JPH0770659B2 - Lead solder plating equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solder plating apparatus that applies solder plating to leads of a semiconductor device such as an IC (semiconductor integrated circuit).

“Prior Art” Conventionally, when mounting a semiconductor device such as an IC, a mounting method having high reliability and low cost has been desired. However, in recent years, as the scale of ICs has increased,
The number of pins in packages and the pitches are becoming narrower,
A situation has arisen that is not accompanied by progress in precision soldering technology corresponding to this.

In other words, when soldering leads (connection terminals) of multi-pin and narrow-pitch ICs, it is extremely difficult to stably supply a certain amount of solder to the fine soldering parts. The current situation is that the lead of these ICs is largely liable to be touched.

However, in the manual work, when the solder is supplied to the fine portion, there is a problem that the amount of the supplied solder is not constant. Therefore, when the amount of supplied solder is excessive, there is a problem that adjacent leads are joined by a bridge of solder and short-circuited.

Therefore, as a method of mounting a semiconductor device of this type on a substrate, a method of preliminarily applying solder plating to the leads of the IC and supplying solder to the joint portion from the outside when joining to the circuit of the substrate is used. Has been taken.

Here, the solder plating applied to the leads of the IC is provided for the purpose of improving wettability with solder supplied from the outside, and is formed with a thickness of about several μm. However, since the joining strength is insufficient only with the solder plating having such a thickness, the insufficient solder is supplied from the outside by the method described below to perform the joining work.

As a solder supply method, a method of using a thread solder, a method of previously applying a solder paste to a pad of a substrate to which a lead is joined by screen printing, a method of applying a solder paste to a pad of a substrate by a dispenser, a melting There is a method of immersing the board in a solder bath.

However, even if a small amount of solder is supplied to an IC with multiple pins such as QFP (Quad Flat Package) and a body with a narrow lead interval, for example, an IC with a lead interval of 0.65 mm or less However, after reflow (melting), a bridge is formed by the solder between the leads, and if it is insufficient even a little, the joining strength becomes insufficient, so that it is extremely difficult to supply an appropriate amount of solder.

Therefore, the present applicant has proposed a method of attaching an appropriate amount of solder to the leads by applying thick film solder plating to the leads of the IC as described below.

FIG. 3 shows a jig 1 for applying electric solder plating to many leads of a multi-pin package IC such as QFP. This jig 1 includes a rectangular upper frame 3 made of metal such as brass, a non-conductive lower frame 2 and screws for connecting them.
It is composed of 4,4 ,.

Then, as shown in FIG. 4, between the lower frame 2 and the upper frame 3,
Leads 6, 6, of the main body 5 of the multi-pin package IC such as QFP
After sandwiching and fixing with screws 4, 4, ..., arrange this jig 1 soaked in the solder plating solution A so that most of the leads 6, 6, ... are immersed in the solder plating solution A. Then, by electroplating the jig 1 as a cathode and the solder ingot 7 as an anode, the leads 6, 6, ... Are plated with solder.

[Problems to be Solved by the Invention] By the way, as described above, the solder plating solution A that is stationary is used.
In the conventional method in which the leads 6, 6, ... Are dipped in the inside and solder-plated, the solder plating solution A is not agitated, so that the flow of ions is extremely small and the required thickness of the solder plating is performed. Requires a great deal of time, and the thickness of the solder plating cannot be controlled, and the solder plating is locally applied, so that all the leads 6, 6, ... There was a problem that plating could not be applied.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a lead solder plating apparatus capable of efficiently performing solder plating of a uniform film thickness on each lead in a short time. There is.

"Means for Solving the Problem" The present invention is directed to a cathode that comes into contact with a plurality of leads arranged around a main body of a semiconductor device, and a cathode provided on the side opposite to the cathode. In a lead solder plating apparatus that has an anode and in which a current is passed between the anode and the cathode in a solder plating solution to deposit solder on the leads, a flow rate that is substantially the same for each lead It is characterized in that a jet means for jetting the solder plating liquid is provided.

[Operation] According to the above configuration, the jetting means continuously jets the solder plating liquid of substantially the same flow rate to the plurality of leads arranged around the main body of the semiconductor device. The leads are solder-plated with a uniform film thickness in a short time.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view showing the structure of a solder plating apparatus according to an embodiment of the present invention. In this figure, 11 is a rectangular frame-shaped cathode made of titanium material, and a contact portion 11a is formed in the lower part of the cathode so as to surround the main body portion 5 of the IC. The lower end surface of the abutting portion contacts all the leads 6, 6, ... Arranged on the four sides of the main body portion 5. The periphery of the cathode 11 is covered with an insulating cover 10 such as epoxy.

Reference numeral 12 is a vertically long rectangular parallelepiped lower pedestal which is made of an insulating material such as PEEK material (organic insulating material) and ceramics. Fence-shaped portions 12a, 12a, ... Abutting on the respective base portions of the leads 6, 6, arranged on each of the four sides are formed. In addition, the base 12
, A large diameter conduit 12b for receiving the solder plating liquid injected from below, and small diameter conduits 12c, 12c, ... Which guide the solder plating liquid injected into this large diameter conduit 12b further upward, Ejection conduits 12d, 12d, ... Which communicate with the small diameter conduits 12c, 12c, ... In this case, the openings of the ejection conduits 12d, 12d, ... Are arranged at positions where the solder plating liquid ejected from these openings reaches the leads 6, 6 ,.
The small-diameter conduits 12c, 12c, ... and the ejection conduits 12d, 12d, ... are set to have the same flow passage cross-sectional area, so that all the leads 6, 6, ... The solder plating solution of substantially the same flow rate is continuously ejected.

Further, a rectangular frame-shaped anode 13 made of a titanium material is provided around the lower pedestal 12, and its upper end face is opposed to the cathode 11 via the leads 6, 6 ,. A thin plate-shaped platinum electrode 14 is provided.

Next, when the solder plating is performed using the solder plating apparatus according to the above-described embodiment, the solder plating is performed as follows.

First, an IC for which lead forming has been completed is placed on the lower pedestal 12, and the bases of the leads 6, 6, ... On the four sides of the main body 5 are supported from below by the fence-shaped portions 12a, 12a ,. Next, the cathode 11 is placed on the IC, and the contact portions 11a, 11 of the cathode 11 are
... and the walls 12a, 12a, ... of the lower pedestal 12 lead
... are sandwiched, and the spacing between the leads 6, 6, ... And the platinum electrode 14 is adjusted to be an appropriate spacing of several mm to several tens of mm, for example, about 5 mm. This completes the mounting of the IC.

Next, the solder plating liquid is pressure-fed by a pump (not shown) and injected into the large diameter conduit 12b. Then, this solder plating liquid is guided to the ejection pipe lines 12d, 12d, ... By the small diameter pipe lines 12c, 12c, ... As shown by the arrow in the figure, and further, obliquely upward by these ejection pipe lines 12d, 12d ,. , And is ejected from the openings toward the leads 6, 6, .... As a result, the solder plating liquid having substantially the same flow rate is continuously ejected to the leads 6, 6 ,. After the jet of the solder plating solution is stabilized, electricity is applied between the cathode 11 and the anode 13. Then, each lead 6, 6, ... Is plated with solder having a uniform film thickness in a short time.

According to the above-described embodiment, the flow paths in the four directions corresponding to the four side surfaces of the main body 5 of the IC, that is, the flow paths of the small diameter conduits 12c, 12c, ... And the ejection conduits 12d, 12d ,. The road cross-section areas are set to be the same, and the leads 6 arranged on the four side surfaces of the main body 5,
Since a uniform flow rate of the solder plating solution is ejected to 6, 6, the solder plating solution of a desired flow rate can be applied to each of the leads 6, 6 by simply controlling the flow rate of the solder plating solution. Can be supplied, and the film thickness of solder plating can be controlled.

In the above-described embodiment, the flow passage cross-sectional areas are the same for each of the four flow passages. However, when the flow passage cross-sectional area is different for each flow passage, each flow passage is independently provided. The same effect can be obtained by adopting a flow path structure capable of controlling the flow rate and adjusting the flow rate so that the jetting of the substantially same flow rate is obtained in each direction. Further, in the above-described embodiment, the solder plating solution is ejected from the direction of the anode 13 toward each of the leads 6, 6, ..., On the contrary, reverse flow from the direction of the cathode 11 Of course, the structure may be such that it flows into the pipelines 12d, 12c, 12b.

[Advantages of the Invention] As described above, according to the present invention, in a state in which a current is passed between the cathode and the cathode that abut on a plurality of leads arranged around the main body of the semiconductor device, Since the jetting means for jetting the solder plating liquid of approximately the same flow rate is provided for each lead, it is possible to efficiently apply the solder plating of a uniform film thickness to each lead in a short time.

[Brief description of drawings]

FIG. 1 is a front sectional view showing the structure of a lead solder plating apparatus according to an embodiment of the present invention, FIG. 2 is a plan view showing the structure of the lower pedestal of the same embodiment, and FIG. 3 is conventional solder plating. FIG. 4 is a perspective view showing the structure of the jig, and FIG. 4 is a view for explaining a solder plating method using the same solder plating jig. 5 ... Main body, 6 ... Lead, 11 ... Cathode, 12 ... Bed, 12b ... Large diameter conduit, 12c ... Small diameter conduit, 12d ... Spout conduit, 13 ... Anode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihisa Maejima 10-1 Nakazawa-machi, Hamamatsu-shi, Shizuoka Yamaha stock company (72) Inventor Atsuka Ota 10-1 Nakazawa-machi, Hamamatsu-shi, Shizuoka Yamaha stock company (56) References Japanese Patent Laid-Open No. 2-107796 (JP, A)

Claims (1)

[Claims] 1. A solder comprising: a cathode that abuts a plurality of leads arranged around a main body of a semiconductor device; and an anode arranged on the opposite side of the cathode with respect to the leads. In a solder plating apparatus for a lead, which deposits solder on the leads by passing a current between the anode and the cathode in a plating solution, a solder plating solution having a substantially same flow rate is jetted to each of the leads. A lead solder plating apparatus characterized by having a jetting means.