JPH07193100A - Method and apparatus for bonding - Google Patents

Abstract

PURPOSE:To provide a bonding method and a bonder with which better joint properties can be obtained. CONSTITUTION:When respective inner leads 3 formed on a carrier tape 1 are jointed with respective electrode pads 5 provided on a semiconductor chip with solder bumps 6, after a part of the inner lead 3 and a part of the solder bump 6 which are brought into contact with each other are covered with oxidation- proof gas (oxidation-proof atmosphere), the joint part is irradiated with laser beam L and the inner lead 3 is jointed with the electrode pad 5 with the solder bumps 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonding method and apparatus for bonding an inner lead provided on a carrier tape and an electrode pad provided on a semiconductor element.

[0002]

2. Description of the Related Art A method of mounting a semiconductor component (semiconductor element) on a carrier tape or a printed circuit board includes a gang bonding method for collectively joining all the leads of the semiconductor component and the above-mentioned lead. It is roughly classified into a single point bonding method in which each of them is individually bonded.

Of these, the single-point bonding method has attracted special attention in recent years because it has a feature that each lead can be reliably bonded to each other by mounting a large ASIC or the like. In addition, by applying the ultrasonic vibration to the tool used in the single-point bonding method, due to the demand for lowering the working temperature accompanying the improvement in quality of semiconductor parts,
There is also a method of jointly using ultrasonic energy as energy required for bonding.

However, in the case of such a single point bonding method, it is necessary to manufacture a dedicated bonding tool depending on the type, and the pressing operation of this bonding tool causes the semiconductor component to be connected to the semiconductor component through the electrode pad. Sometimes it takes damage.

Under these circumstances, various bonding methods using a laser beam have recently been studied. Even in the case of the bonding method using this laser beam, it is possible to irradiate each connection point with the laser beam and perform individual bonding at each connection point as in the single point bonding method. it can.

Hereinafter, this bonding method will be referred to as laser single point bonding.

[0007]

By the way, in the prior art,
In most of the single point bonding, solder is used as a bonding material, and the solder previously supplied to the lead or the electrode pad is heated and melted by the laser energy of the laser light and then cooled. -The electrode and the electrode pad were joined together.

However, in this case, since it is necessary to heat the lead and the electrode pad until the temperature at which the solder melts is reached, the solder supplied in the process of melting and solidifying the solder is very short in time. However, there is a problem that the surface of is oxidized and good solderability (wettability) cannot be obtained.

Further, it is effective to use a flux in order to improve the solderability and the solder wettability, but there is a circumstance that the flux should not be used as much as possible due to problems such as cleaning or corrosion after soldering. .

The present invention has been made in view of the above circumstances, and an object thereof is to provide a bonding method and apparatus capable of obtaining better bondability in laser single point bonding. is there.

[0011]

A first means of the present invention is a bonding method in which each lead is bonded to a corresponding electrode pad via a bonding material, and at least the lead and the electrode pad are bonded. Is covered with an oxidation preventive atmosphere or a reducing atmosphere, and a laser beam is irradiated to the joint portion to join the lead and the electrode pad through the joint material. This is the bonding method.

A second means is a bonding apparatus for connecting each inner lead formed on the carrier tape and each electrode pad formed on the semiconductor element through a solder material, and the carrier tape is used for the carrier tape. Tape running means for running and stopping the portion of the carrier tape provided with the inner lead at a predetermined bonding position, and a transparent hard member, and at the bonding position. A pressing plate that comes into contact with one surface of the inner lead,
The semiconductor element is arranged on the other side of the inner lead to hold the semiconductor element at the bonding position, and the electrode pad provided on the semiconductor element is attached to the other side of the inner lead via a solder material. And a bonding stage to be brought into contact with, and provided on the bonding stage side,
A partition wall that shields the semiconductor element and the portion where the inner lead is located from the outside air, and an antioxidant gas or a reducing gas that prevents oxidation of the solder material is introduced into the partition wall, and each inner layer is introduced. An antioxidant gas supply means for covering the joint between the lead and each electrode pad with an antioxidant atmosphere or a reducing atmosphere, and the inner lead from one side of the inner lead to the inner lead through the pressing plate. -Zabi-
And a laser beam irradiating means for joining the inner lead to the electrode pad by irradiating the solder material to melt the solder material.

A third means is characterized in that, in the second means, the pressing plate is provided with an exhaust hole for sequentially exhausting the gas filled inside the partition wall by the gas supply means. To do.

The fourth means is a bonding apparatus for connecting each outer lead formed on a semiconductor electronic component and an electrode pad formed on a substrate through a solder material, and is formed of a transparent hard member. , A pressing plate that contacts the surface of the outer lead opposite to the surface facing the substrate, and an antioxidant gas or a reducing gas for preventing the oxidation of the solder material is introduced between the pressing plate and the substrate. Then, the inner beam is irradiated with a laser beam through an antioxidant gas supply means for covering the joint portion between each outer lead and each pad with an antioxidant atmosphere or a reducing atmosphere and the pressing plate. , A laser beam for joining the inner lead and the electrode pad by melting the solder material.
A bonding apparatus comprising: a radiation unit.

[0015]

According to this structure, the surface of the bonding material can be effectively prevented from being oxidized by bonding the lead and each electrode pad in an oxidation preventing atmosphere or a reducing atmosphere. It is possible to secure good solderability and solder wettability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the first embodiment will be described.

FIG. 1 shows an inner lead bonding apparatus. In this inner lead bonding apparatus, the inner lead 3 ... Protruding into the device hole 2 of the carrier tape 1 shown in FIG. 2 and the electrode pad 5 of the semiconductor element 4 are joint materials. By connecting (inner lead bonding) via the solder bumps 6, it has a function of mounting the semiconductor element 4 on the carrier tape 1.

This inner lead bonding apparatus is
As shown in FIG. 1, a carrier tape 1 is stretched between a pair of sprockets 8 serving as tape traveling means, and intermittently driven in a direction indicated by an arrow (a) in the figure. A stretched carrier tape is provided between the pair of sprockets 8, 8.
A guide plate 9 (pressing plate) that guides the push-up unit 1 while urging the push-up unit downward is provided. The guide plate 9 is formed of a transparent hard member such as quartz.

The carrier tape 1 is driven intermittently to sequentially stop the portion provided with the device hole 2 at the central portion of the guide plate 9. The central portion of the guide plate 9 is formed on the carrier tape 1 by the semiconductor element 4
Is at the bonding position A for bonding.

Below the bonding position A, a bonding stage 10 for holding the semiconductor element 4 is provided. This bonding stage 10 includes an XYZ stage 12 provided on a base shown by 11 in the figure,
The holding body 13 is attached to the XYZ stage 12 and holds the semiconductor element 4.

As shown in FIG. 2, the upper end of the holding body 13 has a mounting surface 13a on the center of which the semiconductor element 4 is mounted.
And a partition wall 13 that surrounds the mounting surface 13a at the periphery thereof.
b is projected. Further, inside the holder 13, a heater 14 is provided for heating and keeping the temperature of the semiconductor element 4 placed on the placing surface 13a.

Further, the placing surface 13a and the partition wall 13b described above.
A gas supply hole 15 for introducing a reducing gas such as an antioxidizing gas such as nitrogen or a gas mixed with hydrogen inside the partition wall 13b, that is, around the placing surface 13a.
(Gas supply means) is open.

The supply hole 15 is connected to a gas supply source shown by 18 in the drawing through a connection pipe 17 attached to the lower surface of the holding body 13.

On the other hand, above the bonding position A, as shown in FIG. 2B, a laser beam L is irradiated onto the carrier tape 1 through the guide plate 9.
The emitting portion 19 is provided. This laser emitting section 19
Inside, the beam diameter of the laser beam L is set to the above carrier tape.
An optical system (not shown) capable of narrowing down to a size substantially the same as the width of the inner lead 3 (one portion) protrudingly provided in the device hole 2 of the plug 1 is incorporated.

The laser emitting section 19 is held by a holder 20 connected to an XY driving section (not shown). When the holder 20 is driven in the XY directions, the inner reels described above are held. The laser beam L is irradiated so that the laser beam L is sequentially positioned so as to be opposed to the tip of the window 3.

As shown in FIG. 1, the laser emitting section 19 has a laser 22 shown in FIG.
The laser oscillation source 22 is connected to the laser oscillation source, and the laser oscillation source 22 operates to cause a laser beam to appear at the tip of each inner lead 3.
It is possible to irradiate the light L.

Next, the operation of this inner lead bonding apparatus will be described.

First, the semiconductor element 4 is supplied onto the mounting surface 13a provided on the holding body 13 of the bonding stage 10. On each electrode pad 5 provided on the upper surface of the semiconductor element 4, a solder bump 6 as a protruding electrode is preliminarily supplied (formed) in a raised shape.

The bonding stage 10 has the X
By operating the YZ stage 10, the semiconductor element 4 is positioned opposite to the central portion (bonding position A) of the guide plate 9.

On the other hand, the carrier tape 1 is intermittently driven and driven in the direction shown by the arrow (a) in the figure, and the device wheel 2 provided with the inner lead 3 protruding therefrom is provided with the guide plate. It is stopped at the bonding position A, which is the central portion of 9.

Then, the inner lead 3 and the semiconductor element 4 are recognized through the guide plate 9 by using an image pickup recognition means (not shown) provided above the bonding position A. Based on this, the XYZ stage 12 provided on the bonding stage 10 is operated to position the electrode pads 5 (solder bumps 6) of the semiconductor elements 4 and the inner leads 3 respectively. To match.

When the both are positioned, the holder 13 is driven upward, the solder bumps 6 formed on the semiconductor element 4 are pressed against the lower surface of the tip of the inner lead 3, and The upper end surface of the partition wall 13b is brought into contact with the lower surface of the carrier tape 1. This partition wall 13b
As a result, the inner lead 3 and the semiconductor element 4 projecting from the device hole 2 are shielded from the outside air.

Next, the gas supply source 18 is activated, and
As shown in FIG.
An antioxidant gas or a reducing gas is supplied to the inside of the.
As a result, the semiconductor element 4 and the inner lead 3 are
Are covered by an antioxidant atmosphere.

Next, the laser emitting portion 19 is positioned so as to face one of the inner leads 3 ... Protrudingly provided in the device hole 2 to irradiate the laser beam L. To do. This laser beam L is applied to the tip of the inner lead 3 through the transparent guide plate 9.
The solder bumps 6 are heated and melted via the inner leads 3.

During this period, the nitrogen gas is kept in the partition wall 13
The nitrogen gas is continuously supplied to the inside of a, and the nitrogen gas is sequentially discharged above the guide plate 9 from an exhaust hole 9a formed in the center of the guide plate 9.

When the solder bumps 6 are melted, the laser emitting portion 19 stops the irradiation of the laser beam L. As a result, the solder bumps 6 are cooled and solidified in an oxidation preventing atmosphere, and the inner leads 3 and the electrode pads 5 are joined.

The solder dust, water vapor, etc. generated at this time are sequentially discharged from the exhaust hole 9a together with the nitrogen gas.

In this way, a set of inner leads 3
When the electrode pad 5 is joined to the holder 20,
Are driven in the XY directions, and the other inner leads 3 adjacent to each other
And the electrode pads 5 are also sequentially soldered.

According to this structure, the following effects can be obtained.

First, the solder bump 6 which is a joining material for joining the inner lead 3 and the electrode pad 5 is melted in an antioxidation atmosphere and cooled and solidified. As a result, the surface of the solder bump 6 can be prevented from being oxidized, and there is an effect that good solder wettability and solderability can be obtained.

Therefore, since it is not necessary to use the flux, there is an effect that the cleaning step is not necessary and the contamination of the semiconductor element 4 can be effectively prevented.

Secondly, the pressing of the inner lead 3 and the electrode pad 5 can be performed collectively and uniformly by using the guide plate 9. Further, since this guide plate 9 is transparent, unlike the conventional guide plate 9, there is no need for an opening for exposing the inner leads 3 ... At the bonding position A and inserting the bonding tool.

Thirdly, since the guide plate 9 is made of a transparent member, the guide plate 9 is not required to have an opening at this position.
Through the above, the inner lead and the electrode pad of the semiconductor element can be recognized and the both can be aligned.

This has the effect of simplifying the structure of the apparatus.

Next, a second embodiment of the present invention will be described with reference to FIG.

In the second embodiment, a collective pressing jig is not used to press the inner lead 3 against the solder bump 6, but only a part of the inner lead 3 is pressed. This is a method using a pressure jig.

That is, the above bonding stage 10
As the holding body 13 'of the above, the one without the partition wall 13b is used, and the pressing jig 23 is such that the base end portion of the inner lead 3 is pressed downward by the lower end surface as shown in the figure. To use.

After the inner lead 3 and the electrode pad 5 provided on the semiconductor element 4 are pressed against each other via the solder bumps 6 in this manner, a gas supply nozzle 24 shown in the drawing is used. The above gas is supplied to this portion. As a result, the space around the inner lead and the electrode pad of the semiconductor element is divided by the pressure jig 23 into an antioxidant atmosphere space.

In this state, by irradiating the laser beam L from the laser emitting portion 19, the solder bump 6 which is the above-mentioned bonding material is melted and solidified in an oxidation preventing atmosphere, and the above-mentioned inner reel is formed. The electrode 3 and the electrode pad 5 are soldered.

By repeating such an operation for each inner lead 3, each inner lead 3 is individually bonded to each electrode pad 5.

According to this structure, as in the case of the above-mentioned first embodiment, good solderability and solder wettability can be obtained without using flux when performing laser single point bonding. There is an effect that can be.

The second embodiment can be applied to the case where the outer lead of the semiconductor package is connected to the electrode pad provided on the printed board, and is particularly effective in this case.

That is, in the case of the outer lead bonding, unlike the case of the inner lead bonding described above, it is difficult to press the outer leads collectively on the printed circuit board by the flat guide plate 9. Is.

Even if it can be pressed,
The printed circuit board usually has a warp of several tens of μm,
This is because it is difficult to uniformly press the outer lead.

The present invention is not limited to the first and second embodiments described above, and can be variously modified without changing the gist of the invention.

For example, in the first and second embodiments, the heater 14 is provided in the holding portion 13, but the heater 14 is provided.
Such a heating heater is not always necessary if a good connection can be made only with the energy of the beam.

Further, in the first and second embodiments, the solder bump 6 is formed on the electrode pad 5 of the semiconductor element 4, but the present invention is not limited to this, and the inner reel is not limited thereto. It may be formed on the lower surface of the tip portion of the cord 3.

Further, in the first and second embodiments, the long carrier tape 1 was run, but the carrier tape 1 cut into strips is held by the slide carrier (not shown). However, the carrier tape may be run by transporting the slide carrier.

Next, a third embodiment of the present invention will be described with reference to FIG.

The first and second embodiments are the inner reel.
Although it is a debonding apparatus, it can also be applied to an outer bonding apparatus as shown in the third embodiment.

In the figure, numeral 28 indicates the inner lead of the film carrier 9 on the electrode pad of the semiconductor element.
It is a TAB component such as TCP formed by facing the film carrier after debonding.

Reference numeral 3a in the drawing denotes an outer lead of the TAB part 28. When the TAB component 28 is mounted on a board 29 such as a printed board, the outer lead 3a is joined to an electrode pad 30 provided on the board 29 via a solder material.

Next, the structure of this apparatus will be described.

This device is provided with an abutment body 31 which abuts a surface of the tip end portion of the outer lead 3a opposite to the surface abutting the electrode pad 30. The contact body 31 is provided in a U-shape having a vertical cross section that opens downward and is formed of a transparent hard member such as quartz. Also, this contact body 3
1 is provided in a long length over a plurality of outer leads 3a protruding in the same direction of the TAB component 28.

Then, the contact member 31 and the outer member
The space defined by the upper surface of the slot 3a is a flow passage filled with an antioxidant gas and a reducing gas. A gas supply source for introducing gas into the flow passage is connected to one end (not shown) of the flow passage.

At a position facing above the outer lead 3a, the pressing body 31 is inserted to the outer lead 3a.
A laser emitting portion 32 for irradiating the laser beam L is provided on the window 3a. In the laser emitting portion 32, the beam diameter of the laser beam L is equal to the outer lead 3a (for one line).
An optical system (not shown) that can be narrowed down to a size approximately the same as the width of the.

The laser emitting section 32 is held by a holder 33 connected to an XY driving section (not shown), and the holder 33 is driven in the XY directions.
The laser beam L is irradiated so as to be positioned above the outer lead 3a so as to face it.

According to such a configuration, the first and second
The electrode pad 3 provided on the substrate 29 is the same as the embodiment of
Oxidation of the solder material above 0 can be effectively prevented, so that good outer lead bonding can be performed.

The present invention is not limited to the third embodiment, and similar effects can be obtained with other semiconductor electronic components such as QFP other than the TAB component 28.

Further, instead of the abutting body 31, the same action as that of the processing jig 23 of the second embodiment is exerted, and the outer lead is pressed and an oxidizing atmosphere or a reducing atmosphere is defined. You may use a tool.

In each of the above-mentioned first to third embodiments, the laser-single point bonding method is used. This laser single point bonding method is to perform the bonding by turning the laser on / off for each lead, but the present invention is not limited to this, and the laser is not limited to this. ON / O for each lead
It is also possible to use a laser bonding method in which the laser is moved so as to cross the lead in the ON state instead of the FF.

[0073]

As described above, according to the first structure of the present invention, in the bonding method of bonding each lead to each corresponding electrode pad via the bonding material, at least the above lead is used. Cover the bonding area of the electrode pad with an antioxidant atmosphere or a reducing atmosphere, and attach a laser beam to this bonding area.
It is a bonding method in which the lead and the electrode pad are bonded via the bonding material by irradiating a space.

The second structure is a bonding apparatus in which each inner lead formed on the carrier tape and each electrode pad formed on the semiconductor element are connected to each other through a solder material. Tape running means for running and stopping the portion of the carrier tape where the inner lead is provided at a predetermined bonding position, and a transparent hard member and stopping at the bonding position. A pressing plate that comes into contact with one surface of the inner lead,
The semiconductor element is arranged on the other side of the inner lead to hold the semiconductor element at the bonding position, and the electrode pad provided on the semiconductor element is attached to the other side of the inner lead via a solder material. And a bonding stage to be brought into contact with, and provided on the bonding stage side,
A partition wall that shields the semiconductor element and the portion where the inner lead is located from the outside air, and an antioxidant gas or a reducing gas that prevents oxidation of the solder material is introduced into the partition wall, and each inner layer is introduced. An antioxidant gas supply means for covering the joint between the lead and each electrode pad with an antioxidant atmosphere or a reducing atmosphere, and the inner lead from one side of the inner lead to the inner lead through the pressing plate. -Zabi-
And a laser beam irradiating means for joining the inner lead and the electrode pad by irradiating the solder and melting the solder material.

In a third configuration, in the second configuration, the pressing plate is provided with an exhaust hole for sequentially exhausting the gas filled inside the partition wall by the gas supply means.

The fourth structure is a bonding apparatus for connecting each outer lead formed on a semiconductor electronic component and an electrode pad formed on a substrate through a solder material, and is formed of a transparent hard member. , A pressing plate that contacts the surface of the outer lead opposite to the surface facing the substrate, and an antioxidant gas or a reducing gas for preventing the oxidation of the solder material is introduced between the pressing plate and the substrate. Then, the inner beam is irradiated with a laser beam through an antioxidant gas supply means for covering the joint portion between each outer lead and each pad with an antioxidant atmosphere or a reducing atmosphere and the pressing plate. , A laser beam for joining the inner lead and the electrode pad by melting the solder material.
A bonding apparatus including a beam irradiation means.

According to this structure, the lead and each electrode pad are joined in an oxidation preventive atmosphere so that the surface of the joining material can be effectively prevented from being oxidized and good soldering can be achieved. Since the solderability and solder wettability can be secured, there is an effect that a better bondability can be obtained in the laser single point bonding.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2A and FIG. 2B are schematic configuration diagrams each having a partial vertical cross-section showing a main part.

FIG. 3 is an enlarged vertical sectional view showing the operation of the same.

FIG. 4 is an enlarged vertical sectional view showing the operation of the second embodiment.

FIG. 5 is an enlarged process diagram showing a third embodiment.

[Explanation of symbols]

1 ... Carrier tape, 3 ... Inner lead (lead),
4 ... Semiconductor element, 5 ... Electrode pad, 6 ... Solder bump (bonding material), 9 ... Guide plate (transparent hard member), 9a ... Exhaust hole, 10 ... Bonding stage, 13b ... Partition, L
... laser beam, 15 ... Antioxidant gas supply hole (antioxidant gas supply means), 18 ... Antioxidant gas supply source (antioxidant gas supply means), A ... Bonding position.

Claims (4)

[Claims] 1. A bonding method for bonding each lead to a corresponding electrode pad via a bonding material, wherein at least the bonding portion between the lead and the electrode pad is covered with an oxidation preventing atmosphere or a reducing atmosphere. A bonding method characterized by irradiating a laser beam to the bonding portion to bond the lead and the electrode pad via the bonding material. 2. In a bonding apparatus for connecting each inner lead formed on a carrier tape and each electrode pad formed on a semiconductor element via a solder material, the carrier tape is run and Tape running means for stopping the portion of the carrier tape where the inner lead is provided at a predetermined bonding position, and an inner member formed of a transparent hard member for stopping at the bonding position. -A pressing plate that comes into contact with one surface of the inner lead and a second surface of the inner lead that holds the semiconductor element at the bonding position, and the electrode pad provided on the semiconductor element is soldered with a solder material. A bonding stage that is brought into contact with the other surface of the inner lead via the bonding stage, and is provided on the bonding stage side. A partition wall that shields the portion where the inner lead is located from the outside air, and an antioxidant gas or a reducing gas that prevents the oxidation of the solder material is introduced inside the partition wall, and each inner lead and An antioxidant gas supply means for covering the joint portion with the electrode pad with an antioxidant atmosphere or a reducing atmosphere, and a laser beam to the inner lead from one side of the inner lead through the pressing plate. A bonding apparatus comprising: a laser beam irradiating means for joining the inner lead and the electrode pad by irradiating and melting the solder material. 3. The bonding apparatus according to claim 2, wherein the pressing plate is provided with an exhaust hole for sequentially exhausting the gas filled inside the partition wall by the gas supply means. 4. A bonding apparatus for connecting each outer lead formed on a semiconductor electronic component and an electrode pad formed on a substrate through a solder material, wherein the outer lead is formed of a transparent hard member.
A pressing plate that abuts a surface opposite to the surface facing the substrate, and an antioxidant gas or a reducing gas that prevents oxidation of the solder material is introduced between the pressing plate and the substrate. An antioxidant gas supply means for covering the joint portion between the outer lead and each pad with an antioxidant atmosphere or a reducing atmosphere, and the inner beam is irradiated with a laser beam through the pressing plate, and the solder material is used. A bonding apparatus comprising a laser beam irradiating means for joining the inner lead and the electrode pad by melting the inner pad.