JP2003023245A - Jet type soldering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jet type soldering device which can solve the problem that the conventional jet type soldering device is not provided with means for coping with an increase and decrease in quantity of solder in a solder bath and a change in viscosity of solder caused by oxidation and, when the device uses lead-free solder having lower wettability, the productivity of the device declines, because many defective products are produced. SOLUTION: The height jet stream of a jet solder flow from the jet type soldering device 1 is controlled to a fixed value by means of the output of a jet stream pressure detecting sensor 6 provided correspondingly to the position where the solder jetting is performed. Consequently, even when the lead-free solder the height of jet stream of which changes depending upon hourly changing various conditions and which makes the occurring probability of defective products higher due to its lower wettability is used, the height of jet stream of the solder can always be fixed by detecting the jet stream pressure of the solder by means of the sensor 6 in real time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering apparatus for automatically performing a soldering process of electronic parts on a circuit board during the production of electronic products, and more particularly, to a molten state by heating. The present invention relates to a jet-type soldering device in which electronic components are attached by blowing up the solder in the form of a jet (fountain) to a predetermined height and bringing the solder into contact with the back surface of the circuit board.

[0002]

2. Description of the Related Art FIG. 5 shows the structure of a conventional jet type soldering apparatus 90 in a principal part. Inside a solder bath 91, a solder 10 which is in a molten state by a heater (not shown) is held. Inside the solder bath 91, a pump 92 having an appropriate structure such as sirocco driven by a motor 92a is provided.

The molten solder 10 pumped up by the pump 92 is ejected from the jet nozzle 93 installed near the liquid surface, and the circuit board 20 is passed through this jet to mount the mounted electronic component. And the circuit board 20 are soldered.

Here, since the height of the solder 10 ejected from the jet nozzle 93 changes depending on, for example, the amount of the solder 10 in the solder bath 91 or the change in the viscosity of the solder 10 due to oxidation, For example, a glass plate is placed at the same position where the circuit board 20 passes, the contact state is observed through the glass surface, and the rotation speed of the motor 92a is set to a constant value by the drive circuit 92b. It was manually adjusted by 92b and managed.

[0005]

However, in recent years, from the standpoint of environmental protection, the solder 10 is currently shifting to a lead-free solder, which is a lead-free composition. In this case, the lead-free solder has poor wettability as compared with the tin-lead eutectic solder that has been used conventionally, and is applied to the circuit board 20 with a higher pressure than that of the conventional one, in other words, with a high jet height. If they do not come into contact with each other, there is a problem that soldering becomes defective.

On the other hand, if the jet height is set to have a sufficient margin to ensure the wettability, a so-called bridging phenomenon occurs, in which the patterns on the circuit board 20 are short-circuited by the solder 10, and With lead-free solder, it is necessary to control the height of the jet in a much narrower range and in a nearly real-time state. Conventionally, for example, the height of the jet can be visually observed about twice a day. However, it is not something that can be dealt with by management that involves manual adjustment.

[0007]

As a concrete means for solving the above-mentioned conventional problems, the present invention comprises soldering by contacting a solder jet from the back surface of a circuit board on which electronic components are mounted. In the jet-type soldering apparatus, a jet pressure detection sensor is provided at a position corresponding to the position where the solder jet is performed, and the jet height of the solder jet is adjusted to a constant height by the output of the jet pressure detection sensor. The problem is solved by providing a jet flow type soldering device characterized by being controlled.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on the embodiments shown in the drawings. Reference numeral 1 in FIGS. 1 and 2
Is a jet type soldering device according to the present invention,
This jet type soldering apparatus 1 has a solder bath 2, a pump 3 provided in the solder bath 2 and driven by a motor 3a, and a molten solder 10 urged by the pump 3 at an appropriate height. It is the same as that of the conventional example in that it is composed of a jet nozzle 4 that ejects as above, and a board transfer conveyor 5 for passing the circuit board 20 on the jet nozzle 4 at an appropriate interval.

Further, the motor 3a is connected to a drive unit 3b such as an inverter having a variable frequency so that the rotation speed of the motor 3a can be varied, whereby the jet height of the solder 10 ejected from the jet nozzle 4 is increased. It is also similar to the conventional example in that it can be adjusted freely. still,
In this embodiment, the number of jet nozzles 4 is one, but there are some jet nozzles 4 provided in the actual jet type soldering apparatus 1.

Here, in the present invention, it is above the jet nozzle 4 and preferably the circuit board 20.
The pressure detection sensor 6 is provided at a position matched with the height at which the jet nozzle passes. At this time, since the jet nozzle 4 has a long shape in the direction orthogonal to the passing direction of the circuit board 20, the jet nozzle 4 is provided near both ends thereof. It is preferable that the pressure difference between the left and right can be measured, for example, by providing it.

Further, since the pressure detecting sensor 6 directly measures the pressure of the jet flow of the solder 10 in a molten state which is high in temperature as described above, for example, as shown in FIG.
As shown in Fig. 1, the solder 1 is resisted against the biasing force of the spring 6a.
Baffle plate 6b which moves by the jet pressure of 0, and this baffle plate 6
The potentiometer 6d, which is rotated via the lever 6c by the movement of b, is configured to have less measurement error due to heat.

In addition to the pressure detection sensor 6, according to the present invention, a control circuit 7 is also provided. The control circuit 7 is composed of, for example, a comparator circuit, and the pressure (voltage) detected by the pressure detection sensor 6 is provided. Is compared with the standard pressure (standard voltage) held inside to determine the magnitude. If the detected pressure is higher than the standard pressure, the drive unit 3b is instructed to lower the rotation speed of the motor 3a, and the detected pressure is lower than the standard pressure. In this case, an instruction is given to increase the rotation speed of the motor 3a.

By doing so, the jet nozzle 4 is
The height of the solder 10 ejected from the solder 10 is, for example, when the amount of the solder 10 in the solder bath 2 is increased or decreased, or when the viscosity of the solder 10 is changed due to oxidation, the state of soldering to the circuit board 20 is high. Can always be constant.

4 (A) to 4 (D) show the soldered state of the circuit board 20. The drawing shows the through hole in a cross section, and the reference numeral 20a in FIG. The board portion, reference numeral 20b is a land, reference numeral 20c is a through-hole plated portion, and the solder 10 is jetted from below in the illustrated state.

4 (A) to 4 (D) are arranged in order of the height of the solder 10 ejected from the jet nozzle 4, with FIG. 4 (A) being the lowest and FIG. (D) is the highest. Then, in the state of FIG. 4A, the solder 10 reaches only halfway through the through-hole plated portion 20c.

FIG. 4B shows the jet height slightly increased from the state shown in FIG. 4A, and the solder 10 is in a state of filling the entire through-hole plated portion 20c, but the upper land. It does not reach 20b, and in this state, the red land 20a made of copper foil looks like a spherical eye, and is called "red eye".

In FIG. 4C, the height of the jet flow is further increased, and the solder 10 fills the entire through-hole plated portion 20c and reaches a part of the upper land 20b. However, since it does not cover the entire surface of the land 20b, it is called "red eye remaining". FIG. 4 (D) shows the height of the jet flow further increased, and the solder 10 is the land 20b.
It covers the entire surface of, and is called "no red eyes".

In each of the above states, the soldering strength is satisfied both electrically and mechanically, as shown in FIG.
4D, "without red eye". Therefore, it seems that the higher the height of the jet of the solder 10, the better.
According to the results of experiments by the inventor, when the height of the jet flow is excessively increased, a so-called bridging phenomenon in which wirings are short-circuited by the solder 10 is likely to occur, and it takes time for later inspection and correction, and productivity is reduced. found.

Therefore, in the present invention, the number of revolutions of the motor 3a is a jet height at which "red eye remaining" (see FIG. 4C) or more is obtained, and the occurrence of the bridge phenomenon is minimized. The value is set as a range, and this may differ depending on the wiring pattern laid on the circuit board 20. Therefore, the optimum value should be obtained based on the circuit board 20 to be actually soldered. Preferably, the control circuit 7 has a standard pressure (standard voltage).
Is variable.

[0020]

As described above, according to the present invention, the jet pressure detection sensor is provided corresponding to the position where the solder jet flow is performed, and the ejection height of the solder jet is determined by the output of this jet pressure detection sensor. Since the jet type soldering device is controlled to have a constant height, for example, the ejection height changes due to the amount of solder in the solder tank that changes moment by moment, or the change in viscosity due to the progress of oxidation. However, due to poor wettability, the finished state of soldering is more likely to change than before, and even with lead-free solder, which has a high probability of defective products, the jet pressure detection sensor detects the jet pressure in real time. As a result, it is possible to always ensure a constant ejection height, reduce the occurrence of defects, and thus exhibit an extremely excellent effect in improving productivity.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a jet type soldering apparatus according to the present invention.

FIG. 2 is a cross-sectional view taken along the line AA of FIG.

FIG. 3 is an explanatory view showing a main part of the jet type soldering apparatus according to the present invention.

FIG. 4 is an explanatory diagram showing a height of a solder jet flow and a state of soldering performed.

FIG. 5 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

1 ... Jet type soldering device 2 ... Solder tank 3 ... Pump 3 3a ... motor 3b ... Drive unit 4 ... Jet nozzle 5: Substrate transport conveyor 6 ... Pressure detection sensor 6a ... spring 6b ... Baffle plate 6c …… Lever 6d ... Potentiometer 7 ... Control circuit 10 ... Solder 20 ... Circuit board 20a ... substrate part 20b ... land 20c ... through hole

Claims (2)

[Claims] 1. A jet-type soldering apparatus comprising a soldering method in which a solder jet is brought into contact with a rear surface of a circuit board on which electronic components are mounted, and the jet pressure is applied to the position where the solder jet is performed. A jet type soldering device, wherein a detection sensor is provided, and the ejection height of the solder jet is controlled to a constant height by the output of the jet pressure detection sensor. 2. The jet type soldering apparatus according to claim 1, wherein the jet height of the solder jet is adjustable as an appropriate value according to the configuration of the circuit board.