resin insulating layer 3 is adhered to a metal base 2. 4 is a conductor pattern such as a copper foil formed on the surface of the insulating layer 3 of the wiring board 1,
Reference numeral 5 is a chip resistor mounted at a predetermined position on the substrate and solder-bonded to the conductor pattern 4. As is well known, the chip resistor 5 is formed by attaching a thick film resistor 52 on the upper surface of a main body base 51 such as a ceramic material and attaching electrodes 53 at both ends thereof. Mounted on the substrate 1, and the conductor pattern 4 and the electrode 53 are reflow-soldered in this state. The solder layer is indicated by reference numeral 6.

Functional trimming for the chip resistor 5 is performed as follows. That is, as shown in the drawing, a trimming start point is set on the side edge of the chip resistor 5, and the nozzle position of the trimming device 7 such as a sand trimmer is initialized at this point, and the abrasive material of hard fine particles is moved from there to high speed as indicated by arrow P. While jetting, the nozzle is moved and scanned in the direction of arrow Q to cut the thick film resistor 52 from its side edge inward so as to reduce the resistance cross section, and the film surface is cut by the broken line shown in FIG. Including part T
To form. The trimming amount in this case is performed while monitoring the electrical characteristics of the circuit, and the resistance value is adjusted so that the circuit characteristics of the hybrid integrated circuit have desired values.

On the other hand, FIG. 10 shows an example in which the chip resistor dedicated to trimming shown in FIG. 11 is used as the chip resistor, and the chip resistor 50 dedicated to trimming is the normal chip resistor 5 shown in FIG. The trimming space 54 is formed in the thick film resistor side area by making the dimension of the main body base 51 wider than that of the thick film resistor 52 in comparison with the above. The trimming start point is set at, and the thick film resistor 52 is trimmed by moving and scanning the trimming device 7 in the direction of arrow Q from here.

[Problems to be Solved by the Invention]

However, the above-described conventional function trimming method has the following drawbacks. That is, when the ordinary chip resistor 5 is adopted as shown in FIG. 8, the wiring board 1 has the conductor pattern 4 on the base plate made of a robust material such as a ceramic board.
Although there is no problem with a single-sided ceramic substrate on which is directly formed, a chip resistor 5 mounted on a wiring substrate having an insulating layer 3 having a weak material strength, such as the insulating metal substrate 1 shown in the figure, is used. When the functional trimming is performed, the insulating layer 3 on the substrate side is subjected to the trimming action and cut together at the side portion of the chip resistor 5 serving as the trimming start point, and an opening groove is formed in the portion as indicated by a symbol X. As a result, the dielectric strength of the wiring board 1 is impaired. Such a problem is caused not only in the insulating metal substrate shown in the figure but also in a copper clad laminated substrate such as a plastic substrate or a multilayer ceramic wiring substrate in which a plurality of conductor patterns are formed on a ceramic substrate through resin insulating layers. Even if it is attached, the strength of the substrate itself is damaged, and especially in a double-sided wiring board or a multilayer wiring board, the required dielectric strength cannot be ensured between the conductor patterns, resulting in fatal damage.

On the other hand, when the chip resistor 50 dedicated to trimming shown in FIG. 11 is adopted and trimming is performed as described in FIG. 10, the insulating layer on the wiring board side may be directly subjected to the trimming action. Because there is no wiring board, it can be protected safely.
However, chip resistors for trimming (Fig. 11)
Is more expensive than a normal chip resistor (Fig. 9),
Moreover, since the size is large, there is a problem that the circuit integration density is restricted accordingly.

The present invention has been made in view of the above points, and an object thereof is to adopt an inexpensive general product as a chip resistor for various wiring boards without causing any damage to the wiring boards. Another object of the present invention is to provide a function trimming method for a hybrid integrated circuit, which enables the function trimming to be performed safely.

[Means for Solving the Problems]

In order to solve the above problems, in the method of the present invention, the conductor pattern formed on the wiring board is formed in advance so that the dimension of the conductor pattern corresponding to the mounting location of the chip resistor is wider than the dimension of the chip resistor. Aside
A chip resistor is mounted on this wide conductor pattern in an offset manner, and a shield is further provided in the remaining area relative to the mounting area of this chip resistor.In this state, the trimming start point of the trimming device is set on the shield. It is set so that the chip resistor is trimmed.

[Action]

In the above, in the process of forming the conductor pattern on the wiring board by etching, the dimensions of the conductor pattern in the chip resistor mounting area are formed wider than the dimensions of the chip resistor in advance. The body is mounted on the conductor pattern on one side and soldered between the two. On the other hand, when performing functional trimming on the chip resistor, set the trimming start point of the trimming device on the shield on the conductor pattern at the lateral position of the chip resistor, and move and scan the trimming device from here. Trim the chip resistor. As a result, at the trimming start point, the shield and the conductor pattern itself serve as a shield for the insulating layer of the wiring board, and prevent the trimming action from being directly applied to the insulating layer of the wiring board to protect the wiring board safely. be able to.

It should be noted that, as the shield, for example, the solder is piled up in the preliminary soldering process over the entire width of the conductor pattern in the mounting area of the chip resistor, or the remaining portion excluding the chip resistor mounting surface area on the conductor pattern. By preliminarily covering the surface area with the solder resist layer or a metal layer such as aluminum, the protection function as a shield against the trimming effect can be further enhanced.

〔Example〕

1 to 4 are functional trimming process diagrams of reference examples applied to different kinds of wiring boards, and FIGS. 5 to 7 show an embodiment in which the reference example of FIG. 1 is developed. The same members corresponding to FIGS. 8 and 9 are designated by the same reference numerals.

First, FIG. 1 shows a reference example of function trimming when the general-purpose chip resistor 5 shown in FIG. 9 is mounted on the insulating metal substrate 1, and basically, FIG. This is similar to the trimming method described above, but in this example, the conductor pattern 4 previously formed on the insulating layer 3 of the wiring board 1 is smaller than the dimension width A of the chip resistor 5 especially in the mounting area of the chip resistor 5. Is also formed by etching with a wide dimension B, in which the chip resistor 5 is mounted on the conductor pattern 4 with the side edge to be trimmed facing inward, and soldered. In this state, the chip resistor 5
In the case of performing functional trimming with respect to, the trimming start point of the trimming device 7 is set within the surface area of the conductor pattern 4 at the lateral position of the chip resistor 5 as shown in the figure, and trimming is started from here. Set device 7 to arrow Q
The chip resistor 5 is trimmed by moving and scanning as described above.

With such a function trimming method, at the trimming start point, the abrasive material ejected from the nozzle in the direction of arrow P is ejected slightly beyond the side edge of the chip resistor 5, but this ejection is performed on the wide conductor pattern 4. It is received in the residual surface area and does not exert a trimming action on the insulating layer 3 behind it. That is, the wide conductor pattern itself serves as a shield for the insulating layer 3 of the wiring board, and it is possible to reliably prevent the insulating layer 3 from being destroyed by the trimming action.

2 is a reference example for a so-called double-sided copper-clad laminated wiring board in which first and second conductor patterns 4 are formed on both surfaces of an insulating base plate 8 made of resin or the like as the wiring board 1, and FIG. 3 is a ceramic. A reference example for a multilayer ceramic wiring board in which first and second conductor patterns 4 are formed by printing on the upper surface of a material base plate 9 with a resin insulation layer 3 interposed therebetween, and FIG. 4 shows the resin insulation layer 3 and the conductor pattern. 4 shows a reference example for a multi-layered copper-clad laminate type wiring board in which 4 are alternately laminated. In each reference example, the conductor pattern 4 corresponding to the chip resistor 5 is preliminarily provided with the dimensions of the chip resistor as in FIG. The trimming start point is set on the conductor pattern 4 in this state so that the chip resistor 5 is trimmed. As a result, it is possible to prevent the insulation layer 3 from being broken by the trimming action, and to prevent the strength of the wiring board itself and the dielectric strength between the conductor patterns from decreasing.

Next, FIG. 5 to FIG. 7 show an embodiment in which this embodiment is further developed for the reference example of FIG. In the case of the reference example of FIG. 1, since the conductor pattern 4 is thin, it is conceivable that the sand trimmer may break through the conductor pattern and damage the insulating layer and the wiring board depending on the condition setting.
However, the embodiments shown in FIGS. 5 to 7 also take this problem into consideration. First, in the embodiment of FIG. 5, the solder layer 6 is applied over the entire width area of the conductor pattern in the preliminary soldering process for the conductor pattern 4. In the embodiment of FIG. 6, the remaining surface area of the conductor pattern 4 excluding the mounting surface area of the chip resistor 5 is covered with the solder resist layer 10. Further, in the embodiment shown in FIG. 7, a metal layer 11 made of aluminum or the like is used instead of the solder resist layer 10 in the embodiment shown in FIG.
According to these embodiments, the solder layer 6, which covers the upper surface of the conductor pattern 4 in comparison with the reference example of FIG.
The solder resist layer 10 and the metal layer 11 enhance the function as a shield for trimming, and thus the protection function for the insulating layer 3 on the wiring board side can be further enhanced.

In the illustrated embodiment, an example in which a sand trimmer is used as the trimming device has been shown, but it is needless to say that the same effect can be obtained even in the case of a laser trimmer that irradiates a laser beam to perform trimming.

〔The invention's effect〕

As described above, according to the present invention, with respect to the conductor pattern formed on the wiring board, the dimension of the conductor pattern corresponding to the mounting location of the chip resistor is formed in advance to be wider than the dimension of the chip resistor. By setting the trimming start point of the trimming device on the shield on the conductor pattern and trimming the chip resistor in this state, a general chip resistor that can be obtained at low cost without using a chip resistor specifically for trimming When the function trimming is performed while adopting the above, the shield and the conductor pattern itself serve as a shield with respect to the insulating layer of the wiring substrate located behind the conductor and the conductor pattern itself. As a result, the insulating layer of the wiring board is protected from the trimming action, and the functional trimming can be safely performed without impairing the strength and the dielectric strength of the wiring board.

[Brief description of drawings]

1 to 4 are functional trimming process diagrams by the method of the reference example for different types of wiring boards,
5 to 7 are functional trimming process diagrams of an embodiment in which the reference example of FIG. 1 is further developed, and FIG. 8 is a process of a conventional function trimming method for the general-purpose chip resistor shown in FIG. Fig. 9 is a plan view of a general-purpose chip resistor,
FIG. 10 is a process diagram of a conventional functional trimming method for the chip resistor dedicated to trimming shown in FIG. 11, and FIG. 11 is a plan view of the chip resistor dedicated to trimming. In each figure, 1: wiring board, 3: insulating layer, 4: conductor pattern, 5: chip resistor, 7: trimming device, A: width of chip resistor, B: width of conductor pattern, Q: trimming Scanning direction.

Claims (1)

[Claims] 1. A function trimming method for a hybrid integrated circuit in which a circuit including a chip resistor is formed on a wiring board, wherein a conductor pattern formed on the wiring board corresponds to a mounting position of the chip resistor. The dimensions are made wider than the dimensions of the chip resistor in advance,
The chip resistor is mounted on this wide conductor pattern in an offset manner, a shield is further provided in the remaining surface area with respect to the mounting surface area of this chip resistor, and in this state, the trimming start point of the trimming device is set. A trimming method for a hybrid integrated circuit is characterized in that the trimming of a chip resistor is performed by setting the above.