JP3056847B2 - Quadrupole electrode and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quadrupole electrode used for a sensor section of a mass spectrometer or the like and a method for producing the same.

[0002]

2. Description of the Related Art As shown in FIG. 4, a quadrupole electrode used in a mass spectrometer or the like includes four electrode rods 11, 12, 13, 14 each having an opposing surface formed into a hyperbolic cross section. Four electrode rods 1 formed in a circular shape as shown in FIG.
1 ', 12', 13 ', and 14' are arranged by adjusting the positional relationship so as to have a predetermined electrode interval. When ions are sent to the quadrupole electrode in the direction of the arrow toward the center, ions having a specific mass / charge ratio can be extracted from the opposite side with high accuracy. Such conventional quadrupole electrodes need to be maintained at an accurate distance from each other, and require extremely high precision work for assembly, and the change in the distance between the electrodes during analysis is extremely small. Is required.

For example, Japanese Patent Application Laid-Open No. 58-30056 discloses the use of an electrode rod formed by extruding or drawing a metal material into a V shape for the purpose of reducing the weight and improving the dimensional accuracy of the electrode. Have been. Also, JP-A-59-
JP-A-87743 and JP-A-60-64562 show shapes that are easy to assemble, and various other design proposals have been made.

[0004]

The conventional quadrupole electrode is:
In order to obtain a predetermined accuracy between the constituent electrodes, it is usual to assemble manually and then introduce a monitor gas to check the accuracy, and correct the accuracy while repeating the accuracy check. In the present invention, the dimensional accuracy can be accurately arranged without such a trouble, and the predetermined dimensional accuracy between the electrodes during use can be kept high.

[0005]

SUMMARY OF THE INVENTION The present invention is a quadrupole electrode comprising two pairs of opposing electrode rods, wherein the electrode rods are thermally expanded.
Zhang coefficient becomes from ^{4 (× 10 ~ 6 / ℃} ) less insulating the Si ₃ N ₄ ceramics, the adjacent electrode rod positioning jig
(Chip), and joined at the mating surface, each electrode is
The present invention relates to a quadrupole electrode characterized in that opposing inner surfaces except for a mating surface are coated with a conductive metal, and four electrodes are fixed in advance with a predetermined dimensional accuracy. The present invention also relates to a method for producing a quadrupole electrode comprising two pairs of electrode rods facing each other, wherein the coefficient of thermal expansion is 4 (× 10 ~ ⁶ /
° C) Four electrode rods made of the following Si ₃ N ₄ ceramics
After coating the surface of each electrode with a conductive metal,
This electrode is placed next to a positioning jig (chip)
The present invention relates to a method for manufacturing a quadrupole electrode, characterized in that four electrodes are fixed with a predetermined electrode- to- electrode distance accuracy by being brought into contact with and joined to a mating electrode rod at a mating surface .

That is, the present invention has been made in order to form a quadrupole electrode with high precision and good reproducibility and easily, and has been made by processing an insulating low expansion coefficient ceramic as an electrode material with high precision. After coating the conductive metal on the electrode surface, assemble the four electrodes and install them in the mass spectrometer to set the distance between the electrodes to ± 5 μm.
It is possible to minimize the dimensional change between the electrodes during analysis and use with a high degree of accuracy.

This will be described in detail with reference to FIG.
Reference numerals 1, 2, 3, and 4 denote four electrode rods that have been processed with high precision in advance, and the main body is manufactured using ceramics. Ceramics may be insulative and have low thermal expansion, but in particular need to have a low thermal expansion coefficient. The present inventors have conducted intensive studies using various ceramics, and as a result, have a thermal expansion coefficient of 9
(× 10 ⁻⁶ / ° C.) or less, such as Al ₂ O ₃ , Si
C, mullite, quartz, sialon, AlN, cordierite, and Si ₃ N ₄ were found to be effective. As a result of more detailed examination of these ceramics, it has been found that Si ₃ N ₄ ceramics having a thermal expansion coefficient of 4 (× 10 ⁶ / ° C.) or less are preferable. This is particularly because the distance between the electrodes of a quadrupole electrode of an analyzer that requires a high resolution is as large as 20 mm or more, and in this case, it is said that the influence of a temporal change in the distance between the electrodes due to a temperature change affects the analysis accuracy.

If a Si ₃ N ₄ ceramic electrode having a small coefficient of thermal expansion is used, even if it is used for a quadrupole electrode having a large distance between the electrodes, the dimension between the electrodes can be maintained with high accuracy within ± 5 μm, and the analysis accuracy Can be maintained sufficiently.

A portion of the electrode portion of the ceramic body other than the mating surface is provided with conductivity as a conductive metal thin film 5.
The conductive metal is a high melting point metal such as W or Mo or Pt, A
The film is formed by vapor deposition of a metal such as u, Ni, Cu, Ag, and Ti. Further, the metallized surface is processed as necessary to maintain the accuracy.

The four electrodes thus processed are firmly fixed using, for example, a chip 6 or the like. The supply of electricity to the electrode metallized surface 5 is performed by attaching an electrode to the end face or
Alternatively, it is also possible to make a hole 7 in the electrode as shown, and to supply electricity from a lead wire 9 fixed by a screw 8.

[0011]

EXAMPLE The thermal expansion coefficient of a ceramic material is 3.2.
(× 10 ⁻⁶ / ° C.) using Si ₃ N ₄ to form an electrode body having a distance between the electrodes of 8.6 mm and a length of 200 mm;
After processing the bipolar surface with high precision, the active metal (Ti-Cu
-Ag) was deposited to a thickness of 5 μm and Ni was deposited thereon to a thickness of 1 μm to form an electrode, which was assembled as shown in FIG. 1 to obtain a quadrupole electrode. As shown in FIG. 3, an ion source 16 for ion generation is connected to one end of the quadrupole electrode 15.
Is attached to the other end of a secondary electron multiplier 17 for ion detection, and incorporated into an ultra-vacuum apparatus as a quadrupole mass spectrometer.
He, N ₂ , Ar, Kr, Xe after baking at 300 ° C.
The gas was flowed, and this operation was repeated several times to measure the variation of the peak waveform of the mass spectrum.

As a result, the conventional metal electrode (Mo electrode)
Fig. 2 (b) shows the peak waveform of a quadrupole mass spectrometer using
A parabolic shape with a crack at the head of the peak waveform was observed. The numerical value on the vertical axis indicates the number of times of baking. Also, the variation in peak height was large. It is considered that such variations in the peak waveform are caused by variations in dimensional accuracy. On the other hand, the peak waveform of the quadrupole mass spectrometer using the Si ₃ N ₄ ceramic quadrupole electrode is shown in FIG.
And there was almost no variation in peak height. As described above, the adoption of the Si ₃ N ₄ ceramic quadrupole electrode has made it possible to simplify the adjustment of the electrode assembly and maintain a high analysis accuracy.

[0013]

According to the present invention, since each electrode rod is formed of ceramics which can be easily formed to an accurate size, a great effort is required for adjusting the position between the electrodes during assembly. Therefore, a high-performance quadrupole electrode can be provided with good reproducibility. Moreover, unlike ceramics such as Mo and stainless steel, ceramics are the main material, so that they can be obtained at a light weight and at low cost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment in which the electrode of the present invention is incorporated in a mass spectrometer.

FIG. 3 is a graph showing a measurement result of a variation in a peak waveform of a mass spectrum of a mass spectrometer.

FIG. 4 is a perspective view for explaining a configuration of an example of a conventional quadrupole electrode.

FIG. 5 is a perspective view for explaining the configuration of another example of a conventional quadrupole electrode.

[Explanation of symbols]

 1 electrode rod 2 electrode rod 3 electrode rod 4 electrode rod 5 metallization 6 chip 7 hole 8 screw 9 lead wire 11 electrode rod 12 electrode rod 13 electrode rod 14 electrode rod 11 'electrode rod 12' electrode rod 13 'electrode rod 14' electrode Rod 15 Quadrupole electrode 16 Ion source 17 Secondary electron multiplier

──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshio Murakami, Inventor Yoshio Murakami 801 Mukaiyama, Naka-cho, Naka-gun, Ibaraki Pref. No. Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Akira Yamakawa 1-1-1, Koyo Kita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works (72) Inventor Masaya Miyake, Kyoyo, Itami City, Hyogo Prefecture 1-1 1-1 Kita, Itami Works, Sumitomo Electric Industries, Ltd. (56) References JP-A-59-91651 (JP, A) JP-A-52-150992 (JP, A) JP-A-2-220344 ( JP, A) JP-A-58-30056 (JP, A) JP-A-59-87743 (JP, A) JP-A-60-64562 (JP, U) JP-B-51-7069 (JP, B1) (58 ) investigated the field (Int.Cl. ^7, B name) H01J 49/42 G01N 27/62

Claims (6)

(57) [Claims] 1. A quadrupole electrode comprising two pairs of electrode rods facing each other, wherein said electrode rods have a coefficient of thermal expansion of 4 (× 10 to ⁶ /
℃) The following insulating Si ₃ N ₄ ceramics
The mating electrode rods are joined via a positioning jig (chip).
In are bonded, each electrode inner surface opposite to each other except for the mating surface is coated with a conductive metal, four of four electrodes is characterized in that it is fixed at a predetermined inter-electrode distance accuracy Heavy electrode. 2. The quadrupole electrode according to claim 1, wherein the inner surface of the electrode is hyperbolic. 3. The quadrupole electrode according to claim 1, wherein the inner surface of the electrode is circular. 4. A method for producing a quadrupole electrode comprising two pairs of opposed electrode rods, wherein the coefficient of thermal expansion is 4 (× 10 to ⁶ /
° C) Four electrode rods made of the following Si ₃ N ₄ ceramics
After coating the surface of each electrode with a conductive metal,
This electrode is placed next to a positioning jig (chip)
A method for manufacturing a quadrupole electrode , comprising: contacting and joining a mating electrode rod at a mating surface, and fixing the four electrodes with a predetermined inter-electrode distance accuracy. 5. The method for manufacturing a quadrupole electrode according to claim 4 , wherein the inner surface of the electrode is hyperbolic. 6. The method for manufacturing a quadrupole electrode according to claim 4 , wherein an inner surface of said electrode is circular.