JPH05267391A - Mounting of component by precipitation soldering method - Google Patents

Abstract

PURPOSE:To provide the method for mounting components by which the solder of the desired thickness can be formed at the same time with a highly reliable connection between a substrate electrode and a component electrode. CONSTITUTION:In a method for mounting a components 14 on a substrate 11 by precipitation soldering, paste 17 for precipitation soldering is applied on a component mounting section of the substrate 11 and a substrate electrode 12 and a component electrode 15 are aligned, with the substrate 11 and the component 14 being separated by placing a spacer 16 for solder height adjustment between the substrate 11 and the component 14, and then the whole body is heated to the specified temperature. By this method, the solder is precipitated from the substrate electrode 12 side and from the component electrode 15 side for connection between the substrate electrode 12 and the component electrode 15.

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 fine parts on a substrate. Along with the demand for miniaturization of electronic devices such as communication devices, miniaturization of components and high-density packaging by forming fine wiring using photolithography technology are rapidly progressing. Accordingly, there is a demand for establishment of a fine bonding technique even in the component mounting for bonding the miniaturized component electrode pad and the substrate electrode pad.

[0002]

2. Description of the Related Art FIG. 6 shows a conventional mounting method for a small component such as a capacitor. First, as shown in FIG. 6A, solder bumps 3 are formed on the electrode pads 2 of the substrate 1,
Next, as shown in (b), the component 4 is aligned and mounted on the solder bumps 3, and the solder bumps 3 are melted and solidified by reflow, and the substrate electrodes are soldered with the solder 7 as shown in FIG. 6C. Bonding between the pad 2 and the component electrode pad 5 is performed.

Among the bare chip mounting methods, a flip chip mounting method which is particularly effective in reducing the mounting area will be described with reference to FIG. First, as in the conventional example of FIG.
In FIG. 7A, the solder bumps 3 are formed on the electrode pads 2 of the substrate 1, and then the bare chip component 4 having the bumps 6 formed on the electrodes 5 is soldered on the substrate 1 as shown in FIG. 7B. The bumps 3 are aligned with each other and mounted on the substrate, and then the solder bumps 3 are melted and solidified. Then, as shown in FIG. 7C, the solder bumps 3 are provided between the substrate electrode pads 2 and the component electrode pads 5 with solder 7. We are joining.

In any of the mounting methods described above, it is necessary to form bumps on the substrate or component electrodes in advance, but it is difficult to print solder paste for finer electrode pads and narrower pitches. Although gold transfer bumps and the like are used, there are problems such as high cost as compared with solder materials and high temperature heating required for joining.

Therefore, a solder bump forming method using a plating method has been proposed. However, it takes a lot of man-hours, and the bump height and surface shape formed are not uniform, which makes it difficult to perform alignment, resulting in poor connection and solder bridge. There was a problem such as the risk of causing it.

On the other hand, as a method for forming solder bumps on a substrate electrode pad which has been made finer and has a narrower pitch, Japanese Patent Laid-Open No. 157/157 has been proposed.
No. 796 proposes a deposition solder method. The deposition solder method is a solder formation method that deposits solder only on electrode pads by a chemical reaction, does not generate solder balls or bridges, and is compatible with fine and narrow pitch (75 μm width, 150 μm pitch) pads. Attention has been paid.

The deposition solder method is a process in which a paste containing organic lead acid and tin powder as main components is applied on a metal pad and a solder is deposited only on the metal pad by a chemical reaction, and ionization of Pb and Sn is performed. The different tendencies lead to the formation of a solder alloy, which is then followed by a metal pad (eg Cu).
It reacts with the above metal salt to deposit solder only on the metal pad.

A conventional example of component mounting using the deposition solder method will be described with reference to FIG. As shown in FIG. 8 (a), the lead electrode 5'of the component 4 is brought into contact with the electrode 2 of the substrate 1, and then, as shown in FIG. The paste 8 is applied on the substrate electrode 2.

Then, when heated to about 185 to 225 ° C., Cu (electrodes 2, 5 ') reacts with the activator in the paste to form a Cu salt. Between the organic lead acid in the paste and the tin powder, lead is deposited due to the difference in the ionization tendency, and the lead is instantly diffused in the tin powder to form a solder alloy. Then, a diffusion reaction occurs between the solder alloy and Cu salt,
As shown in FIG. 8C, the solder 9 is deposited only on the board electrode 2 and the component electrode 5 '.

The paste residue and the solder balls which have not reacted with the electrodes 2 and 5'can be easily removed by washing.
As the cleaning agent, either a chlorocene-based solvent or an alcohol-based solvent can be used.

[0011]

It has been proposed in Japanese Patent Laid-Open No. 1-157796 that soldering of lead parts is performed at the same time as solder deposition by using the deposition soldering method. In the case of a mounted component that requires a certain space (solder height) between the component electrode and the substrate pad, the substrate electrode and the component electrode are brought into contact with each other.
The component mounting method described in No. 157796 could not be used.

Therefore, in the same manner as in the conventional case, the components are mounted after forming the solder bumps on the substrate electrodes in order to obtain a sufficient solder height, and the shear stress caused by the difference in the thermal expansion coefficient between the component and the substrate is generated. There was a drawback that it became vulnerable to solder destruction.

The present invention has been made in view of the above circumstances, and an object thereof is to form a solder having a desired film thickness and to bond a highly reliable substrate electrode and a component electrode. It is an object of the present invention to provide a component mounting method using a deposition solder method that can be performed at the same time.

[0014]

In order to solve the above-mentioned problems, the present invention provides a method for mounting a component on a substrate by a deposition solder method, wherein a paste for deposition solder is provided on a component mounting portion of the substrate. By coating, the spacer for adjusting the solder height is interposed between the substrate and the component, the substrate electrode and the component electrode are aligned while the substrate and the component are separated from each other, and the substrate electrode is heated to a predetermined temperature. Provided is a component mounting method characterized in that solder is deposited from the electrode side and the component electrode side to bond the substrate electrode and the component electrode.

Instead of interposing a spacer for adjusting the solder height between the substrate and the component, a protrusion for adjusting the solder height is formed on the substrate, or a component for adjusting the solder height is mounted on the component to be mounted. You may make it provide a protrusion.

[0016]

According to the present invention, the solder is deposited on the substrate electrode and the component electrode which are not in contact with each other through the spacer until they are joined to the solders on the electrodes facing each other. In the case of a mounted component that requires a certain space between the substrate electrode and the substrate electrode, solder bonding having a desired film thickness can be performed.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, referring to FIG. 1, there is shown a component mounting method according to a first embodiment of the present invention. As shown in FIG. 1 (A), the solder paste 17 is applied to the component mounting portion of the substrate 11 where the electrode 12 is formed. As the substrate 11, a glass epoxy substrate, an alumina substrate, or the like, which has heat resistance against solder deposition and heating during bonding, can be used.

The material of the substrate electrode 12 is Cu or Au.
A general electrode material such as the above can be used, and a bumpless substrate can also be used. The coating thickness of the deposited solder paste 17 depends on the desired solder deposition film thickness, but is about 500 μm when depositing about 50 μm of solder.

Next, a spacer 16 for adjusting the solder height is placed in a region other than the electrode portion in the component mounting portion on the substrate 11.
The spacer 16 is a heat-resistant glass bead having a particle diameter according to the desired solder height, the substrate and the shape of the component.

The component 14 is aligned with the spacer 16 so that the electrode 15 and the substrate-side electrode 12 face each other. This alignment is performed visually, for example. Thereafter, the deposition reaction proceeds at a temperature corresponding to the deposited solder until the respective solders are joined from both sides, and as shown in FIG. 1 (C), the solder between the substrate electrode 12 and the component electrode 15 is joined by the deposited solder 18. I do.

FIG. 1 (B) is a perspective view of FIG. 1 (A). The reaction temperature is preferably about the melting temperature of the precipitated solder + 30 ° C. That is, when solder having a melting temperature of about 180 ° C. is deposited, about 210 ° C. is desirable. The reaction time is about 60 seconds depending on the amount of deposited solder.

After the precipitation reaction, the paste residue is washed with a chlorocene-based or alcohol-based solvent. The mounted parts are desired to have heat resistance against the solder deposition reaction, but bumpless parts, bump-formed parts, lead parts and the like can also be used.

Referring to FIG. 2, a second embodiment of the solder height adjusting spacer is shown. Board 11 and component 14
A rectangular parallelepiped spacer 19 or 1 formed of a heat-resistant film such as polyimide having a thickness corresponding to the solder height between
9'is interposed and attached in advance to a part of the outer periphery of the component electrode surface or a corresponding portion on the substrate side.

It is also possible to enhance the heat dissipation effect of the components (heat transfer effect to the substrate side or the heat dissipation member) by using a material such as SiC having a heat conductivity as high as that of Al as the spacer.

Referring to FIG. 3, there is shown a third embodiment of the solder height adjusting spacer. Claw members 20 made of a heat-resistant resin are attached to the four corners of the component 14, and the claw members 20 are interposed therebetween. Then, the component 14 is mounted on the substrate 11. The claw member 20 may be removed after the completion of the solder deposition reaction,
Further, the component 14 can be positioned and adhered to the substrate 11 and used as a fixing base for the component 14.

FIG. 4 shows a fourth embodiment for adjusting the solder height. In this embodiment, a protrusion 21 as shown in FIG. 4 (A) is formed on a part of the substrate material at the stage of producing the substrate, and the component 14 is mounted on the protrusion 21. Using the photolithographic polyimide multilayer technology,
It is possible to form fine and accurate protrusions. Also,
At this time, the protrusion 22 having a step as shown in FIG.
If formed, it can be used as a guide for alignment.

FIG. 5 shows a fifth embodiment for adjusting the solder height. The fifth embodiment is intended to adjust the solder height on the component side. That is, as shown in FIG. 5A, in the lead component 24 (including TAB and the like), the distance between the lead 25 and the electrode 12 of the substrate 11 is adjusted by forming the lead 25. Or, as shown in FIGS. 5B and 5C,
Protrusions 36 or 36 'are provided on the lower surface (substrate side) of the component 34, and the distance between the lead 35 of the component 34 and the electrode 12 of the substrate 11 is adjusted by these protrusions.

As another embodiment, it is possible to use a jig for controlling the distance and position between the substrate and the component without using a spacer or the like.

[0029]

As described in detail above, according to the present invention, by depositing a deposition type solder between a substrate electrode and a component electrode which are not in contact with each other via a spacer, a certain constant interval (solder height) is maintained. It is possible to simultaneously perform the solder formation between the required substrate electrodes and component electrodes and the joining of the electrodes.

Since the solder height can be controlled as described above, there is no concern of causing a defective connection or a bridge, the connection reliability is improved, and the fine bumps are formed on the substrate through complicated steps.
Alternatively, it need not be formed on the part.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a mounting method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a solder height adjusting method according to a second embodiment.

FIG. 3 is a diagram illustrating a solder height adjusting method according to a third embodiment.

FIG. 4 is a diagram showing a solder height adjusting method of a fourth embodiment.

FIG. 5 is a diagram showing a solder height adjusting method of a fifth embodiment.

FIG. 6 is an explanatory diagram of a conventional component mounting method.

FIG. 7 is an explanatory view of another conventional example.

FIG. 8 is an explanatory view of still another conventional example.

[Explanation of symbols]

 11 substrate 12 substrate electrode 14 component 15 component electrode 16 glass bead spacer 17 paste for deposition solder 18 deposition solder 19, 19 'rectangular parallelepiped spacer 20 claw member 21, 22, 36, 36' protrusion

Claims (5)

[Claims] 1. A component (14) on a substrate (11) by a deposition solder method.
In the method of mounting, the paste (17) for deposition solder is placed on the component mounting part of the substrate (11).
A spacer for solder height adjustment between the substrate (11) and the component (14).
By positioning the substrate electrode (12) and the component electrode (15) while separating the substrate (11) and the component (14) with (16, 19, 20) interposed, and heating them to a predetermined temperature. A method for mounting a component, characterized in that solder is deposited from the substrate electrode (12) side and the component electrode (15) side to join the substrate electrode (12) and the component electrode (15). 2. The component mounting method according to claim 1, wherein glass beads (16) are used as the spacers. 3. The component mounting method according to claim 1, wherein a rectangular parallelepiped heat-resistant resin (19, 19 ′) is used as the spacer. 4. A component (14) on a substrate (11) by a deposition solder method.
In the method of mounting, the protrusions (21, 22) for solder height adjustment are formed on the substrate (11), and the paste (17) for deposition solder is applied on the component mounting part of the substrate (11), The component (14) to be mounted is mounted on the protrusions (21, 22), and the substrate electrode (12) and the component electrode (15) are aligned while the substrate (11) and the component (14) are separated from each other. It is characterized in that the solder is deposited from the board electrode (12) side and the component electrode (15) side by heating to a predetermined temperature, and the board electrode (12) and the component electrode (15) are joined. How to mount parts. 5. A component (34) on a substrate (11) by a deposition solder method.
In the method of mounting, soldering height adjustment protrusions (36,36 ') are mounted on the component (34) to be mounted.
And paste (17) for deposition solder on the component mounting part of the substrate (11), and mount the component (34) on the substrate (11) with the protrusions (36, 36 ') facing down. Then, the substrate electrode (12) and the component electrode (35) are aligned, and by heating to a predetermined temperature, solder is deposited from the substrate electrode (12) side and the component electrode (35) side, and the substrate electrode ( A method for mounting a component, which comprises joining the electrode 12) to the component electrode (35).