JP2003158154A - Electronic component mounting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic component mounting method which can simplify a reinforcing resin forming process by applying reinforcing resin beforehand and avoid mounting defects caused by gases produced from a board. SOLUTION: In an electronic component mounting method wherein an electronic component 1 is mounted on a board 3 by connecting solder bumps 2 with electrodes 4 with solder, thermosetting resin 6 having an oxide film removing capability is supplied to the bumps 2 beforehand with quantities not filling a space between the board 3 but keeping gaps for degassing after the mounting. In this state, the electronic component 3 is mounted on the board 3, the bumps 2 are connected with the electrodes 4 by reflow soldering, and the resin 6 is thermally cured to form reinforcing resin parts reinforcing the solder connections of the bumps 2 and the electrodes 4. With such a constitution, gases produced from the board 3 in a heating process can be exhausted out and mounting defects caused by voids in the resin 6 can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting method for mounting electronic components on a board.

[0002]

2. Description of the Related Art As a mounting method of an electronic component in which a bump, which is a connecting electrode, is provided on a semiconductor element such as a flip chip, a method of soldering the bump to an electrode of a substrate is widely used. In this mounting method, a reinforcing resin portion is provided between the electronic component and the substrate for the purpose of reinforcing the solder joint between the bump and the substrate. The reinforcing resin portion is formed by injecting a reinforcing resin between the electronic component and the substrate after soldering, or by applying the reinforcing resin in advance to the entire mounting position before mounting the electronic component. The method was used.

In the latter case, a thermosetting resin containing an active component having the ability to remove the solder oxide film on the bump surface is used as a reinforcing resin, and the substrate is heated by reflowing after mounting the electronic component to the bump. The electrodes and the electrodes are soldered together, and the resin is heat-cured to form the resin reinforcing portion. At this time, by using the resin containing the active component, the solder bonding and the reinforcing resin portion formation can be performed in the same process without hindering the solder bonding even if the resin enters the bonding interface between the bump and the electrode. Has the advantage of being simplified.

[0004]

However, in the method of applying the reinforcing resin in advance, since the space between the electronic component and the substrate is almost completely filled with the resin, the voids generated in the reflow process are caused. The problem that electronic components can be lifted easily occurs. That is, when the substrate is heated in the reflow, water and organic components contained in the substrate are gasified and enter the reinforcing resin from the upper surface of the substrate to form voids inside.

When the void further grows between the electronic component and the substrate due to the temperature rise, the electronic component is lifted from below, and a gap is created between the bump and the electrode to prevent normal solder joining. As described above, the conventional electronic component mounting method in which the reinforcing resin is applied in advance has a problem in that the gas generated from the substrate forms voids in the reinforcing resin, resulting in mounting failure. It was

Therefore, the present invention provides an electronic component mounting method which can apply a reinforcing resin in advance to simplify the step of forming the reinforcing resin portion and prevent the mounting failure due to the gas generated from the substrate. The purpose is to

[0007]

According to a first aspect of the present invention, there is provided an electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode of the substrate. A resin supplying step of supplying a thermosetting resin having an oxide film removing ability to the connecting electrode of the electronic component, and mounting the electronic component on the substrate after the resin supplying step to heat the connecting electrode. A component mounting step of landing on the electrode of the substrate through the curable resin, and a heating step of heating the substrate after the component mounting step to solder-bond the connection electrode to the electrode and heat cure the thermosetting resin. The thermosetting resin is supplied so as to secure a deaeration gap between the substrate and the electronic component after the component mounting process in the resin supplying process, and the resin is generated from the substrate in the heating process. Discharging the gas from the degassing gap to the outside.

The electronic component mounting method according to a second aspect is the electronic component mounting method according to the first aspect, wherein a reinforcing resin is injected into a gap between the electronic component and the substrate after the heating step.

An electronic component mounting method according to a third aspect of the invention is an electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode of the substrate. A resin supplying step of supplying a thermosetting resin having an oxide film removing ability to the electrodes of the electrodes, and an electronic component is mounted on the substrate after the resin supplying step, and the connecting electrodes are connected to the electrodes of the substrate through the thermosetting resin. In the resin supply step, including a component mounting step of landing on, and a heating step of soldering the connecting electrode to the electrode by heating the substrate after the component mounting step and thermosetting the thermosetting resin. By supplying a thermosetting resin so as to secure a deaeration gap between the substrate and the electronic component after the component mounting step, the gas generated from the substrate in the heating step is removed by the deaeration gap. Discharged to the Luo outside.

An electronic component mounting method according to a fourth aspect is the electronic component mounting method according to the third aspect, wherein a reinforcing resin is injected into a gap between the electronic component and the substrate after the heating step.

According to a fifth aspect of the present invention, there is provided an electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode on the substrate. A first resin supplying step of supplying a thermosetting first resin to the electronic component fixing point set on the upper surface of the electronic component, and a second resin having an oxide film removing ability to the connecting electrode of the electronic component. A second resin supplying step of
Component mounting step of mounting the electronic component after the resin supplying step on the substrate after the first resin supplying step and landing the connection electrode on the electrode of the substrate through the second resin, and the component mounting step A heating step of soldering the connection electrode to the electrode by heating the subsequent substrate and thermosetting the first resin, and the parts in the first resin supplying step and the second resin supplying step. By supplying the first resin and the second resin so as to secure a degassing gap between the board and the electronic component after the mounting step, the gas generated from the board in the heating step is degassed. Discharge to the outside through the clearance.

An electronic component mounting method according to a sixth aspect is the electronic component mounting method according to the fifth aspect, wherein the second resin is a thermosetting resin and the second resin is thermoset. A resin reinforcement portion is formed to reinforce the solder joint portion between the connection electrode of the electronic component and the electrode of the substrate.

An electronic component mounting method according to a seventh aspect is the electronic component mounting method according to the fifth aspect, wherein the second resin is a solder joining flux.

According to the present invention, in the resin supplying step of supplying the reinforcing thermosetting resin onto the substrate in advance, the deaeration gap is secured between the substrate and the electronic component after the component mounting step. By supplying the thermosetting resin, the gas generated from the substrate in the heating step can be discharged to the outside through the degassing gap, and the mounting failure due to the gas generated from the substrate can be prevented.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIGS. 1 and 2 are process explanatory views of an electronic component mounting method according to Embodiment 1 of the present invention. In FIG. 1A, a bump 2 as a connecting electrode is provided on the lower surface (bump formation surface) of the electronic component 1 using solder as a forming material. FIG. 1A shows the bump 2
The resin supply step for applying the resin is shown in FIG. 1, and the electronic component 1 is located on the resin application part 5. The resin coating part 5 includes a resin transfer container 5a on which a coating film of resin 6 is formed. By vertically moving the electronic component 1 with respect to the resin transfer container 5a, a predetermined amount of resin is applied to the lower surface side of the bump 2. 6
Are supplied by transfer. The resin 6 is a base containing a thermosetting resin such as an epoxy resin as a main component, and an active component having an oxide film removing ability contained therein.

The resin supply amount in this resin supply step is
In a state where the electronic component 1 is mounted on the substrate 3 in a later process, the upper surface of the substrate 3 and the lower surface of the electronic component 1 are excessively sealed so that the gas released from the substrate 3 during reflow is discharged to the outside. It is adjusted so as not to hinder it and to be equal to or more than the lower limit amount for ensuring the reinforcing effect after the resin 6 is thermoset. The supply amount is adjusted by adjusting the thickness of the coating film of the resin 6 formed in the resin transfer container 5a or adjusting the descending height of the electronic component 1 with respect to the coating film. In short,
It is sufficient that the resin 6 does not adhere to the entire surface on which the bumps are formed, and preferably the resin 6 is adhered only to the bumps 2.

FIGS. 1B and 1C show a component mounting process for mounting the electronic component 1 on the substrate 3 after the resin supplying process. Here, the bumps 2 are aligned with the electrodes 4 formed on the upper surface of the substrate 3, the electronic component 1 is lowered with respect to the substrate 3, and the bumps 2 land on the electrodes 4 via the resin 6. As a result, the resin 6 transferred onto the lower surface of the bump 2 adheres to the electrode 4 and further spreads over the upper surface of the substrate 3 so as to cover the electrode 4. At this time, the supply amount of the resin 6 is controlled as described above. Therefore, the resin 6 is applied to the upper surface of the substrate 3 and the electronic component 1.
It is not possible to fill the space between the bottom surface of and.

Next, the substrate 3 is sent to a reflow device, where a heating process for heating the substrate 3 after the component mounting process is performed as shown in FIG. 1 (d). By this heating, the bump 2 is melted and soldered to the electrode 4. In this solder joining, the oxide film formed on the surface of the bump 2 is removed by the resin 6 having an oxide film removing ability, so that good solder joining with good joining property is performed. At this time, the thermosetting reaction of the resin 6 proceeds in parallel, and the solder joint between the bump 2 and the electrode 4 is wrapped from the surroundings to reinforce. In this reflow, the resin 6 does not have to be completely cured, but may be in a semi-cured state.

In the heating step, the organic components and water contained in the substrate 3 are gasified and released from the surface by heating, but as described above, the upper surface of the substrate 3 and the lower surface of the electronic component 1 are separated. The gap between them is not filled with the resin 6, and a degassing gap for discharging these gases to the outside is secured between the bumps. Therefore, even if a void occurs due to these gases being trapped inside the resin 6 in the form of bubbles, it grows to a certain size and communicates with the degassing gap to disappear.

Therefore, in the conventional electronic component mounting in which the resin is filled between the electronic component and the substrate and soldered, the defect caused by such a void, that is, the electronic component is lifted by the void. As a result, the solder joint failure due to the bump rising from the electrode does not occur.

Next, the substrate 3 after this heating step is sent to the resin sealing step. It should be noted that this resin encapsulation is performed in order to secure a higher reinforcing effect, and is not necessarily required depending on the required reinforcing level. Figure 2 (a)
As shown in, the dispenser 7 injects the reinforcing resin 8 into the gap between the lower surface of the electronic component 1 and the upper surface of the substrate 3. Then, as shown in FIG. 2B, after the space between the substrate 3 and the electronic component 1 is completely filled with the reinforcing resin 8, the substrate 3 is heated again as shown in FIG. 2C.
The heating causes the reinforcing resin 8 to be thermally cured, so that the electronic component 1 and the substrate 3 are resin-sealed. This heating also completely cures the resin 6 and firmly reinforces the periphery of the solder joint between the bump 2 and the electrode 4.

In the electronic component mounting structure realized by the above method, the solder bondability between the bump 2 and the electrode 4 is secured by the ability of the active component in the resin 6 to remove the oxide film. In addition, the resin 6 is thermally cured after solder bonding to reinforce the solder bonding portion, and the reinforcing resin 8 that seals between the substrate 3 and the electronic component 1 makes it possible to connect the substrate 3 and the electronic component 1 after mounting. The thermal stress generated between them can be relaxed, and a highly reliable mounting structure can be realized.

Further, since the resin 6 contains an active component, it is not necessary to apply the flux which is required for soldering in the conventional electronic component mounting. Most of the active component in the resin 6 is consumed as a curing agent in the heat effect process, and the residual component of the active component is also trapped in the cured resin. There is no occurrence. Therefore, the cleaning process required in the conventional method using the flux is unnecessary. Further, when the above-mentioned resin sealing step is omitted, the solder joining and the formation of the reinforcing resin portion are completed in the same step, and the simplification and cost reduction of the step are realized.

The heating temperature for hardening the reinforcing resin 8 is preferably lower than the heating temperature at the time of solder joining in order to suppress generation of new gas from the substrate 3. When degassing from the substrate 3 is sufficiently performed by the heating at the time of joining, it may be cured by heating at a heating temperature at the time of solder joining or higher.

(Embodiment 2) FIG. 3 is a process explanatory view of an electronic component mounting method according to Embodiment 2 of the present invention. In the second embodiment, when mounting the electronic component 1 similar to that of the first embodiment on the substrate 3, the resin 6 is previously supplied onto the electrodes 4 of the substrate 3.

In FIG. 3A, the resin 6 similar to that shown in the first embodiment is supplied onto the electrode 4 of the substrate 3. The resin supply amount in this resin supply step is also adjusted in the same manner as in the first embodiment, and in a state where the electronic component 1 is mounted on the substrate in the subsequent step, the upper surface of the substrate and the lower surface of the electronic component 1 are excessively sealed. Then, it is set so as not to hinder the discharge of the gas released from the substrate 3 to the outside during the reflow and to be equal to or more than the lower limit amount for ensuring the reinforcing effect after the resin 6 is thermally cured.

3 (b) and 3 (c) show a component mounting process for mounting the electronic component 1 on the substrate 3 after the resin supplying process.
Lands on the electrode 4 via the resin 6. As a result, the resin 6 transferred onto the lower surface of the bump 2 adheres to the electrode 4 and further spreads over the upper surface of the substrate 3 so as to cover the electrode 4. At this time, the supply amount of the resin 6 is controlled as described above. Therefore, the resin 6 does not fill the space between the upper surface of the substrate 3 and the lower surface of the electronic component 1. That is, a deaeration gap is secured between the bumps.

Next, the substrate 3 is sent to a reflow device, where a heating process for heating the substrate 3 after the component mounting process is performed as shown in FIG. 3 (d). By this heating, the bumps 2 are melted and solder-bonded to the electrodes 4 as in the first embodiment. In this heating step as well, the degassing gap for discharging the gas released from the substrate 3 to the outside is ensured as in the first embodiment, so that the defect caused by such a void does not occur. After this, the substrate 3 after the heating step is sent to the resin sealing step shown in FIG. 2 as in the first embodiment.
Similarly, resin sealing with the reinforcing resin 8 is performed.

The heating temperature for hardening the reinforcing resin 8 is preferably lower than the heating temperature at the time of solder joining in order to suppress the generation of new gas from the substrate 3. When degassing from the substrate 3 is sufficiently performed by the heating at the time of joining, it may be cured by heating at a heating temperature at the time of solder joining or higher. The mounting structure thus realized has the same characteristics as those of the first embodiment.

(Embodiment 3) FIG. 4 is a process explanatory diagram of an electronic component mounting method according to Embodiment 3 of the present invention. In the third embodiment, when mounting the electronic component 1 on the substrate 3 similarly to the first and second embodiments, instead of resin-sealing the electronic component 1 and the substrate 3, the electronic component 1 is made of a reinforcing resin. The reinforcing effect is obtained by locally fixing the substrate 3 and the substrate 3.

In FIG. 4A, a thermosetting reinforcing resin 9 (first resin) is previously supplied to the electrode 4 located at the outermost edge among the electrodes 4 of the substrate 3 (first resin). Resin supply process). The electrode 4 at the outermost edge serves as an electronic component fixing point set on the upper surface of the substrate 3 for fixing the electronic component 1 to the substrate 3. Further, the thermosetting resin 6 (second resin) having an oxide film removing ability is supplied to the bumps 2 of the electronic component 1 similarly to the resin supply shown in FIG. 1A of the first embodiment. (Second resin supply step).

Supply amount of the reinforcing resin 9 in the first resin supplying step and resin 6 in the second resin supplying step
Similarly to the first and second embodiments, the supply amount of the component is excessively sealed between the upper surface of the substrate 3 and the lower surface of the electronic component 1 with the electronic component 1 mounted on the substrate 3 in a later step. It is adjusted so as not to hinder the discharge of the gas released from the substrate 3 during reflow to the outside and to be the lower limit amount or more for ensuring the reinforcing effect after the resin 6 is thermally cured.

FIGS. 4B and 4C show a component mounting process for mounting the electronic component 1 after the second resin supplying process on the substrate 3 after the first resin supplying process. When the component 1 is lowered, the bumps 2 pass through the resin 6 and the electrodes 4
Land on. At this time, the bump 2 having the lower surface coated with the resin 6 lands on the electrode 4 while being embedded in the reinforcing resin 9 in the electrode 4 at the outermost edge. In this mounted state,
Since the supply amounts of the resin 6 and the reinforcing resin 9 are controlled as described above, the resin 6 and the reinforcing resin 9 do not fill the space between the upper surface of the substrate 3 and the lower surface of the electronic component 1.

Next, the substrate 3 is sent to a reflow device, where a heating process for heating the substrate 3 after the component mounting process is performed as shown in FIG. 4 (d). By this heating, the bumps 2 are melted and solder-bonded to the electrodes 4 as in the first and second embodiments. Resin 6 and reinforcing resin 9 together with this solder joint
Together with each other, a thermosetting resin 6 forms a resin reinforcing portion that reinforces the solder joint portion between the bump 2 and the electrode 4 from the surroundings, and the thermosetting reinforcing resin 9 forms the electronic component 1
The main body of is directly fixed to the substrate 3. In this heating step as well, similar to the first and second embodiments, the degassing gap for discharging the gas released from the substrate 3 to the outside is secured, so that the defect caused by such a void does not occur.

In the third embodiment, instead of supplying the resin 6 to the lower surface of the bump 2, a flux having an activating effect may be applied. As a result, the oxide film of the bump 2 is removed by the flux in the solder joint between the bump 2 and the electrode 4, and good solder joint property is secured. In this example, there is no effect of reinforcing the solder joint between the bump 2 and the electrode 4 from the surroundings, but since the electronic component 1 is directly fixed to the substrate 3 by the reinforcing resin 9, it has sufficient reinforcing strength. It has a mounting structure.

In the first, second and third embodiments described above, an example has been shown in which the electronic component 1 provided with the bump 2 made of solder as a connecting electrode is used as the connecting electrode. The present invention is not limited to the type of electrode, and the electronic component 1 and the substrate 3 may be mounted by solder bonding with a gap maintained, even if a connecting electrode having another shape is used. The invention can be applied.

[0037]

According to the present invention, a degassing gap is secured between the board and the electronic parts after the parts mounting step in the resin supplying step of supplying the reinforcing thermosetting resin onto the board in advance. Since the thermosetting resin is supplied as described above, the gas generated from the substrate in the heating process can be discharged to the outside through the degassing gap, and the mounting failure caused by the gas generated from the substrate can be prevented. You can

[Brief description of drawings]

FIG. 1 is a process explanatory diagram of an electronic component mounting method according to a first embodiment of the present invention.

FIG. 2 is a process explanatory view of the electronic component mounting method according to the first embodiment of the present invention.

FIG. 3 is a process explanatory diagram of an electronic component mounting method according to a second embodiment of the present invention.

FIG. 4 is a process explanatory diagram of an electronic component mounting method according to a third embodiment of the present invention.

[Explanation of symbols]

1 electronic components 2 bumps 3 substrates 4 electrodes 6 resin 8, 9 Reinforcing resin

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Maeda             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Shoji Sakami             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5E319 AA07 AB05 AC01 BB02 BB20                       CC33 CC70 CD21 CD25 GG20                 5F044 LL01 LL11 RR18 RR19

Claims (7)

[Claims] 1. An electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode on the substrate, wherein an oxide film is removed on the connecting electrode of the electronic component. A resin supplying step of supplying a thermosetting resin having a capability, and a component mounting step of mounting the electronic component after the resin supplying step on a substrate and landing the connection electrode on the electrode of the substrate through the thermosetting resin. And a heating step of soldering the connection electrode to the electrode by heating the board after the component mounting step and thermosetting the thermosetting resin, and the board after the component mounting step in the resin supply step. By supplying a thermosetting resin so as to secure a deaeration gap with the electronic component, the gas generated from the substrate in the heating step is discharged to the outside through the deaeration gap. Electronic component mounting method to. 2. The electronic component mounting method according to claim 1, wherein a reinforcing resin is injected into a gap between the electronic component and the substrate after the heating step. 3. An electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode on the substrate, wherein the electrode on the substrate has an oxide film removing ability. A resin supplying step of supplying a thermosetting resin, a component mounting step of mounting an electronic component on the substrate after the resin supplying step and landing the connecting electrode on the electrode of the substrate via the thermosetting resin, A heating step of heating the substrate after the mounting step to solder-bond the connection electrode to the electrode and heat-curing the thermosetting resin, and the substrate and the electronic component after the component mounting step in the resin supply step. By supplying a thermosetting resin so that a deaeration gap is secured between the gas and the gas, the gas generated from the substrate in the heating step is discharged to the outside from the deaeration gap. Child component mounting method. 4. The electronic component mounting method according to claim 3, wherein a reinforcing resin is injected into a gap between the electronic component and the substrate after the heating step. 5. An electronic component mounting method for mounting an electronic component on a substrate by soldering a connecting electrode provided on the electronic component to an electrode on the substrate, wherein the electronic component is fixed on the upper surface of the substrate. A first resin supplying step of supplying a thermosetting first resin to the spot, and a second resin supplying step of supplying a second resin having an oxide film removing ability to the connecting electrode of the electronic component, A component mounting step of mounting the electronic component after the second resin supply step on the substrate after the first resin supply step and landing the connection electrode on the electrode of the substrate through the second resin; The connection electrode is soldered to the electrode by heating the substrate after the mounting step, and
And a heating step of thermally curing the resin, so that a deaeration gap is secured between the board and the electronic component after the component mounting step in the first resin supplying step and the second resin supplying step. An electronic component mounting method, wherein the gas generated from the substrate in the heating step is discharged to the outside from the degassing gap by supplying the first resin and the second resin. 6. The second resin is a thermosetting resin, and when the second resin is thermoset, the resin reinforcing portion reinforces a solder joint portion between a connecting electrode of an electronic component and an electrode of a substrate. 6. The electronic component mounting method according to claim 5, wherein: 7. The electronic component mounting method according to claim 5, wherein the second resin is a flux for solder joining.