JP3138779B2 - How to mount chip components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to a chip-type passive component (hereinafter referred to as a "chip component") which is temporarily fixed on a circuit board with a thermosetting adhesive and then externally attached to the chip component. The present invention relates to a chip component mounting method applied to automatically mount a chip component on a circuit board by soldering and fixing electrodes to a conductive pattern on a circuit board.

[0002]

2. Description of the Related Art Conventionally, when a chip component is mounted on a circuit board, the chip component is sucked by the tip of a nozzle of a mounting head, and the mounting head is lowered toward the circuit board, thereby lowering the lower surface of the body of the chip component. Is pressed against a thermosetting adhesive pre-applied on the circuit board, and the external electrodes of the chip component are brought into contact with conductive patterns on the circuit board, and the chip component is placed on the circuit board with the thermosetting adhesive. A temporary fixing is performed, and an external electrode of the chip component is fixed by soldering to a conductive pattern on a circuit board.

[0003] In the chip component mounting process, it is necessary that an appropriate amount of adhesive is applied as a condition for properly soldering and fixing the chip component. If the applied amount is too large, an excessive amount of the adhesive will protrude to the land side of the conductive pattern due to the pressing force of the chip component, resulting in poor soldering. Also, if the amount of application is too small, the chip component will fall off due to insufficient adhesive strength.

The application of the adhesive includes screen printing,
Methods such as dispenser and pin transfer are applied. In the screen printing method, the amount of the adhesive applied can be appropriately controlled by changing the resist thickness on the screen or the mesh of the screen, or by changing the printing conditions. In the dispenser, the amount of the adhesive applied can be controlled by the magnitude of the pressure applied to the liquid surface of the adhesive, the application time of the pressure, and the like. In the pin transfer method, the amount of coating can be adjusted appropriately by changing the thickness and shape of the pin.

[0005] In addition to the above, application conditions of the above-mentioned adhesive include maintaining an appropriate degree of wettability of the adhesive with respect to each bonding surface of the chip component and the circuit board. If the wet adaptability is poor, the adhesive strength is weak, and problems such as the position and angle deviation of the chip component occur due to the surface tension of the solder melted at the time of soldering the chip component.

Usually, an epoxy-based thermosetting resin which cures at a relatively low temperature in a short time is used as the adhesive in consideration of a heat failure to a chip component. The thermosetting adhesive has a pot life, and the viscosity increases as time elapses after application to the circuit board, until the adhesive is not completely cured. In order to suppress the progress of curing during storage, the circuit board after application of the adhesive is stored at a low temperature.

[0007] However, once the temperature is returned to normal temperature with the mounting of the chip component, the adhesive softens, and the curing progresses rapidly because there is always a lapse of time before the chip component is pressed. In particular, the deterioration of the adhesiveness of the surface portion in contact with the outside air is accelerated. For the adhesive, a sufficient familiarity cannot be obtained simply by pressing the chip component held by the nozzle tip of the mounting head with the pressure, which causes the chip component to fall off as described above.

An acrylic U which has a long pot life and does not cure unless exposed to ultraviolet light even when left unattended
V-curable resins have also been used as adhesives. However, in this case, the portion which is shaded by the ultraviolet rays is not sufficiently cured, and it is necessary to use both heat and ultraviolet rays.

[0009] Further, as an appropriate soldering condition of the chip component, it is necessary that the external electrodes of the chip component and the land surface of the conductive pattern are accurately connected. The electrode surface of the chip component and the land surface of the conductive pattern are silver, solder,
It is plated with copper, nickel, etc.
Silver, solder, copper, etc. are easily oxidized during storage. Since the film due to the oxidation has a bad influence on the solderability, a strong active flux is used, and the heating temperature is increased and the heating is performed for a long time to prevent the failure due to the oxide film.

However, soldering by high-temperature heating causes a change in characteristics of the chip component due to melting of the electrodes, breakage of the conductive pattern, and the like. Therefore, it is desirable that the soldering be performed at low temperature in a short time.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a chip component which uses a thermosetting resin as an adhesive, and which can securely and temporarily fix the chip component to a circuit board with the adhesive, and which can be accurately soldered and fixed. It is intended to provide a mounting method.

[0012]

According to a first aspect of the present invention, there is provided a method for mounting a chip component, comprising: a thermosetting adhesive in which a chip component sucked by a tip of a nozzle of a mounting head is applied to a circuit board in advance. After pressing the external electrodes of the chip component on the circuit board and temporarily fixing the chip component on the circuit board with a thermosetting adhesive, the external electrodes of the chip component are connected to the circuit board. In order to fix the solder to the conductive pattern by soldering, the chip component is pressed against the thermosetting adhesive on the circuit board to hold the external electrode of the chip component in contact with the land surface of the conductive pattern. Micro vibration is applied from the nozzle side of the mounting head.

According to a second aspect of the present invention, there is provided a method of mounting a chip component, wherein a fine vibration is applied simultaneously from a nozzle side of a mounting head holding the chip component and a table side on which a circuit board is mounted. Have been.

[0014]

In the method of mounting a chip component according to the first aspect of the present invention, the chip component is pressed against a thermosetting adhesive on a circuit board to temporarily contact an external electrode of the chip component with a land surface of the conductive pattern. At the time of fixing, a minute vibration is applied from the nozzle side of the mounting head holding the chip component, so that the minute vibration can directly act on the land surface of the thermosetting adhesive and the conductive pattern via the chip component.

In the chip component mounting method according to the second aspect of the present invention, the fine vibration is simultaneously applied from the table side on which the circuit board is mounted together with the nozzle side of the mounting head holding the chip component. Micro-vibration can be more effectively applied to the thermosetting adhesive and the land surface of the conductive pattern.

Thus, even if the adhesive force on the surface of the adhesive is reduced, a frictional force can be applied to the adhesive surface due to the elasticity and thickness of the adhesive, and the wettability between the lower surface of the chip component body and the adhesive can be reduced. Because of the adaptability, the chip components can be securely temporarily fixed to the circuit board, and the temporal application range of the adhesive can be expanded to extend the apparent pot life, so that the management cost and the like can be reduced.

Even if the oxide film is formed on the electrode surface of the chip component or the land surface of the conductive pattern, a frictional force acts on the external electrode of the chip component and the land surface of the conductive pattern, and the oxide film on the surface is mechanically changed. Since the conductive part with good solderability can be exposed to the outside by partially destroying it, the soldering process can be performed at a low temperature in a short time, and the electrical connection between the external electrode of the chip component and the land surface of the conductive pattern can be established. It can be accurately removed and the chip components can be securely soldered and fixed to the circuit board.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, FIG. 1 shows that an adhesive 3 is applied between soldering lands of conductive patterns 2 and 2 provided on a plate surface of a circuit board 1. FIG. Indicates the status. As the adhesive 3, a thermosetting resin such as an epoxy resin (hereinafter, simply referred to as "adhesive") is used. The adhesive 3 can be applied by screen printing, dispenser, pin transfer, or the like. In addition to the application in the form of a sheet, the application may be in the form of a plurality of small dots.

FIG. 2 shows a step different from the step of applying the adhesive 3.
A step of temporarily fixing the chip component 4 held by the nozzle tip of the mounting head H to the circuit board 1 mounted on an XY table (not shown) with the adhesive 3 is shown. In this temporary fixing step, the mounting head H holding the chip component 4 descends, and the chip component 4 is placed on the lower surface of the main body 4a.
And presses the external electrodes 4b and 4c of the chip component 4 to contact the land surfaces of the conductive patterns 2 and 2 so as to apply a slight vibration.

The micro-vibration is given from the nozzle side of the mounting head H holding the chip component 4. This minute vibration is applied to the adhesive 3, the conductive pattern 2,
2 can act directly on the land surface. In addition, a minute vibration can be simultaneously applied from the nozzle side of the mounting head H holding the chip component 4 and the table side on which the circuit board 1 is mounted. In this case, the micro vibration can be effectively applied to the adhesive 3, the land surfaces of the conductive patterns 2, 2.

The minute vibration is given by mounting a magnetostrictive vibrator or an electrostrictive vibrator as a vibration source on the mounting head side or the XY table side. The vibration frequency may be higher than the audible frequency from the standpoint of noise prevention, and the vibration direction may be any angle such as a parallel mode and a vertical mode with respect to the crimping surface of the chip component 4.

The micro-vibration is a short period of time until the mounting head H moves down to a predetermined position and the chip component 4 presses the lower surface of the main body 4a against the adhesive 3 to crush the adhesive 3. Give to. In this process, a frictional force acts on the adhesive 3 from the lower surface of the main body 4a of the chip component 4 and applies a force that sticks the adhesive 3 to the main body 4a of the chip component 4 and the adhesive 3. This causes the wet-familiarity.

Further, the mounting head H moves down until the external electrodes 4b and 4c of the chip component 4 come into contact with the soldering lands of the conductive patterns 2 and 2, and gives a slight vibration for a short time while maintaining this contact state. Due to the vibration, a frictional force acts on the external electrodes 4b, 4c of the chip component 4 and the land surfaces of the conductive patterns 2, 2, and the external electrodes 4b, 4
Even if an oxide film is formed on the land surfaces of the conductive patterns c and / or the conductive patterns 2, 2, the oxide film can be partially destroyed mechanically to expose the conductive portion having good solderability to the outside.

FIG. 3 shows a step different from the step of temporarily fixing the chip part 4, in which the external electrodes 4b and 4c of the chip part 4 are soldered to the land surfaces of the conductive patterns 2 and 2, respectively.
Shows a state in which is fixedly mounted on the circuit board 1. This soldering can be performed using cream solder or the like.

During the soldering process, the chip component 4 is securely fixed temporarily by the adhesive 3, so that there is no problem that the chip component 4 falls off. In addition, since the external electrodes 4a and 4b of the chip component 4 and the land surfaces of the conductive patterns 2 and 2 have good solderability at least in the exposed conductive portions, a short-time and low-temperature soldering process is performed. Also, the chip component 4 can be securely fixed and mounted on the land surfaces of the conductive patterns 2 and 2 by the solder 5.

[0026]

According to the mounting method of the chip component according to the present invention, when the chip component is temporarily fixed to the circuit board with the adhesive, the micro-vibration from the nozzle side of the mounting head holding the chip component. Or from the table side on which the circuit board is placed, so that the chip parts can be wet-adhered to the adhesive, and the chip parts can be temporarily and securely fixed to the circuit board, and the external electrodes of the chip parts can be fixed. The solderability between the chip component and the land surface of the conductive pattern can be kept good, and the chip component can be accurately soldered and fixed to the circuit board.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a circuit board to which a chip component mounting method according to the present invention is applied.

FIG. 2 is an explanatory view showing a step of temporarily fixing chip components to the circuit board of FIG. 1;

FIG. 3 is an explanatory diagram showing a soldering fixed state of a chip component temporarily fixed to the circuit board of FIG. 1;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 circuit board 2, 2 conductive pattern 3 thermosetting adhesive 4 chip component 4 a body portion of chip component 4 b, 4 c external electrode of chip component 5 solder H mounting head

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-184887 (JP, A) JP-A-60-152093 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05K 3/34

Claims (2)

(57) [Claims] 1. A chip component held by a tip of a nozzle of a mounting head is pressed against a thermosetting adhesive applied in advance on a circuit board, and an external electrode of the chip component is brought into contact with a conductive pattern on the circuit board. A method for temporarily fixing the chip component on a circuit board with a thermosetting adhesive, and then soldering and fixing external electrodes of the chip component to a conductive pattern on the circuit board. At the time of temporarily fixing the external electrode of the chip component to the land surface of the conductive pattern by pressing against the thermosetting adhesive above, the micro head vibrates from the nozzle side of the mounting head that is holding the chip component. A method of mounting a chip component, characterized in that: 2. The chip component according to claim 1, wherein a fine vibration is simultaneously applied from a nozzle side of the mounting head holding the chip component and a table side on which the circuit board is mounted. How to attach.