JP2011238669A - Solder ball mounting flux and solder bump forming method using thereof - Google Patents

Solder ball mounting flux and solder bump forming method using thereof Download PDF

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Publication number
JP2011238669A
JP2011238669A JP2010106909A JP2010106909A JP2011238669A JP 2011238669 A JP2011238669 A JP 2011238669A JP 2010106909 A JP2010106909 A JP 2010106909A JP 2010106909 A JP2010106909 A JP 2010106909A JP 2011238669 A JP2011238669 A JP 2011238669A
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Japan
Prior art keywords
solder
solder ball
flux
ball mounting
metal film
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Pending
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JP2010106909A
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Japanese (ja)
Inventor
Takehiko Murakami
武彦 村上
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Minami Co Ltd
ミナミ株式会社
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Priority to JP2010106909A priority Critical patent/JP2011238669A/en
Publication of JP2011238669A publication Critical patent/JP2011238669A/en
Application status is Pending legal-status Critical

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Abstract

An object of the present invention is to significantly reduce the rate of occurrence of defective bonding by improving the bondability between solder balls and terminals of a silicon wafer.
A solder ball mounting flux 4 contains fine solder particle powder having the same components and mixing ratio as solder balls 5 within a volume ratio of 8 to 15%. An under barrier metal film 3 made of electroless nickel plating and electroless gold plating is formed on the aluminum terminal 2 of the silicon wafer 1. Thereafter, the solder ball mounting flux 4 is applied thereon. A solder ball 5 is mounted on the under barrier metal film 3 with the adhesive force of the flux 4. Thereafter, the solder balls 5 are joined to the under barrier metal film 3 by heating to form bumps.
[Selection] Figure 1

Description

  The present invention relates to a solder ball mounting flux and a solder bump forming method using the same.

  The process of forming solder bumps on the electrodes of a silicon wafer by the solder ball mounting method is generally as follows. First, an under barrier metal film (UBM) is formed on a terminal of a silicon wafer by performing electroless nickel plating and electroless gold plating. This is because the terminal is often made of aluminum or an aluminum alloy, and in this case, the wettability with the solder is poor and the solder cannot be firmly bonded.

  Next, a solder ball mounting flux is applied on the under barrier metal film (UBM). The solder ball is mounted by the adhesive force. The solder balls are made of Sn, Ag, and Cu, and the lead-free solder has a low Ag content. For example, it is a mixing ratio of Sn (96 to 96.5%), Ag (3.0 to 0.5%), and Cu (0.5%). That is, when the Ag content is large, the melting point is about 40 ° C. higher than that of Sn and Pb, and when the chip is mounted on the silicon wafer, the silicon wafer itself is damaged by high-temperature heating. Because there is.

  Next, the solder balls are melted by heating (reflow) and bonded to the electrodes, and bumps are formed on the terminals. Then, the whole process is completed by cooling thereafter.

  The solder ball mounting flux used in such a process consists of a conventional general flux material. In this case, there is a problem that a part thereof remains when heated and adversely affects the bondability at the interface between the molten solder ball and the terminal, strictly speaking, the under barrier metal film (UBM). It was. As a result, many defective joints are produced, and wasteful labor and cost are required.

  As a result of diligent research to solve the above problems, the present inventor has found that the joining property is greatly improved by containing a small amount of fine solder particle powder in a predetermined ratio in the flux. It came to see completion. It has also been found that by forming solder bumps using such a flux, the solder bumps are not easily detached from the terminals, and the incidence of defective bonding can be greatly reduced.

  Thus, the present invention is intended to provide a solder ball mounting flux and a solder bump forming method using the same.

  In order to solve the above problems, the solder ball mounting flux according to the present invention contains fine solder particle powder having the same components and mixing ratio as the solder ball within a volume ratio of 8 to 15%. It is characterized by. The fine solder particle powder is preferably 2-5 μm or 5-12 μm.

  In the solder bump forming method using the solder ball mounting flux according to the present invention, the solder ball mounting flux is applied onto a terminal of a silicon wafer, and the solder is applied to the terminal of the silicon wafer with the adhesive force of the flux. A ball is mounted, and then a solder ball is bonded to an electrode by heating to form a bump.

  According to the solder ball mounting flux according to the present invention, when heated, the fine solder particle powder and the solder ball contained in the flux are integrated by melting, and the fine solder particle powder contained in the flux and Since the solder balls have the same components and mixing ratio, they are more strongly integrated. In this state, since the solder ball is bonded to the terminal of the silicon wafer, the solder ball and the terminal are bonded much more firmly than in the case of the conventional flux alone. Therefore, it is possible to greatly reduce the incidence of defective bonding.

  Further, according to the solder bump forming method of the present invention, the solder bumps are not easily detached from the terminals, and the occurrence rate of defective bonding can be greatly reduced.

It is explanatory drawing of the solder bump formation method which concerns on this invention, and shows the state which mounted the solder ball. The state after the heating is shown.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  In the figure, 1 is a silicon wafer and 2 is an aluminum terminal of the silicon wafer 1. Reference numeral 3 denotes an under barrier metal film made of electroless nickel plating (not shown) performed on the aluminum terminal 2 and electroless gold plating (not shown) performed on the electroless nickel plating.

  A solder ball mounting flux 4 is applied on the under barrier metal film 3. Reference numeral 5 denotes a solder ball mounted on the aluminum terminal 2, strictly speaking, on the under barrier metal film 3. The solder ball 5 is composed of the same components as in the prior art. Reference numeral 6 denotes an insulating film.

  Thus, the solder ball mounting flux 4 contains fine solder particle powder (not shown) having the same components and mixing ratio as the solder ball 5 within a volume ratio of 8 to 15%. Is. The other components are the same as in the prior art, and the volume ratio with the fine solder particle powder is 85 to 92%. Moreover, it is preferable to use a fine solder particle powder of 2 to 5 μm or 5 to 12 μm.

  According to the solder ball mounting flux 4, when heated, the fine solder particle powder and the solder ball 5 contained in the flux 4 are integrated by melting, and the fine solder particles contained in the flux 4 are integrated. Since the powder and the solder ball 5 have the same components and mixing ratio, they are more strongly integrated. In this state, the solder ball 5 is bonded to the silicon wafer 1, the aluminum terminal 2, and strictly speaking, the under barrier metal film 3. Therefore, the solder ball 5 and the aluminum terminal 2 are far more than the conventional flux alone. It joins firmly. Therefore, it is possible to greatly reduce the incidence of defective bonding.

  The solder bump forming method using the solder ball mounting flux 4 is performed by forming the under barrier metal film 3 composed of electroless nickel plating and electroless gold plating on the aluminum terminal 2 of the silicon wafer 1 and then soldering the solder bump. A ball mounting flux 4 is applied, a solder ball 5 is mounted on the under barrier metal film 3 with the adhesive force of the flux 4, and then the solder ball 5 is bonded to the under barrier metal film 3 by heating to form a bump. Is.

  According to such a method for forming solder bumps, the solder bumps are not easily detached from the aluminum terminal 2, and the occurrence rate of defective bonding products can be greatly reduced.

1 Silicon wafer 2 Aluminum terminal 3 Under barrier metal film (UBM)
4 Solder ball mounting flux 5 Solder ball 6 Insulating film

Claims (3)

  1.   A solder ball mounting flux comprising fine solder particle powder having the same components and mixing ratio as a solder ball in a volume ratio of 8 to 15%.
  2.   2. The solder ball mounting flux according to claim 1, wherein the fine solder particle powder is 2-5 [mu] m or 5-12 [mu] m solder powder.
  3. The solder ball mounting flux according to claim 1 is applied onto a terminal of a silicon wafer, the solder ball is mounted on the terminal of the silicon wafer with the adhesive force of the flux, and then the solder ball is bonded to the terminal by heating to bump. Forming a solder bump.
JP2010106909A 2010-05-07 2010-05-07 Solder ball mounting flux and solder bump forming method using thereof Pending JP2011238669A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2010106909A JP2011238669A (en) 2010-05-07 2010-05-07 Solder ball mounting flux and solder bump forming method using thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2010106909A JP2011238669A (en) 2010-05-07 2010-05-07 Solder ball mounting flux and solder bump forming method using thereof

Publications (1)

Publication Number Publication Date
JP2011238669A true JP2011238669A (en) 2011-11-24

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JP2010106909A Pending JP2011238669A (en) 2010-05-07 2010-05-07 Solder ball mounting flux and solder bump forming method using thereof

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013095670A1 (en) * 2011-12-23 2013-06-27 Intel Corporation Hybrid low metal loading flux

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2013095670A1 (en) * 2011-12-23 2013-06-27 Intel Corporation Hybrid low metal loading flux
US20130341379A1 (en) * 2011-12-23 2013-12-26 Rajen S. Sidhu Hybrid low metal loading flux
US9950393B2 (en) 2011-12-23 2018-04-24 Intel Corporation Hybrid low metal loading flux

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