JP3402478B2 - Thick film multilayer substrate - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film multilayer substrate. 2. Description of the Related Art In a conventional thick film multilayer substrate, when a resistor is formed inside a glass insulating layer, a thick film resistor 6 is printed on a ceramic substrate 1 as shown in FIGS. After firing, a plurality of glass insulating layers 2
4 are sequentially printed and baked, a wiring pattern is printed and baked on the glass insulating layers 2 to 4, and the laser trimming of the thick film resistor 6 is performed at the following time. In the first prior art, the process is performed before firing of the all-glass insulating layer. In the second prior art, as shown in FIG. 6, after firing all glass insulating layers 2 to 4, all glass insulating layers 2 to 2 are fired.
4 is carried out through a window provided with an opening. Third, as shown in FIG. 7, the process is performed through windows provided in the upper glass insulating layers 3 and 4 and through the lowermost glass insulating layer 2. Since the windows opened in the glass insulating layers 2 to 4 can be subjected to laser trimming after the formation of the glass insulating layers, there is an advantage that the fluctuation of the resistance value of the thick film resistor 6 due to the firing of the glass insulating layers 2 to 4 can be eliminated. are doing. [0004] However, the window for laser trimming provided on the glass insulating layer 4 and the like described above is restricted by wiring routing and circuit component arrangement on the surface of the glass insulating layer 4 and the like, and is free. This was an obstacle to efficient circuit component placement and wiring. In particular, when a large number of such laser-trimmed thick-film resistors are provided, the surface of the uppermost glass insulating layer 4 is full of holes, which hinders optimal arrangement of circuit components, makes it difficult to route wiring, and increases wiring resistance. Such a problem also occurred. The present invention has been made in view of the above problems, and an object of the present invention is to provide a thick film multilayer substrate capable of reducing a dead space by a window for laser trimming formed in an uppermost glass insulating layer. That is the purpose. A thick film multilayer substrate according to the present invention comprises a ceramic substrate, thick film resistors and wiring formed on the ceramic substrate, and alternately formed on the ceramic substrate. Glass insulating layer and wiring, a window for laser trimming that opens at least a part of the glass insulating layer immediately above the laser trimming region of the thick film resistor,
A circuit component fixed on the uppermost glass insulating layer, wherein the circuit component is disposed immediately above the laser trimming window , and at least
Also the glass insulation closest to the upper layer of the thick film resistor
A layer is deposited over the thick film resistor and the thick film resistor
Formed on the upper layer of the glass insulating layer deposited on the entire area
The remaining of the glass insulating layer is characterized that you have had the window. In the thick-film multilayer substrate of the present invention, since the circuit components are arranged immediately above the laser trimming window provided on the uppermost glass insulating layer, the dead space can be reduced. It becomes possible. In addition, by designing the wiring by setting the circuit component position right above the window, wiring routing can be reduced, and wiring resistance loss can be reduced. (Embodiment 1) An embodiment of a thick film multilayer substrate according to the present invention will be described with reference to FIG. FIG. 1 shows an alumina substrate 1
A thick multilayer substrate having three glass insulating layers 2 to 4 is shown above. On a substrate 1, an internal wiring 5 and a thick film resistor 6 are printed and fired, and glass insulating layers 2 to 4 are formed thereon, and a surface wiring 7 and a protective glass are formed on the glass insulating layer 4. 71 are formed. Circuit components 81 to 83 are soldered on the glass insulating layer 4. Reference numeral 9 denotes a hole filling conductor filled in the via hole. Glass insulation layer 3
4, a window 10 for laser trimming is opened just above the laser trimming region 61 of the thick film resistor 6, and a laser beam is irradiated from this window 10 to perform laser trimming of the thick film resistor 6. ing. Particularly, in this embodiment, a circuit component 81 is disposed immediately above the window 10. The circuit component 81 is a chip-shaped passive component having soldering electrode surfaces 81a and 81b at both ends, and the electrode surfaces 81a and 81b are soldered to the surface wiring 7 extending to the periphery of the window 10. Of course, the circuit component 81 may be an active component such as an IC having leads. Hereinafter, a manufacturing process of the thick film multilayer substrate will be described. (Thick film resistor forming step) First, as shown in FIG. 2, ethyl cellulose as a binder and terbineol as a solvent are kneaded with Ag powder to prepare a conductor paste, and then alumina fired at about 1600 ° C. This conductor paste is printed on the substrate 1 and in air at 800 to 950 ° C.
The wiring 5 is formed by firing with a firing profile that is held for about 10 minutes. Next, after melting at 1200 to 1500 ° C., the mixture was quenched in water and pulverized at a predetermined mixing ratio of PbO and Al ₂ O.
₃ , an average particle size of a mixture of SiO ₂ and B ₂ O ₃ , etc.
The glass powder 50～80Vol% of ~5μm form a Ru0 ₂ powder predetermined vol% mixed powder mixed solvent to the mixed powder (e.g. terpineol), a binder (e.g. ethylcellulose) was put kneaded to resistor paste The thick film resistor 6 is formed by printing this resistor paste on the surface of the alumina substrate 1 and firing it in a firing profile in which the temperature is kept at 800 to 950 ° C. for about 10 minutes in the air. (Step of forming the lowermost layer of the glass insulating layer on the thick film resistor)
Next, as shown in FIG. 3, after melting at 1200 to 1500 ° C., quenched in water, and pulverized CaO, A at a predetermined mixing ratio.
A predetermined amount of a solvent (for example, terpineol) and a binder (for example, ethyl cellulose) are added to a glass powder having a mean particle size of 2 to 5 μm made of a mixture of l ₂ O ₃ , ZrO, PbO, etc., and kneaded to prepare a glass paste. This glass paste is printed on the alumina substrate 1, and the
The glass insulating layer 2 is formed by firing at a firing profile of about 950 ° C. for about 10 minutes. (Remaining Glass Insulating Layer and Internal Wiring Forming Step) Next, as shown in FIG. 4, a glass insulating layer 3 is formed in the same step as the above-described manufacturing step of the glass insulating layer 2, and then the above-mentioned conductive paste is applied. The via holes communicating with each other of the glass insulating layers 2 and 3 are filled by screen printing and filled in the air at 800 to 95%.
The lower portion of the hole-filled conductor 9 is formed by firing at a firing profile maintained at 0 ° C. for about 10 minutes. Next, a glass insulating layer 4 is formed in the same process as the above-mentioned process of manufacturing the glass insulating layer 2, and then a conductive paste is filled in the via holes of the glass insulating layer 4 communicating with the via holes by screen printing. And in the air, 800-
The upper portion of the hole-filled conductor 9 is formed by firing at a firing profile of about 950 ° C. for about 10 minutes. The window 10 for laser trimming is formed in the same printing step as the via holes of the glass insulating layers 3 and 4, but the window 10 is not filled with the hole filling conductor 9 as a matter of course. (Surface Layer Circuit Forming Step) Next, as shown in FIG. 5, a conductor paste is printed on the surface of the glass insulating layer 4 and baked at a firing profile of 800 to 950 ° C. for about 10 minutes to form the wiring 7. A protective glass paste was printed thereon and fired in air with a firing profile having a peak temperature of 500 to 650 ° C. to form a protective glass layer 71. The protective glass paste is 1200 to 150
After melting at 0 ° C., the mixture was quenched in water, crushed in water and crushed into a glass powder having an average particle diameter of 2 to 5 μm composed of a mixture of PbO, SiO ₂ , and B ₂ O ₃ , and a solvent (eg, terpineol) and a binder (eg, ethyl cellulose) ) Was added and kneaded. (Laser trimming step) Next, as shown in FIG.
While monitoring the resistance value of the thick film resistor 6, the laser trimming region of the thick film resistor 6 is irradiated with laser light through the glass insulating layer 2 to trim the thick film resistor. (Circuit Component Mounting Step) Next, as shown in FIG. 1, the circuit components 81 to 83 were soldered to the surface of the glass insulating layer 4 to complete the process. In the substrate forming process, a mixed powder of Ag and Pd or a mixed powder of Ag and Pt may be used instead of the Ag powder of the conductive paste. Cu can also be used, but in this case, firing must be performed in an N ₂ atmosphere to prevent oxidation. Further, in the surface circuit forming step, after forming the wiring using the conductive paste, a resistor can be formed between the wirings. In this case, the resistor inside the glass insulating layer and the resistor on the surface can be trimmed at the same time. (Embodiment 2) In the above embodiment, the window 10 for laser trimming is provided only in the glass insulating layers 3 and 4. However, the window 10 for laser trimming is provided only in the glass insulating layer 4. , And laser trimming can be performed. Also in this case, the window 10 of the glass insulating layer 4
By disposing the circuit component 81 so as to cover the above, the degree of freedom of the circuit component and the wiring is improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing a thick-film multilayer substrate of an embodiment. FIG. 2 is a schematic cross-sectional view showing a manufacturing process in Example 1. FIG. 3 is a schematic cross-sectional view showing a manufacturing process in Example 1. FIG. 4 is a schematic cross-sectional view showing a manufacturing process in Example 1. FIG. 5 is a schematic cross-sectional view showing a manufacturing process in Example 1. FIG. 6 is a schematic sectional view showing a conventional thick film multilayer substrate. FIG. 7 is a schematic sectional view showing a conventional thick film multilayer substrate. [Description of References] 1 is a substrate, 2 to 4 are glass insulating layers, 6 is a thick film resistor, 7 is a surface wiring, 81 is a circuit component, and 10 is a window for laser trimming.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H05K 3/46

Claims (1)

(57) [Claim 1] A ceramic substrate, a thick film resistor and a wiring formed on the ceramic substrate, and a glass insulating layer and a wiring formed alternately on the ceramic substrate, A thick film multilayer substrate comprising: a window for laser trimming that opens at least a part of the glass insulating layer immediately above the laser trimming region of the thick film resistor; and a circuit component fixed on the uppermost glass insulating layer. In, the circuit component is disposed immediately above the laser trimming window , at least the closest in the upper layer of the thick film resistor
A glass insulating layer is applied over the entire thickness of the thick film resistor,
On top of the glass insulating layer deposited over the entire area of the thick film resistor
The remaining glass insulating layer formed has the window
Thick film multilayer substrate, wherein Rukoto have.