JP2002158244A - Method and apparatus for evaluating wettability of component electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for evaluating wettability, capable of evaluating solder wettability of a solder ball for an electronic component having the ball with safety, efficiency and high reliability at a low cost. SOLUTION: The method for evaluating the wettability of the solder ball comprises the steps of preparing a plurality of valuating members (evaluating plates 10) for mounting electrodes at a base, heating electrodes (electrodes 12) of the plurality of the members in a state that the electrodes are opposed to different connecting component electrodes (solder ball electrodes 41) of the components, welding them and evaluating the wettability after the heating is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for evaluating the wettability of a component electrode, and more particularly to an electronic component having a solder ball as a bonding component electrode such as a BGA in a safe environment. The present invention relates to a method and an apparatus for evaluating the wettability of a component electrode, which can efficiently and highly reliably evaluate the solder wettability of the bonding component electrode.

[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, as a semiconductor component package shape, for example, QFP (Quad F1at Package), a component electrode (component electrode) for joining to a mother board (see FIG. 8) to be connected is drawn out from the side surface of the package in a gull wing shape. In recent years, the component electrodes have been replaced with BGA (Ba1
1 Grid Array), LGA (Land Grid Array), LCC
(Lead1ess Chip Carrier), QFN (Quad F1at No
As in the case of a lead package, a package arranged on the lower surface or side surface of the package has come to be frequently used. 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.

When a component having a bonding component electrode on the lower surface such as a BGA (lower electrode component) is mounted on a mother substrate, as shown in FIGS.
The solder paste 103 is printed on the electrode 102 of No. 01, and a component 104 such as a BGA component is mounted on the solder paste with the component-side bonding component electrode mounted thereon, and soldering is performed 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, due to long-term storage in the air, an oxide film is formed on the surface of the bonding component electrode,
If foreign matter is attached in the process of manufacturing a component such as a BGA, the wettability of the bonding component 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 detecting an imperfect connection, such as contact or non-contact, 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 surface of the joining component electrode.

A conventional example will be specifically described. Axial,
Regarding the solder wettability of the electrodes of components with a small number of electrodes, such as radial lead components and surface mount components such as chip resistors, immerse them in a molten solder bath and use the meniscus method to capture the wetting behavior Has been evaluated. For example, JP-A-7-8380
No. 4, “Solderability tester”.

As for an area array type component soldered to a substrate, a method for examining the density of an X-ray transmission image as disclosed in "Inspection Apparatus for Solder Joints of Semiconductor Devices" in JP-A-4-35947. JP-A-9-89
As disclosed in Japanese Patent Application Publication No. 536, “BGA joint inspection apparatus”, there is a method of judging a soldering state by using light in an infrared region wavelength after mounting components on a motherboard.

[0008]

However, according to the method disclosed in Japanese Patent Application Laid-Open No. Hei 7-83804, the amount of solder supplied to the bonding component electrode is not constant, and during the evaluation of a plurality of samples, the bonding is performed. The metal composition of the solder bath changes due to the melting of the component electrode and the formation of oxides due to continuous heating, and it is difficult to continue accurate evaluation.

Further, a component having a large number of bonding component electrodes on the lower surface or side surface of the component, for example, BGA, LGA, LCC,
For components such as QFN, it was possible to immerse the entire component in the solder bath at a time and determine the average value of the wettability of the entire component. Sex could not be determined. In particular, in the case of BGA, a solder ball is fixed to a BGA component in advance as a bonding component electrode, and the solder of the component electrode and the solder of the bath are mixed. Therefore, the wettability evaluation method using a solder bath is appropriate. However, 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 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 infrared device must be strictly performed, and since the amount of transmission of X-rays and infrared rays is reduced in the chip portion embedded in the semiconductor package,
There is a drawback that it is difficult to accurately observe the soldering state of all solder joints.

Further, the solder wettability after melting including the BGA solder ball electrode itself varies depending on the BGA component itself, the type of solder paste (alloy composition, flux composition) to be mated, and the type of surface treatment of the printed circuit board. However, from the viewpoint of appropriately selecting these solder pastes and substrate surface treatments, it is important to evaluate the wettability of BGA components, and to evaluate various combinations with the least possible time and cost. A method, particularly a method of investigating a plurality of combinations in one evaluation, has been desired.

Accordingly, an object of the present invention is to reduce the solder wettability of a bonding component electrode in an inexpensive and efficient manner in an electronic component having a solder ball as a bonding component electrode, such as a BGA, in a safe environment. It is an object of the present invention to provide a method and an apparatus for evaluating the wettability of component electrodes which can be evaluated under high reliability.

[0013]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention is to previously attach an electronic component to be electrically and mechanically joined to a member to be joined on a printed circuit board by soldering. In the method for evaluating the wettability of a component electrode for evaluating the wettability of a bonding component electrode, a plurality of evaluation members each having an electrode attached to a base material are prepared, and each of the plurality of evaluation member electrodes is provided. Are heated and melt-bonded in a state where they face different bonding component electrodes of the electronic component, and the wettability is evaluated after the heating is completed.

In the present invention, for example, as shown in FIG. 7, a plurality of evaluation members (evaluation plates 10) are prepared (eight in FIG. 7), and each of the electrodes 12 of the plurality of evaluation members is
The electronic component (BGA component 40) was heated and melt-bonded in a state of facing different bonding component electrodes (solder ball electrodes 41) of the electronic component (BGA component 40), and the wettability was evaluated after the completion of the heating.
Therefore, the solder wettability of the bonding component electrode can be efficiently and highly reliably evaluated in a safe environment.

According to a second aspect of the present invention, different kinds of surface treatments are applied to the electrodes of the plurality of evaluation members, respectively, and the different kinds of surface treatments are applied to one kind of the joining component electrodes. Is characterized in that the solder wettability is evaluated. In this way, for example, as shown in FIG. 9, different types of surface treatments are performed (the first surface treatment 14).
a, the second surface treatment 14b), it is possible to efficiently evaluate the solder wettability of one kind of bonding component electrode (solder ball) with a different kind of surface treatment at the same time.

According to a third aspect of the present invention, different types of solder paste are applied to each of the plurality of evaluation members, and a plurality of types of solder paste are applied to one type of the bonding component electrode. It is characterized in that the solder wettability is evaluated. In this way, for example, as shown in FIG. 8, different types of solder pastes are applied (the first solder paste 13a, the second solder paste 13b, and the third solder paste 13c), and one type of solder paste is used. The solder wettability of a component electrode (solder ball) with a plurality of types of solder paste can be simultaneously and efficiently evaluated.

According to a fourth aspect of the present invention, there is provided a component for evaluating the wettability of a bonding component electrode previously attached to an electronic component which is electrically and mechanically bonded to a member to be bonded on a printed circuit board by soldering. In the electrode wettability evaluation device, an evaluation member supporting means (plate holder 22 in FIG. 6) to which a plurality of evaluation members each having an electrode attached to a base material can be attached, and the evaluation member supporting means are supported by the evaluation member supporting means. Opposing means (component holder 21, plate holder 22) for causing the plurality of evaluation members thus formed to face the joining component electrode, and heating the plurality of evaluation members in a state where the plurality of evaluation members face the joining component electrode. Heating means (heating jig 23), and observation means (imaging unit 24) for observing the solder wettability between the electrode of the evaluation member and the bonding component electrode after being heated by the heating means. Feature

In this way, for example, as shown in FIGS. 6 to 9, a plurality of evaluation members (evaluation plates 10) are prepared (eight in FIG. 7), and the electrodes of the plurality of evaluation members are provided. 1
2 are heated and melt-bonded in a state where they are opposed to different bonding component electrodes (solder ball electrodes 41) of the electronic component (BGA component 40), and the wettability can be evaluated after the heating is completed. Therefore, the solder wettability of the bonding component electrode can be efficiently and highly reliably evaluated in a safe environment.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and apparatus for evaluating component electrode wettability according to the present invention will be described below with reference to the illustrated embodiments. (1) Outline description of the present invention In view of the solution of the above-mentioned problems, the present invention provides a BG
By using an evaluation plate corresponding to each solder ball electrode of the A component, the wettability of the bonding component electrode is evaluated on the electrode provided on the evaluation plate with an area where the solder has melted and spread after the heat treatment. It is. Also, by changing the surface treatment of the evaluation plate electrode or the type of solder paste applied on the electrode, the combination of the bonding component electrode (solder ball electrode), the evaluation plate electrode surface treatment, and the solder paste is improved. It evaluates evil.

(2) First Embodiment FIGS. 1A and 1B are a plan view and a side view of an evaluation plate applied to this embodiment, FIG. 2 is a layout diagram of an initial position of an evaluation apparatus, FIG. 3 is a three-view drawing of a plate holder forming a part of the evaluation device. As shown in FIGS. 1A and 1B, an evaluation plate 10 for evaluating wettability is provided on a surface of a substrate 11 made of, for example, a glass epoxy material on a member equivalent to an electrode of a printed circuit board (for example, a motherboard). Is provided.

The size of the evaluation plate 10 can be selected, but is, for example, about 5 mm × 15 mm × 0.3 mm. The electrode 12 on the evaluation plate 10 is, for example, 2 mm ×
A copper foil of 5 mm × 0.018 mm is used as a material, and is manufactured by a normal method for manufacturing a printed circuit board. As shown in FIG. 2, the evaluation device 20 includes a BGA to which a BGA is attached in advance.
A component holder 21 for holding components, a plate holder 22 for holding the evaluation plate 10, and a plate holder 22
Jig 23 for heating evaluation plate 10 held in
And an imaging unit 24 for observing solder wettability after heating.

As shown in FIG. 3, the plate holder 22 is made of a somewhat thick rectangular metal material such as aluminum or brass. The evaluation plate 10 is inserted and held along the center of the plate holder 22 in the longitudinal direction. Multiple holding holes 2
2a is drilled. Next, the operation of the present embodiment will be described with reference to FIGS. 4A to 4F are enlarged side views of the operation of the main part of the evaluation device, and FIGS.
2) is an enlarged view illustrating the state of the solder ball before and after heating,
6A to 6D are side views showing the outline of the operation process of the evaluation device. In FIG. 5, the positional relationship between the BGA component and the solder ball is deformed and drawn.

As shown in FIG. 4A, prior to the evaluation of the wettability, a solder paste 13 is applied on the electrodes 12 of the evaluation plate 10 by using a method using a dispenser 30 or a screen printing method. Next, as shown in FIG. 4B, the evaluation plate 10
Is inserted and fixed in the holding hole 22a of the plate holder 22.

On the other hand, as shown in FIG. 4C, a BGA component 40 on which a BGA or the like is mounted in advance is sucked and held by a component holder 21. Solder paste 13 applied to evaluation plate 10 by solder ball electrode 41 of BGA component 40
The plate holder 22 moves to a position where it comes into contact with (FIG. 6).
(See FIG. 5B) and stand still (see FIGS. 5A and 6C). As shown in FIG. 4D, by applying heat for a predetermined time by the heating jig 23 (see FIG. 6C), the solder paste 13 and the solder ball electrode 41 are melted, and the copper electrode on the evaluation plate is melted. Spreads wet on top. Next, as shown in FIG. 4E, when heating is stopped after a predetermined time, the solder is re-solidified.

When the solder ball electrode 41 has good wettability, the solder ball electrode 41 is melted and spreads flat on the electrode 12 of the evaluation plate 10 as shown in FIGS. 5 (B1) and 5 (B2). On the contrary, when the wettability is poor, FIG.
As shown in 1) and (C2), the spread of the solder material is not perfect. Reference numeral 41a denotes solder having good wettability after melting, and reference numeral 41b denotes solder having poor wettability after melting. Regarding the shape of the re-solidified solder, as shown in FIG.
The video is sent to an image processing unit (not shown) to determine whether the wettability is good or not (see FIG. 6D).

(3) Second Embodiment In this embodiment, a plurality of evaluation plates are used to simultaneously evaluate the solder wettability of a plurality of solder ball electrodes. As shown in FIG. 7, the evaluation plates 10 corresponding to the plurality of solder ball electrodes 41 respectively.
And solder wettability after heating is evaluated in the same manner as in the first embodiment. In this way, the plurality of solder ball electrodes 41 can be individually and simultaneously efficiently evaluated.

(4) Third Embodiment In this embodiment, solder pastes having different alloy compositions are applied in advance to the electrodes of the evaluation plate, and the solder wettability to a plurality of types of solder pastes is simultaneously evaluated. Is the case. As shown in FIG. 8, solder pastes 13 a to 13 c having first to third different alloy compositions are applied to the electrodes 12 of the three evaluation plates 10 in advance. The evaluation plate 10 is arranged corresponding to each of the plurality of solder ball electrodes 41, and the solder wettability is evaluated after heating in the same manner as in the first embodiment. This makes it possible to evaluate a plurality of types of solder pastes 13a to 13c individually and simultaneously efficiently.

By controlling the heating temperature and the heating time when using the heating jig 23, it is possible to evaluate the solder wetting behavior at various heating and cooling rates even for a certain solder paste. It is.

(5) Fourth Embodiment In this embodiment, the electrodes of the evaluation plate are subjected to different surface treatments in advance, and the solder wettability for a plurality of types of surface treatments is simultaneously evaluated. As shown in FIG.
With respect to the surface treatment of the electrode 12 of the evaluation plate 10, for example, a different kind of surface treatment (a first surface treatment 14 a, a second surface treatment
4b) is used in combination. In this way, it is possible to efficiently evaluate a plurality of types of surface treatments 14a and 14b individually and simultaneously.

(6) Modified Example Hereinafter, a modified example of each embodiment will be described. The electrode 12 of the evaluation plate 10 can be evaluated not only by the type of plating but also by oxidizing or sulfurizing it in advance, taking various environments into consideration. Various materials can be selected for the material of the evaluation plate 10. For example, ceramics or metal materials can be used for the purpose of increasing the thermal conductivity.

For parts other than BGA (for example,
LGA, LCC, QFN) and each embodiment can be used to evaluate the wettability of component electrodes. The shape of the plate holder 22 can also be freely designed,
The shape of the plate holder can be selected according to the number of electrodes and electrode arrangement of the BGA component, and according to the number of electrodes to be evaluated.

[0032]

As described above, according to the present invention, the following effects can be obtained. Since it is possible to select the surface treatment of the electrode and the solder paste to be applied for each evaluation plate, it is possible to evaluate multiple conditions at once, thereby shortening the evaluation time, reducing the cost of parts, and evaluating auxiliary materials such as parts materials and solder for evaluation. Contribute to reduction of material costs and labor costs. Compared with a method of immersing in a solder bath, it is easier to prevent undesired mixing of metal elements.

It is possible to directly observe the phenomenon of the spread of wetness by comparing with a method of transmitting through X-rays and judging wetness by a shadow of a soldered portion. At the time of evaluation, the observation of the wet-spread shell joint was performed at the end of the BGA part.
This can be performed simultaneously for one row, and it is easy to compare the wettability, especially in the case of evaluation using a combination of a plurality of solder pastes.

[Brief description of the drawings]

FIG. 1 is a diagram showing an evaluation plate applied to each embodiment of the present invention, wherein (A) is a plan view and (B) is a side view.

FIG. 2 is a diagram showing an initial arrangement state of an evaluation device applied to each embodiment.

FIG. 3 is a three-view drawing of a plate holder in the evaluation apparatus.

FIGS. 4A and 4B are side views showing an operation process of the first embodiment, in which FIG. 4A is a diagram in which a solder paste is applied, FIG. 4B is a diagram in which an evaluation plate is held in a plate holder, and FIG. Is a diagram of contact between the component electrode and the electrode of the evaluation plate, (D)
FIG. 4 is a diagram in which a solder ball or the like is heated by a heating jig, (E) is a diagram showing resolidification of solder, and (F) is a diagram in which solder wettability is imaged.

FIG. 5 is a diagram showing a relationship between a solder ball electrode and an electrode of an evaluation plate according to the first embodiment, and FIG.
Is a side view before heating, (B1) and (B2) are a side view and a plan view when wettability after solder melting is good, and (C)
1) and (C2) are a side view and a plan view when wettability after solder melting is poor.

6A and 6B are diagrams showing an operation of the evaluation apparatus according to the first embodiment, wherein FIG. 6A is a layout diagram of each unit in an initial state,
(B) is a diagram in which the plate holder is brought closer to the component electrode,
(C) is a diagram that brings the heating jig closer to the evaluation plate, etc.
(D) is a figure which observes wettability in an imaging part.

FIG. 7 is a side view showing the second embodiment.

FIG. 8 is a side view showing the third embodiment.

FIG. 9 is a side view showing the fourth embodiment.

FIG. 10 is an explanatory diagram showing a conventional BGA component soldering process.

[Explanation of symbols]

10 ... Evaluation plate, 11 ... Substrate, 12 ... Electrode, 13 ...
Solder paste, 13a ... First solder paste, 13b ...
Second solder paste, 13c... Third solder paste, 1
4a: first surface treatment, 14b: second surface treatment, 20
... Evaluation device, 21 ... Parts holder, 22 ... Plate holder, 22a ... Holding hole, 23 ... Heating jig, 24 ... Imaging unit,
Reference numeral 30: dispenser, 40: BGA component, 41: solder ball electrode, 41a: solder having good wettability after melting, 41b
... Solder with poor wettability after melting, 101 ... Mother board, 1
02 ... electrode, 103 ... solder paste, 104 ... BG
A parts

Claims (4)

[Claims] 1. A wettability of a component electrode for evaluating a wettability of a bonding component electrode previously attached to an electronic component electrically and mechanically bonded to a member to be bonded on a printed circuit board by soldering. In the evaluation method, prepare a plurality of evaluation members each having an electrode attached to the base material,
Each of the electrodes of the plurality of evaluation members is heated and melt-bonded in a state where the electrodes face different bonding component electrodes of the electronic component, and the wettability is evaluated after the completion of the heating. Method for evaluating wettability of component electrodes. 2. Each of the plurality of evaluation member electrodes is subjected to a different type of surface treatment, and one type of the bonding component electrode is subjected to solder wettability with the different type of surface treatment. 2. The method according to claim 1, wherein the evaluation is performed.
The method for evaluating wettability of the component electrode described in the above. 3. A different kind of solder paste is applied to each of the plurality of evaluation members, and the solder wettability of the one kind of bonding component electrode with a plurality of kinds of solder pastes is evaluated. 2. The method for evaluating wettability of component electrodes according to claim 1, wherein: 4. A wettability of a component electrode for evaluating a wettability of a bonding component electrode previously attached to an electronic component electrically and mechanically bonded to a member to be bonded on a printed circuit board by soldering. In the evaluation device, an evaluation member supporting means capable of attaching a plurality of evaluation members each having an electrode attached to a base material; and a plurality of evaluation members supported by the evaluation member supporting means, Facing means for facing the component electrode; heating means for heating the plurality of evaluation members in a state of facing the bonding component electrode; electrodes for the evaluation member heated by the heating means and the bonding component An observing means for observing solder wettability with an electrode. An apparatus for evaluating wettability of a component electrode.