JP3334728B2 - Electrode terminal of electronic component and surface treatment method of electrode terminal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode terminal of an electronic component and a surface treatment method of the electrode terminal, and more particularly, to an electrode terminal of a multi-pin IC or LSI such as a quad flood package (QFP) or a small outline package (SOP). And electrode terminals of a printed circuit board for surface mounting these semiconductor elements.

[0002]

2. Description of the Related Art Generally, an IC or an LSI is mounted on a printed circuit board.
When surface mounting electronic components such as the above, solder and flux are supplied to the surface of the electrode terminal formed on the printed circuit board to clean the surface of the electrode terminal and to impart wettability. Conventionally, when supplying solder and flux to a printed circuit board, generally, cream solder mixed with solder and flux is screen-printed on the surface of the electrode terminal of the printed circuit board.

[0003]

However, in the above-described conventional method of printing cream solder on the electrode terminals, the electrode terminals are formed in the openings of the print mask formed corresponding to the respective electrode terminals on the printed circuit board. Each one of them must be aligned, and the mesh of the opening cannot be so fine due to the nature of cream solder, so the supply of cream solder will vary when printing, However, there is a problem in the progress of high-density mounting and high integration of electronic components.

That is, recently, with the miniaturization and high performance of electronic devices, the size of printed circuit boards has been rapidly reduced, and the number of semiconductor elements mounted on one printed circuit board has tended to increase. The integration of semiconductor devices themselves is also increasing. For this reason, high-density mounting of semiconductor elements on a printed circuit board is inevitable, and circuit patterns and electrode terminals printed on the printed circuit board in response to the increase in the number of pins and the narrow pitch due to the high integration of semiconductor elements. And the pitch between the electrode terminals is further reduced. Therefore, in a printing method using a screen similar to the conventional one, first, high precision is required for the alignment between the electrode terminal and the opening when the print mask is placed on the printed circuit board. Matching work becomes troublesome. Secondly, because the cream solder cannot be supplied stably, the supplied cream solder protrudes from the electrode terminals and comes into contact with the cream solder supplied to the surface of the adjacent electrode terminal to cause a short circuit between the electrodes, There is a risk that cream solder that has been supplied too much may cause surface tension to form solder balls between the electrodes.

As one means for solving such a problem, for example, the supply amount of cream solder can be reduced by reducing the opening area of a mask used for printing. Will not be able to be removed from the opening, and will be printed on the surface of the electrode terminal, and new problems will occur such that the opening of the mask is likely to be clogged. On the other hand, a method of forming a thick solder plating on each electrode terminal of a semiconductor element is also known (see Japanese Patent Application Laid-Open No. 3-85750). However, in this method, a separate flux must be supplied when the semiconductor element is mounted on the printed circuit board, and there is a problem that the mounting operation becomes complicated.

Accordingly, the present invention provides a method for supplying solder or flux to the surface of each electrode terminal of a printed circuit board or an electronic component mounted thereon at a high density by appropriately supplying the solder or flux and using simple means. The purpose is to be able to supply.

[0007]

That is, according to the present invention, there is provided an electrode terminal provided on an electronic component.
There wherein the rough surface coating of the bonding material, the electrode terminals of an electronic component formed by formed by a powdered flux filled in the recess of the rough surface coating.

[0008] Further, a step of spraying a powdery flux on the electrode terminal on which the roughened film of the bonding material is formed, and at least a concave portion formed in the roughened film of the powdered flux spread on the electrode terminal. Leaving the powdered flux as it is and removing the other powdered flux.

The above-mentioned electronic component is a printed circuit board on which a circuit pattern is printed, a semiconductor element mounted on the printed circuit board, or a combination thereof.

[0010]

According to the former means, since many concaves are formed in the roughened surface film of the bonding material formed on the surface of the electrode terminal, the concaves are filled with a powdery flux. It can be replaced with conventional cream solder.

Further, according to the latter means, the electrode material terminal is immersed in the electrolytic solution in which the bonding material is dissolved, and the coating of the bonding material is applied to the electrode terminal having a narrow gap pitch at an appropriate position. In addition to being able to be formed, by selecting plating conditions, it is possible to easily form irregularities for filling the powdery flux on the surface of the film. In addition,
Spraying powdery flux on pole terminals and unnecessary powder
Process to remove the state flux.
Reliable powder flux only in the recesses formed in the film
Can be filled.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the following embodiments, a case will be described in which a printed circuit board and a semiconductor element such as a QFP or an SOP are used as electronic components.

FIGS. 1 to 3 show a part of a printed circuit board 1 and a semiconductor element 2 whose electrode terminals have been subjected to a surface treatment. A circuit pattern 3 for mounting the semiconductor elements 2 at high density is formed on the surface of the printed circuit board 1 (only a part of the circuit pattern formed on the entire printed circuit board is shown in FIG. 1). Are arranged in parallel. These electrode terminals 4 correspond to the electrode terminals 5 provided on the semiconductor element 2, and the adjacent electrode terminals 4
The pitch between them is very narrow. As shown in FIGS. 2 and 3, a solder film 7 is first applied to the entire surface of each electrode terminal 4, and a flux 9 is further fixed thereon. The thickness h of the solder film 7 is desirably about 100 μm if the pitch between the electrode terminals 4 is 0.5 mm, for example. The solder film 7
Instead, a tin film may be attached. These solder film 7 and tin film can be generally applied by electrolytic plating, as described later.

The surface of the solder film 7 has an uneven rough surface as shown in FIG. 2 and FIG. This rough surface can be formed by plating conditions for attaching the solder film 7 by, for example, electrolytic plating. The degree of the irregularities can be changed by appropriately changing the conditions. However, the diameter of the concave portion 10 is preferably about 50 to 100 μm for the solder film 7 having a thickness of about 100 μm.

A large number of recesses 10 are formed on the surface of the solder film 7 thus formed, and each recess 10 is filled with a flux 9. As will be described later, this flux 9 is filled in a state in which it is buried in the concave portion 10 and fixed to the inner wall of the concave portion 10 because the powdery material is once semi-molten on the surface of the solder film 7. Have been.

As described above, the electrode terminals 4 of the printed circuit board 1
By forming the solder film 7 and the flux 9 beforehand, complicated high-precision alignment of the print mask as in the related art is not required, and an appropriate amount can be controlled by plating conditions. There's nothing too little or too little. As a result, even if the pitch of the electrode terminals 4 is narrow, there is no short circuit between the adjacent electrode terminals 4 and no connection failure due to insufficient solder. In addition, since the flux 9 is necessary and sufficiently filled in the concave portion 10 of the solder film 7, when mounting the semiconductor element 2, the surface of the electrode terminal 4 can be cleaned and wetted without additional flux. Is ensured.

Next, an example of a surface treatment method for the electrode terminals 4 on the printed circuit board 1 will be described with reference to FIGS. First, the printed circuit board 1 is removed except for the electrode terminals 4.
Is covered with a resist film 8 to prevent the solder film 7 from being formed on the high-density circuit pattern 3 (step 1). Next, as shown in FIG. 4, the printed circuit board 1 that has been subjected to pretreatment such as degreasing and washing is immersed in a solder plating electrolytic solution 12 together with the solder plate 11 to make the printed circuit board 1 a “−” electrode. An electric current is applied using the solder plate 11 as a “+” electrode (step 2). When a current is passed, a solder film 7 is gradually formed on the surface of the electrode terminal 4 of the printed circuit board 1. In this case, the amount of the brightener in the electrolyte 12 is reduced to reduce the solder film. An uneven surface as shown in FIG. 2 and FIG. 3 can be formed on the entire surface of FIG. As described above, the thickness of the solder film 7 formed in this manner is 1 to the fine electrode terminal 4 having a pitch of 0.5 mm.
It is appropriate that the thickness is about 00 μm.
About 0 to 100 μm is desirable.

After the plating is completed, the printed circuit board 1 is taken out of the electrolytic solution 12, dried sufficiently, and then a powdery flux 9 as shown in FIG. 2 is sprinkled on the entire surface of the printed circuit board 1 (step 3). This powdery flux 9
Is obtained by removing the solvent component of the liquid flux, and consists of a collection of particles of about 50 μm or less. Therefore, the powdered flux 9 is evenly spread on the printed circuit board 1 so that the powdered flux 9 is
It fits inside 0. Next, air is blown onto the surface of the printed circuit board 1 to leave only the particles of the powdery flux 9 fitted into the concave portions 10 of the solder film 7 as shown in FIG. It is removed by blowing off (step 4). That is, the powdery flux 9
Since the size of each particle is 50 μm or less, the particles fitted in the concave portion 10 of the solder film 7 do not easily jump out of the concave portion 10 even when air is blown, but remain as they are. Since the powdery flux 9 in the portion other than the concave portion 10 of the coating 7 has only particles on the surface of the printed circuit board 1, it can be easily removed by blowing air. When the removal is not sufficient, the excess powdery flux 9 attached to the surface of the printed circuit board 1 may be brushed off.

Finally, the printed circuit board 1 is placed in an oven or a conveyor furnace to heat the entire printed circuit board 1 (step 5). By setting the temperature of the furnace to 80 to 100 ° C., which is slightly higher than the softening temperature of the powdery flux 9 of 40 to 60 ° C., the powdery flux 9 in the recess 10 is semi-melted. The semi-molten powder flux 9 is filled into the recess 10 with increasing fluidity as shown in FIG.
In addition, it does not easily fall because it is fixed to the inner wall of the recess 10 when it is solidified. When the amount of the flux 9 is insufficient, the amount can be adjusted by repeatedly performing the above steps 2, 3, and 4.

The printed circuit board 1 having undergone the above series of surface treatment steps is inspected and then shipped as a product (step 6).

FIG. 6 is a cross-sectional view after surface treatment of the electrode terminals 5 of the semiconductor element 2 mounted on the printed board 1.
FIG. 7 is a view showing a state in which the entire semiconductor element 2 packaged in a mold is directly immersed in an electrolytic solution 12 for plating, and FIG. 8 is a view showing a process when surface treatment is performed on the electrode terminals 5 of the semiconductor element 2. . First, the semiconductor element 2 is immersed together with the solder plate 11 in the same electrolytic solution 12 as described above. The semiconductor element 2 is used as a “−” electrode, and the solder plate 11 is used as a “+” electrode to flow an electric current.
A solder film 13 having an uneven surface is attached to the portion (step 1).

After the plating is completed, the semiconductor element 2 is taken out of the electrolytic solution 12, the electrode terminals 5 are sufficiently dried, and the whole is covered with a powdery flux 14 (step 2). In this case, as shown in FIG. 6, the powdery flux 14 is sprinkled in a state where the semiconductor element 2 is turned upside down, or the semiconductor element 2 is passed through the powdery flux 14 in the form of a spray, so that the electrode terminals are formed. 5 tip back side surface 5
The powdered flux 14 is also sufficiently adhered to a. Although the powdered flux 14 hangs not only on the electrode terminals 5 but also on the mold portion, the air is blown over the entire semiconductor element 2 as described above, so that the powdered flux 1
4 can be easily removed (step 3). Most of the powdered flux 14 attached to the electrode terminals 5 is also blown away except for the powdered flux 14 fitted into the recess 15 of the solder film 13. If the powdered flux 14 is not sufficiently removed by air alone, the powdered flux 14 may be brushed off as in the above-described embodiment.

Finally, the semiconductor element 2 is placed in an oven or a conveyor furnace to heat the entire semiconductor element 2 (step 4). The furnace temperature is the same as described above. By heating, the powdered flux 14 contained in the concave portion 15 of the solder film 13 is softened and semi-melted, the fluidity increases, and the fluid flux is filled in the concave portion 15, and is fixed to the inner wall of the concave portion 15 to be easily attached. Will not fall. After all of the above surface treatment steps are completed, the semiconductor element 2 is inspected and then shipped (step 5).

In the case where the above-described semiconductor element 2 is mounted on the printed circuit board 1 on which the electrode terminals 4 and 5 have been subjected to the surface treatment as described above and are surface-mounted, the semiconductor element 2 is connected to the electrode terminal 4 of the printed circuit board 1. When the electrode terminals 5 of the semiconductor element 2 are positioned and passed through a reflow furnace, the solder films 7 and 13 and the fluxes 9 and 14 on the surfaces of the electrode terminals 4 and 5 are melted by heat and the electrode terminals 5 of the semiconductor element 2 are separated. It is soldered to the electrode terminals 4 on the printed circuit board 1.

In the above embodiment, the case where the electrode terminals 4 and 5 of both the printed circuit board 1 and the semiconductor element 2 are surface-treated has been described. In the present invention, at least one of the electrode terminals of the electronic component is subjected to the surface treatment. It should just be done. In the above embodiment, the case where the surface treatment of the electrode terminals 5 of the semiconductor element 2 is performed after the mold package is performed is described. However, in the present invention, the surface treatment is performed at the stage of punching the hoop material which is the material of the electrode terminals 5. Of course, you can. Further, in the above embodiment, the case where the semiconductor element 2 is used as an electronic component mounted on the printed circuit board 1 has been described. However, according to the present invention, capacitors, resistors, hybrid components, and the like are connected to the printed circuit board 1 by electrode terminals. Of course, electronic components are not limited to semiconductor elements.

[0026]

As described above, according to the electrode terminal of the electronic component according to the present invention, the rough surface film of the bonding material formed on the surface of the electrode terminal is printed while being shifted from the surface of the electrode terminal. Therefore, even if the pitch between the adjacent electrode terminals is narrow, the adjacent electrode terminals are not adhered to the adjacent electrode terminals by a bonding material as in the related art. In addition, many concaves are formed on the surface of the roughened film, and since the concaves are filled with the flux, they have the same cleaning effect as the conventional cream solder, and can maintain good wettability. Since it is possible, it is not necessary to supplement flux separately at the time of mounting, and the operation in the mounting process can be simplified.

Further, according to the surface treatment method for an electrode terminal according to the present invention, the electronic element is simply immersed in the electrolytic solution in which the bonding material is dissolved, and the electrode element can be properly positioned even with a narrow pitch electrode terminal. A film of the bonding material can be formed. As a result, it is possible to avoid the work of high-accuracy alignment by the conventional printing method. In addition, irregularities can be easily formed on the surface of the film deposited according to the plating conditions, so that the flux can be filled into the concave portions simply by dusting the powdery flux on the irregular surface. Play.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of an electrode terminal of an electronic component according to the present invention.

FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, showing a state in which a powdery flux enters a concave portion of a solder film.

FIG. 3 is a cross-sectional view taken along line AA in FIG. 1 showing a state in which a powdery flux is filled in a concave portion of a solder film.

FIG. 4 is an explanatory view when an electrode terminal of a printed circuit board is plated with an electrolytic bath.

FIG. 5 is a process chart when surface treatment is performed on an electrode terminal of a printed circuit board.

FIG. 6 is a cross-sectional view showing an electrode terminal of a semiconductor device subjected to a surface treatment.

FIG. 7 is an explanatory diagram when an electrode terminal of a semiconductor element is solder-plated in an electrolytic bath.

FIG. 8 is a process chart in surface treatment of an electrode terminal of a semiconductor element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 printed circuit board (electronic component) 2 semiconductor element (electronic component) 4 electrode terminal of printed circuit board 5 electrode terminal of semiconductor element 7 solder film (rough surface film) 9 flux 10 concave portion 13 solder film (rough surface film) 14 flux 15 concave portion

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 23/50 B23K 3/00 H05K 3/34 503

Claims (3)

(57) [Claims] 1. A electrode terminals provided on the electronic component, wherein a rough surface film on the surface of the electrode terminals joining material, in that it is formed by the powdered flux filled in the recess of the rough surface coating Electrode terminals of electronic components. 2. The electrode terminal according to claim 1, wherein the electronic component is a printed circuit board on which a circuit pattern is printed, a semiconductor element mounted on the printed circuit board, or a combination thereof. 3. A step of applying a powdery flux to the electrode terminal on which the roughened film of the bonding material is formed, and at least a concave portion of the powdery flux applied to the electrode terminal is formed in the concave portion formed on the roughened film. Removing the other powdery flux while leaving the powdery flux as it is, a method of surface treating electrode terminals in an electronic component.