JPH08191179A - Forming method of solder dam for solder bump and forming method of solder bump - Google Patents

Abstract

PURPOSE: To provide a forming method of a solder dam for solder bump which prevents solder on a board electrode flowing out at the time of reflowing, in the case of face down reflow mount using solder bumps. CONSTITUTION: An example of forming a solder dam is as follows. When a solder bump is formed on an electrode 2 on a board 1 by using a solder grain 3, thermosetting solder resist 5 is spread on the electrode 2, and a transfer plate 6 wherein a protrusion is formed so as to correspond to the part where the solder bump is to be formed is pressed against the board 1. In this state, the solder resist 5 is heated and hardened by using a heater 7 or the like. By removing the transfer plate 6 after hardening, a recessed part 8 turning to a solder dam for a solder bump is formed in the solder resist of a solder grain mount part. A solder grain 3 is arranged in the recessed part 8, heated, and fixed. Thereby a solder dam for preventing solder flowing-out can be formed by a small number of processes, and the formation of a solder bump is also facilitated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique relating to a structure in which electrodes need to be electrically connected to each other, such as mounting of general electronic parts, and in particular, LS using solder bumps.
The present invention relates to a solder dam solder dam forming method and a solder bump forming method relating to a mounting structure of an electronic component such as I (Large Scale Integration) and a manufacturing method thereof.

[0002]

2. Description of the Related Art In face-down reflow mounting using solder bumps, there is an example of forming solder bumps on the chip side of an LSI or the like (for example, Tsuyoshi Hayashi, “An Innov.
ativeBonding Technique for Optical Chips Using So
lder Bumps That EliminateChip Positioning Adjustme
nts ”, IEEE TRANSACTIONS ON COMPONENTS, HYBRIDS, AND
MANUFACTURING TECHNOLOGY, VOL.15, NO.2, APRIL 199
2) A predetermined amount of solder is provided on the electrodes of the LSI by using a wet process such as a plating method. However, with this method, a special process must be added at the LSI manufacturing stage.

Usually, the electrodes of the LSI are aluminum (A
Since it is formed by l), the solder particles cannot be melted and bonded on the electrodes. Therefore, a structure has been considered in which conductive particles are mounted on the LSI side and solder bumps provided on the substrate side are reflowed to aim for a self-alignment effect. However, if the solder is melted on the board-side electrode, the solder may flow along the electrode and the self-alignment effect may not be obtained. For example, as shown in FIG. 7, when forming a solder bump on the electrode 2 of the substrate 1,
Solder particles 3 are placed on the electrodes 2 on the substrate 1 and the heater 7
When it is heated and melted by such as the solder 3, the solder 3 flows along the electrode 2, and the amount of solder in the connecting portion is reduced. Therefore, the self-alignment effect may not be obtained.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in face-down reflow mounting using solder bumps, the solder on the substrate electrode does not flow even if reflowed. The present invention provides a method for forming a solder bump solder dam. Further, the present invention provides a method for forming solder bumps, in which the solder dam and the solder bump are simultaneously formed to further simplify the solder bump forming process.

[0005]

In order to achieve the above object, in a method for forming a solder dam for a solder bump according to claim 1, when a solder bump is provided on a substrate electrode by using solder particles, the electrode is provided. Solder particle mount by applying a thermosetting solder resist on top, heat-curing the transfer plate with protrusions corresponding to the places where solder bumps are provided while pressing it against the substrate, and removing the transfer plate after curing. It is characterized in that a recess serving as a solder dam for a solder bump is formed in a portion of the solder resist.

According to a second aspect of the present invention, there is provided a solder bump solder dam forming method, wherein when a solder bump is provided on a substrate electrode by using solder particles, a photocurable solder resist is applied onto the electrode to form a solder bump. The transparent transfer plate provided with convex portions corresponding to the places where is provided is irradiated with light from above the transfer plate while pressing the substrate, and the transfer plate is removed after curing, so that the solder resist on the solder particle mount part is soldered. It is characterized by forming a concave portion which becomes a solder dam for bumps.

According to a third aspect of the present invention, there is provided a solder dam forming method for solder bumps, wherein when a solder bump is provided on a substrate electrode by using solder particles, a solder resist is applied onto the electrode and after curing, the solder bump is applied. Corresponding to the place where the point is provided, by pressing one or a plurality of needle-shaped projecting hole jigs having a desired curvature at the tip, a concave portion to be a solder dam for a solder bump is formed at a predetermined position. It is characterized by that.

According to a fourth aspect of the present invention, there is provided a solder bump solder dam forming method according to the third aspect, wherein an ultrasonic wave is applied simultaneously with pressing the needle-shaped projecting hole jig.

According to a fifth aspect of the present invention, there is provided a method of forming a solder bump, wherein when a solder bump is provided on a substrate electrode by using solder particles, a predetermined amount of solder is arranged at a desired position on the electrode to form a solder bump. Heating from below the substrate at a temperature near the melting point, lowering the temperature at the stage where only the vicinity of the interface with the electrode has melted to fix the solder, then apply photo-curable solder resist and irradiate light from the top surface to remove the solder resist. It is characterized by forming a solder dam and a solder bump by curing.

According to a sixth aspect of the present invention, in the method for forming solder bumps, when the solder bumps are provided on the electrodes of the substrate by using the solder particles, a photo-curable solder resist is applied onto the electrodes, and the solder particles are applied from above. Embedded in, heat from below the substrate at a temperature near the melting point of the solder, lower the temperature when only the solder near the interface with the electrode has melted and fix the solder, then irradiate light from the top surface to cure the solder resist This is characterized by forming solder dams and solder bumps.

[0011]

In FIG. 6, a hole serving as a solder dam for a solder bump is opened in the solder resist 4, and the solder particle 3 is mounted in the opening and heated by a heater 7 or the like to be melted to form a solder bump 3 '. It is a diagram showing an example, and by forming the solder dam by the resist 4 in this way, it is possible to prevent the solder 3'on the electrode 2 of the substrate 1 from flowing out even if it is reflowed. A resist 4 as shown in FIG. 6 is formed on the electrode 2 of the substrate 1.
As a method of forming the solder dam by the method, a method of forming a film by coating a photoresist on the entire surface of the substrate and then forming a hole by a photolithography process using a photomask is considered. However, this method has a problem in that the number of steps for forming a photoresist film, mounting a photomask, exposing, developing, and drying and providing a solder dam is large.

The present invention seeks to simplify the process for providing solder dams on the electrodes of the substrate.
In the forming method, a thermosetting solder resist is used, and the transfer plate having the convex portions corresponding to the positions where the solder bumps are provided is heated and cured while being pressed against the substrate, and the transfer plate is removed after curing, so that it is easy. A solder dam is formed at the solder arrangement position. Further, in the forming method according to claim 2, a photo-curable solder resist is used, and a transparent transfer plate having protrusions corresponding to positions where solder bumps are provided is irradiated with light from above the transfer plate while being pressed against the substrate. By removing the transfer plate after curing, the solder dam is easily formed at the solder arrangement position.
Further, in the forming method of claims 3 and 4, a solder resist is applied on the electrodes, and after hardening, a needle-shaped projecting hole jig having a desired curvature at the tip is provided corresponding to the place where the solder bump is provided. By pressing one or a plurality of solder balls, solder dams are easily formed at the solder arrangement positions. Thus, claims 1 to
According to the forming method of No. 4, the solder dam can be formed in a smaller number of steps as compared with the photolithography process.

Further, in the method of forming solder bumps according to the present invention, after the solder particles are first fixed on the electrodes of the substrate, a photo-curable solder resist is applied, and the solder resist is cured by irradiating light from the upper surface. By doing so, a solder dam and a solder bump are formed. Further, in the method of forming a solder bump according to claim 6, a photo-curing solder resist is applied on the electrode, and solder particles are embedded from above to form a melting point of the solder. The solder dam and solder are heated by heating from below the substrate at a near temperature, lowering the temperature when the solder near the interface with the electrode has melted and fixing the solder, and then irradiating light from above to cure the solder resist. Since the bumps are formed, in the forming method according to claims 5 and 6, the solder dam and the solder bumps can be simultaneously formed without using a special device such as a transfer plate or a projecting hole jig. Kill.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is an explanatory view of a process of forming a solder dam and a solder bump showing an embodiment of claim 1. Figure 1
As shown in (a), a thermosetting solder resist 5 is applied on the electrode 2 of the substrate 1. Next, as shown in FIG. 3B, a transfer plate (mold) 6 having convex portions corresponding to positions where solder bumps are provided is pressed against the substrate 1 side, and is heated by a heater 7 or the like while being pressed, and solder resist is applied. Cure 5
After that, the transfer plate 6 is removed to form recesses 8 that will serve as solder dams for solder bumps in the solder resist 5 at the portions corresponding to the protrusions of the transfer plate 6, that is, at the portions where the solder particles are mounted. Next, as shown in FIG. 3C, the solder particles 3 are placed in the recesses 8 formed in the solder resist 5.
Are arranged, heated and fixed to form solder bumps. The solder bump thus formed does not flow out even if it is reflowed because it is in the concave portion 8 which becomes the solder dam.

(Embodiment 2) FIG. 2 is an explanatory view of a process of forming a solder dam and a solder bump showing an embodiment of claim 2. First, as shown in FIG. 2A, a photocurable solder resist 9 is applied on the electrode 2 of the substrate 1. Next, as shown in FIG. 2B, a transparent transfer plate (mold) 10 having convex portions corresponding to the positions where the solder bumps are provided is pressed against the substrate 1 side, and is pressed from above the transfer plate 10. Light is applied to cure the solder resist 9. After this, the transfer plate 10
By removing the above, a concave portion 11 to be a solder bump solder dam is formed in the solder resist 9 at a portion corresponding to the convex portion of the transfer plate 10, that is, a portion where the solder particles are mounted. Next, as shown in FIG. 3C, the solder particles 3 are placed in the recesses 11 formed in the solder resist 9.
If heated and fixed, solder bumps are formed. The solder bumps formed in this way are recesses 1 that will become solder dams.
Since it is within 1, it will not flow out even if it is reflowed.

(Embodiment 3) FIG. 3 is an explanatory view of a process of forming solder dams and solder bumps showing the third and fourth embodiments. First, as shown in FIG. 3A, the electrode 2 of the substrate 1
A solder resist 12 is applied on the top and cured. Next, as shown in FIG. 3B, a hole is formed in the solder resist 12 by pressing a needle-shaped projecting hole jig 13 having a desired curvature at the tip, corresponding to the place where the solder bump is provided. ,
A recess 14 is formed to serve as a solder bump solder dam. Next, as shown in FIG. 3C, the solder particles 3 are placed in the recesses 14 formed in the solder resist 12, and heated and fixed to form solder bumps. The tip of the needle-shaped projecting jig 13 is, for example, hemispherical with a curvature slightly larger than the diameter of the solder particles 3 to be used. Further, when the projecting hole jig 13 is pressed, if not only the pressing but also ultrasonic vibration is applied (Claim 4), the hole can be easily and stably formed. Further, a plurality of needle-shaped projecting hole jigs 13 can be simultaneously used to form holes at a plurality of positions at the same time.

(Embodiment 4) FIG. 4 is an explanatory view of a process of forming a solder dam and a solder bump showing a fifth embodiment of the present invention. First, as shown in FIG. 4A, the solder particles 3 are arranged at predetermined positions on the electrodes 2 of the substrate 1. As a placement method,
For example, it is performed by a mask having holes through which the solder particles 3 pass. Next, as shown in FIG. 3B, the substrate 1 is heated from below under the temperature around the melting point of the solder using the heater 7 or the like. Then, when the vicinity of the interface between the solder particle 3 and the electrode 2 begins to melt and then is cooled, the solder particle 3 is fixed on the electrode 2. Next, as shown in FIG. 1C, a photo-curable solder resist 15 is applied onto the electrode 2 of the substrate 1 so as to have a thickness smaller than the solder particle diameter, and the solder resist 15 is cured by irradiating light from the upper surface to cure the solder. Dams and solder bumps are formed.

(Embodiment 5) FIG. 5 is an explanatory view of a process of forming a solder dam and a solder bump showing an embodiment of claim 5. First, as shown in FIG. 5A, the photo-curable solder resist 16 is applied onto the electrode 2 of the substrate 1 so as to have a thickness smaller than the solder particle diameter. Next, as shown in FIG. 3B, the solder particles 3 are arranged and embedded at predetermined positions from above the solder resist 16. Next, as shown in FIG. 2C, the heater is heated from below the substrate 1 at a temperature near the melting point of the solder. Then, when the vicinity of the interface between the solder particle 3 and the electrode 2 begins to melt and then is cooled, the solder particle 3 is fixed on the electrode 2. Next, as shown in FIG. 5D, the solder resist 16 is cured by irradiating light from above to form the solder dam and the solder bump.

[0019]

As described above, in the method for forming the solder dam for solder bumps according to the first aspect, the thermosetting solder resist is used, and the transfer plate having the convex portions corresponding to the places where the solder bumps are provided is provided. A solder dam for preventing solder outflow can be easily provided at a solder arrangement position by heating and curing while pressing the substrate and removing the transfer plate after curing. Further, since the arrangement position of the solder bump is determined by the transfer plate (mold), the relative position between the electrodes is secured, so that the efficiency of the self-alignment effect does not decrease (the directions of force are aligned).

In the method for forming a solder dam for solder bumps according to a second aspect of the present invention, a photocurable solder resist is used, and a transparent transfer plate having protrusions corresponding to positions where solder bumps are provided is transferred to the substrate while being pressed. By irradiating light from above the plate and removing the transfer plate after curing, a solder dam for preventing solder outflow can be easily provided at the solder arrangement position. Also,
Since the placement position of the solder bump is determined by the transfer plate (mold), the relative position between the electrodes is secured, so the efficiency of the self-alignment effect does not decrease (the directions of the forces are aligned).

In the method for forming a solder dam for solder bumps according to a third aspect, a solder resist is applied on the electrodes, and after curing,
A solder dam for preventing solder outflow can be easily provided at the solder placement position by pressing one or a plurality of needle-shaped projecting hole jigs having a desired curvature at the tip corresponding to the places where the solder bumps are provided. Can be provided. In addition, the transfer plate (mold) as described above is unnecessary, and the solder resist is also thermosetting type,
Any of photo-curing type may be used.

In the method for forming a solder dam for solder bumps according to claim 4, in the method for forming solder bumps according to claim 3, by applying ultrasonic waves at the same time as pressing the needle-shaped projection hole jig, there is a concern that the resist may be pressed only. Can be completely removed, and the electrode surface can be surely exposed.

In the method of forming solder bumps according to a fifth aspect of the present invention, after the solder particles are first fixed on the electrodes of the substrate, a photocurable solder resist is applied, and the solder resist is cured by irradiating light from above. Thus, the solder dam and the solder bump are formed, and the solder dam and the solder bump can be simultaneously formed without using a special device such as a transfer plate or a projecting hole jig.

In the method of forming solder bumps according to the sixth aspect, a photo-curable solder resist is applied on the electrodes, solder particles are embedded on the electrodes, and the solder is heated from below the substrate at a temperature near the melting point of the solder to form electrodes. At the stage where only the solder near the interface is melted, the temperature is lowered to fix the solder, and then the solder resist and the solder bump are formed by irradiating light from the upper surface to cure the solder resist. The solder dam and the solder bump can be simultaneously formed without using a special device such as a hole jig.

As described above, according to the inventions of claims 1 to 6,
In either case, the process for providing the solder dam and the solder bump on the substrate electrode can be simplified, and the solder bump having the solder dam can be easily formed. Therefore,
In face-down reflow mounting using the solder bumps formed in this way, a solder dam that can prevent solder outflow secures the amount and position of solder during reflow, so a self-alignment effect can be obtained and high accuracy can be obtained. Can be chip mounted.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a process of forming a solder dam and a solder bump showing an embodiment of claim 1;

FIG. 2 is an explanatory diagram of a process of forming a solder dam and a solder bump showing an embodiment of claim 2;

FIG. 3 is an explanatory diagram of a process of forming solder dams and solder bumps showing the third and fourth embodiments.

FIG. 4 is an explanatory diagram of a process of forming a solder dam and a solder bump showing an embodiment of claim 5;

FIG. 5 is an explanatory diagram of a process of forming a solder dam and a solder bump showing an embodiment of claim 6;

FIG. 6 is a diagram showing an example of a solder dam and a solder bump formed in the dam.

FIG. 7 is an explanatory diagram of a problem at the time of reflow using a conventional solder bump.

[Explanation of symbols]

 1: Substrate 2: Electrode 3: Solder particle 4: Solder resist 5: Thermosetting solder resist 6: Transfer plate (mold) 7: Heater 8, 11, 14: Recessed part which becomes solder dam 9, 15, 16: Photocuring Mold solder resist 10: Transparent transfer plate (mold) 12: Solder resist 13: Needle-shaped projecting jig

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Kuwazaki 1-3-3 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd.

Claims (6)

[Claims] 1. When a solder bump is formed on a substrate electrode by using solder particles, a thermosetting solder resist is applied on the electrode, and a protrusion is provided corresponding to a place where the solder bump is provided. Solder for solder bumps, characterized in that the plate is heated and cured while being pressed against the substrate, and after the curing, the transfer plate is removed to form recesses to be solder dams for solder bumps in the solder resist at the solder particle mount portion. How to form a dam. 2. When a solder bump is provided on a substrate electrode by using solder particles, a photo-curable solder resist is applied on the electrode and a convex portion is provided corresponding to a place where the solder bump is provided. It is possible to form recesses that will become solder dams for solder bumps in the solder resist on the solder particle mount part by irradiating light from above the transfer plate while pressing the transfer plate against the substrate and removing the transfer plate after curing. A method for forming a solder dam for a solder bump. 3. When a solder bump is formed on a substrate electrode by using solder particles, a solder resist is applied on the electrode, and after curing, a desired curvature is provided at a tip end corresponding to a place where the solder bump is provided. A method for forming a solder dam for solder bumps, characterized in that a concave portion to be a solder dam for a solder bump is formed at a predetermined location by pressing one or a plurality of needle-shaped projecting hole jigs . 4. The method for forming a solder dam for solder bumps according to claim 3, wherein ultrasonic waves are applied simultaneously with pressing the needle-shaped jig. 5. When a solder bump is formed on a substrate electrode by using solder particles, a predetermined amount of solder is placed at a desired position on the electrode and heated from below the substrate at a temperature near the melting point of the solder. , The temperature is lowered at the stage where only the interface with the electrode is melted to fix the solder, and then the photocurable solder resist is applied, and the solder dam and the solder bump are cured by irradiating light from the top surface to cure the solder resist. A method for forming a solder bump, which comprises forming the solder bump. 6. When a solder bump is provided on a substrate electrode by using solder particles, a photo-curable solder resist is applied on the electrode, and the solder particles are embedded on the electrode, and the substrate is heated at a temperature near the melting point of the solder. After heating, the temperature is lowered to fix the solder when only the solder near the interface with the electrode has melted, and then the solder dam and solder bump are formed by irradiating light from the upper surface to cure the solder resist. A method for forming a solder bump, which is characterized by the above.