JPH0714111B2 - Multilayer substrate with built-in capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a capacitor-embedded multilayer substrate, and more particularly to a capacitor-embedded multilayer substrate that incorporates capacitors having laminated substrates as dielectrics.

[Prior art]

Internal electrodes are printed on a ceramic green sheet, laminated and pressure-bonded, and integrally fired. Multilayer substrates with built-in capacitors are well known.

[Problems to be Solved by the Invention]

Since the conventional multilayer board with a built-in capacitor cannot be trimmed, the variation in the capacitance value of the built-in capacitor was as large as ± 20%. Therefore, a high-precision capacitor that requires an accuracy of ± 3% is not built in, but a capacitor chip is added as an external component. The fact that an external capacitor has to be added in this way impedes high density.

Therefore, the main object of the present invention is to be able to incorporate a more accurate capacitor. A multilayer substrate with a built-in capacitor is provided.

[Means for Solving the Problems]

Briefly, the present invention provides a multilayer ceramic substrate made of a non-reducing ceramic material, a capacitor region formed in a part of the multilayer ceramic substrate, and a laser formed on the surface of the multilayer ceramic substrate so as to correspond to the capacitor region. It is a multilayer board with a built-in capacitor, which has a hole or a recess for trimming.

[Action]

Irradiation with laser light through the laser trimming hole or recess removes all or part of the internal electrodes forming the capacitor in the capacitor region, thereby changing the capacitance.

Since the non-reducing material is used for the multi-layer ceramic substrate, the insulation resistance of the multi-layer ceramic substrate is not deteriorated by irradiating the laser beam.

〔The invention's effect〕

According to the present invention, since the laser trimming hole or recess is provided, it is possible to perform trimming by laser light later. Therefore, the accuracy of the capacitance value of the built-in capacitor is improved, and external parts are added. There is no need to do it. Therefore, according to the present invention, high density can be achieved.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of the embodiments with reference to the drawings.

〔Example〕

FIG. 1 is a perspective view showing a main part of an embodiment of the present invention. The multilayer ceramic substrate 10 of this embodiment is formed by stacking five layers of ceramic substrates 12 to 20. On the lower surface of the ceramic substrates 12, 16 and 20, as shown in FIG.
Capacitor electrodes 24 are respectively formed on the lower surface of 18. These capacitor electrodes 22 and 24 form a capacitor area similar to known monolithic ceramic capacitors.

That is, the capacitor electrode 22 is connected to the through-hole conductor 26 penetrating the integrated ceramic substrates 12 to 20, and the capacitor electrode 24 is connected to the through-hole conductor 28, respectively. The through-hole conductor 26 is connected to the pattern conductor 30 formed on the surface of the ceramic substrate 12,
The through-hole conductor 28 is connected to the pattern conductor 32. Therefore, a plurality of capacitances formed between the respective capacitor electrodes 22 and 24 are connected in parallel between the pattern conductors 30 and 32. Capacitance is calculated by measuring the facing area of capacitor electrodes 22 and 24,
And the dielectric constant of the ceramic substrate itself sandwiched between the capacitor electrodes 22 and 24, and the like.

A hole 34 for laser trimming is formed directly above the capacitor electrode 22 in the ceramic substrate 12 arranged on the top of the multilayer ceramic substrate 10. Therefore, in this hole 34, the capacitor electrode 22 is exposed. Therefore, when laser light is irradiated through the hole 34, a part of the capacitor electrode 22 is deleted, and the area facing the capacitor electrode 22 is reduced. In this way, after firing, by irradiating laser light such as YAG laser or CO ₂ laser through the hole 34, the capacitance value built in the multilayer ceramic substrate 10 can be adjusted. The size of the hole 34 is, for example, 1 mm or 1 mm in diameter to facilitate irradiation with laser light.
It is set to about square.

In this way, after the laser trimming is completed, the hole 34 is filled with, for example, glass so as not to deteriorate the moisture resistance.

When the electrode 22 is trimmed, the laser light is emitted through the hole 34. At this time, it is considered that the laser light reduces the ceramic substrates 12 and 14 and deteriorates the insulation resistance thereof. Therefore, in this embodiment, a non-reducing ceramic is used for at least the portion of the ceramic substrate that is affected by the laser light. As such a non-reducing ceramic material, for example, in the case of a crystallized glass-based material, if the cordierite-based ZnO / MgO / Al ₂ O ₃ / SiO ₂ is a glass composite-based material, SiO ₂ / B ₂ O ₃ system glass + Al ₂ O
_{If 3} is a non-glass type, Al ₂ O ₃ · CaO · SiO ₂ MgO ·
B ₂ O ₃ or BaO / SiO ₂ / Al ₂ O ₃ / CaO / B ₂ O ₃ system, etc. can be used respectively.

Thus, if non-reducing ceramic is used, Cu can be used for the capacitor electrodes 22 and 24. Ag, A
It can be used as the capacitor electrodes 22 and 24 such as g / Pd, but it is inexpensive if Cu can be used.

In the above-described embodiment, the holes 34 formed in the ceramic substrate 12
Had reached the capacitor electrode 22, but as shown in FIG. 3, a hole having a depth such that the capacitor electrode 22 was not exposed.
May be 34 '. On the capacitor electrode 22, thin,
Even if the material of the ceramic substrate 12 remains, the remaining ceramic substrate 12 can be formed by irradiating the laser beam.
Since it can also be deleted, there is no particular problem in trimming. According to this embodiment, since the uppermost capacitor electrode 22 is not exposed at first, when trimming is not necessary, the capacitor electrode 22 may be left as it is without filling the glass.

Note that the above-mentioned multilayer ceramic substrate has holes 34 (or 3
After preparing the ceramic substrate 12 provided with 4 ') and the other ceramic substrates 14 to 20 in the state of the respective ceramic green sheets, after printing and forming the necessary capacitor electrodes and other conductors on the respective ceramic green sheets. It can be made by stacking and firing integrally.

However, the ceramic substrate 12 and the blocks made of the other ceramic substrates 14 to 20 may be separately fired, and then the two may be joined with solder or glass.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention. FIG. 2 is a schematic sectional view of the embodiment shown in FIG. FIG. 3 is a schematic sectional view showing another embodiment. In the figure, 12 to 20 are ceramic substrates, 22 and 24 are capacitor electrodes, 26 and 28 are through-hole conductors, and 34 and 34 'are holes.

Claims (1)

[Claims] 1. A multilayer ceramic substrate made of a non-reducing ceramic material, a capacitor region formed on a part of the multilayer ceramic substrate, and laser trimming formed on a surface of the multilayer ceramic substrate so as to correspond to the capacitor region. Multilayer substrate with built-in capacitor, which has holes or dents for the capacitor.