JP2002280731A - Wiring board equipped with solder ball and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which is equipped with solder balls excellent in connection reliability after a thermal treatment and its manufacturing method. SOLUTION: An electrolytic nickel alloy plating film, an electroless palladium plating film, and an electrolytic gold plating film are successively formed on a conductor terminal. A wiring board is equipped with the above conductor terminal and a solder ball that has such a certain composition which never increases in shear strength by 10% or above by a thermal treatment and is formed on the above conductor terminal, and a solder ball connection terminal is mounted with a solder ball. A wiring board manufacturing method is that solder paste having composition which hardly increases in shear strength by 10% or above by a thermal treatment is applied onto a board equipped with a conductor terminal successively coated with an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film and melted into solder balls by heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board having solder balls and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the density of printed wiring boards on which electronic components are mounted and semiconductor mounting substrates on which semiconductors are directly mounted have been increasing, and mounting methods have been adapted to higher densities. The mounting method in which the terminal pins of the electronic component are inserted into the holes and fixed with solder has been changed to the surface mounting method in which the terminal pins of the surface layer of the wiring board are fixed with solder.

[0003] Also, in electronic parts for surface mounting, lead terminals are provided on four sides of a dual in-line package (hereinafter referred to as DIP) in which lead terminals for solder connection are formed in two rows in parallel, or a square package. In addition, a ball grid array (hereinafter, referred to as BGA) has been changed from a quad flat package (hereinafter, referred to as QFP), which is connected to the back surface of the package by solder balls arranged in a grid.

In the terminal structure of the BGA to which the solder balls are connected, the solder balls are connected to the conductor terminals.

[0005] The solder balls used here are eutectic solder balls in which the ratio of tin to lead is 6: 4. In recent years, dozens or more types of solders that do not use lead have been proposed due to the problem of the global environment, but they have not been substituted for eutectic solder balls.

[0006]

However, in the conventional terminal structure in which eutectic solder balls are connected, there is a problem that the heat treatment after the connection of the solder balls may significantly reduce the connection reliability. In the connection failure of the solder ball, there are a case where the solder ball itself is broken and a case where the interface between the solder ball and the solder ball connection terminal is peeled off.
There is a problem that the connection failure in a normal use state is almost caused by the peeling of the interface between the solder ball and the solder ball connection terminal unless a considerably large external force is applied.

An object of the present invention is to provide a wiring board having solder balls, which has excellent connection reliability after heat treatment, and a method of manufacturing the same.

[0008]

The present invention is characterized by the following. (1) An electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are applied on a conductor terminal formed in this order to have a shear strength of 10 by heat treatment.
A wiring board having a solder ball having a composition that does not increase by more than 10%. (2) heat treatment, leaving treatment at 0 ° C. or more and 170 ° C. or less,
Alternatively, the wiring board having the solder balls according to (1), which is any one of cooling and heating cycling treatments in which the temperature is alternately changed within a range of -100 ° C or more and 170 ° C or less. (3) A solder ball connecting terminal on which a solder ball is mounted, wherein an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are heat-treated on a substrate having conductor terminals formed in this order. A method of manufacturing a wiring board in which a solder paste having a composition that does not increase the shear strength by 10% or more is applied and heated and melted to form a solder ball. (4) A solder ball connection terminal for mounting a solder ball, wherein an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are heat-treated on a substrate having conductor terminals formed in this order. A method of manufacturing a wiring board in which solder plating having a composition in which the shear strength does not increase by 10% or more is performed and heated and melted to form a solder ball. (5) heat treatment, leaving treatment at 0 ° C. or more and 170 ° C. or less,
Or the method of manufacturing a wiring board according to (3) or (4), which is one of cooling and heating cycle treatments in which the temperature is alternately changed within a range of −100 ° C. or more and 170 ° C. or less.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The wiring board of the present invention has a solder ball connection terminal for mounting a solder ball, and can be used without being limited to a substrate material such as a ceramic substrate or an organic substrate. As the ceramic substrate, an alumina substrate, an aluminum nitride substrate, or the like can be used. As the organic substrate, an FR-4 substrate in which a glass cloth is impregnated with an epoxy resin, a BT substrate in which a bismaleimide-triazine resin is impregnated, and a polyimide film substrate using a polyimide film as a base material can be used. .

The wiring structure may be any of single-sided wiring, double-sided wiring, and multilayer wiring, and may be used as required. In particular, when using a wiring board provided with non-through holes that can respond to high density even among multilayer wiring, it is difficult to ensure reliability because the area ratio of component mounting is large, but it is bonded through an adhesive containing the above conductive particles. By using the metal foil thus obtained for the conductor pattern, it is possible to improve the connection reliability. On the wiring board provided with non-through holes, a ceramic substrate was formed by sintering and laminating a conductive pattern of a green sheet and a conductive paste and a multilayer material filled with a conductive paste in via holes provided in the green sheet. A substrate can be used. On the organic substrate, an insulating layer is formed on the surface of the inner layer circuit board, a non-through hole is provided in the insulating layer by a laser method or a photo method, and a conductor circuit connected to the inner layer circuit is formed, and this is sequentially repeated and manufactured. A substrate manufactured by a build-up method can be used.

Further, if the substrate is capable of mounting solder balls, it is a tape automated bonding (hereinafter, referred to as TAB), a lead frame, and a ball grid array (hereinafter, referred to as BGA) as currently used. ), A chip size package (hereinafter, referred to as CSP), a multi-chip module (hereinafter, referred to as MCM), and the like.

Usually, such wiring boards mount electronic components such as semiconductor chips and connect them to a motherboard by solder balls in many cases. What mounts a solder ball may be used. Further, not only a semiconductor chip but also a chip capacitor and a chip resistor may be mounted.

[0013] The material of the solder ball connection terminal is copper,
Metals such as tungsten and molybdenum can be used. The surface treatment of the conductor of the present invention is electroless nickel alloy plating, in which nickel ions in the plating solution are activated by the movement of a reducing agent for nickel ions, and the surface of the conductor, such as copper, tungsten, or molybdenum, is activated. The composition of the electroless nickel alloy plating film is
Usually, it contains an element (phosphorus, boron, nitrogen, etc.) derived from a reducing agent and becomes an alloy with nickel, such as an electroless nickel / phosphorus alloy plating film and an electroless nickel / boron alloy plating film. The electroless nickel alloy plating film is preferably made of nickel having a purity of 80% by weight or more, and if less than 80% by weight, the reliability of the connection may be reduced. Further, it is more preferable that the purity is 90% by weight or more. The thickness of the electroless nickel alloy plating film is
0.1 μm to 20 μm, preferably 0.1 μm
If it is less than m, there is no plating effect and the connection reliability does not improve, and if it exceeds 20 μm, the effect does not improve further,
It is not preferable because it is not economical. Further, the thickness of the electroless nickel alloy plating is more preferably in the range of 0.5 to 10 μm.

In the electroless palladium plating, palladium ions in a plating solution are deposited on the nickel surface by the action of a reducing agent. When a formic acid compound is used as the reducing agent, the purity of the electroless palladium plating film is 99%. % By weight or more, the connection reliability is high and preferable. When a phosphorus-containing compound or a boron-containing compound is used as a reducing agent, the plating film becomes palladium-phosphorous or palladium-containing.
Although it becomes a boron alloy and the purity of palladium becomes 90% by weight or more, there is no problem in the solder ball connection reliability. The purity of the palladium may be 90% by weight or more. The thickness of the electroless palladium plating film is preferably 0.01 μm to 5 μm,
If it is less than 01 μm, there is no effect of plating and the connection reliability is not improved. If it exceeds 1 μm, the effect is not further improved and it is not economical. Further, the thickness of the electroless palladium is more preferably in the range of 0.01 to 1 μm.

Among the electroless gold platings, the substitutional electroless gold plating forms a gold film on the nickel surface by a substitution reaction between the underlying nickel and gold ions in the solution. Some plating solutions include compounds and some do not, but any plating solution can be used. Among electroless gold plating, reduction type electroless gold plating is
The action of the reducing agent causes gold to be deposited on the substitutional electroless gold plating film by a chemical reaction. As the reducing agent, those containing boron or those containing sulfur can be used. The electroless gold plating film is preferably gold having a purity of 99% by weight or more, and if it is less than 99% by weight, the reliability of connection may be reduced. Further, the purity of the electroless gold plating film is more preferably 99.5% by weight or more. The thickness of the electroless plating film is 0.005 μm or more.
When the thickness is less than 0.005 μm, there is no effect of plating and the reliability of the connection is not improved.
If it exceeds m, the effect is not further improved and it is not economical, so that it is not preferable. Further, the thickness of the electroless gold plating film is more preferably in the range of 0.005 to 0.5 μm.

The present invention is also characterized in that a solder ball having a composition whose shear strength does not increase by 10% or more by heat treatment is used on a terminal of a conductor which is a terminal for connecting the solder ball.

The fact that the shear strength does not increase to 10% or more by this heat treatment means that, before the heat treatment, the spherical solder ball or the cylindrical solder wire is bonded to the fixing table as shown in FIG. Then, the shearing tool / strength sensor is moved in the horizontal direction at a speed of 0.3 mm / sec. At that time, the maximum load weight applied to the strength sensor is measured, and a leaving treatment at 0 ° C or higher and 170 ° C or lower is performed. Alternatively, it can be confirmed by performing a thermal cycling treatment in which the temperature is alternately changed within a range of -100 ° C or more and 170 ° C or less, and measuring the shear strength by the same method.

It is more preferable that the increase in shear strength does not increase to 5% or more. Such a composition of the solder may be a eutectic solder which is an alloy of lead and tin, or may further contain one or more metals of silver, antimony, copper and nickel other than these metals in the alloy of lead and tin. good.
In addition, silver as a metal other than tin in a tin alloy containing no lead,
Copper, zinc, nickel, bismuth, indium, a tin alloy containing at least one kind of nickel may be used,
Any material can be used as long as it does not exhibit a shear strength of 10% or more as determined by the method described above.

In order to manufacture such a wiring board, a solder paste having a composition whose shear strength does not increase by 10% or more by heat treatment is applied to a substrate having solder ball connection terminals on which solder balls are mounted, and heated and melted. This is possible by forming solder balls. Instead of this solder paste, solder plating can be performed.

[0020]

EXAMPLE A copper foil having a thickness of 18 μm was attached to both sides, and a thickness of 0.5
MCL-E-679 mm copper-clad epoxy laminate
Unnecessary portions of copper foil (made by Hitachi Chemical Co., Ltd.) are removed by etching, the etching resist is removed,
A semiconductor mounting substrate having a solder resist-formed copper solder ball connecting terminal with an exposed conductor pattern was prepared. The substrate for mounting a semiconductor was replaced with a degreasing liquid Z-2.
00 (made by World Metal Co., Ltd., trade name)
Immersed at 0 ° C for 1 minute, washed with water at room temperature for 2 minutes, 100 g /
Immersion in 1 liter of ammonium persulfate solution for 1 minute at room temperature, soft etching, washing with water for 2 minutes at room temperature, immersion in 10% by weight sulfuric acid for 1 minute at room temperature, pickling, washing with water for 2 minutes at room temperature Activation of electroless plating, SA-100
(Hitachi Kasei Kogyo Co., Ltd., trade name) for 5 minutes at room temperature, immersed for 2 minutes at room temperature, the solution into NIPS-100 (Hitachi Chemical Co., Ltd., trade name) which is an electroless nickel plating solution Immersion at a temperature of 85 ° C. for 20 minutes to form a Ni-P plating (P content: about 7% by weight) film, washing with water at room temperature for 2 minutes, and an electroless palladium plating solution, Paratec (manufactured by Atotech Japan KK) Product name), liquid temperature 7
Immersion at 0 ° C. for 5 minutes to form a film of pure palladium (purity 99.9% by weight), washing with water at room temperature for 2 minutes, and a non-cyanide substitution type electroless gold plating solution HGS-100 (Hitachi Chemical Co., Ltd.) (Trade name, manufactured by Kogyo Co., Ltd.) at a liquid temperature of 85 ° C. for 10 minutes to form a film of pure gold (purity: 99.9% by weight). The solder ball connecting terminals of the semiconductor mounting substrate prepared by the above method were added with a tin alloy of 97.25% by weight of tin, 3.5% by weight of silver and 0.75% by weight of copper at 150 ° C.
After leaving it at a high temperature for 0 hour, a solder ball whose change in shear strength was reduced by 10% was connected in a reflow furnace.

EXAMPLE 2 IM-GOLD (trade name, manufactured by Nippon Kojundo Chemical Co., Ltd.), which is a cyan substitutional electroless gold plating solution, was used for gold plating.
At 85 ° C. for 10 minutes in pure gold (purity 99.9).
% By weight), washed with water at room temperature for 2 minutes, and then added to HGS-2000 (manufactured by Hitachi Chemical Co., Ltd., trade name) as a reduction type electroless gold plating solution at a solution temperature of 65 ° C. for 40 minutes.
The same procedure as in Example 1 was conducted except that a film of pure gold (purity: 99.9% by weight) was formed by immersion for minutes. A semiconductor mounting substrate having solder ball connection terminals was prepared. 97.25% by weight of tin, 3.5% by weight of silver and 0.75% of
The solder ball whose shear strength was reduced by 10% was connected to a reflow furnace by being left at a high temperature of 150 ° C., which is a tin alloy of copper by weight, for 100 hours.

Comparative Example 1 A semiconductor mounting substrate was produced in the same manner as in Example 1. The solder ball connection terminal of the semiconductor mounting board prepared by the above method is a eutectic solder of 60% by weight of tin and 40% by weight.
Of solder balls, which is an increase in the number of solder balls, was connected in a reflow furnace.

Comparative Example 2 A semiconductor mounting substrate was manufactured in the same manner as in Example 2. 60% by weight of tin and 40% by weight of eutectic solder solder on the terminal for solder ball connection of the semiconductor mounting substrate prepared by the above method. Was connected in a reflow furnace.

(Shear Test Method) The shear test method for solder is performed using a universal bond tester. As shown in the figure, a spherical solder ball or a cylindrical solder wire is adhered to the fixed base, and the shearing tool / strength sensor is moved horizontally at a speed of 0.3 mm / sec. Measure the shear strength from the maximum load weight.
(4000 type, manufactured by Daiji Co., Ltd.) The BGAs produced in Examples 1 and 2 and Comparative Examples 1 and 2 to which solder balls were connected were subjected to a heat treatment at 150 ° C. for 100 hours, and then a shear (shear) test of the solder balls was performed. As a result, in the samples of Examples 1 and 2, all the solder balls were able to withstand the destruction due to the shearing in the balls, but the solder balls of Comparative Examples 1 and 2 had about 90% of the terminals. In the above, destruction occurred at the interface between the electroless nickel plating and the solder ball, and the connection reliability after the heat treatment was poor.

[0025]

As described above, according to the present invention, it is possible to provide a wiring board having solder balls having excellent connection reliability and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a schematic side view for explaining a measuring method of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B23K 3/06 B23K 3/06 H 31/02 310 31/02 310F H01L 23/12 501 H01L 23/12 501Z H05K 3/24 H05K 3/24 A F term (reference) 5E319 AC18 BB02 CC33 CD01 GG20 5E343 AA17 BB18 BB23 BB24 BB44 BB48 BB54 BB55 BB67 CC33 CC46 CC67 DD33 DD43 DD76 EE02 GG13

Claims (5)

[Claims] 1. A solder ball having a composition whose shear strength does not increase by 10% or more due to heat treatment on a terminal of a conductor in which an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are formed in this order. Having a wiring board. 2. The heat treatment is one of a leaving treatment at a temperature of 0 ° C. or more and 170 ° C. or less, or a cooling / heating cycle treatment of alternately changing the temperature within a range of −100 ° C. or more and 170 ° C. or less. A wiring board having the solder ball according to 1. 3. A solder ball connecting terminal for mounting a solder ball, wherein an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are formed on a substrate having conductor terminals formed in this order. And a method of manufacturing a wiring board in which a solder paste having a composition whose shear strength does not increase by 10% or more by heat treatment is applied, and heated and melted to form a solder ball. 4. A solder ball connection terminal for mounting a solder ball, wherein an electrolytic nickel alloy plating film, an electroless palladium plating film, and an electroless gold plating film are formed on a substrate having conductor terminals formed in this order. And a method of manufacturing a wiring board in which solder plating is performed so that the shear strength does not increase by 10% or more due to heat treatment, and the solder ball is formed by heating and melting. 5. The method according to claim 1, wherein the heat treatment is any one of a leaving treatment at a temperature of 0 ° C. or more and 170 ° C. or less, and a cooling / heating cycle treatment of alternately changing the temperature within a range of −100 ° C. or more and 170 ° C. 5. The method for producing a wiring board according to 3 or 4.