JPH03268385A - Solder bump and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a bump from being stripped off and to prevent a main conductor from being disconnected by a method wherein a metal whose solderability is poor as compared with that of a solderadhesion part is formed around the solder-adhesion part. CONSTITUTION:In order to prevent a solder 17 from coming into contact with a main conductor 8 of Cu, a metal 23 whose solderability is poor as compared with that of a solder-adhesion part is formed around the solder-adhesion part at the outer circumference part of the solder-adhesion part. When the outer circumference part of the solder-adhesion part is surrounded by the metal 23 whose solderability is poor, the solder 17 for bump use does not flow out from the solder-adhesion part. Consequently, the solder does not come into contact with the main conductor 8 and is not alloyed. Thereby, it is possible to prevent a bump from being stripped off and to prevent the main conductor from being disconnected.

Description

[Detailed Description of the Invention] [Summary] Regarding a solder bump for mounting components on an electronic circuit board that performs high-density surface mounting and a method for manufacturing the same, the copper of the pad or the main conductor is alloyed with the solder and the mechanical strength is increased. In order to prevent the solder from coming into contact with the Cu main conductor, the outer circumferential part of the solder joint is coated to prevent the solder from coming into contact with the Cu main conductor. In comparison, a metal having poor solder wettability is provided around the solder attachment part.

[Industrial application field]

The present invention relates to a solder bump for mounting components on an electronic circuit board that performs high-density surface mounting, and a method for manufacturing the same.

[Prior Art] In recent electronic circuits of electronic computers, as semiconductor components such as ICs and LSIs have become highly integrated, the density of component mounting on circuit boards has also increased. For this reason, surface mounting using solder bumps has come to be used for mounting components on circuit boards. FIG. 7 is a diagram showing an example of this surface mounting. In this case, solder bumps 2 are formed on the conductors of a ceramic circuit board 1, while an IC chip 3 is mounted on a ceramic carrier 4, and its electrodes are connected to an internal conductor 5 with wires 6. There is. Further, a large number of lead pins 7 connected to the internal conductor 5 are implanted on the lower surface of the ceramic carrier 4, and the lead pins 7 are soldered to the circuit board 1 by solder bumps 2.

The solder bumps are as shown in FIG. 8(a) or (b).
On the ceramic circuit board 1, a wiring pattern 11 having a main conductor 8 made of Cu, adhesive layers 9 and 10 made of Cr above and below, and a resin insulating layer 12 made of polyimide or the like are provided. In the case of Cr layer 13, Cu layer 14, Ni layer 15, A
A pad made of a U layer 16 is formed, and a solder 17 is mounted on the Au layer 16. (b) In the case of the figure, the adhesion layer 10 and the Cr layer 13 and Cu layer 14 thereon are shown in figure a.
is lacking.

[Problem to be solved by the invention]

In the above conventional solder bump, the solder is Sn/Pb
There is no problem with solder that corrodes copper only slightly, such as eutectic solder. penetrates into the Cu layer 14 (the main conductor 8 in the case of FIG. 8) from the side surface of the pad, forming an alloy layer 19. Since this alloy layer 19 has poor mechanical strength and adhesion, there is a problem in that bumps may peel off, main conductors may break, etc., and reliability may be significantly reduced.

Furthermore, since the Ni layer 15 in the pad has a large residual stress when formed by sputtering, as shown in FIG. 9(b),
There is also the problem that cracks 20 are generated in the resin insulating layer 12 from the edge portions.

In view of the above-mentioned conventional problems, the present invention provides a solder bump that can prevent the copper of the pad or the main conductor from becoming alloyed with the solder, resulting in a decrease in mechanical strength, resulting in peeling of the bump, disconnection of the main conductor, etc. The purpose is to provide.

[Means to solve the problem]

To achieve the above object, in the solder bump of the present invention, in order to prevent the solder 17 from coming into contact with the Cu main conductor 8 on the outer peripheral part of the solder attachment part, the solder bump has a higher solder wettability than the solder attachment part. It is characterized by providing a bad metal around the solder attachment part.

In addition, a multilayer wiring using a resin insulating layer 12 and a conductor 8 is formed on the substrate 1 (in addition, each layer of an adhesion layer 21, a Ni layer 22, and an adhesion layer 23 are sequentially provided, and the uppermost adhesion layer 2
3 is provided with a hole, and the Ni layer 24 and Au or Pt are formed in the hole.
It is characterized in that a layer 25 is provided, and a solder 17 is mounted on the Au or Pt layer 25.

Further, a step of sequentially forming an adhesive layer 9, a main conductor 8, an adhesive layer 10, and a resin insulating layer 1i12 on the substrate 1, and etching the adhesive layer 11 in the bump forming area of the resin insulating layer 12 are performed.
a step of opening a window so that 0 is exposed; a step of sequentially forming an adhesion layer 21, a Ni layer 22, and an adhesion layer 23 on the exposed adhesion layer 10; and a step of forming a bump forming area of the uppermost adhesion layer 23. The process of etching and removing, and the Ni layer 24 and A
a step of forming the u or pt layer 25; a step of etching away the adhesion layer 23 and the underlying nickel layer 22 and adhesion layer 21 so that the adhesion layer 23 remains in a ring shape; It is characterized by comprising a step of mounting solder 17 on top.

Further, a resin insulating layer 2 is placed on the substrate 1, and an adhesive layer 9 is placed on the top and bottom.
10, a hole is provided in the upper adhesion layer 10, and a ring-shaped Cu
A layer 27 is provided, and further a Ni layer 28 and an Au layer 29 are provided on the main conductor 8 including the Cu layer 27, further including the Cu layer 27.
It is characterized in that the solder 17 is mounted on the U layer 29.

Further, a step of sequentially forming the adhesion layer 9, the main conductor 8, the adhesion layer 10, and the Cu layer 27 on the substrate 1, a step of removing the bump forming regions of the Cu layer 27 and the adhesion layer 10 by etching, and It is slightly thicker than the part where layer 27 was removed (
The step of forming the Ni layer 28 and the Au layer 29, and the step of forming the Au layer 29,
A step of etching away the Cu layer 27 using the layer 29 as a mask to leave the Cu layer 27 in a ring shape under the Ni layer 28, and a step of forming the resin insulating layer 12 around the ring-shaped Cu layer 27. and mounting the solder 17 on the Au layer 29.

In addition, in the bump formation region on the main conductor 8 made of Cu,
A metal with poor solder wettability is provided, a metal with good solder wettability is provided on top of the metal with a ring shape remaining around the outer periphery of the metal with good solder wettability, and a solder 17 is provided on the metal with good solder wettability. It is characterized by being equipped with.

Further, a step of forming an adhesion layer 9, a main conductor 8, an adhesion layer 10, and a Cu layer 27 on the substrate 1, and a step of etching the Cu layer 27 by photolithography to leave the Cu layer 27 in a ring shape. , the adhesive layer 1 under the ring-shaped Cu layer 27
Ni is removed by etching in an area slightly smaller than the inner circumference of the Cu layer 27, and Ni is removed on the main conductor 8 exposed by the removal of the adhesive layer 10 and on the ring-shaped Cu layer 27.
The process of forming the layer 28 and the Au layer 29, and the step of forming the Au layer 2
The method is characterized by comprising a step of mounting a solder 17 on the solder 9.

[For production]

By surrounding the outer periphery of the solder attachment part with a metal that has poor solder wettability, the bump solder does not flow out from the solder attachment area, and therefore does not come into contact with the copper of the main conductor and is not alloyed. Therefore, peeling off of bumps, disconnection of main conductors, etc. are prevented.

〔Example〕

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

In this embodiment, as shown in the figure, a conductor pattern 11 is provided on a ceramic substrate 1, with Cu as the main conductor and adhesion layers 9 made of Cr and lO arranged above and below the conductor pattern 11. A resin insulating layer 12 is provided with a window formed therein, and a Cr layer 21 and a Ni layer 22 are provided on the conductor pattern 11 exposed in the window.
A ring-shaped CrN 23 and a Ni layer 24 and an Au (or Pt) layer 25 formed inside the ring-shaped CrN 23 are provided on the layer 22, and the solder 17 is mounted on the Au layer 25.

In this embodiment configured in this way, since the Cr metal of the ring-shaped Cr layer 23 is a metal with poor wettability to solder, it acts as a barrier to the solder 17 and
7 can be prevented from flowing out. Also, the Ni layer 22
Since the edges 24 and 24 are stepped by the Cr layer 23, the stress at the edges is dispersed, and defects as shown in FIG. 9(c) are prevented from occurring.

FIG. 2 is a diagram for explaining the manufacturing method of the first embodiment of the present invention, and (a) to (e) show the steps.

In this embodiment, first, as shown in FIG. 2(a), a conductor pattern 11 consisting of an adhesive layer 9, a main conductor 8, an adhesive layer 10 and a polyimide resin insulating layer 12 are placed on a ceramic substrate 1.
After forming the bump formation area of the resin insulating layer 12, a window is formed by etching to expose the conductive pattern 12, and a Cr layer 2 is formed in contact with the exposed conductive pattern 12.
1 (approximately 1,000 layers thick), and a Ni layer 22 is formed on it.
(thickness approx. 1μm) and Cr layer 23 (thickness approx. 1000 people)
form. The above Cr layers 21, 23 and Ni layer 22 are formed by sputtering or vapor deposition. Next, as shown in FIG. 2 et al., the uppermost Cr layer 23 is masked with a resist 26 and etched to remove the Cr in the bump forming area.

Next, as shown in FIG. 2C, a Ni layer 24 and an Au (or Pt)li layer 25 are formed by plating on the portion where the Cr layer 23 has been removed, and then the resist 26 is removed. Next, as shown in FIG. 2(d), the Cr layer 23 is masked with a resist 26 so that it remains in a ring shape on the Au layer 25 and the Cr layer 23, and the Cr layer 23, the Ni layer 22 and the Cr layer 23 are masked with a resist 26. Etch and remove unnecessary parts. Finally, as shown in FIG. 2(e), the resist 26' on the Au layer 25 is removed, and the solder 17 is mounted thereon.

Although the Au layer 25 is shown in FIG. 1 and FIG. 2(e), in reality, when the solder 17 is mounted,
The melt penetrates into the solder and becomes invisible.

(The same applies to each of the following embodiments.) FIG. 3 is a diagram showing a second embodiment of the present invention.

In the figure, 1 is a ceramic substrate, and C
A conductor pattern 11 is formed in which u is a main conductor 8 and adhesion layers 9 and 10 made of Cr are arranged above and below it.

Then, the bump forming portion of the adhesive layer 10 on the upper layer of the conductor pattern 11 is removed, and a ring-shaped Cu layer 27 is provided on the adhesive layer 10 around it, and the Cu layer 27 and the conductor pattern are exposed. A Ni layer 28 and an Au layer 29 are provided on the main conductor 8, a solder 17 is mounted on the Au layer 29, and a resin insulating layer 12 is further formed around the Cu layer 27.

In the manufacturing method of this embodiment, first, as shown in FIG. ), Cu layer 27
(thickness: 5000 mm) is formed by sputtering, a photoresist 30 is applied thereon, and the Cu layer 27 and adhesive layer 10 in the bump formation area are removed by photolithography and etching. Next, as shown in FIG. 4(b), a resist 31 that is 5 to 10 μm larger than the pattern obtained by removing the Cu layer 27 and the adhesive layer 10 is provided, and a Ni layer 28 and an Au layer 29 are formed by plating.

Next, as shown in FIG. 4C, the Cu layer 27 is etched away using the Au layer 29 as a mask, leaving only a ring shape under the Ni layer 28. Next, a resin insulating layer 12 is formed around this ring-shaped Cu layer 27, and a solder 17 is further mounted on the Au layer 29 to complete the process.

In this embodiment configured in this way, when plating the Ni layer 28, the Cu layer 27 is replaced with Cr, which is the adhesion layer 10.
It is provided as an intermediate layer since it cannot be plated directly on the Nt layer 28, and even if it is alloyed with solder, the solder can be blocked at the boundary between the Nt layer 28 and the adhesive layer 10. Therefore, the main conductor 8 is not attacked by the solder.

FIG. 5 is a diagram showing a third embodiment of the present invention.

In this figure, the same parts as in FIG. 3 are designated by the same reference numerals.

This embodiment has almost the same structure as the second embodiment shown in FIG. 3, and the difference is that the ring-shaped Cu layer 27 is
0, and a space 32 is provided between the Ni layer 28 and the Ni layer 28. Note that when the Ni layer 28 is formed by plating on the adhesion layer 10 in this space, it is plated very thinly.

In this embodiment configured as described above, the distance from the solder 17 to the main conductor 8 is larger than in the previous embodiment, and the risk of solder diffusion is further reduced than in the previous embodiment, and the reliability is improved.

FIG. 6 is a diagram for explaining the manufacturing method of the third embodiment of the present invention, and (a) to (d) show the steps.

In this example, first, as shown in FIG. 6(a), an adhesive layer 9, a main conductor 8, an adhesive layer 10, and a Cu layer 27 are sequentially formed on a substrate 1 by sputtering, and then a photolithography method is used. Then, the Cu layer 27 is etched so that it remains in a ring shape. Next, as shown in FIG. 6 Φ), a resist 26 is formed on the inner and outer peripheries of the ring-shaped Cu layer 27, and then, as shown in FIG. The adhesion layer 10 is removed, and a Ni layer 28 is formed on the portion where the adhesion layer 10 has been removed and on the ring-shaped Cu layer 27.
and an Au layer 29 are sequentially formed by plating. Next, Figure 6 (
As shown in d), the solder 17 is mounted on the Au layer 29.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a metal with poor solder wettability on the outer periphery of the solder attachment part, it is possible to prevent the solder from coming into contact with the main conductor, thereby preventing the peeling of bumps and the contact of the main conductor. This can contribute to improving reliability by preventing wire breakage.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, FIG. 2 is a diagram for explaining the manufacturing method of the first embodiment of the present invention, and FIG. 3 is a diagram showing a second embodiment of the present invention. FIG. 4 is a diagram for explaining the manufacturing method of the second embodiment of the present invention, FIG. 5 is a diagram showing the third embodiment of the present invention, and FIG. 6 is a diagram for explaining the manufacturing method of the second embodiment of the present invention. FIG. 7 is a diagram showing an example of surface mounting using conventional solder bumps. FIG. 8 is a diagram showing conventional solder bumps. FIG. 9 is a diagram showing the method of manufacturing the invention. FIG. In the figure, 1 is a ceramic substrate, 8 is a main conductor, 9, IO is an adhesion layer, 11 is a conductor pattern, 12 is a resin insulation layer, 17 is a solder, 21, 23 are Cr layers, 22, 24, and 28 are Ni layers. , 25.29 is an Au layer, 27 is a Cu layer, and 26.30.31 is a resist. Figure showing the second embodiment of the present invention Figure 1 showing the first embodiment of the present invention Substrate 8 Main conductor 17 Solder 27 Cu layer 28 Circuit layer 29...Au layer 25...Au layer (d) (b) (e) Diagram for explaining the manufacturing method of the first embodiment of the present invention (
b) ＼ (C) Figure 2 for explaining the manufacturing method of the second embodiment of the present invention (b) (d) Figure 4 for explaining the manufacturing method of the third embodiment of the present invention Figure 6 shows the third embodiment of the present invention Figure 5 1...Substrate 8...Main conductor 9.10...Adhesion layer 11...Wiring pattern 12...Resin insulating layer 17...・Solder 27...Cu layer 28...N1 layer 29...Au layer 32...Space Figure 7 (0) showing an example of surface mounting using conventional solder bumps 17 Conventional solder bumps Figure 9 (0) showing the problem to be solved by the invention Figure 9

Claims (1)

[Claims] 1. In order to prevent the solder (17) from coming into contact with the Cu main conductor (8) on the outer periphery of the solder joint, a metal with poor solder wettability compared to the solder joint is soldered. A solder bump characterized by being provided around a bonding part. 2. A multilayer wiring using a resin insulating layer (12) and a conductor (8) is wrapped on the substrate (1), and an adhesive layer (21),
A Ni layer (22) and an adhesion layer (23) are sequentially provided, and a hole is provided in the uppermost adhesion layer (23), and a Ni layer (24) and an Au or Pt layer (25) are formed in the hole. 1. A solder bump, characterized in that the Au or Pt layer (25) is provided with a solder (17) mounted thereon. 3. Step of sequentially forming an adhesive layer (9), a main conductor (8), an adhesive layer (10) and a resin insulating layer (12) on the substrate (1), and a bump forming area of the resin insulating layer (12). a step of opening a window to expose the adhesive layer (10) by etching; and forming an adhesive layer (21) on the exposed adhesive layer (10);
a step of sequentially forming a layer (22) and an adhesive layer (23);
A step of etching and removing the bump forming area of the uppermost adhesive layer (23), and a Ni layer (24) and an Au or Pt layer on the Ni layer (22) in the portion where the adhesive layer (23) has been removed. (25) forming the adhesive layer (23) so that the adhesive layer (23) remains in a ring shape;
23) and the underlying Ni layer (22) and adhesion layer (21)
A method for manufacturing a solder bump, comprising: a step of etching away the Au or Pt layer (25); and a step of mounting a solder (17) on the Au or Pt layer (25). 4. In a multilayer wiring board in which multilayer wiring is enclosed by a resin insulating layer (12) on a substrate (1) and a main conductor (8) having adhesive layers (9, 10) above and below, the upper adhesive layer ( 10) is provided with a hole, and a ring-shaped Cu layer (27) is provided on the adhesive layer (10) around the hole, and further includes the Cu layer (27) to form a main conductor (8).
) A solder bump characterized in that a Ni layer (28) and an Au layer (29) are provided on the solder bump, and a solder (17) is further mounted on the Au layer (29). 5. Step of sequentially forming an adhesive layer (9), a main conductor (8), an adhesive layer (10) and a Cu layer (27) on the substrate (1);
A step of removing the bump forming regions of the Cu layer (27) and the adhesion layer (10) by etching;
A step of forming a layer (28) and an Au layer (29), etching and removing the Cu layer (27) using the Au layer (29) as a mask, and replacing the Cu layer (27) with the Ni layer (28). A process of leaving a ring-shaped layer underneath, and a step of leaving a resin insulating layer (1 layer) around the ring-shaped Cu layer (27).
2); and mounting a solder (17) on the Au layer (29). 6. A metal with poor solder wettability is provided on the bump forming region on the main conductor (8) made of Cu, and a metal with good solder wettability is formed on the outer circumference of the metal with poor solder wettability in a ring shape. A solder bump characterized in that the solder bump (17) is provided on the metal with good solder wettability. 7. Forming an adhesive layer (9), a main conductor (8), an adhesive layer (10), and a Cu layer (27) on the substrate (1), and etching the Cu layer (27) by photolithography. a step of leaving the Cu layer (27) in a ring shape, and etching away the adhesive layer (10) under the ring-shaped Cu layer (27) in an area slightly smaller than the inner circumference of the Cu layer (27). a main conductor (8) exposed by removing the adhesive layer (10);
and a Ni layer (28) on the ring-shaped Cu layer (27).
) and an Au layer (29), and a step of mounting a solder (17) on the Au layer (29).