JP2897100B2 - Method of forming solder flow stop film for electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a solder flow stopping film for preventing a flow of solder when soldering a terminal or the like to an electronic component.

[0002]

2. Description of the Related Art For example, when a terminal or the like is soldered to a piezoelectric ceramic resonator, the solder flows from the soldered portion along the electrode on the element surface and adheres to a portion where the solder should not be attached (for example, a vibrating portion). Sometimes. In order to solve such a problem, there is one in which a solder flow stopping film such as solder resist ink is formed on the element surface to prevent the flow of solder.

[0003]

Usually, screen printing is used to form a solder flow stopping film. However, since screen printing is a contact printing method, there is a disadvantage that cracks and chips are likely to occur in the ceramic substrate during printing. For example, in the case of a ceramic substrate having a thickness of 0.2 to 0.4 mm, 5 to 10%
Cracks of some degree had occurred. In addition, since the thickness of the flow stop film formed by screen printing is as thick as several tens of μm, when the mother substrate is cut after printing, the mother substrate cannot be reliably attracted to the cut sheet, and handling becomes unstable, There are drawbacks such as cracking of the substrate. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a solder flow stopping film for an electronic component, which can form a thin solder flow stopping film without applying a load to a substrate when the solder flow stopping film is formed.

[0004]

In order to achieve the above object, a method for forming a solder flow stopping film according to the present invention is to apply a solder resist ink to a substrate by dots using an ink-jet type marking device. This is to form a film having a substantially uniform thickness by the flow action of the solder resist ink.

[0005]

The marking device of the ink jet type can apply the solder resist ink in a non-contact manner, so that a load is not applied to the substrate when applying the ink, and the substrate does not crack or chip. Moreover, after the ink is applied in the form of dots, it has a substantially uniform film thickness due to its own flow action.
An extremely thin solder flow stop film of 1 μm or less can be formed. Therefore, when the mother substrate is sucked and held on the cut sheet in order to cut the mother substrate, there is no gap between the cut sheet and the mother substrate, and the mother substrate can be surely sucked. That is,
Poor handling and cracking during suction can be prevented, and there is no problem in cutting. Even if the thickness of the flow stopping film is small, there is no difference in the flow stopping effect of the solder as long as it covers the electrodes on the substrate surface. In addition, if the application pattern is registered in the marking device in advance, the application shape, position, film thickness, and the like can be freely set, so that setup is easy even if the type of electronic component changes. In addition, since the ink-jet marking method has a higher ink application speed than the screen printing method, there is an advantage that productivity is improved.

The solder resist ink used in the present invention preferably has a low viscosity and a small change with time in viscosity in order to impart fluidity. In addition, organic solder resist inks are classified into a thermosetting type and an ultraviolet curing type. However, since they are exposed to flux during soldering, those having solvent resistance are desirable. Ink-jet marking devices include electrification-controlled ink-jet printers, as well as drop-on-demand (DO)
D) Inkjet printers are also included. Electronic components to which the present invention is applied include non-piezoelectric components such as capacitors, and composite components of piezoelectric components and capacitors, in addition to piezoelectric components such as piezoelectric resonators. In particular, it is suitable for an electronic component having a substrate made of a brittle material such as ceramics.

[0007]

FIG. 1 shows an example of a method for forming a solder flow stopping film according to the present invention. A mother substrate 1 made of a piezoelectric ceramic material is subjected to a polarization treatment in a plane direction, and electrodes 2 and 3 are formed on the front and back surfaces so as to partially face each other. Above the mother substrate 1, a marking device 4 composed of, for example, a charge control type ink jet printer is close. The mother substrate 1 is transported in the long side direction (X direction), and the solder resist ink 5 is applied on the electrodes 2 in a streak form from the marking device 4 with the transport. As is well known, a charge control type ink-jet printer divides a pattern to be marked into pixels in a dot matrix, charges ink particles with a voltage proportional to positional information of each pixel, and deflects the charged ink particles by an electrostatic field. Then, a predetermined pattern is marked by arriving at an object to be marked. In this embodiment, the ink deflection direction of the marking device 4 is the same as that of the mother substrate 1.
In the short side direction (Y direction).

When the ink 5 is applied on the electrode 2, the ink 5 is composed of a group of dots as shown in FIG. 2A and FIG. 3A, but each dot is spread due to the fluidity of the ink 5. As a result, the film 5 'has a substantially uniform thickness as shown in FIGS. 2 and 3B. Then, the uniform film 5 'is cured by heating or irradiating ultraviolet rays to form the solder flow stopping film 5a. The thickness of the solder flow stopping film 5a formed as described above is extremely thin, and a film having an average thickness of 1 μm or less can be easily formed. The film thickness can be freely changed by selecting the dot size or dot density of the ink 5. In addition, the solder flow stop film 5a is similarly formed on the back surface of the mother substrate 1.

FIG. 4 shows how the mother substrate 1 on which the solder flow stopping film 5a is formed as described above is cut. The mother substrate 1 is cut by a dicing device in a direction orthogonal to the direction of the solder flow stop film 5a with a width of one element. At the time of cutting, the mother substrate 1 is adsorbed on the cut sheet of the dicing apparatus. Or cracks may occur. However, since the thickness of the solder flow stopping film 5a is as thin as 1 μm or less as described above, the problem at the time of cutting can be solved.

By cutting the mother substrate 1 as described above, the resonator element 6 in the thickness shear vibration mode can be obtained. Electrodes 7, 8 formed on the front and back of this resonator element 6
Are partly opposed to each other, the vibrating electrode parts 7a, 8a are constituted by the opposed parts of the electrodes 7, 8, and the terminal electrode parts 7b, 8b
Is composed. Vibrating electrode portions 7a, 8a and terminal electrode portion 7
The solder flow stop film 5a is formed in a band shape between the solder flow stop films 5b and 8b. Terminals (not shown) are soldered to the terminal electrode portions 7b and 8b. The solder flow stop film 5a is 1 μm.
Since the thin film having a thickness of not more than m is covered so as to cross the electrodes 7 and 8, it is possible to reliably prevent the solder from flowing to the vibrating electrode portions 7a and 8a.

FIG. 1 illustrates a case where the solder resist ink 5 is applied to one mother substrate 1.
The plurality of mother substrates 1 are
May be accommodated one by one, and the solder resist ink 5 may be continuously applied onto the mother substrate 1 from the pallet 10 by the marking device 4. The solder resist ink 5 may be applied intermittently on the pallet 10 so as not to be applied. By using such a method, productivity is further improved.

In the above embodiment, an example was shown in which the solder resist ink was applied to the mother substrate, and then the mother substrate was cut into the respective elements. However, after the mother substrate was separated and cut, the elements were arranged in a line. May be applied with a solder resist ink. Note that the present invention is not limited to the above-described piezoelectric components, but can be applied to any other electronic components. Therefore, the shape of the solder flow stopping film is not limited to a linear streak as in the embodiment.

[0013]

As is apparent from the above description, according to the present invention, since the solder resist ink is applied onto the substrate by using the ink jet type marking device, the solder flow can be easily stopped without contact. A film can be formed and no load is applied to the substrate. Further, since the solder resist ink is applied in a dot shape on the substrate to form a substantially uniform film due to the fluidity of the ink, the thickness of the solder flow stopping film can be made extremely thin, 1 μm or less. Therefore, the thickness can be reduced to tens of minutes or less as compared with the conventional screen printing method, and problems caused by the thickness can be eliminated. Further, since the ink jet type marking device has a higher coating speed than the screen printing method, the productivity is improved, and the coating shape, position, and film thickness can be freely set, so that there is an advantage that setup is easy.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a solder resist ink is applied to a mother substrate according to the present invention.

FIG. 2 is a diagram showing an example of a coating pattern according to the present invention.

FIG. 3 is a cross-sectional view taken along a line CC and a line DD in FIG. 2;

FIG. 4 is a diagram showing a state in which a mother substrate on which a solder flow stopping film is formed is cut.

FIG. 5 is a perspective view showing another method of applying a solder resist ink to a mother substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mother board 2, 3 electrode 4 Marking device 5 Solder resist ink 5 'Solder stoppage film 6 Resonator element

Claims (1)

(57) [Claims] 1. A method for forming a solder flow stopping film by applying a solder resist ink on an electrode formed on a surface of a substrate, wherein the solder resist ink is applied to the substrate in a dot-like manner by an ink-jet marking device. And forming a film having a substantially uniform thickness by the flow action of the dot-shaped solder resist ink.