JP2001274203A - 2-metal substrate and BGA structure - Google Patents

Abstract

(57) [Problem] To provide a two-metal substrate and BGA structure in which the number of manufacturing steps is reduced by performing a blind via hole filling process to improve productivity and reliability. A blind via hole (17) is formed by a laser beam (7) from the copper foil surface on one side of a copper foil (1) / base material (2) / copper foil (4) constituting a double-sided copper-coated laminate without an adhesive layer. In a two-metal substrate in which the blind via hole 17 is subjected to Cu plating 13 to make it conductive, only the opening of the blind via hole 17 is covered with the Cu plating 1
After 3, Ni plating 18 and Au plating 8 are sequentially performed to fill the blind via holes 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a BGA (Ball Gri
d Array) 2-layer wiring TAB (Tape AutomatedBondin)
g) A two-metal substrate (two-layer wiring board) having a wiring pattern on both sides of an insulating substrate such as a tape, particularly a two-metal substrate suitable for obtaining a wiring pitch of 80 μm or less, and a BGA structure using the same as a base material It is about.

[0002]

2. Description of the Related Art As electronic devices have become smaller and lighter, their components have been further enhanced in function and density. In recent years, mounting components of semiconductor devices such as LSIs have been increased in number of pins with higher integration.
GA (Ball Grid Array) / CSP (Chip Size Packag)
e or Chip Scale Package), a package mounting technology that allows a wide pin pitch and allows the use of bare chips is being developed. In order to promote high-density mounting, fine patterns on substrates such as TAB tapes and printed wiring boards have been made, and multilayered printed wiring boards have been promoted like build-up multilayer wiring boards. I have.

In a TAB tape, a polyimide tape is used as a base material and a wiring pattern is formed on one surface thereof.
Metal TAB tapes are generally used, but the frequency of chips mounted on personal computers and the like is increasing, and the necessity of circuits with high transmission speeds is increasing. A two-metal (two-layer wiring) TAB tape in which a polyimide tape is used as a base material and wiring patterns are formed above and below the base material has been put to practical use.

As a conventional technique for manufacturing this two-metal TAB tape, as shown in FIG. 9, an adhesiveless two-layer Cu-bonded CCL having a polyimide resin layer 2 as an insulating layer between two copper foils 1 and 4 is shown. (Copper Clad Laminate) Tape 3
Is prepared as a base material (FIG. 9A), a photoresist 6 is applied to the copper foil 4 on one side thereof, and a Cu wiring pattern 34 having a via hole pattern is formed by exposure and etching (FIG. 9B). (E)), a blind via hole 17 reaching the copper foil 1 from the via hole pattern portion is formed in the polyimide resin layer 2 by laser processing (FIG. 9).
(F)). Next, Cu plating 13 is performed in the blind via hole 17 to connect the Cu wiring pattern 34 to the copper foil 1 on the other side (FIGS. 9F to 9H). Further, a Cu wiring pattern is formed on the other surface by photoresist and etching. After a Cu wiring pattern is formed on both sides, a photo solder resist or an epoxy solder resist is applied thereon by a printing method as needed, and coated, followed by baking. And Ni on the wiring pattern
/ Au plating is performed.

[0005]

However, since the base material does not require an adhesive, the number of processing steps increases, and the blind via hole (blind via) structure fills the blind via hole even when the conductive material is provided by a Cu plating layer. Insufficiently, bubbles are generated at the time of the next photoresist coating, and the wire is disconnected at the time of etching the wiring of the Cu layer, the yield is reduced, and the wiring pitch: CSP (Chip Scale) of 50 μm or less
Package) cannot be used as BGA.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to form a blind via hole by forming a hole in a double-sided Cu-bonded base tape without an adhesive by using a laser (having a diameter of 80 μm or less) from the Cu surface. By forming a structure in which only portions are plated with Cu and then plated with Ni and Au, blind via holes can be filled, thereby reducing the number of manufacturing steps, and without limiting the type of copper foil used for wiring. Another object of the present invention is to provide a two-metal substrate such as a two-layer wiring TAB tape and a BGA structure with improved productivity and reliability.

[0007]

In order to achieve the above object, the present invention provides a method of forming a blind via hole structure of a double-sided copper-adhesive-less base material by laser processing, and using only Cu plating and Ni plating on the blind via hole and its surroundings. The main point is to adopt a structure of plating and Au plating. Specifically, the structure is as follows.

(1) According to the first aspect of the present invention, a blind via hole is formed by a laser beam from a copper foil surface on one side of a copper foil / base material / copper foil structure constituting a double-sided copper-coated laminate without an adhesive layer. Then, in the two-metal substrate in which the blind via hole was subjected to copper plating to make it conductive, only the opening of the blind via hole was subjected to Ni plating and Au plating sequentially after the Cu plating to fill the blind via hole. Features.

(2) The two-metal substrate according to the first aspect, wherein the copper foil of the double-sided copper-coated laminate is any one of a rolled foil, an electrolytic foil, and an electrolytic foil. Characterized by comprising:

(3) The invention of claim 3 is the invention according to claim 1 or 2
3. The two-metal substrate according to claim 1, wherein the base material of the double-sided copper-coated laminate is made of any one of polyimide, BT resin, and glass epoxy, and has a water absorption of 2.8 or less (24-hour immersion test in 23 ° C. water). ).

(4) The invention according to claim 4 is the two-metal substrate according to claim 1, 2 or 3, wherein the Cu plating, N
i-plated and Au-plated blind via holes
Further, a Ni, Au, or Sn solder plating layer is formed.

(5) The invention according to claim 5 is directed to a BGA structure, wherein a semiconductor element is mounted on the two-metal TAB tape according to claim 1, and the wiring pattern of the copper foil is provided. A solder ball is provided on a wiring pattern of the other copper foil which is connected to one of the copper foils and is electrically connected to the wiring pattern through a via hole.

(Supplementary explanation of the main points) (a) Only the opening of the blind via hole, that is, only the blind via hole and the periphery thereof are plated with Cu,
i-plating and Au-plating structure.

The blind via hole is filled by Ni plating and Au plating after Cu plating only the blind via hole and its periphery. Especially Ni
The plating has good plating coverage and is effective for filling holes. After that, the Au plating is performed on the Ni plating in order to improve adhesion and oxidation resistance (prevention of oxidation due to heat history in the process) when Ni plating and Au plating are performed again later. It is.

By filling the blind via holes, the photoresist can be prevented from being broken by foaming due to baking after the application of the photoresist, and the number of processing steps can be reduced by filling the holes.

(B) The base material is polyimide, BT resin, glass epoxy and has a water absorption of 2.8 or less (immersion test in water at 23 ° C. for 24 hours).

This is because if the water absorption of the base material is large at the time of solder reflow, a so-called hop cone phenomenon occurs, in which the base material peels off from the copper foil, making the BGA structure unreliable. By going away.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment.

(Embodiment 1, FIGS. 1-2) FIGS. 1 and 2
Next, a first embodiment of the two-metal substrate and the BGA structure of the present invention is shown.

FIG. 1A shows a two-layer CCL (Copper Clad).
Laminate) Tape 3, a double-sided copper-clad laminate without adhesive (here double-sided copper cast base material without adhesive layer). The material composition of this two-layer CCL tape 3 is 18
μm high-temperature high elongation foil HTE foil copper foil 1/50 μm thick polyimide resin layer 2/18 μm thick
This is the configuration of the copper foil 4 which is a high-temperature, high-stretch foil HTE foil made by Mitsui Kinzoku. That is, using an HTE foil thickness of 18 μm of a high temperature and high elongation foil made of Mitsui Kinzoku Co., Ltd.
An L (thickness 18 μm / 50 μm / 18 μm) casting material was prepared. Note that the copper foil 1 is a portion to be a signal layer later, and the copper foil 4 is a portion to be a ground layer later.

Next, as shown in FIG. 1 (b), a device hole 9 and a blind via hole 17 are formed in one side of the copper foil 4 and the polyimide resin layer 2 by using a direct laser (laser beam 7). Carried out.

A photoresist is coated on the perforated copper foil 4 leaving only the blind via hole 17 and its periphery, and as shown in FIG.
The plating 13 was applied to a thickness of 15 μm to make the blind via holes 17 conductive. However, this alone does not sufficiently fill the blind via holes, and bubbles may be generated at the time of the next photoresist coating, and the wires may be disconnected at the time of etching the wiring of the Cu layer. Therefore, subsequently, a Ni plating 18 is formed on the Cu plating 13 of the blind via hole 17.
Was plated at a thickness of 8 μm, and Au plating 8 was further applied thereon at a thickness of 1 μm, thereby completely filling the blind via holes 17.

Next, a dry film resist is applied on both sides, and a new ground pattern is formed on the layer side of the plated copper foil 4 by Cu etching. A wiring pattern having a beam lead 25 (wiring pitch 50 μm) was formed (FIG. 1).
(D)).

Next, as shown in FIG. 1 (e), a photosensitive solder resist 6 is applied by printing, and is exposed and developed to pattern the photo solder resist 6 (processing accuracy of 10 μm) to obtain a 1.0% After developing with an alkaline aqueous solution (NaOH), baking and curing at 150 ° C (thickness of 20μ after curing)
m) to form the solder ball via 6a. Thereafter, the wiring pattern was plated with Ni / Au to obtain a two-layer wiring TAB tape for BGA of the product.

For comparison, a double-sided copper-coated CC without an adhesive using a normal copper foil, SLP foil manufactured by Nihon Denshi Co., Ltd.
L, that is, copper foil 1/18 μm-thick SLP foil manufactured by Nihon Denshi / polyimide resin layer 2/50 μm thick 2/18 μm thick
2 layer CC made of copper foil 1 which is SLP foil manufactured by Nihon Denshi
A product was prepared using the L tape in the same process as above.

Subsequently, as shown in FIG. 2, a semiconductor device having a BGA structure was constructed by using the above-described BGA two-layer wiring TAB tape. First, as shown in FIG. 2 (f), direct bonding to the Al element electrode of the LSl chip 12 was performed by inner lead bonding 10. Thereafter, the joint was sealed with a sealing resin 23. Also, the ground plane, that is, copper foil 4
, A stiffener 20 was attached via an adhesive 19. Further, the solder balls were reflowed into the solder ball vias 6a, and as shown in FIG.
A total of 864 solder balls 16 were mounted.

The thus obtained embodiment and comparative example B
As a characteristic test of the GA structure, both were tested at 85 ° C x 85% RH.
After holding for 196 hours and absorbing moisture, the temperature cycle was -65 ° C.
(Holding for 30 minutes) + 150 ° C. (holding for 30 minutes) was carried out for 2000 cycles, and a comparative study was conducted. As a result, in the comparative example, no lead disconnection occurred in the product of the combination of both up to 2000 cycles, and good results were obtained in the combination with the adhesive of the present invention.

In the above embodiment, the embodiment having the device hole has been described. However, the present invention is not limited to this, and the case where the beam lead is directly bonded to the bump as shown in FIGS. The present invention can be applied to a flip chip without a device hole as shown in FIGS. 5 to 6 and a bonding type TAB tape as shown in FIGS.

(Embodiment 2, FIGS. 3-4) FIGS. 3-4
Next, an example in which the beam lead 25 is directly bonded to the bump will be described.

As shown in FIG. 3A, the thickness 18
μm high-temperature high elongation foil HTE foil copper foil 1/50 μm thick polyimide resin layer 2/18 μm thick
A two-layer CCL tape 3 having a configuration of a copper foil 4 which is a high-temperature, high-stretch foil HTE foil made by Mitsui Kinzoku is prepared.

Next, as shown in FIG. 3B, a device hole 9 and a blind via hole 17 are formed in the copper foil 1 and the polyimide resin layer 2 on one side by using a laser beam 7.

A dry film 26 is provided on the perforated copper foil 1 leaving only the blind via hole 17 and the periphery thereof. As shown in FIG. 3C, a Cu plating 13 is applied to a thickness of 15 μm. Blind beer hall 1
7 is made conductive. Next, this blind beer hall 1
7, Ni plating 18 is applied to a thickness of 8 μm on the Cu plating 13, and Au plating 8 is applied thereon to a thickness of 1 μm, thereby completely filling the blind via holes 17.

Next, a wiring pattern (wiring pitch 50 μm) is formed on the layer side of the plated copper foil 1 by Cu etching by applying a dry film resist on both sides, and the opposite copper foil 4 not plated is formed. On the layer side, a wiring pattern having a beam lead 25 is formed (FIG. 4).
(D)).

Next, as shown in FIG. 4D, a photosensitive solder resist 6 is applied by printing, and is exposed and developed to pattern the photo solder resist 6 (processing accuracy of 10 μm) to obtain a 1.0% After developing with an alkaline aqueous solution (NaOH), baking and curing at 150 ° C (thickness of 20μ after curing)
m) to form the solder ball via 6a. Thereafter, the wiring pattern is plated with Ni / Au to obtain a two-layer wiring TAB tape for BGA of the product.

Then, as shown in FIG. 4D, the LSl chip 12 is fixed via the die attach agent 11 to the side where the solder ball via 6a is not formed.

Next, as shown in FIG. 4E, the beam lead 25 is pressed down by a bonding tool and cut.
It is directly joined to the Al element electrode of the LSl chip 12 as it is. Thereafter, the joint is sealed with the sealing resin 23. Then, the solder balls 16 are mounted on the solder ball vias 6a by reflow.

(Embodiment 3, FIGS. 5 to 6) FIGS. 5 to 6
FIG. 1 shows an example of a form of a flip chip without a device hole.

First, as shown in FIG.
μm high-temperature high elongation foil HTE foil copper foil 1/50 μm thick polyimide resin layer 2/18 μm thick
A two-layer CCL tape 3 having a configuration of a copper foil 4 which is a high-temperature, high-stretch foil HTE foil made by Mitsui Kinzoku is prepared.

Next, as shown in FIG. 5B, a blind via hole 17 is formed in the copper foil 4 and the polyimide resin layer 2 on one side by using a laser beam. A dry film 26 is provided on the perforated copper foil 4 leaving only the blind via hole 17 and the periphery thereof.
As shown in (c), a Cu plating 13 is applied to a thickness of 15 μm to make the blind via holes 17 conductive. Subsequently, Ni plating 18 is applied to the Cu plating 13 of the blind via hole 17 to a thickness of 8 μm, and further, Au plating 8 is applied to the Cu plating 13 to a thickness of 1 μm, whereby the blind via hole 17 is completely filled. .

Next, a wiring pattern (wiring pitch: 50 μm) is formed on the layer side of the plated copper foil 4 by Cu etching by applying a dry film resist on both sides, and the opposite copper foil 1 not plated is formed. On the layer side, a wiring pattern having a flip chip bonding region 27 is formed (FIG. 6D).

Next, as shown in FIG. 6D, a photosensitive solder resist 6 is applied by printing, and is exposed and developed to pattern the photo solder resist 6 (processing accuracy of 10 μm) to obtain a 1.0% After developing with an alkaline aqueous solution (NaOH), baking and curing at 150 ° C (thickness of 20μ after curing)
m) to form the solder ball via 6a. Thereafter, the wiring pattern is plated with Ni / Au to obtain a two-layer wiring TAB tape for BGA of the product.

Subsequently, as shown in FIG. 6D, the LSI chip 12 is fixed via the die attach agent 11 on the side where the solder ball via 6a is not formed. At this time, the Al element electrode of the LSI chip 12 is directly bonded to the flip chip bonding region 27 of the copper foil 1 by the flip chip bonding 14. Then, the joint is sealed with an underfill agent 15.

Finally, as shown in FIG. 6E, the solder balls 16 are reflowed and mounted in the solder ball vias 6a.

(Embodiment 4, FIGS. 7 and 8) FIGS. 7 and 8
An example of application to a bonding type TAB tape is shown in FIG.

First, as shown in FIG.
μm high-temperature high elongation foil HTE foil copper foil 1/50 μm thick polyimide resin layer 2/18 μm thick
A two-layer CCL tape 3 having a configuration of a copper foil 4 which is a high-temperature, high-stretch foil HTE foil made by Mitsui Kinzoku is prepared.

Next, as shown in FIG. 7B, blind via holes 17 are formed in the copper foil 4 and the polyimide resin layer 2 on one side by using a laser beam. A dry film 26 is provided on the perforated copper foil 4 leaving only the blind via hole 17 and the periphery thereof.
As shown in (c), a Cu plating 13 is applied to a thickness of 15 μm to make the blind via holes 17 conductive. Subsequently, Ni plating 18 is applied to the Cu plating 13 of the blind via hole 17 to a thickness of 8 μm, and further, Au plating 8 is applied to the Cu plating 13 to a thickness of 1 μm, whereby the blind via hole 17 is completely filled. .

Next, a dry film resist is applied to both sides, and a wiring pattern (wiring pitch 50 μm) is formed on the layer side of the plated copper foil 4 by Cu etching, while the opposite copper foil 1 not plated is formed. On the layer side, a wiring pattern having a bonding region 28 is formed (FIG. 6).
(D)).

Next, as shown in FIG. 8D, a photosensitive solder resist 6 is printed and coated, and is exposed and developed to pattern the photo solder resist 6 (processing accuracy of 10 μm) to obtain a 1.0% After developing with an alkaline aqueous solution (NaOH), baking and curing at 150 ° C (thickness of 20μ after curing)
m) to form the solder ball via 6a. Thereafter, the wiring pattern is plated with Ni / Au to obtain a two-layer wiring TAB tape for BGA of the product.

Subsequently, as shown in FIG. 8D, the LSI chip 12 is fixed via the die attach agent 11 on the side where the solder ball via 6a is not formed.
The device electrode and the bonding region 28 of the copper foil 1 are connected by wire bonding 22.

Then, as shown in FIG. 8E, the joint is sealed with an underfill agent 15, and the solder balls 16 are reflowed and mounted on the solder ball vias 6a.

The two-layer wiring board and B according to the second to fourth embodiments.
The GA structure eliminates photoresist breakage due to air bubbles, does not break due to wiring etching, and has excellent reliability against repeated thermal stress loads in temperature cycle tests.
A two-layer wiring TAB tape or a two-layer wiring board with fine wiring (pitch: 80 μm or less) and a package having a BGA structure could be supplied.

[0052]

As described above, the present invention has the following excellent effects.

(1) According to the first, second, and fifth aspects of the present invention, the blind via hole can be filled, the photoresist is not broken by air bubbles, there is no disconnection due to wiring etching, and high reliability is achieved. A two metal substrate and a CSP / BGA structure could be provided.

(2) According to the third and fifth aspects of the present invention, since the base material of the double-sided copper-coated laminate is made of a polyimide resin layer having a low water absorption, the migration resistance of the two-layer wiring TAB tape is reduced. Improved. Further, due to the roughness of the polyimide due to the transfer of the roughened surface of the copper foil after the removal of the copper foil, the adhesion to the photo solder resist is high and the reliability is high.

(3) According to the invention as set forth in claims 4 and 5, Ni, Au, or S is further provided in the blind via hole plated with Cu, Ni, and Au.
n-layer wiring TAB
The blind via holes in the tape are completely filled,
For this reason, even if the cost of the base material is high, the production yield and productivity are improved and stable, so that mass production can be performed, and the overall production cost is reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a two-metal substrate according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a BGA structure following the manufacturing process of FIG. 1;

FIG. 3 is a cross-sectional view illustrating a manufacturing process of a two-metal substrate according to a second embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a manufacturing process of a two-metal substrate and a manufacturing process of a BGA structure following the manufacturing process of FIG. 3;

FIG. 5 is a cross-sectional view showing a manufacturing process of a two-metal substrate according to a third embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a manufacturing process of a two-metal substrate and a manufacturing process of a BGA structure following the manufacturing process of FIG. 5;

FIG. 7 is a cross-sectional view illustrating a manufacturing process of a two-metal substrate according to a fourth embodiment of the present invention.

FIG. 8 is a cross-sectional view showing a manufacturing step of the BGA structure following the manufacturing step of FIG. 7;

FIG. 9 is a cross-sectional view showing a manufacturing process of a conventional two-metal substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 copper foil (signal layer) 2 polyimide resin layer 3 two-layer CCL (adhesive-less double-sided copper-coated CCL) tape 4 copper foil (ground layer) 6 photosensitive solder resist 6 a solder ball via 7 laser beam 8 Au plating 9 device Hole 12 LSI chip 13 Cu plating 16 Solder ball 17 Blind via hole 18 Ni plating

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05K 1/11 H05K 3/00 N 3/00 3/34 505A 3/34 505 H01L 23/12 Q

Claims (5)

[Claims] 1. A blind via hole is formed by laser light from a copper foil surface on one side of a copper foil / base material / copper foil structure constituting a double-sided copper-coated laminate without an adhesive layer, and copper plating is applied to the blind via hole. In the two-metal substrate that has been made conductive by applying
Ni plating and Au plating are sequentially performed after plating to fill the blind via holes.
Metal substrate. 2. The copper foil of the double-sided copper-coated laminate is a rolled foil,
2. The two-metal substrate according to claim 1, wherein the two-metal substrate is made of an electrolytic foil or any one of a copper foil material of the electrolytic foil. 3. The base material of the double-sided copper-coated laminate is made of a resin selected from the group consisting of polyimide, BT resin and glass epoxy, and has a water absorption of 2.8 or less (24% water at 23 ° C.).
3. A time immersion test).
A two-metal substrate as described. 4. The method according to claim 1, wherein the blind vias plated with Cu, Ni, and Au are further provided with Ni, Au, or S.
4. The two-metal substrate according to claim 1, wherein an n solder plating layer is formed. 5. The two-metal T according to claim 1, 2, 3, or 4.
A BGA structure wherein a semiconductor element is mounted on an AB tape, connected to one of the copper foil wiring patterns, and solder balls are provided on the other copper foil wiring pattern which is conducted through the wiring pattern and via holes.