JP2001313464A - Evaluation substrate, evaluation device and evaluating method for wettability of brazing material electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate, device 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 a BGA can be evaluated readily under a safe environment and with high reliability. SOLUTION: Through holes 14 are formed on a tabular base material 11, and a metal film 14a is formed on the inner wall of each through-hole. At the same time, metal electrodes 12 and 13 are formed on both upper and lower surfaces of each through-hole, and an evaluation substrate 10 for solder balls 15 is produced. The metal electrodes of the evaluation substrate and solder balls of a BGA component 104 are heated, in a state where they abut against each other to melt and re-solidify. After that, the copper electrode 13 side on the backside of the evaluation substrate 10 is observed to determine the wettability of the solder (Refer to Fig. 3).

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, an evaluation device and an evaluation method using the same, and particularly suitable for evaluating the solder wettability of a BGA component to which a solder ball is fixed. The present invention relates to a substrate for evaluating wettability of a brazing material electrode, an evaluation device, and an evaluation method.

[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. With regard to electronic components used, especially semiconductor components (semiconductor integrated circuit devices), efforts are being made to keep component volumes small in response to performance trends such as high-performance integration, faster signal processing, and increased memory capacity. Efforts have been made to keep the component mounting area on the board small.

Conventionally, a connection electrode (component electrode) for connecting to a mother board (see FIG. 6) to be connected, such as a QFP (Quad F1at Package) as a package shape of a semiconductor component.
In many cases, the component electrodes were pulled out from the side of the package in a gull wing shape.
rid Array), LGA (Land Grid Array), LCC
(Lead1ess Chip Carrier), QFN (Quad F1at Nol)
e.g., ead Package), which are disposed on the lower surface or the side surface of the package, has come to be used frequently. The reason for this is that the use of the semiconductor component having such a configuration makes it possible to significantly reduce 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 shortened, and the electrical characteristics of the circuit are improved.

[0006] When mounting a component having a connection electrode on the lower surface (lower electrode component), such as BGA or LGA, on the mother substrate, as shown in FIGS.
The solder paste 103 is printed on the electrode 102 of No. 01, a component such as the BGA component 104 is mounted on the solder paste with the connection electrode on the component side mounted thereon, and solder is applied by using a heating device such as a reflow device. In general, 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 becomes incomplete after the above-mentioned reflow. This is not just a defect at the manufacturing site. If a product is shipped to the market without an imperfect connection, such as touching or no touching, being detected at the manufacturing site, this can lead to significant consequences during consumer use. Therefore, it is very important to examine the solder wettability of the component electrode surface. In particular, for a component such as a BGA using a solder ball as an electrode, there is no conventional method for directly examining the solder wettability.・ A device was desired.

A conventional example will be specifically described. Axial,
The solder wettability of electrodes with a small number of electrodes, such as radial lead components and surface-mounted components such as chip resistors, is evaluated by immersing the electrodes in a molten solder bath and using the meniscus method to capture the wetting behavior. That has been done. For example, there is a "solderability test apparatus" disclosed 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. Hei 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.
And a method of judging the soldering state by using light in the infrared region wavelength after mounting the component on the motherboard.

[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 the evaluation of the component electrode during the evaluation of a plurality of samples. The metal composition of the solder bath changes due to the formation of oxides due to melting or continuous heating, and 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, BGA, LGA, L
For components such as CC and QFN, it was possible to immerse the entire component in a solder bath at a time and determine the average value of the wettability of the entire component. Leakability could not be determined. In particular, in the case of BGA, the solder ball is fixed to the component in advance as an electrode, and the solder of the component electrode and the solder of the bath are mixed, so that the wettability evaluation method using the solder bath cannot be said to be appropriate. ,
A new evaluation method was desired.

Further, in the apparatus and method disclosed in JP-A-4-35947 and JP-A-9-89536, the X-ray and infrared irradiation and the imaging apparatus 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, and in the chip part embedded in the semiconductor package, the amount of transmission of X-rays and infrared rays decreases, so all solder joints Has a drawback that it is difficult to observe the soldering state accurately.

Accordingly, an object of the present invention is to provide a simple and highly reliable solder wettability of a connection electrode in a safe environment for an electronic component having a solder ball as a connection electrode such as a BGA. It is an object of the present invention to provide an evaluation board which can be evaluated under the following conditions, an evaluation apparatus and an evaluation method using the same.

[0011]

According to a first aspect of the present invention, a through hole is formed in a flat base material, a metal film is formed on an inner wall of the through hole, and the through hole is formed. A brazing material electrode wettability evaluation substrate, wherein metal electrodes are formed on both upper and lower surfaces of a hole.

The invention according to claim 2 is a substrate for evaluating wettability of a brazing material electrode, wherein a plurality of through holes are formed in the base material.

In the substrate for evaluating the wettability of the brazing material electrode according to the first aspect, for example, an evaluation substrate 10 shown in FIG.
A through hole 14 is formed in a flat base material 11, copper plating 14 a is formed as a metal film on the inner wall of the through hole 14, and copper electrodes 12 and 13 are formed as metal electrodes on both upper and lower surfaces of the through hole 14. I do.

According to a third aspect of the present invention, there is provided an apparatus for evaluating the wettability of a brazing material electrode using the wettability evaluation substrate according to the first or second aspect, wherein the brazing material is fixed to the surface in advance. A brazing target member mounting unit for mounting the brazing target member, a wettability evaluation substrate mounting unit for mounting the wettability evaluation substrate, and the brazing material of the brazing target member to the wettability evaluation substrate Contact means for contacting the surface electrode of
Heating means for heating the brazing target member and the wettability evaluation substrate in the corresponding contact state to melt the brazing material, and observation means for observing the back electrode of the wettability evaluation substrate after heating by the heating means. An apparatus for evaluating wettability of a brazing material electrode.

In the apparatus for evaluating the wettability of a brazing material electrode according to a third aspect of the present invention, a solder ball as a brazing material is used as in a wettability evaluating apparatus 20 shown in FIG. 4 (see also FIGS. 2 and 5). A movable stage 21 for mounting a BGA component 104 (a member to be brazed) to which a surface 15 is fixed in advance, a substrate holder 22 as a wettability evaluation substrate mounting means, and a solder ball 15 are connected to a surface electrode of the evaluation substrate 10. Stage 21 and component suction device 26 as contact means for contacting the BGA component 104 and the evaluation board 10
Heating device 27 that heats solder balls 15 by heating
And a camera unit 24 for observing the back surface electrode of the evaluation substrate 10 heated by the heating device.

According to a fourth aspect of the present invention, there is provided a method for evaluating the wettability of a brazing material electrode using the wettability evaluating substrate according to the first or second aspect, wherein the brazing material is fixed to the surface in advance. A step of preparing a brazing target member; a step of preparing the wettability evaluation substrate; and a step of bringing a brazing material of the brazing target member into contact with a surface electrode of the wettability evaluation substrate. A step of heating the brazing target member and the wettability evaluation substrate, and a step of observing the brazing wettability of the back electrode of the wettability evaluation substrate after the heating. This is a wettability evaluation method.

In the above wettability evaluation method, for example, an evaluation substrate 10 shown in FIGS. 1A to 1C is prepared as a wettability evaluation substrate for a brazing material electrode, and the evaluation substrate 10 is attached to a wettability evaluation apparatus. 20 is mounted on the substrate holder 22 (see FIG. 4). On the other hand, the BGA component 104 which is a member to be brazed
Are prepared, and the BGA component 104 is stored in the component storage unit 23.
To be mounted on. This state is shown as “at the time of board recognition” in FIG. Hereinafter, the evaluation device 10 is operated to sequentially perform flux application, component suction, and component mounting, and the solder balls 15 are brought into contact with the surface copper electrodes 12 of the evaluation substrate 10 (see FIG. 2). In this state, when the solder ball 15 is melted by heating using the heating device 27, the molten solder is
4 and while it is wet (see FIG. 3).

If the wettability of the solder ball 15 is good, the molten solder penetrates to the back side of the evaluation board 10 as shown in FIGS. The copper electrode 13 is also wetted. Conversely, when the solder ball has poor wettability, the molten solder stops in the middle of the through-hole and does not reach the back surface of the evaluation board. Therefore, FIG.
By observing the state (B) with the camera unit 24, the degree of wettability of the solder ball can be grasped.

According to a fifth aspect of the present invention, a plurality of the wettability evaluation substrates having different thicknesses are prepared, and the thickness of the wettability evaluation substrate is determined according to the wettability of the brazing material. And evaluating the solder wettability of the brazing material electrode. In this wettability evaluation method, the thickness of the evaluation substrate 10 is selected according to the wettability of the brazing material (solder ball), so that the degree of wettability can be accurately measured.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. The parts already described are given the same reference numerals, and redundant description is omitted.

(1) Explanation of Principle First, the principle of the present invention will be described with reference to the drawings. 1A is a plan view of an evaluation substrate 10 applied to the present invention, FIG. 1B is a side sectional view thereof, and FIG. 1C is an enlarged view of FIG.

For example, an evaluation substrate 10 for evaluating component electrodes in a BGA or the like includes a base material 11 made of an organic material,
For example, copper electrodes 12 and 13 that are “metal electrodes” are provided on the front and back of a glass epoxy base material, and these front and back electrodes are connected to each other by a through hole 14 in which a through hole formed in the base material 11 is plated with copper 14 a. To conduct. Usually BGA
Since the electrodes on the front and back of the component are provided at regular intervals, these electrodes 12 and 13 and the through holes 14 are provided.
Are arranged in a grid on the evaluation board 10 so that a single type of evaluation board 10 can
This evaluation board can be used not only for components but also for BGA components having various numbers of electrodes.

FIG. 2A is a plan view showing a state (before heating) in which the BGA component 104, which is a “member to be brazed”, is mounted on the evaluation board 10, and reference numeral 15 denotes “brazing material”. Solder balls. In this specification, the portion before melting is referred to as a solder ball 15, and the portion after melting is referred to as a solder ball electrode 15A (see FIG. 3).

Next, a case where the wettability of the solder ball electrode in the BGA component is evaluated using the evaluation board 10 will be described. For solder ball electrodes with good wettability,
The heating for a certain period of time causes the solder balls 15 to melt and fill the through holes 14, and the melted solder is further applied to the evaluation board 10.
Of the solder ball electrode can be evaluated by visually observing the degree of the wetting spread from the back surface.

The electrode spacing of the BGA component is 1.27 mm,
There are various types such as 1.00 mm, 0.80 mm, and 0.50 mm. For example, in a BGA component having a pitch of 0.80 mm between electrodes, the diameter of a solder ball as an electrode is 0.50 mm.
Therefore, the volume per solder ball is about 0.065 mm ³ . In this case, the thickness of the evaluation board and the inner diameter of the through hole are each, for example, 0.6
About 0 mm and about 0.25 mm are desirable.

As shown in FIGS. 3 (A) (a)-(d),
After applying a flux to the copper electrode 12 on the substrate surface having an outer diameter of, for example, 0.3 mm to 0.6 mm (FIG. 3A)
(B)), the solder balls 15 of the BGA component 104 are mounted thereon (FIGS. 3A and 3C), and the solder is subsequently melted and re-solidified by heating means (FIG. 3A).
(D)). When the solder ball electrode 15A has good wettability, the solder ball 15 breaks its sphere when melted and flows into the through-hole 14, the copper plating 14a on the inner wall is sufficiently wetted with the solder, and the through-hole 14 is filled. After that, it further reaches the copper electrode 13 on the back surface of the substrate and spreads cleanly (FIG. 3B- (1)). On the other hand, when the wettability of the solder ball electrode 15A is poor, the solder does not sufficiently flow into the through hole 14, the solder wetting of the copper plating 14a on the inner wall is insufficient, and It does not reach (FIG. 3 (B)-(2)). Note that FIG.
(A) It is a bottom view of (d), and shows solder ball electrode 15A.
Is viewed from the back side of the substrate.

After heating and re-solidification for a certain period of time, by observing whether or not the through hole 14 is filled with solder, or by observing the spread of the solder on the copper electrode 13 on the back surface of the substrate, the component electrode, ie, the solder It is possible to determine the wettability of the ball electrode 15A. Further, by determining the ratio of the spread area of the solder to the area of the copper electrode 13 on the back surface of the substrate, it is possible to directly determine whether the wettability of the solder ball is good or not.

(2) Embodiment Hereinafter, the present embodiment will be described in detail with reference to the drawings. 4 and 5 show a wettability evaluation apparatus 20 applied to the present embodiment and a wettability evaluation method using the same. FIG. 4 shows the first half of the wettability evaluation step, and FIG. 5 shows the latter half.

As shown in FIG. 4, the movable stage 21 is movable in the horizontal direction, and on the movable stage 21 constituting the "contact means", there is provided a substrate holder 22 serving as a "wetting evaluation substrate mounting means". , And a component storage unit 23 that is a “brazing target member mounting unit”. In the component storage unit 23, a BGA component 104 to be evaluated and the like are mounted. Further, a camera unit 24 serving as “observing means”, a flux coating device 25, a component suction device 26 constituting “contacting means”,
Each of the heating devices 27 as “heating means” is movable in the vertical direction.

As shown in FIG. 4A, the evaluation board 10 is mounted on the movable stage 21. The camera unit 24 recognizes the electrode position information (position information on where the front surface side copper electrode 12 is present on the evaluation board 10) and controls the control unit (not shown).
Is stored (FIG. 4A), the flux coating device 25
To apply flux onto the component electrodes (Fig. 4
(B)). The BGA component 104 mounted on the component storage unit 23 is suctioned by the component suction device 26 (FIG. 4).
(C)) Subsequently, the BGA component 104 is mounted on the evaluation substrate 10 so that the solder ball 15 of the BGA component contacts the copper electrode 12 on the surface of the evaluation substrate on which the flux is applied (FIG. 4D). ).

Next, as shown in FIG. 5A, when the solder balls are heated and melted by the heating device 27, the melted solder flows into the through holes of the board, and further flows to the copper electrodes 13 on the back surface of the evaluation board. Wrap around. After the solder is re-solidified by natural cooling, the fixed BGA component 104 and the evaluation board 10 are inverted using the inversion jig 28 so that the camera unit 24 can recognize the back side of the evaluation board. (FIG. 5B), the evaluation board 10 is observed by the camera unit 24 (FIG. 5C), and the solder wettability of the BGA component 104 is evaluated (see FIG. 3).

(3) Modification A modification of this embodiment will be described below. As the base material of the evaluation substrate, not only organic materials but also inorganic materials such as ceramics can be used.

Further, by using a board having a different thickness of the evaluation board, it is possible to make an evaluation according to the wettability of the component electrodes. For example, when it is expected that the wettability of the solder balls is insufficient (for example, when the storage period is long), it is possible to use a thinner evaluation board such that molten solder goes around to the back surface of the board. In addition, it is possible to appropriately observe the spread of the wetness on the copper electrode on the back surface of the substrate. Conversely, when excessive wettability of the solder balls is expected, it is possible to appropriately observe the spread of the wettability on the copper electrodes on the rear surface of the substrate by using a thicker evaluation substrate. Also, the component (BGA component 104) and the board (evaluation board 10)
Can be passed through the heating device 27 upside down.

The case where the present invention is applied is as follows.
For example, lots of BGA parts and the like stored for a long time (for example, 1 lot)
000 pieces) or multiple BGs
There is a case where the tendency of wettability of each manufacturer of parts such as A is grasped.

[0035]

As described above, according to the present invention, the following effects can be obtained. (1) Components with connection electrodes on the lower surface (lower electrode components)
The above-mentioned electrode, in particular, a solder ball electrode such as a BGA part, can be evaluated easily and directly in a safe environment with high reliability. (2) Even for components having the same electrode pitch but different numbers of electrodes, if the number of electrodes is less than the number of electrodes on the wettability evaluation substrate prepared in advance, wettability evaluation should be performed using one type of evaluation substrate. Is possible, which can contribute to cost reduction in manufacturing an evaluation substrate. (3) Since there is no possibility that solder other than the solder ball electrode to be evaluated is mixed, an appropriate wettability evaluation can be performed while maintaining the alloy composition appropriately, as compared with a method using a solder bath. (3) Since no X-ray or the like is used, a safe working environment can be configured.

[Brief description of the drawings]

1A and 1B are explanatory diagrams of a configuration of a wettability evaluation substrate according to the present invention, wherein FIG. 1A is a plan view, FIG.
3 is an enlarged view of FIG.

2A is a plan view showing a state (before heating) in which a BGA component is mounted on the wettability evaluation board of FIG. 1, and FIG. 2B is a side sectional view thereof.

FIG. 3 is a diagram illustrating the principle of a wettability evaluation method according to the present invention, wherein (A) is a diagram illustrating a melting process of a solder ball;
(B) is a diagram for explaining the solder wrap around the back surface of the wettability evaluation substrate.

FIG. 4 relates to an embodiment of the present invention, and shows a configuration of a wettability evaluation apparatus and a first half of a detailed process from mounting of a wettability evaluation board and a BGA component to observation of solder wettability. FIG.

FIG. 5 is an explanatory diagram showing a latter half of a detailed process from mounting of a wettability evaluation board and a BGA component to observation of solder wettability according to the embodiment of FIG. 4;

FIG. 6 is a view for explaining a conventional BGA component soldering process.

[Explanation of symbols]

Reference Signs List 10: wettability evaluation substrate, 11: base material, 12: copper electrode on front surface, 13: copper electrode on back surface, 14: through hole, 14a
... Copper plating, 15 ... Solder ball, 15A ... Solder ball electrode, 20 ... Wettability evaluation device, 21 ... Movable stage, 2
2 ... board holder, 23 ... parts storage part, 24 ... camera part,
25: flux coating device, 26: component suction device, 27
... heating device, 28 ... reversing jig, 101 ... mother board,
102 ... electrode, 103 ... solder paste, 104 ... B
GA parts

Claims (5)

[Claims] 1. A through hole is formed in a flat base material,
A metal film is formed on the inner wall of the through hole, and metal electrodes are formed on both upper and lower surfaces of the through hole. 2. The substrate for evaluating wettability of a brazing material electrode according to claim 1, wherein the substrate has a plurality of through holes formed therein. 3. A brazing material electrode wettability evaluating apparatus using the wettability evaluating substrate according to claim 1 or 2, wherein a brazing target member having a brazing material fixed to a surface in advance is placed. A brazing target member mounting unit; a wettability evaluation substrate mounting unit for mounting the wettability evaluation substrate; and a brazing material of the brazing target member abutting on a surface electrode of the wettability evaluation substrate. Contact means, heating means for heating the brazing target member and the wettability evaluation substrate in the corresponding contact state to melt the brazing material, and observation for observing the back electrode of the wettability evaluation substrate after heating by the heating means. Means for evaluating the wettability of a brazing material electrode. 4. A method for evaluating the wettability of a brazing material electrode using the wettability evaluation substrate according to claim 1 or 2, wherein a brazing target member having a brazing material fixed on its surface in advance is prepared. Preparing the wettability evaluation substrate; bringing the brazing material of the brazing target member into contact with the surface electrode of the wettability evaluation substrate; and evaluating the brazing target member in the contact state and the wettability. A method for evaluating the wettability of a brazing material electrode, comprising: a step of heating a substrate; and a step of observing a brazing wettability of a back electrode of the wettability evaluation substrate after the heating. 5. A plurality of wettability evaluation substrates having different plate thicknesses are prepared, and according to the wettability of the brazing material,
5. The method for evaluating wettability of a brazing material electrode according to claim 4, wherein the solder wettability is evaluated by selecting a thickness of the wettability evaluation substrate.