JP2000022310A - Method of mounting electronic components - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of mounting electronic components whereby it is possible to prevent electronic components mounted on a circuit board with adhesives from turning over, etc., to effectively avoid causing troubles due to their turnover, etc. SOLUTION: In a coating step, conductive adhesives 6 are coated on conductor lands 2. In a heating step, a circuit board 1 is mounted on a hot plate 7 to heat the adhesives 6 at 50 deg.C for 10 min. In a mounting step, the lead terminals 5 of an Al electrolytic capacitor 3 are laid on the conductive adhesives 6, this raising the adhering force of the conductive adhesives 6 owing to the heating step to increase the mechanical connection strength of the lead terminals 5 to the conductor lands 2. This, even for a high-gravity-center electronic component such as Al electrolytic capacitors 3, etc., makes it possible to avoid turning the Al electrolytic capacitors 3 over.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting an electronic component in a predetermined mounting area on a circuit board with an adhesive.

[0002]

In recent years, an electronic component is mounted on a circuit board by applying an adhesive to a mounting area on the circuit board and mounting the electronic component on the mounting area to which the adhesive has been applied. An implementation method is considered. By the way, in this case, some adhesives have low adhesive strength due to their components.For example, when mounting an electronic component having a high center of gravity such as an aluminum electrolytic capacitor, the adhesive has low adhesive strength. If a small conductive adhesive is used, there is a risk that the electronic component may fall over, and the quality of the product may deteriorate due to such a fall of the electronic component.

In this case, it is conceivable to add, for example, a higher alcohol or the like to the conductive adhesive for the purpose of increasing the adhesive strength. However, this is realized due to a problem such as a decrease in conductivity. It is difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent electronic components from falling down when mounting electronic components on a circuit board with an adhesive. It is an object of the present invention to provide a method of mounting an electronic component that can effectively prevent the occurrence of a defect caused by the above.

[0005]

According to the electronic component mounting method of the present invention, an application step of applying an adhesive to a mounting area is performed, and then the adhesive is applied to a predetermined adhesive strength. A heating step of heating at a predetermined temperature for a predetermined time is performed. Immediately after the heating step is performed, a mounting step of mounting the electronic component on the mounting area is performed. As described above, the adhesive is made to have a predetermined adhesive strength by performing the heating step, that is, the electronic component is mounted in a state where the adhesive strength is increased. Even if the electronic component has a high center of gravity, it is possible to prevent the electronic component from overturning, and as a result, it is possible to effectively prevent the occurrence of troubles caused by such overturning of the electronic component.

According to the electronic component mounting method of the present invention, the predetermined adhesive force of the adhesive is set based on the adhesive force characteristics of the adhesive with respect to the temperature and the heating time. The predetermined temperature and the predetermined time required for obtaining the force can be appropriately determined based on the adhesive force characteristics.

According to the electronic component mounting method of the third aspect, the heating step is performed using a heat transfer member heated to a predetermined temperature or higher. The hot plate method can heat the adhesive to a predetermined temperature.

According to the electronic component mounting method of the present invention, the adhesive is made conductive, so that the circuit board and the electronic component are electrically connected in addition to the mechanical connection. Can also.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 2 schematically shows a mounting form of the electronic component obtained by the present embodiment. In FIG. 2, a circuit board 1 is formed by printing and firing a Cu thick film paste material on a ceramic substrate.
Conductor lands (mounting areas according to the present invention) 2, 2 are provided at the predetermined portions. The aluminum electrolytic capacitor (electronic component according to the present invention) 3 has lead terminals 5, 5 protruding from its cylindrical main body 4, and a conductive adhesive 6.
6, it is mounted on the circuit board 1 by being connected to the conductor lands 2 and 2. The conductive adhesives 6, 6 are obtained by filling a mixture of an amine-based curing agent and a bisphenol F type epoxy resin with an Ag filler.

As shown in FIG. 3, such a mounting mode is performed by sequentially executing a coating step A1, a heating step A2 and a mounting step A3. Hereinafter, specific steps A1 to A3 will be described. The contents will be described. Here, it is assumed that the adhesive force characteristics of the conductive adhesive used in the present embodiment with respect to the temperature and the heating time are obtained in advance as a graph shown in FIG.

Before explaining the steps A1 to A3, FIG. 4 will be briefly described. The adhesive force characteristics shown in FIG. 4 were obtained as follows. That is,
The adhesive force is applied to the conductive adhesive used in this embodiment on the substrate, and when a predetermined condition is satisfied, that is, when a predetermined time has elapsed after the conductive adhesive has reached a predetermined temperature,
The head member is pressed against the conductive adhesive at a load of 0.2N for 0.2 seconds, then pulled up at a pulling speed of 60 cm / min, and the drag force applied to the head member when pulled up is measured. It is. In this case, as a comparison target,
A solder paste is employed, and the adhesive strength of the conductive adhesive used in this embodiment is shown as a relative value when the initial adhesive strength of the solder paste at room temperature is converted to 1N.

Hereinafter, each of the steps A1 to A3 will be described with reference to FIG.
This will be described with reference to FIG. First, in the application step A1, the conductive adhesives 6, 6 are applied on the conductor lands 2, 2 of the circuit board 1 by mask printing. In this case, the thickness of the mask is 7
The printing conditions were as follows: a metal squeegee was used, the printing load was 1.0 N, and the moving speed of the squeegee was 30.
mm / sec, on-contact, and the thickness (film thickness) of the applied conductive adhesives 6, 6 is 70 ± 10 μm (see (a) in FIG. 1).

Next, in the heating step A2, the circuit board 1 is mounted on the hot plate 7 (see (b) in FIG. 1). At this time, the hot plate 7 is maintained at a predetermined temperature previously determined so that the temperature of the conductive adhesives 6, 6 applied on the conductor lands 2, 2 of the circuit board 1 becomes 50 ° C. It is. Then, the circuit board 1 is held on the hot plate 7 for 10 minutes after the temperature of the conductive adhesives 6 and 6 reaches 50 ° C., and after 10 minutes, the circuit board 1 is 7
Separate from.

Here, the adhesive strength of the conductive adhesives 6, 6 is:
As is clear from the adhesive force characteristics shown in FIG. 4, the temperature increased from about 0.74 N in the initial state to about 1.4 N by heating at 50 ° C. for 10 minutes (P in FIG. 4).
reference). This is considered to be because the conductive adhesives 6 and 6 were softened by heating at 50 ° C. for 10 minutes, and the fluidity was increased. For reference, when the conductive adhesives 6 and 6 were heated at 80 ° C. for 10 minutes, on the contrary, the adhesive strength was reduced (see Q in FIG. 4).
This is the curing temperature of the conductive adhesives 6,6 (in this case,
(150 [deg.] C.), the curing started and the fluidity was reduced.

In the mounting step A3, the lead terminals 5, 5 of the aluminum electrolytic capacitor 3 are placed on the conductive adhesives 6, 6, and a load is applied to the aluminum electrolytic capacitor 3 to place the aluminum electrolytic capacitor 3 on the circuit board 1. To be mounted on. At this time, the mounting conditions are a load of 6 N and a load application time of 1 second. At this time, since the adhesive force of the conductive adhesives 6, 6 has been increased by performing the heating step A2 as described above, the mechanical force between the lead terminals 5, 5 and the conductor lands 2, 2 has been increased. The connection strength increases.

The above description has been made on the assumption that the adhesive properties of the conductive adhesives 6, 6 have been obtained in advance, as described above. If the force characteristics have not been obtained, each of the above-described steps A1
Prior to performing A3, the adhesive properties of the adhesive to be used may be measured.

As described above, according to the present embodiment, the application step A1 for applying the conductive adhesives 6, 6 onto the conductor lands 2, 2
Then, a heating step A2 of mounting the circuit board 1 on the hot plate 7 and heating the conductive adhesives 6, 6 at 50 ° C. for 10 minutes.
And a mounting step A3 of mounting the lead terminals 5, 5 of the aluminum electrolytic capacitor 3 on the conductive adhesives 6, 6.
Therefore, in the mounting step A3, the heating step A3 is performed.
By performing Step 2, the adhesive strength of the conductive adhesives 6, 6 increases, and the mechanical connection strength between the lead terminals 5, 5 and the conductor lands 2, 2 increases. Therefore, even if the electronic component has a high center of gravity such as the aluminum electrolytic capacitor 3, the aluminum electrolytic capacitor 3 can be prevented from falling down.
As a result, it is possible to effectively prevent the occurrence of a problem due to such a fall of the aluminum electrolytic capacitor 3.

In particular, in this case, when heating the conductive adhesives 6, 6, a method of mounting the circuit board 1 on the hot plate 7 is adopted. The conductive adhesives 6, 6 can be heated to 50 ° C.

The present invention is not limited to the embodiment described above, but can be modified or expanded as follows. The adhesive is not limited to the conductive adhesive, but may be an insulating adhesive, that is, a configuration in which the circuit board and the electronic component are mechanically connected only. In the heating step, not only the hot plate method but also a known hot air supply method may be used.

[Brief description of the drawings]

FIG. 1 is a side view showing the operation of an embodiment of the present invention.

FIG. 2 is a perspective view schematically showing a mounting mode.

FIG. 3 is a flowchart showing a process flow.

FIG. 4 is a diagram showing the adhesive strength of a conductive adhesive with respect to temperature and heating time.

[Explanation of symbols]

In the drawings, 1 is a circuit board, 2 is a conductor land (mounting area),
Reference numeral 3 denotes an aluminum electrolytic capacitor (electronic component), 6 denotes a conductive adhesive, and 7 denotes a hot plate (heat transfer member).

Claims (4)

[Claims] An electronic component mounting method for mounting an electronic component on a predetermined mounting area on a circuit board with an adhesive, a coating step of applying an adhesive to the mounting area, and applying a predetermined adhesive force to the adhesive. A heating step of heating at a predetermined temperature at a predetermined temperature for a predetermined time, and a mounting step of mounting the electronic component in the mounting area immediately after the execution of the heating step. . 2. The electronic component mounting method according to claim 1, wherein the predetermined adhesive force of the adhesive is set based on adhesive force characteristics of the adhesive with respect to temperature and heating time. 3. The electronic component mounting method according to claim 1, wherein the heating step is performed using a heat transfer member heated to the predetermined temperature or higher. 4. The method for mounting an electronic component according to claim 1, wherein the adhesive is conductive.