JP2002368400A - Method for mounting electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent contamination of a substrate due to solder scattering or an overflow of flux when mounting electronic components on substrate using solder. SOLUTION: Solder paste 2a is printed on one surface 1a of a substrate 1, and an electronic component 3 is mounted on the solder paste 2a. On a non- solder arranging region 9 where the solder paste 2a is not arranged of the surface 1a of the substrate 1A, a covering member 11 for covering the region 9 in a state that an outer peripheral portion 11b contacts with the surface 1a of the substrate 1. Thereafter, the component 3 is connected to the substrate 1 by melting the solder paste 2a.

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 on a surface of a substrate through which an electronic component is connected via solder. It is suitable for use on a mounting board or the like in which bonding connection is mixed.

[0002]

2. Description of the Related Art In general, this type of mounting method generally involves arranging a solder paste in a predetermined area on one surface of a substrate by printing or the like,
The electronic component is mounted on the solder paste, and subsequently, the electronic component is connected to the substrate by melting the solder paste.

[0003]

However, in this mounting method, when the solder paste is melted, the solder paste should be arranged because the solder is scattered or the flux in the solder paste flows out. There is a problem that an area (non-solder-arranged area) other than the area (solder-arranged area) is contaminated by the scattered solder and the flowing-in flux.

For example, in a mounting board on which a circuit is formed or a mounting board in which solder connection and wire bonding connection are mixed on the same board, circuit wiring and bonding pads located in a non-solder arrangement region are contaminated, and Problems such as short-circuiting of wire and a decrease in bondability of wire bonding occur.

To solve such problems, the substrate is cleaned, a dam is formed between the solder arrangement area and the non-solder arrangement area, or the non-solder arrangement area is covered with a protective film such as wax. Means have been proposed, but in substrate cleaning, flux can be removed but scattered solder cannot be removed,
At the dam, the scattered solder cannot be completely prevented, and the protective film has a problem that a residue of the protective film remains when the protective film is removed.

There is also a method of performing wire bonding prior to disposing the solder paste. Then, when disposing the solder paste, a special mask or printing method for covering and protecting the wire bonding connection portion is used. It is not easy.

Japanese Patent Application Laid-Open No. Hei 5-299898 also proposes a method of covering a non-solder-arranged area using a cover member instead of the above-mentioned protective film. However, in this method, contamination due to solder scattering is prevented. Although it can be prevented, since a gap is provided between the cover member and the substrate, it is difficult to prevent the inflow of the flux.

In view of the above problems, it is an object of the present invention to easily prevent contamination of a substrate due to scattering of solder and outflow of flux when mounting electronic components on the substrate using solder. And

[0009]

According to the first aspect of the present invention, there is provided an electronic component for connecting an electronic component (3) to one surface of a substrate (1) via a solder (2). Disposing a solder paste (2a) on a predetermined area on one surface of a substrate, a solder disposition area (8) on the one surface of the substrate where the solder paste is disposed, and a non-solder disposition area on which no solder paste is disposed. A step of disposing a cover member (11) covering at least one region of the substrate (9) in a state where at least a part of the outer peripheral portion (11b) is in contact with one surface of the substrate; After the process of mounting electronic components on the above and the above three processes,
Melting the solder paste and connecting the electronic component and the substrate.

According to the present invention, at least one of the solder arrangement area where the solder paste is arranged and the non-solder arrangement area where the solder paste is not arranged on one surface of the substrate is covered with the cover member. At least a part of the outer peripheral portion can be in a state in contact with one surface of the substrate.

According to this, when the solder arrangement region is covered with the cover member, the solder can be prevented from scattering to the outside, and when the non-solder arrangement region is covered, the solder that has scattered can be prevented from scattering. The arrangement area can be protected.

Further, at a portion where the flux easily flows,
Because the outer peripheral portion of the cover member can be in contact with one surface of the substrate, the flux flows out of the solder arrangement area, or
It is possible to prevent the flux from flowing into the non-solder arrangement region.

[0013] Such a cover member can be applied even when, for example, wire bonding connection is performed after solder connection. Therefore, a special configuration is not required and a simple configuration can be achieved.

Therefore, according to the present invention, when electronic components are mounted on a substrate by using solder, contamination of the substrate due to scattering of solder and outflow of flux can be easily prevented.

According to the second aspect of the present invention, as the cover member (11), the end of the outer peripheral portion (11b) facing one surface of the substrate (1) is arranged from the solder disposition area (8) to the non-solder disposition. It is characterized by using a tapered shape away from one surface of the substrate toward the region (9).

According to this, at the outer peripheral portion of the cover member that is in contact with one surface of the substrate, if there is a gap,
Even if the flux tries to pass from the solder disposition area to the non-solder disposition area from the gap, the tapered portion at the outer peripheral end has a function of accumulating the flux by surface tension, so that the flux is easily removed. Can be prevented from passing through.

Therefore, the effect of the invention of claim 1 can be achieved at a higher level, which is preferable.

The reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An embodiment of the present invention shown in the drawings will be described below. FIG. 1 is a schematic sectional view showing a mounting structure of an electronic component according to the first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a substrate made of a ceramic circuit board, a printed circuit board, or the like. On one surface 1a of the substrate 1, electronic components such as capacitors and resistance elements (shown in FIG. In this case, the capacitor 3 is electrically connected. As the solder 2, a normal solder that can be printed with a solder paste can be used.

On one surface 1a of the substrate 1, an IC chip 4 is fixed via a conductive adhesive 5 made of Ag paste or the like.
The pad 6 made of u or Al and the IC chip 4 are Au
And are electrically connected by bonding wires 7 made of Al or the like.

Here, the area of the one surface 1a of the substrate 1 to which the electronic component 3 is connected by solder is a solder arrangement area 8 in which a solder paste 2a described later is arranged, and the IC chip 4
Is a non-solder-arranged area 9 where the solder paste 2a is not arranged.

Next, a method of mounting the mounting structure shown in FIG. 1 will be described with reference to the explanatory diagram of FIG. 2A is a diagram showing the mounting method in a cross section corresponding to FIG. 1, and FIG. 2B is an enlarged view of a portion A surrounded by a circle in FIG.

First, a solder paste 2a, which finally becomes the solder 2, is arranged on the one surface 1a of the substrate 1 in the solder arrangement area 8 by printing or the like (solder printing step). Then, the electronic component 3 is mounted on the placed solder paste 2a (component mounting step).

At this time, as shown in FIG. 2A, the cover member 11 is mounted on the non-solder mounting area 9 using the mounter 10 for mounting electronic components (cover mounting step). The cover member 11 includes a plate-like portion 11a corresponding to the area of the non-solder arrangement region 9 and an outer peripheral portion 11b provided on the outer periphery of the plate-like portion 11a. Of shape.

FIG. 2B shows an enlarged view of the vicinity of the end of the outer peripheral portion 11b facing the one surface 1a of the substrate 1 in the cover member 11, and the end is located in the solder arrangement area. 8 to the non-solder placement area 9
tapered portion 11c tapered away from a
have.

With the mounting of the cover member 11, FIG.
As shown in FIG.
In the outer peripheral portion of the non-solder arrangement region 9, the end of the outer peripheral portion 11 a of the cover member 11 is in contact with the one surface 1 a of the substrate 1.

The entire peripheral edge of the outer peripheral portion 11a of the cover member 11 does not have to be in contact with the one surface 1a of the substrate 1, but at least at the boundary between the solder arrangement area 8 and the non-solder arrangement area 9. Just do it.

When the steps of component mounting and cover mounting are performed in this manner, a state as shown in FIG. 2A is obtained. Then, in this state, the solder paste 2a is melted (reflowed), and the electronic component 3 And the substrate 1 are connected (reflow process). In the reflow process, as shown in FIG. 2A, when the solder paste 2a is melted, the solder 2 scatters or the flux 2b in the solder paste 2a flows out.

In this embodiment, since the cover member 11 covers the non-soldering area 9 as described above, the non-soldering area 9 can be protected from the scattered solder 2. . In addition, the flux 2b flowing out is covered by the outer peripheral portion 11b of the cover member 11.
Is in contact with one surface 1 a of the substrate 1, it is possible to prevent the flux 2 b from flowing into the non-solder arrangement region 9.

In particular, in the present embodiment, as a preferred embodiment, since the above-described tapered portion 11c is formed at the end of the outer peripheral portion 11b of the cover member 11, the outer peripheral portion 11b of the cover member 11 Even if there is a gap therebetween, the taper portion 11c has a function of accumulating the flux 2b by the surface tension (see FIG. 2B), so that the passage of the flux 2b can be easily prevented.

By the way, as shown in FIG. 2C, the outer peripheral portion 1 of the cover member 11 facing the one surface 1a of the substrate 1 is provided.
If the tapered portion 11c is not formed at the end of 1b, the flux that enters through the gap reaches deeper inside the non-solder disposition region 9 than when the tapered portion 11 exists. Easier to do. That is, the tapered portion 11
Due to the presence of c, the width corresponding to the plate thickness of the outer peripheral portion 11b of the cover member 11 can be used as a pool for the flux 2b.

In this embodiment, after the reflow process, the cover member 11 is removed (cover removal process), and the substrate 1 is subsequently washed (substrate cleaning process). Next, a conductive adhesive 5 such as Ag paste is applied to the non-solder disposition area 9 (conductive adhesive applying step), and the IC chip 4 is mounted on the conductive adhesive 5 (chip mounting step). Then, the conductive adhesive 5 is cured (a conductive adhesive curing step).

Next, the IC chip 4 and the pad 6 are wire-bonded, so that the connection is performed by the bonding wire 7. Thus, the mounting structure shown in FIG. 1 is completed.

As described above, according to the mounting method of the present embodiment, by mounting the cover member 11 having a simple shape having the plate-shaped portion 11a and the outer peripheral portion 11b, the solder generated during the reflow process is provided. 2 can be easily prevented from being contaminated in the non-solder-arranged area 9 of the substrate 1 due to the scattering of the flux 2 and the outflow of the flux 2b. This effect is exerted at a higher level by forming the tapered portion 11.

In the cover disposing step, in order to make the cover member 11 hard to move, a part of the outer peripheral portion 11b is bonded and fixed by solder, and in the cover removing step, the solder is heated so that the cover member 11 is heated. May be removed.

The cover member 11 is provided with tin plating or solder plating on the surface of the cover member 11 so that the solder 2 scattered on the surface of the cover member 11 will not be repelled and fly to other places. The solder wettability may be improved.

If there are a plurality of IC chips to be connected by wire bonding, a plurality of cover members 11 may be arranged as necessary.

The mounting and dismounting of the cover member 11 can be automated using a component mounting mounter or the like, so that the cost is hardly increased as compared with the conventional process.

(Second Embodiment) FIG. 3 is an explanatory diagram for explaining a method of mounting an electronic component according to a second embodiment of the present invention. Differences from the first embodiment will be mainly described.

In the first embodiment, one surface 1a of the substrate 1
Among them, the cover member 11 is arranged in the non-solder arrangement area 9 where the solder paste 2a is not arranged, and the scattering of the solder 2 and the inflow of the flux 2b from the solder arrangement area 8 to the non-solder arrangement area 9 are prevented. Conversely, as in the embodiment, the cover member 1 is placed in the solder placement area 8 where the solder paste 2a is placed.
1 may be arranged.

In the mounting method of the present embodiment, first, a solder printing step and a component mounting step are performed as in the first embodiment. In this component mounting step, the cover member 11 is mounted on the solder mounting area 8 as shown in FIG. 3 using the above-described electronic component mounting mounter (cover mounting step).

With the mounting of the cover member 11, as shown in FIG. 3, the upper part of the solder arrangement area 8 is covered with a plate-like portion 11a of the cover member 11, and the outer peripheral part of the solder arrangement area 8 is covered with the cover member. The end of the outer peripheral portion 11a of the substrate 11
a. At this time, the end of the outer peripheral portion 11a of the cover member 11 only needs to be in contact with the one surface 1a of the substrate 1 at least at the boundary between the solder arrangement region 8 and the non-solder arrangement region 9.

Subsequently, a reflow process is performed in the state shown in FIG. Here, in the present embodiment, since the solder arrangement area 8 is covered by the cover member 11 as described above, the scattered solder 2 and the flux (not shown) to flow out are placed in the solder arrangement area 8. The solder 2 and the flux can be prevented from entering the non-solder arrangement region 9.

Next, as in the first embodiment, after the reflow step, the cover removing step, the substrate cleaning step, the conductive adhesive applying step, the chip mounting step, the conductive adhesive curing step, and the wire bonding step are sequentially performed. By doing so, the mounting structure of the electronic component is completed.

As described above, according to the mounting method of the present embodiment, similarly to the first embodiment, the contamination of the non-solder arrangement area 9 of the substrate 1 due to the scattering of the solder 2 and the outflow of the flux 2b can be easily prevented. be able to.

As is apparent from the present embodiment,
In the cover arranging step, one of the solder arranging area 8 and the non-solder arranging area 9 on one surface 1a of the substrate 1,
Alternatively, the cover member 11 may be arranged in both regions 8 and 9.

(Third Embodiment) FIG. 4 is an explanatory diagram for explaining an electronic component mounting method according to a third embodiment of the present invention. Differences from the first embodiment will be mainly described.

In the first embodiment, one surface 1a of the substrate 1
When disposing the cover member 11 in the non-solder disposition area 9, the cover member 11 was mounted on the substrate 1 by a mounter for mounting the electronic component 3 in the same manner as the component mounting.

In the third embodiment, as shown in FIG. 4, the cover member 11 is supported on a tray 20 used when handling the substrate 1 via a movable arm 21, and the movable arm 21 is moved. As a result, the substrate 1 of the cover member 11
Attachment to and removal from the unit.

The tray 20 and the movable arm 21 are made of a heat-resistant material such as a metal or a ceramic so as to withstand the reflow process. To move like a hinge,
Are linked. The cover member 11 is joined and fixed to the movable arm 21 so as to move integrally with the movable arm 21.

In the mounting method of the present embodiment, first, a solder printing step and a component mounting step are performed as in the first embodiment. In the present embodiment, after the component mounting step, the substrate 1 is placed on the tray 20 and the cover member 11 is moved to the movable arm 2.
By (1), the cover member 11 is mounted on the non-solder arrangement area 9 (or the solder arrangement area 8) (cover arrangement step). The substrate 1 may be placed on the tray 20 from the beginning, and the solder printing process and the component mounting process may be performed.

In this embodiment, as shown in FIG.
As shown by the solid cover member 11, the cover member 11 is arranged so that the non-solder arrangement region 9 is protected from solder and flux in a reflow process in a later step.

Subsequently, after performing a reflow process in the state shown in FIG.
1, the cover member 11 is removed from the substrate 1 as shown by a two-dot chain line in FIG.

Thereafter, the substrate cleaning step, the conductive adhesive applying step, the chip mounting step, the conductive adhesive curing step, and the wire bonding step are sequentially performed to complete the electronic component mounting structure shown in FIG.

As described above, according to the mounting method of the present embodiment, similarly to the first embodiment, the contamination of the non-solder arrangement area 9 of the substrate 1 due to the scattering of the solder 2 and the outflow of the flux 2b can be easily prevented. be able to. Further, since the cover member 11 is integrated with the tray 20, the cover member 1
1 can be easily positioned when mounted on the substrate 1.

In the above embodiment, for example, after the cover disposing step is performed on the non-solder disposing area 9, the solder printing step and the component mounting step may be performed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a mounting structure of an electronic component according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view for explaining a method of mounting the electronic component according to the first embodiment.

FIG. 3 is a schematic sectional view illustrating a method for mounting an electronic component according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view illustrating a method for mounting an electronic component according to a third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... board | substrate, 2 ... solder, 2a ... solder paste, 3 ... electronic components, 8 ... solder arrangement area, 9 ... non-solder arrangement area, 11 ... cover member, 11b ... outer peripheral part of a cover member.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B23K 101: 42 B23K 101: 42 (72) Inventor Yuji Otani 1-1-1 Showacho, Kariya, Aichi Prefecture F-term in DENSO Corporation (Reference) 5E319 AA03 AA07 AB05 AC04 BB05 BB08 CC34 CD01 CD07 CD29 GG20

Claims (2)

[Claims] 1. An electronic component mounting method for connecting an electronic component (3) to one surface of a substrate (1) via solder (2), wherein a solder paste (2a) is arranged in a predetermined region of the one surface of the substrate. And forming an outer peripheral portion (11b) on at least one of a solder placement area (8) where the solder paste is placed and a non-solder placement area (9) where the solder paste is not placed on one surface of the substrate. A cover member (1) that covers the one area while at least a part thereof is in contact with one surface of the substrate.
Disposing 1), mounting the electronic component on the solder paste, and after the three steps, melting the solder paste and connecting the electronic component and the board; A method of mounting an electronic component, comprising: 2. An end portion of the outer peripheral portion (11b) facing one surface of the substrate (1) as the cover member (11) extends from the solder arrangement region (8) to the non-solder arrangement region (9). 2. A tapered shape which is separated from one surface of the substrate toward the surface is used.
The electronic component mounting method described in the above.