JP3504073B2 - Method of manufacturing wiring board having solder bumps and support jig - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring board having solder bumps such as a flip chip mounting board and a ball grid array board, and a supporting jig.

[0002]

2. Description of the Related Art Conventionally, when an integrated circuit chip (hereinafter referred to as a flip chip) is mounted on a wiring board, solder bumps are provided on the wiring board, and the solder bumps are heated and melted so that the flip chip and the wiring are connected. Bonded to the substrate.

[0003]

However, since the solder bumps are merely formed by heating and melting the solder paste into a spherical shape, their heights are not necessarily uniform, that is, (the height of each position on the plane is The degree of unevenness)
There is a problem that the co-planarity is large and therefore the bondability with the flip chip is not sufficient.

As a measure against this problem, the inventor has already
A flattening jig made of a flat plate having left and right legs is used to propose a method for improving the bondability by flattening the tops of the solder bumps on the flat plate to reduce the coplanarity. (See No. 8-108287).

However, even if the above measures are taken, the following problems may occur.
Further measures are required. If there is a warp on the wiring board, the corporality will deteriorate. For example, as shown in FIG. 9, in the case where the wiring board P1 has a warp and the central portion of the wiring board has a high warp (left column), the flatness of the wiring board is kept unchanged,
Although the solder bumps P2 having good coplanarity can be formed without any problem, in the case of a valley warp, when the flattening jig P3 is placed on the wiring board P1, the wiring board P is weighted by the flattening jig P3.
The warp of No. 1 is temporarily flattened, and apparently the flatness is temporarily improved. Therefore, when the solder bumps P2 are melted and flattened in this state, if the flattening jig P3 is removed after the solder bumps P2 are melted, the wiring board P is removed.
Since the warp of 1 returns, the corporality of the solder bump P2 becomes worse.

A solder bridge occurs. When solder bumps are applied by a printing method or a dispenser and melted to form, it is desirable to melt the solder and flatten the solder bumps simultaneously in order to shorten the process.
, The wiring board P coated with the solder paste P4
When 1 is covered with the flattening jig P3, the flat plate lower surface of the flattening jig P3 comes into contact with the solder paste P4 and crushes it downward, so that the solder paste P4 spreads laterally and the solder paste P4 between the adjacent pads P5 The distance will be shortened. Further, when the wiring board P1 moves in the flattening jig P3 due to vibration or the like, the solder paste P4 has an adhesive property due to the flux. Therefore, the solder paste P4 shifts in accordance with the movement of the flattening jig P3 and is adjacent to it. It will be connected to the solder paste P4 of the pad P5. Therefore, if the solder is melted as it is, a "solder bridge" in which the solder is connected and solidified between the adjacent pads P5 in a bridging manner may occur, resulting in a short circuit defect.

The present invention has been made in order to solve the above problems, and a method of manufacturing a wiring board having solder bumps capable of preventing the occurrence of solder bridges as well as improving the bondability by reducing the coplanarity. It is intended to provide a supporting jig.

[0008]

The invention according to claim 1 for achieving the above object is mounted on an upper main surface of a wiring board .
For wiring boards that heat solder material to form solder bumps
In the manufacturing method, when the solder bump is formed, the half
By controlling the height of the top of the field bump, the top of the bump is flattened
A flattening jig for forming a surface on the upper main surface of the wiring board.
And arranged from the lower main surface side of the wiring board,
Use a support jig to maintain the warp of the wiring board itself.
Hold and maintain the flatness, support the wiring board,
The gist is a method for manufacturing a wiring board having solder bumps, which is characterized by heating in this state to melt the solder material.

Here, the meaning of "maintaining the flatness" includes the meaning that the warp is not extended and the meaning that the warp is not promoted. -As the solder used for the solder bump, Pb-S
In addition to n-based soft solder, A which is usually used as a bump material
It is possible to employ a brazing material having a melting point of 450 ° C. or lower, such as u-Sn type and Au-Si type.

As the wiring board having the solder bumps, there are a flip chip mounting board and a BGA board. In this case, the BGA board has connection pads arranged in a grid and solder balls arranged on each pad. The installed ball grid array substrate is meant.

The temperature for heating and melting may be equal to or higher than the melting point of the solder material (that is, the melting point of the solder). For example, a temperature 10 to 40 ° C. higher than the melting point of the solder can be adopted. The invention of claim 2, the planarization tool to have a leg portion, said
Placed on the upper main surface of the wiring board, and flattened
The support jig support placed at the position corresponding to the jig leg
The holding member allows the wiring from the lower main surface side of the wiring board.
A method of manufacturing a wiring board having solder bumps according to claim 1 is characterized in that the board is supported .

A third aspect of the present invention is a supporting jig used in the method for manufacturing a wiring board having solder bumps according to the second aspect, wherein the supporting jig supports the wiring board from the lower main surface side. A gist of a support jig is that the member is provided on the upper surface side.

[0013] invention 請 Motomeko 4 above the mounting solder material on a main surface of the wiring board, the plane for regulating the height of the solder bumps formed by heating and melting the solder material A step of holding the regulating member having a height that does not come into contact with the solder material by a height holding means before melting, a step of heating and melting the solder material, and a step of heating and melting the solder material.
And holding the regulating member down to a predetermined height and regulating the height of the top of the melted solder bump with the flat surface to form a flat surface on the top. The gist is a method of manufacturing a wiring board having a solder bump.

According to a fifth aspect of the present invention, before the heating and melting of the solder material, the regulating member is soldered by a pre-melting height holding member made of solder having a melting point higher than the melting point of the solder material and lower than the heating melting temperature. A method of manufacturing a wiring board having solder bumps according to claim 4 is characterized in that the height is maintained so as not to contact the material.

As the shape of the pre-melting height holding member,
Various shapes such as ball shape, columnar shape (cylindrical shape, prismatic shape) and ring shape can be adopted. A sixth aspect of the present invention provides a method for manufacturing a wiring board having solder bumps according to the fifth aspect, wherein the pre-melting height holding member is ball-shaped solder.

The invention of claim 7 is characterized in that, after heating and melting the solder material, the post-melting height holding member holds the regulating member at the predetermined height.
The gist of the method is a method of manufacturing a wiring board having a solder bump according to any one of the above.

The post-melting height holding member may be integral with the regulating member, or may be a separate body (spacer). The invention according to claim 8 is characterized in that the post-melting height holding member is a leg portion formed on a lower surface of the regulating member.
The gist is a method of manufacturing a wiring board having a solder bump described in (1).

According to a ninth aspect of the present invention, before heating and melting the solder material, the pre-melting height holding member formed of a temperature sensitive displacement body holds the regulating member at a height that does not come into contact with the solder material. A method of manufacturing a wiring board having solder bumps according to claim 4, wherein the regulating member is lowered by displacing the temperature sensitive displacement body after heating and melting the material.

As the temperature sensitive displacement body, for example, bimetal, shape memory alloy, or the like whose shape changes depending on temperature can be adopted. A tenth aspect of the present invention provides a method of manufacturing a wiring board having solder bumps according to the ninth aspect, wherein the temperature-sensitive displacement body is a bimetal.

[0020]

According to the first aspect of the present invention, the flattening jig is arranged on the upper main surface of the wiring board, while the lower jig is provided on the wiring board itself from the lower main surface side of the wiring board. Have
The wiring board is supported while maintaining its flatness while maintaining its flatness.

That is, in the present invention, the warp of the wiring board itself is not stretched or promoted even when the flattening jig is placed, and the flatness of the board is maintained.
When the top of the solder bump is flattened by the flattening jig, the difference in height of each solder bump due to the warp can be canceled by flattening the top of the solder bump.

Therefore, according to the present invention, for example, the height (from the substrate surface) of the solder bump in the vicinity of the (raised) end of the warped wiring board is largely flattened at the top. On the contrary, the height of the solder bump in the central portion (recessed) of the wiring board becomes high because the degree of flattening of the top portion thereof is small, and as a result, the coplanarity becomes small.

According to the second aspect of the invention, the flattening jig having the legs is arranged on the upper main surface side of the wiring board, and the lower flat surface of the wiring board corresponds to the leg portions of the flattening jig. The wiring board is supported by the supporting member provided at the position. That is,
In the present invention, the wiring board is sandwiched between the legs of the flattening jig and the support.
Since the wiring board is supported by aligning the positions of the supporting members of the holding jig , the warp of the wiring board is not extended or promoted.

Since the supporting jig of the invention of claim 3 has a supporting member for supporting the lower main surface of the wiring board on the upper surface side, the warping of the wiring board is extended by using this supporting jig. It is possible to support the wiring board without causing any increase. According to the invention of claim 4, the pre-melting height holding means
Hold the regulating member above the solder material on the main surface of the wiring board at a height that does not contact the solder material, and then heat and melt the solder material to lower and hold the regulating member to a predetermined height. Then, the height of the top of the melted solder bump is regulated by a flat surface to form a flat surface on the top.

That is, in the present invention, the plane of the regulating member is
Since it is not in contact with the solder material before heating, the solder material will not be crushed and spread laterally, and even if the regulation member is displaced due to vibration or the like, the solder material does not move together with the regulation member. The solder materials do not come too close to each other or come into contact with each other. Therefore, when the regulating member is lowered to flatten the tops of the solder bumps, that is, at the time of heating and melting, the solders are not joined to each other to form a solder bridge, so that a short circuit can be prevented.

According to the fifth aspect of the present invention, before heating and melting the solder material, the regulating member is brought into contact with the solder material by the pre-melting height holding member made of solder having a melting point higher than the melting point of the solder material and lower than the heating melting temperature. Not held at a height. Therefore,
Before heating, the non-melted pre-melting height holding member raises the regulating member to a height that does not contact the solder material, thereby preventing the solder materials from approaching or contacting each other (during heating). It is possible to prevent the formation of solder bridges, and at the time of heating, the pre-melting height holding member melts, so that the regulating member can be automatically lowered to flatten the tops of the solder bumps. Further, since the restriction member is held by the melt height holding member made of solder, the restriction member can be easily set in the holding state.

In the sixth aspect of the invention, ball-shaped solder can be adopted as the pre-melting height holding member. When the solder is melted on a plate of ceramic or the like that does not get wet with the solder, it becomes ball-shaped due to surface tension. Therefore, if the pre-melting height holding member (ball-shaped solder) that has been used and crushed once is heated and melted into a ball shape again, it can be used any number of times.

According to the seventh aspect of the invention, after the solder material is heated and melted, the post-melting height holding member holds the regulating member at a predetermined height. Therefore, even if the height holding member before melting cannot hold the height of the regulating member due to melting, the height holding member after melting holds the regulating member at a predetermined height, so that the height of the solder bump is determined. It is also possible to prevent the solder bumps from being crushed more than necessary (by the regulating member).

According to the eighth aspect of the present invention, the leg portion formed on the lower surface of the regulating member can be adopted as the post-melting height holding member. With this configuration, it is not necessary to bit a separate spacer, and the working process is simplified. In the invention of claim 9, since the pre-melting height holding member formed of the temperature sensitive displacement body holds the regulating member at a height that does not contact the solder material,
When the solder material is heated and melted, the temperature sensitive displacement body is displaced and the regulation member is lowered.

Therefore, since this temperature-sensitive displacement body does not melt or roll like a solder ball, it is easy to handle. If the temperature-sensitive displacement body is a shape memory alloy, it can be reused by returning its shape after use, and it is not necessary to reheat it by melting it like a solder ball. .

In the tenth aspect of the invention, bimetal can be used as the temperature sensitive displacement body. This bimetal is easier to handle than a shape memory alloy, and returns to its original shape when the temperature returns, so that it can be reused as it is.

[0032]

EXAMPLE An example of a method of manufacturing a wiring board having solder bumps according to the present invention will be described below together with a jig to be used. Here, a resin-made circuit board (flip chip mounting board, hereinafter simply referred to as wiring board) for mounting an integrated circuit chip (LSI element, simply referred to as flip chip) face down is referred to as a flip chip. A method of manufacturing a wiring board having solder bumps for bonding by the flip chip method will be described. (Embodiment 1) As shown in FIG. 1, the wiring board manufactured by the manufacturing method of this embodiment has one of the front side (top surface in the drawing).
This is a resin multilayer wiring board having a solder bump 1 formed in a region of 2 mm × 17.5 mm, an outer diameter of about 23 mm square, and a plate thickness of about 1 mm.

Hereinafter, a method of manufacturing the wiring board 3 of this embodiment will be described. Here, an example will be described in which the wiring board 3 has a valley warp lower by 40 μm in the central portion. When manufacturing the wiring board 3 on which the solder bumps 1 are to be formed, as shown in the enlarged and broken view of FIG. 1B, first, the insulating layer 7 made of epoxy resin is formed on the BT core substrate 5. At the same time, the Cu internal wiring 9 is formed and laminated over the BT core substrate 5 and the insulating layer 7 by a semi-additive method using electroless Cu plating and electrolytic Cu plating. The Cu internal wiring 9 may be formed by a subtractive method or a full additive method.

Next, on the outermost surface of the wiring board 3, the C
In order to prevent corrosion of the Cu wiring 11 joined to the u internal wiring 9 and to improve adhesion with solder, electroless Ni-P
The Ni—P layer 13 having a thickness of about 3 μm is formed by plating, and the Au layer 15 having a thickness of about 0.1 μm is further formed thereon by electroless Au plating to form the Ni—P layer 13 and the Au layer 15.
An underlying conductive pad consisting of (hereinafter simply referred to as pad) 1
Create 7. In addition, the solder resist layer 19 is formed of acrylic or epoxy resin on other portions.

Since the above-mentioned plating method is the same as the well-known method for plating a multilayer printed wiring board, it will not be described in detail (for example, "Multilayer printed wiring board step 365"; Fujihira / Fujimori Co .; Industrial Research Committee; 1989). Issued annually). Next, as shown in FIG. 2, 37Pb-63Sn eutectic solder paste (melting point 183 ° C.) is applied to the front side pad 17 of the wiring board 3 by a known printing method to form the eutectic solder paste layer 21. Form.

As a method of forming the eutectic solder paste layer 21, other than this method, there is a method of dropping the solder paste with a dispenser. Further, instead of forming the solder paste layer 21, solder balls or solder preforms may be placed on the pads 17.

Next, the front side of the wiring board 3 (upper side in the figure)
Then, a flattening jig 23 is arranged to regulate the height of the solder bump 1 to be formed. The flattening jig 23 is made of alumina ceramic and has a plate-shaped flat portion 23a (vertical 23
mm × width 25 mm × thickness 1 mm) and leg portions 23b (length 23 mm × width 3 mm ×) provided on the left and right of the flat portion 23a
Height 60 μm).

At the same time, a supporting jig 25 for supporting the left and right ends of the wiring board 3 is provided on the back side (lower side in the figure) of the wiring board 3 so as not to extend the warp of the wiring board 3. The support jig 25 is a jig made of alumina ceramic,
As shown in FIG. 3, a plate-shaped flat portion 25a (23 mm long × 23 mm long)
A projecting support portion 25b (23 mm long × 3 mm wide × 1 mm high) for supporting the wiring board 3 is provided at both ends of the width 25 mm × thickness 1 mm).

In this state, the eutectic solder on the front side is melted by passing through a reflow furnace having a maximum temperature of 220 ° C., and then cooled. As a result, the solder bumps 1 (height 100 μm) for flip-chip bonding having flattened tops are formed on the front side of the wiring board 3. As described above, according to this embodiment, the flattening jig 23 is arranged on the front side of the wiring board 3, and the supporting portion 25b is located at a position corresponding to the leg portion 23b of the flattening jig 23. A supporting jig 25 is arranged on the back side of the wiring board 3 and is heated in this state.

Therefore, the top of the solder bump 1 can be flattened while the warp of the wiring board 3 is not extended by the flattening jig 23 (and the warp is not promoted). When the top portion is flattened, the warp of the wiring board 3 can be absorbed by lowering the height of the solder bump 1 at a portion where the solder bump 1 is lifted by the warp, for example. Therefore, since the coplanarity of the wiring board 3 can be reduced (for example, to 0.3 μm / mm or less), the bondability with the flip chip can be improved.

Particularly, when the leg portions 23b of the flattening jig 23 and the supporting portions 23b of the supporting jig 25 are arranged at the same positions on the front and back sides, the warp of the wiring board 3 is not extended at all and the flatness is maintained. There is an advantage. (Experimental Example) Next, an experimental example will be described.

This experimental example compares the case where only the flattening jig is used (comparative example) with the case where the flattening jig and the supporting jig are used as in the present embodiment. The results are shown in FIG. 4. When a flattening jig and a supporting jig are used as in the present embodiment, there are no warp of the wiring board, a case of a warp, and a case of a valley warp. In all cases, the coplanarity was small at 0.3 μm / mm or less, which was preferable. On the other hand, when only the flattening jig was used, the coplanarity was as small as 0.3 μm / mm or less in the case of no warp of the wiring board and in the case of mountain warp, but in the case of valley warp In addition, since the warp of the wiring board is extended, the coplanarity is increased to 0.7 μm / mm, which is not preferable. (Second Embodiment) Next, a second embodiment will be described.

In this embodiment, when the solder material is heated and melted, the solder balls are melted and the regulating member is lowered to flatten the tops of the solder bumps. Hereinafter, the method of manufacturing the wiring board of the present embodiment will be described, but the description of the same parts as those in the first embodiment will be omitted or simplified. In the following drawings, the solder particles contained in the solder paste are also shown in order to make the description easier to understand.

The wiring board 31 and the pads 33 as shown in FIG. 5 are formed by the same steps as those in the first embodiment. Next, the same eutectic solder paste as that of the first embodiment is printed on the pads 33 on the front side of the wiring board 31 to form a convex eutectic solder paste layer 35. In the eutectic solder paste layer 35, the solder particles 35b are dispersed in the flux 35a.

Next, the wiring board 31 is placed on the lower jig 37. This lower jig 37, as shown in FIG.
A plate-shaped member made of alumina ceramic (length 25 mm x
The width is 35 mm × thickness 2 mm), the groove 37a (width 19 mm × depth 1 mm) is formed in the center, and the conical recesses 37b (diameter 1.4 mm × depth 0.7 mm) are formed at the four corners. Are formed. The wiring board 31
Are arranged so as to be hung over the groove portion 37. This is because the warp of the wiring board 31 is not extended.

Next, as shown in FIG.
A spherical pre-melting height holding member (solder ball) 39 is placed in the recess 37b. This solder ball 39 is 55Sn
It is a ball made of -45Pb and having a diameter of 2 mm, and its melting point is 203 ° C. That is, the melting point of the solder ball 39 is about 2 times higher than the melting point of the solder grain 35b that becomes the solder bump 43.
Since the solder balls 39 are set to melt at a temperature higher by 0 ° C., the solder balls 39 melt after the solder particles 35b melt.

Next, on the solder ball 39, as shown in FIG.
A plate-shaped regulating member as shown in (b) (25 mm long x 35 mm wide)
(mm × thickness 2 mm) 41 is placed. This restriction member 41
Is a member that descends when the solder balls 39 melt and flattens the tops of the solder bumps 43. The members are made of alumina ceramic, and the lower surface side thereof has both ends of the wiring board 31, that is, a lower jig. A pair of left and right leg portions 41a (having a height of 60 μm) protruding downward are provided at positions corresponding to both side portions of the groove portion 37a of the groove 37.

In particular, in this embodiment, as shown in FIG. 5, when the regulating member 41 is placed on the solder ball 39, the regulating member 41 forms the eutectic solder paste layer 35. The height is set so that the leg portions 41a do not come into contact with the wiring board 31 so that they do not come into contact with each other. In particular,
The distance h1 between the lower jig 37 and the regulating member 41 is 1.7 mm
And the distance h2 between the regulating member 41 and the wiring board 31 is
(0.7 mm-warp amount of substrate), and the interval h3 between the leg portion 41a and the wiring substrate 31 is 0.64 mm.

In this state, it is passed through a reflow furnace having a maximum temperature of 220 ° C. Then, when the temperature rises to 183 ° C., the solder particles 35b having a low melting point in the eutectic solder paste layer 35 are first melted and aggregated to form spherical solder bumps 43. At this stage, Since the solder balls 39 are not melted, the height of the regulating member 41 is maintained.
The flux 35a is attached around the solder balls 39.

Thereafter, the heating temperature rises and the solder balls 3
When the melting point (203 ° C.) of 9 is reached, the solder balls 39 are melted, so that the regulating member 41 descends accordingly and presses the tops of the solder bumps 43 to flatten them. With this operation, the height of the regulation member 41 is maintained by the leg portions 41a coming into contact with the wiring board 31, so that the height of the solder bump is set.

Then, after cooling, the regulating member 41,
The solder balls 39 and the lower jig 37 are removed, and the flux 3
By removing 5a as well, the solder bump 4 having a flat top
The wiring board 31 having 3 is completed. As described above, in this embodiment, since the regulation member 41 is lifted by the solder balls 39 so as not to come into contact with the eutectic solder paste,
Even if the solder paste layer 35 is not crushed and does not spread laterally and the regulating member 41 is displaced, the regulating member 41
Along with the movement of the paste layer 35, the eutectic solder paste layer 3
The five parts do not come too close to each other or come into contact with each other, and therefore a solder bridge is not formed during heating and melting.

Further, during heating, the solder particles 35b are melted and aggregated, and the solder balls 39 are not melted before the solder bumps 43 are formed, so that the regulating member 41 does not descend, and therefore, this point Also, no solder bridge is formed. Further, once the solder particles 35b are melted and agglomerated to form the spherical and molten solder bumps 43, the solder gathers in the vicinity of the pads, and the flux 35a surrounds the surroundings. The distance increases. Therefore, even if the regulating member 41 descends and pushes the solder bumps 43, the adjacent bumps will not be bridged. Further, even if the regulating member 41 is displaced in this state, only the flux 35a is displaced and the solder bridge is not formed.

As described above, in this embodiment, the regulating member 41 is used.
Since it is not necessary to hold the restricting member 41 so as not to shift after placing the sheet, there is an advantage that the work is simplified. Further, when the solder balls 39 are melted by heating, the regulation member 41 can be lowered to flatten the tops of the solder bumps 43.

Further, since the regulating member 41 is provided with the leg portion 41a, the regulating member 41 is provided below the predetermined height.
Does not descend. This makes it possible to set the height of the solder bumps 43 and prevent the solder bumps 43 from being crushed below a predetermined height by the regulation member 41.

Although the solder balls 39 are used to hold the regulating member 41 in this embodiment, solder having another shape (for example, a columnar shape or a prismatic shape) may be used. However, since the solder ball 39 returns to the original spherical shape when heated after use, it is easy to reuse, and since the shape of the solder ball 39 is determined only by the volume of the solder, it is easy to obtain a constant shape. There are advantages. (Experimental example) In order to confirm the effect of the present embodiment, an experiment of a method of manufacturing a wiring board having solder bumps is actually conducted separately for the case where the solder balls adopted in this example are used and the case where they are not used. It was

According to this, when the solder balls are not used, the solder bumps on the 140,000 pads are 30
A solder bridge was formed at the location, but when the solder ball of this example was used, no solder bridge was formed. (Third Embodiment) Next, a third embodiment will be described.

In this embodiment, when the solder material is heated and melted, the bimetal is operated to lower the regulating member to flatten the top of the solder bump. Hereinafter, the method of manufacturing the wiring board of the present embodiment will be described, but the description of the same parts as those of the first and second embodiments will be omitted or simplified.

The wiring substrate 51 and the pad 53 as shown in FIG. 7 are formed by the same steps as those in the first embodiment. Next, the same eutectic solder paste as that of the first embodiment is printed on the front side pad 53 of the wiring board 51 to form a convex eutectic solder paste layer 55. In the eutectic solder paste layer 55, the solder particles 55b are dispersed in the flux 55a.

Next, the wiring board 51 is placed on the lower jig 57. This lower jig 57, as shown in FIG.
A plate-shaped member made of alumina ceramic (length 25 mm x
The width is 35 mm × thickness 2 mm), and the groove 57a (25 mm length × 19 mm width × 1 mm depth) is formed in the center thereof, and the bimetal 59 having a height of 3 mm is formed at the four corners.
Is erected. The bimetal 59 is attached so as to bend outward as the temperature rises,
At the tip of the bimetal 59, there is a claw 59a protruding inward.
Is provided.

Similar to the solder ball of the second embodiment, the bimetal 59 functions as a pre-melting height holding member for holding the regulating member 61 described later, and is higher than the melting point of the solder grain 55b to be the solder bump. At a temperature about 20 ° C. higher, the regulation member 59 can be bent to such an extent that it can be lowered.

Next, on the bimetal 59, as shown in FIG.
A plate-shaped regulating member as shown in (b) (25 mm long x 35 mm wide)
(mm × thickness 2 mm) 61 is placed. This restriction member 61
Is a member made of alumina ceramic for descending at the time of heating to flatten the tops of the solder bumps 63, and its lower surface corresponds to both ends of the wiring board 51. Pair of left and right legs 6 projecting downward at the position
1a (height 60 μm) is provided.

In this embodiment, as in the second embodiment, the height of the bimetal 59 is adjusted so that the regulating member 6 is located above the bimetal 59.
1 is placed on the wiring board 5 so that the regulating member 61 does not contact the eutectic solder paste layer 55
It is set not to contact 1.

In this state, it is passed through a reflow furnace having a maximum temperature of 220 ° C. Then, when the temperature rises and reaches 186 ° C., the solder particles 55b are first melted and aggregated to form spherical solder bumps 63. At this stage, the bimetal 59 is formed.
Does not bend so much, the height of the regulating member 61 remains held.

Thereafter, when the temperature at which the bimetal 59 reaches a sufficient bending temperature is reached, the bimetal 59 is largely bent outward, so that the claw portion 59a is disengaged from the lower surface of the regulation member 61, whereby the regulation member 61 is lowered and the solder bump Press the top of 63 to flatten it. In addition, the height of the regulation member 61 is maintained by the leg portions 61b coming into contact with the wiring substrate 51, so that the height of the solder bump 63 is set.

Then, after cooling, the restricting member 61 and the lower jig 57 are removed to complete the wiring board 51 having the solder bumps 63 with flat tops. As described above, in this embodiment, the restriction member 6 is formed by the bimetal 59.
1 is lifted so as not to come into contact with the eutectic solder paste. Therefore, the same effects as those of the second embodiment can be obtained such that the solder bridge is not formed.

In particular, the bimetal 59 has the advantage that it can be reused much more easily than the case of using solder balls, because its shape returns to its original shape when the temperature returns to its original value. Needless to say, the present invention is not limited to the above-mentioned embodiments, and can be carried out in various modes without departing from the scope of the present invention.

(1) The material forming the solder bumps used in each of the above-mentioned embodiments may be appropriately selected according to the heat resistant temperature of the substrate material and the application, such as Pb / Sn alloy and Ag.
Any solder such as or solder containing In can be used. Further, when a material having a high heat resistant temperature such as ceramic is used as the substrate material, it is also possible to use a high melting point solder such as Pb90% solder. Further, as the type of flux contained in or used in the solder paste, any of R type (from the one having smaller reducing property), RMA type and RA type can be used. Here, as the bump material,
In addition to the Pb-Sn brazing material usually called solder, A
Alloys such as u-Sn type and Au-Si type can also be used.

(2) As a method of applying the solder on the pad, other than the method of printing the solder paste described above,
A method of dropping a solder paste on a pad using a dispenser, a method of placing a solder ball or a solder preform on the pad, and the like can be adopted.

[0069]

As described above in detail, according to the method of manufacturing the wiring board having the solder bumps and the supporting jig of the present invention, the following effects can be obtained. According to the invention of claim 1, the warp of the wiring substrate itself is not extended or promoted even when the flattening jig is placed, and therefore the top of the solder bump is flattened by the flattening jig. In this case, the influence of the warp can be canceled by flattening the tops of the solder bumps. Moreover, since the warp of the substrate does not change even after the flattening jig is removed, the coplanarity is reduced and the bondability is improved.

According to the second aspect of the present invention, since the wiring board is supported at the position corresponding to the leg portion of the flattening jig, the warp of the wiring board is not extended or promoted. When the support jig of the invention of claim 3 is used, the warp of the wiring board is not extended or promoted.

According to the invention of claim 4, even if the regulating member is displaced due to vibration or the like, the solder materials do not come too close to each other or come into contact with each other. Therefore, when heating and melting, the solders are not joined to each other to form a solder bridge,
The occurrence of short circuit can be prevented.

According to the fifth aspect of the invention, before heating, contact of the solder material and the like can be prevented to prevent formation of a solder bridge (during heating), and at the time of heating, the pre-melting height holding member melts. By doing so, the regulating member descends and the tops of the solder bumps can be flattened.

In the invention of claim 6, since ball-shaped solder is used as the pre-melting height holding member, it can be reused and the cost can be reduced. In the invention of claim 7, since the post-melting height holding member can hold the regulating member at a predetermined height, it is possible to prevent the solder bump from being crushed below the predetermined height by the regulating member.

In the eighth aspect of the invention, the construction of the leg portion formed on the lower surface of the regulating member does not require a separate spacer to be bitten, and the working process is simplified. In the invention of claim 9, the temperature sensitive displacement body is easier to use than the solder ball.
In the invention of claim 10, since the bimetal returns to its original shape when the temperature returns, it is easy to reuse.

[Brief description of drawings]

1A and 1B show a wiring board having solder bumps according to a first embodiment, FIG. 1A is a perspective view thereof, and FIG.

FIG. 2 is an explanatory diagram showing a method for manufacturing a wiring board having solder bumps according to the first embodiment.

3A and 3B show a supporting jig used in Example 1, where FIG. 3A is a plan view thereof, FIG. 3B is a front view thereof, and FIG.

FIG. 4 is an explanatory diagram showing an experimental result of Example 1.

FIG. 5 is an explanatory diagram showing a method of manufacturing a wiring board having solder bumps according to a second embodiment.

6A and 6B show a jig used in Example 2; FIG. 6A is an explanatory view showing the upper surface side of a lower jig, and FIG. 6B is an explanatory view showing the lower surface side of a regulating member.

FIG. 7 is an explanatory diagram showing a method for manufacturing a wiring board having solder bumps according to a third embodiment.

8A and 8B show a jig used in Example 3, FIG. 8A is an explanatory view showing the upper surface side of a lower jig, and FIG. 8B is an explanatory view showing the lower surface side of a regulating member.

FIG. 9 is an explanatory diagram illustrating a problem when a flattening jig is used.

FIG. 10 is an explanatory diagram illustrating a problem when a flattening jig is used.

[Explanation of symbols]

3, 31, 51 ... Wiring board 1, 43, 63 ... Solder bump 21, 35, 55 ... Eutectic solder paste layer 23 ... Flattening jig 25 ... Support jig 41, 51 ... Regulating member 37, 57 ... Lower jig 39 ... Solder ball 59 ... Bimetal

Claims (10)

(57) [Claims] 1. A solder material placed on an upper main surface of a wiring board.
Method of manufacturing wiring board by heating solder to form solder bumps
Method, when forming the solder bump, the height of the top of the solder bump is increased.
By forming a flat surface on the top by regulating the flatness
The jig is placed on the upper main surface of the wiring board.
A support jig from the lower main surface side of the wiring board.
The warp of the wiring board itself is retained and its plane
A method for manufacturing a wiring board having solder bumps, characterized in that the wiring board is supported while maintaining the temperature and heated in this state to melt the solder material. Wherein said flattening jig which have a leg portion, the distribution
The support placed on the upper main surface of the linear substrate and at a position corresponding to the leg of the flattening jig.
Depending on the supporting member of the holding jig, the lower main surface side of the wiring board
The preceding claims, characterized in that the supporting al, the wiring substrate
1. A method for manufacturing a wiring board having solder bumps according to 1 . 3. A supporting jig used in the method for manufacturing a wiring board having solder bumps according to claim 2, wherein a supporting member for supporting the wiring board from the lower main surface side is an upper surface side. A support jig characterized by having. Above 4. A solder material placed on the main surface of the wiring board, the regulating member having a planar surface for regulating the height of the solder bumps formed by heating and melting the solder material, the molten a step of holding at a height which does not contact with the solder material before the height holding means, a step of heating and melting the solder material, after heating and melting of the solder material, and held to lower the said regulating member to a predetermined height And a step of forming a flat surface on the top by regulating the height of the top of the melted solder bump with the flat surface, and a method of manufacturing a wiring board having a solder bump. 5. Prior to heating and melting the solder material, a height-pre-melting holding member made of solder having a melting point not lower than the melting point of the solder material and not higher than the heating melting temperature prevents the regulating member from coming into contact with the solder material. 5. The method for manufacturing a wiring board having solder bumps according to claim 4, wherein the wiring board is held at a height. 6. The method for manufacturing a wiring board having solder bumps according to claim 5, wherein the pre-melting height holding member is ball-shaped solder. 7. The solder according to claim 4, wherein after the solder material is heated and melted, the post-melting height holding member holds the regulating member at the predetermined height. Manufacturing method of wiring board having bumps. 8. The method of manufacturing a wiring board having solder bumps according to claim 7, wherein the post-melting height holding member is a leg portion formed on the lower surface of the regulation member. 9. Before heating and melting the solder material, the pre-melting height holding member made of a temperature-sensitive displacement body holds the regulating member at a height that does not contact the solder material, and after heating and melting the solder material. The method for manufacturing a wiring board having solder bumps according to claim 4, wherein the regulating member is lowered by displacing the temperature sensitive displacement body. 10. The method for manufacturing a wiring board having solder bumps according to claim 9, wherein the temperature sensitive displacement body is a bimetal.