JP2001313463A - Substrate for evaluating wettability, and method for evaluating wettability of brazing material electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate and method for evaluating, by which the solder wettability of a connection electrode of an electronic component with a solder ball as a connection electrode, e.g. such as BGA can be evaluated readily under a safe environment and with high reliability. SOLUTION: An evaluating substrate 10 is provided with wettability evaluating electrodes 11, each being made of a metal film which is formed on an end side on one surface of a base material 13. Each evaluating electrode 11 comprises a circular part 11a in one side and a strip part 11b extending from the circuit part 11a to the end edge side of the base material 13. The circular part 11a is used as a melting/fixing electrode for melting and fixing a solder ball of a BGA component (component electrode). For evaluating wettability, after a component is mounted on the evaluation substrate 10 (the solder ball is abutted on the circular part 11a), the solder ball is melted and the wet spread of the solder onto the evaluating electrode is observed visually, so that, wettability of the solder ball can be evaluated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate for evaluating the wettability of a brazing material electrode and a method for evaluating the wettability using the same, and more particularly, to the wettability of the solder in a BGA or the like having a solder ball as a brazing material electrode. TECHNICAL FIELD The present invention relates to a substrate for evaluating wettability of a brazing material electrode and an evaluation method suitable for evaluating the wettability.

[0002]

2. Description of the Related Art In recent years, the trend of reducing the size and weight of electronic equipment has become increasingly significant. In electronic components used, especially semiconductor components (semiconductor integrated circuit devices), in order to reduce the component volume in response to demands related to performance such as high-performance integration, high-speed signal processing, and an increase in memory capacity, a substrate is required. Efforts have been made to reduce the component mounting area above.

Conventionally, as a package shape of a semiconductor component, for example, a QFP (Quad F1at Package), a connection electrode (component electrode) to a mother board (see FIG. 6) to be connected is formed in a gull-wing shape from the side of the package. In recent years, BGA (Ba11 Grid Ar
ray), LGA (Land Grid Array), LCC (Lead1e
ss Chip Carrier), QFN (Quad F1at No lead Pack)
age), those in which the component electrodes are arranged on the lower surface or side surface of the package have come to be used frequently.
The reason is that, by using the semiconductor component having such a configuration, the area occupied by the semiconductor component when the semiconductor component is mounted on the mother board by a method such as soldering can be significantly reduced, and the electric wiring can be reduced. This is because the electrical characteristics of the circuit are improved because the length can be reduced.

When a component having a connection electrode on the lower surface (lower electrode component), such as BGA or LGA, is mounted on the mother substrate, the mother substrate is mounted as shown in FIGS. A solder paste 103 is printed on an electrode 102 of 101, a component such as a BGA component 104 is mounted on the solder paste with a connection electrode on the component side mounted thereon, and solder is applied using a heating device such as a reflow device. Generally, a method of electrically and mechanically connecting a component and a mother board by melting and re-solidifying in a lump is generally used.

However, an oxide film is formed on the surface of the component electrode due to long-term storage in the air,
In the case where a foreign matter is attached in a component manufacturing process such as that described above, the wettability of the electrode is reduced, and the electrical and mechanical connection after the above-mentioned reflow is incomplete. Therefore, it is very important to examine the solder wettability of component electrodes,
In particular, for a component such as a BGA using a solder ball as an electrode, there is no technology for directly examining solder wettability, and a method and apparatus for evaluating the wettability have been desired.

To explain the conventional example in detail, regarding the electrode wettability of components having a small number of electrodes, such as axial and radial lead components and surface mount components such as chip resistors, the electrodes are immersed in a molten solder bath. An evaluation method for capturing the wetting behavior using the meniscus method has been adopted. As an example, there is a "solderability test apparatus" in JP-A-7-83804.

[0007] Further, regarding an area array type component soldered to a substrate, especially an electronic component such as a BGA, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 9-89536 discloses a method for examining the density of an X-ray transmission image, as disclosed in Japanese Patent Application Laid-Open No. 9-89536.
A method for judging a soldering state by using light having a wavelength in an infrared region after mounting a component on a motherboard has been proposed, as shown in "A-Junction Inspection Apparatus and Method".

[0008]

However, according to the method disclosed in Japanese Patent Laid-Open No. 7-83804, the amount of solder supplied to the component electrode is not constant, and while the evaluation of a plurality of samples is performed, the component electrode is not connected to the electrode. Since the metal composition of the solder bath changes due to the formation of oxides due to the penetration and continuous heating, it is difficult to continue accurate evaluation. Further, a component having a large number of electrodes on the bottom or side surface of the component, for example, B
In the case of components such as GA, LGA, LCC, and QFN, it was possible to immerse the entire component in a solder bath at a time and determine the average value of wettability of the entire component. No electrode wettability could be determined. In particular, in the case of BGA, solder balls are pre-fixed to the component as electrodes, and mixing of the component electrode solder and the bath solder occurs, so that the wettability evaluation method using a solder bath cannot be said to be appropriate. A new evaluation technique was desired.

Further, in the apparatus and method disclosed in the above-mentioned Japanese Patent Application Laid-Open Nos. 4-35947 and 9-89536, the X-ray and infrared irradiation and imaging devices are large and expensive, and the X-rays are required to maintain the health of workers. There is a problem that the safety management and maintenance of the device and the infrared device must be strictly performed.In addition, since the amount of transmission of X-rays and infrared rays is reduced in the chip part built in the semiconductor package,
There is a disadvantage that it is difficult to accurately observe the soldering state of all solder joints.

Therefore, an object of the present invention is to provide, for example, a BGA
The solderability of the brazing material electrode can be evaluated easily and with high reliability in a safe environment for electronic components that have solder balls as the connection electrodes An object of the present invention is to provide an evaluation substrate and a method for evaluating wettability.

[0011]

In order to solve the above-mentioned problems, a substrate for evaluating the wettability of a brazing material electrode according to the present invention comprises:
A wettability evaluation electrode is formed on the end surface of the base material, and the evaluation electrode is a fusion-fixing electrode portion for fusion-fixing a brazing material electrode of a brazing target member, and the fusion-fixing electrode portion. And an extended portion extending toward the edge of the base material. In the following description, the “wetability evaluation substrate” may be described as “evaluation substrate”, and the “wetability evaluation electrode” may be described as “evaluation electrode”.

According to such an evaluation board, the solder wettability of the connection electrode can be evaluated easily and with high reliability in a safe environment. That is, lower electrode parts,
In particular, the wettability of a component electrode having a solder ball electrode such as BGA can be directly visually evaluated.

In the wettability evaluation substrate of the present invention, the evaluation electrode is a metal film formed on an end surface of the base material,
What consists of a circular part which is the electrode part for fusion fixation, and a strip part which is the extension part is preferred. According to such an evaluation board, after the brazing material electrode of the brazing target member is positioned and abutted on the circular portion, the brazing material electrode is melted, so that the wettability can be easily and accurately evaluated. It can be carried out.

In the wettability evaluation substrate of the present invention, it is preferable that a plurality of the evaluation electrodes are formed on an end surface of the base material. In this case, it is desirable that the widths of the plurality of evaluation electrodes be different from each other, or the lengths of the plurality of evaluation electrodes be different from each other. In these evaluation substrates, since a plurality of evaluation electrodes are formed on the end surface of the base material, the wettability of the brazing material electrode can be performed at a plurality of locations, so that the wettability evaluation can be performed more accurately. it can.

In particular, when a plurality of evaluation electrodes having different widths or lengths of the strips are formed, a plurality of evaluation substrates having the same specifications are prepared to prepare brazing material electrodes having various wettability. And its wettability can be easily evaluated. Also, brazing material electrodes whose wettability (how much wettability) is unknown can be easily evaluated.

Further, in the wettability evaluation substrate of the present invention, it is preferable that the evaluation electrode is formed on one surface of the base material. By providing the evaluation electrode only on one side of the base material, the evaluation substrate can be manufactured inexpensively and in a short time.

Further, the method for evaluating the wettability of a brazing material electrode according to the present invention is an evaluation method using the above-described substrate for evaluating wettability, wherein the member to be brazed is attached to the electrode portion for melting and fixing of the evaluation substrate. And melting and fixing the brazing material electrode, and observing and evaluating the wettability of the brazing material electrode at the evaluation electrode during the melting and fixing. By such a method, brazing material (solder)
The quality of wettability can be easily and safely evaluated.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. (1) Explanation of Principle First, the principle of the present invention will be described. According to the present invention, the method for evaluating the wettability of the brazing material electrode and the evaluation method are electronic components including a semiconductor component having a solder ball as a component electrode such as BGA, after mounting the component on the evaluation board,
The solder ball is melted by the heating means, and the degree of spread of the solder to the wettability evaluation electrode provided at the end of the evaluation board is visually inspected. Can be directly evaluated.

For example, as shown in FIGS. 1 and 2, a wettability evaluation substrate 11 of the present invention is provided with a wettability evaluation electrode 11 made of a metal film on one end of a base material 13. in this case,
One end side of the wettability evaluation electrode 11 is a circular portion 11a, and a band portion (linear portion) 11b is extended from the circular portion 11a (that is, as a lead electrode). To place. The circular portion 11a is a BGA component 20 or 20A as a member to be brazed.
This is for melting and fixing the solder ball 21 (brazing material electrode) of FIG. 2. In addition, these BGA parts 2
The solder balls 21 are previously fixed to the surfaces of 0 and 20A.

In this way, as shown in FIGS. 3 and 4, for example, a brazing material (solder) having good wettability wets the wettability evaluation electrode 11 (large wet area) and has poor wettability. The brazing material does not wet cleanly (small wet area). Therefore, the quality of wettability can be evaluated at a glance.

For example, the wettability evaluation substrate 1 shown in FIG.
0, the solder having good wettability is the evaluation electrode 1 having a narrow electrode width.
1d (more precisely, the evaluation electrode having a narrow width of the strip portion 11b) can be wetted cleanly, but the evaluation electrode 11c having a wide electrode width cannot be completely wetted. Also,
For example, in the evaluation board 10 of FIG. 5B, the solder having poor wettability can wet the evaluation electrode 11e having a short electrode length (more precisely, the evaluation electrode having a short length of the strip 11b). The evaluation electrode 11f having a long electrode length cannot be completely wetted.

(2) First Embodiment Hereinafter, details of an evaluation substrate and a wettability evaluation method according to the present embodiment will be described with reference to the drawings.

FIG. 1A is a plan view of an evaluation board, and FIG. 1B is a sectional view thereof. FIGS. 2A and 2B are explanatory diagrams of a case where a BGA component is mounted on the evaluation board, wherein FIGS. 2A and 2A are plan views when a large BGA component is mounted, and FIGS. . (B) and (a) are plan views when a small BGA component is mounted, and (B) and (b) are cross-sectional views thereof. FIG. 3 is a view for explaining a process in which the solder ball is melted on the evaluation electrode of the evaluation board and a principle for evaluating the wettability of the solder ball to the evaluation electrode. FIG. 4 is also a diagram for explaining the principle of evaluating the wettability of the solder ball with respect to the evaluation electrode, and is an enlarged partial plan view showing a case where the wettability is good and a case where the wettability is bad.

In FIG. 2, the electrode spacing of the BGA component 20, which is the "member to be brazed", is 1.27 mm, 1.0
For example, in a BGA component having a pitch of 0.80 mm between electrodes, the solder ball 21 as an electrode has a diameter of 0.50 mm, for example, 0 mm, 0.80 mm, and 0.50 mm.
The electrodes on the substrate side for mounting these are generally 0.30 to 0.60 mm in diameter.
The degree is used.

In FIG. 1, an evaluation substrate 10 has a substrate 13 made of an organic material, for example, a glass epoxy substrate. It has a single-sided substrate structure. Each of these evaluation electrodes 11 is a metal film and includes a circular portion 11a and a band-shaped portion (linear portion: extraction electrode) 11b extending from the circular portion 11a to the edge of the substrate 13.
At one end. The circular portion 11a
This is a fusion-fixing electrode portion for fusion-fixing a brazing material electrode of a brazing target member.

The diameter of the circular portion 11a is smaller than that of the copper electrode 12, for example, about 0.20 to 0.50 mm. The band 11b has a width of, for example, 0.10.
1.00 mm and the length is 0.50 to 30.00 mm. By making the diameter of the circular portion 11a smaller than that of the copper electrode 12, the solder ball having a certain volume can be formed in the circular portion 11a.
When melted above, the molten solder is likely to spread on the strip 11b.

Usually, the electrodes of the BGA component are provided on the component at a specified electrode interval.
m, the evaluation electrode 1 as shown in FIGS. 2 (A) and 2 (B) irrespective of the component outer dimensions and the number of electrodes.
Evaluation substrate 10 while observing the wettability observation in
Components (such as BGA components) can be mounted thereon. Since the evaluation substrate 10 of the present embodiment is a single-sided substrate having a simple structure, it can be manufactured at low cost and in a short time.

Here, the details of the wettability evaluation method in the present embodiment will be described with reference to FIGS. The evaluation electrode 11 and the copper electrode 1 of the evaluation substrate 10 (FIG. 3A) described above.
A flux is applied to the surface 2 by printing or dispensing (FIG. 3B). Next, the BG is positioned such that a row of solder balls 21 (brazing material electrodes) on the outer peripheral portion of the BGA component 20 is in contact with the circular portion 11a of the evaluation electrode 11.
The A component 20 is mounted (FIG. 3C). Subsequently, the solder ball 21 is melted by heating means such as reflow,
Further, re-solidification is performed by natural cooling (FIG. 3D). At this time, by checking how much the molten solder spreads on the evaluation electrode 11, the brazing material electrode, that is, the BGA
It is possible to evaluate the wettability of the electrodes (solder balls 21) of the component 20.

In the case of the solder ball 21 having good wettability, as shown in FIG. 3D- (1) and FIG. After wetting the circular portion 11a of the electrode 11, the band portion 11b
Leaks over the whole On the other hand, in the case of the solder ball 21 having poor wettability, FIG.
As shown in (2) and FIG. 4- (2), the evaluation electrode 11
Cannot be sufficiently wetted. According to the above procedure, it is possible to directly evaluate the wettability of the solder ball 21 visually.

(3) Other Embodiments Hereinafter, modifications of the present embodiment will be described. Other Embodiment 1 As shown in FIG. 5A, by providing a plurality of evaluation electrodes having different electrode widths on the evaluation substrate 10, the magnitude of wettability (how much wettability) is unknown. The brazing material electrode can also be easily evaluated. Specifically, a solder ball having poor wettability can sufficiently wet the wettability evaluation electrode 11d having a small width (more precisely, the width of the band-shaped portion 11b), but completely wet the wide evaluation electrode 11c. Can not be wet.

Another Embodiment 2 As shown in FIG. 5B, by providing a plurality of evaluation electrodes having different electrode lengths on the evaluation substrate 10, the magnitude of wettability is unknown as in the first modification. A brazing material electrode can also be easily evaluated. Specifically, in the case of a solder ball having poor wettability, the short (more precisely, the length of the strip portion 11b is short) wettability evaluation electrode 11e can be sufficiently wetted, but the long evaluation electrode 11f can be completely wetted. Can not be wet.

Other Embodiment 3 In the evaluation electrodes of FIGS. 5A and 5B, the extraction electrode extending from the circular portion is formed in a band shape (linear shape), but the present invention is not limited to this. Instead, the extraction electrode extends from the circular portion 11a (FIG. 1A) toward the edge of the base material 13 and has a width or length sufficient to evaluate the wettability (that is, the area of the extraction electrode). What is necessary is just to have. For example, the evaluation substrate 10 shown in FIG.
By providing the evaluation electrodes 11g corresponding to the odd-numbered rows of copper electrodes 12 on the base material 13, the width can be considerably increased. Specifically, the component electrode interval is 0.8 m
In the case of an evaluation substrate for evaluating a substrate having a width of m, the width of the extraction electrode can be increased to about 1.5 mm. In addition,
In FIG. 5C, the wide evaluation electrode 11g is replaced with the copper electrode 12
Are provided every other row, but they can be arranged at a pitch of every other row or more.

As the base material of the evaluation substrate 10, not only organic materials but also inorganic materials such as ceramics can be used. As a case to which the present invention is applied, for example, a lot of BGA parts or the like stored for a long time (for example, 10 lots).
00) or when multiple BGAs
In some cases, the wettability tendency of each manufacturer of parts or the like is grasped.

[0034]

As described above, according to the present invention, the following effects can be obtained. (1) The substrate for evaluating wettability according to claim 1 has an electrode for evaluating wettability formed on an end surface of a base material, and the evaluation electrode is used for melting and fixing a brazing material electrode of a member to be brazed. Since the fusion-fixed electrode portion, and the extended portion extending to the edge side of the base material connected to the fusion-fixed electrode portion, and so on,
In a safe environment, the solder wettability of the connection electrode can be evaluated easily and with high reliability. That is, the wettability of a lower electrode component, particularly a component electrode provided with a solder ball electrode such as a BGA, can be directly visually evaluated.

(2) In the wettability evaluation substrate according to the second aspect, the evaluation electrode is a metal film, and the evaluation electrode extends so as to be continuous with the circular portion serving as the fusion-fixing electrode portion and the circular portion. Since it was configured with a band-shaped portion, after positioning and abutting the brazing material electrode of the brazing target member to the circular portion,
By melting the brazing material electrode, the wettability can be easily and accurately evaluated.

(3) In the wettability evaluation substrate according to the third aspect, since a plurality of evaluation electrodes are formed on the end surface of the base material, the wettability of the brazing material electrode can be performed at a plurality of locations. Sex evaluation can be performed more accurately.

(4) In the wettability evaluation substrate according to the fourth and fifth aspects, a plurality of evaluation electrodes having different widths or lengths of the strips are formed, so that a plurality of evaluation substrates having the same specifications are prepared. With respect to brazing material electrodes having various wettability, the wettability can be easily evaluated. Also,
The brazing material electrode whose wettability (how much wettability) is unknown can be easily evaluated.

(5) In the substrate for evaluating wettability according to claim 6, since the evaluation electrode is formed on one side of the base material, the structure is simple.
It can be mass-produced at a high yield and can be provided at a low cost.

(6) In the wettability evaluation method according to the seventh aspect, the member to be brazed is attached to the melt-fixed electrode portion of the evaluation substrate by using the wettability evaluation substrate according to any one of the first to sixth aspects. The brazing material electrode was melted and fixed, and the wettability of the brazing material electrode at the time of the melting and fixing was evaluated by observation. Therefore, the lower electrode component, particularly, a solder ball electrode such as BGA was provided. With respect to the component electrodes, the wettability can be directly evaluated visually.

Further, according to the evaluation board and the evaluation method of the present invention, one type of substrate can be used for components having the same electrode pitch but different numbers of electrodes, provided that the number of electrodes is equal to or less than the number of substrate electrodes prepared in advance. The evaluation substrate can be manufactured at low cost because the wettability can be evaluated by using the above method.

Further, according to the evaluation board and the evaluation method of the present invention, since there is no possibility that the solder other than the solder ball electrode to be evaluated is mixed, the alloy composition can be adjusted more appropriately than the conventional method using a solder bath. It is possible to perform an appropriate wettability evaluation while maintaining the value. Further, since no X-ray or the like is used, a safe working environment can be configured.

[Brief description of the drawings]

FIG. 1 shows an evaluation substrate according to an embodiment of the present invention, wherein (A) is a plan view and (B) is a cross-sectional view thereof.

FIGS. 2A and 2B are explanatory diagrams of a case where a BGA component is mounted on the evaluation board, wherein FIGS. 2A and 2A are plan views when a large BGA component is mounted, and FIGS. is there. (B) and (a) are plan views when small BGA components are mounted, and (B) and (b) are cross-sectional views thereof.

FIG. 3 is a diagram illustrating a process of melting a solder ball on an evaluation electrode of the evaluation board and a principle of evaluating the wettability of the solder ball to the evaluation electrode.

FIG. 4 is a diagram illustrating the principle of evaluating the wettability of a solder ball with respect to an evaluation electrode, and is an enlarged partial plan view showing a case where wettability is good and a case where wettability is bad.

FIG. 5 is a plan view showing a modification of the embodiment,
(A) shows an evaluation substrate provided with a plurality of evaluation electrodes having different widths, and (B) shows an evaluation substrate provided with a plurality of evaluation electrodes having different lengths. (C) shows an evaluation substrate provided with an evaluation electrode including a circular portion and a wide band-like portion having a wider width.

FIG. 6 is an explanatory view showing a conventional BGA component soldering process.

[Explanation of symbols]

10: wettability evaluation substrate, 11: wettability evaluation electrode, 11a
... Circular part, 11b ... Strip (linear part), 11c ... Wide evaluation electrode, 11d ... Narrow evaluation electrode, 11e ... Short evaluation electrode, 11f ... Long evaluation electrode, 11g ... Wide evaluation electrode, 12 ... copper electrode, 13 ... substrate, 20, 20A, 1
04 BGA parts, 21 solder balls, 101 mother board, 102 electrodes, 103 solder paste

Claims (7)

[Claims] An electrode for evaluating wettability is formed on an end surface of a base material, the evaluation electrode comprising: an electrode portion for melting and fixing a brazing material electrode of a member to be brazed; A brazing material electrode wettability evaluation substrate, comprising: an extension portion extending to the edge side of the base material in continuation with the fusion fixing electrode portion. 2. The evaluation electrode is a metal film formed on an end surface of the base material, and includes a circular portion serving as the fusion-fixing electrode portion and a band-shaped portion serving as the extension portion. 2. The substrate for evaluating wettability of a brazing material electrode according to claim 1, wherein: 3. The substrate for evaluating wettability of a brazing material electrode according to claim 2, wherein a plurality of the evaluation electrodes are formed on an end surface of the base material. 4. The substrate for evaluating wettability of a brazing material electrode according to claim 3, wherein the plurality of evaluation electrodes have different widths of the band-shaped portions. 5. The substrate for evaluating wettability of a brazing material electrode according to claim 3, wherein the plurality of evaluation electrodes have different lengths of the band-shaped portions. 6. The substrate for evaluating wettability of a brazing material electrode according to claim 1, wherein the evaluation electrode is formed on one surface of the base material. 7. A method for evaluating the wettability of a brazing material electrode using the wettability evaluation substrate according to claim 1, wherein the electrode portion for fusion and fixation of the evaluation substrate includes: A wettability evaluation of the brazing material electrode, wherein the brazing material electrode of the brazing target member is melt-fixed, and the wettability of the brazing material electrode at the time of the fusion bonding is observed and evaluated at the evaluation electrode. Method.