JPH02224870A - Soldering device - Google Patents

Abstract

PURPOSE:To allow good soldering without defects by blowing air to the parts where the contact of a printed circuit board and molten solder is completed and thereby removing the excess solder. CONSTITUTION:The knife-shaped hot air HE is blown from an air nozzle 19 toward a peeling back point P when there are insertion type electronic parts 23a of a micropitch or panel mounting type electronic parts 23b, such as microchip parts, in electronic parts 23... in the case of soldering the electronic parts 23... to the printed circuit board 15. The excess solder is blown by lowering the surface tension of the solder. Defects, such as bridge (e), flag (f), and icicle (g), are prevented and the defects, such as solder excess (h), icicle, wrinkle, and ruggedness, on the electrodes of the face mounting type electronic parts 23b are prevented.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention involves transporting a printed circuit board on which electronic components are mounted so that it comes into contact with molten solder flowing out from a jet port of a solder bath, and This invention relates to an improvement of a flow-type soldering device for soldering components and printed circuit boards.

(Prior Art) Normally, in a printed circuit board unit of an electronic device, insertable electronic components b1 such as connectors and DIPs, chip components, etc. mounted on a printed circuit board (PC board) a are mounted on a printed circuit board (PC board) a, as shown in FIG. Electronic components b, such as surface-mounted electronic components b2
When soldering..., a so-called flow type soldering device is used, in which the soldered part d... is soldered by contacting with the molten solder C flowing out from the jet port (not shown) of the solder bath. Ru.

In addition, conventionally, the electronic components b... mounted on the printed circuit board a and soldered are mainly insertion-type electronic components b1 such as connectors and DIPs, and many have a normal pitch of 2.54 m. However, recently, with the miniaturization of electronic devices, high-density packaging has been carried out, and electronic components b... have been miniaturized, and chip components have been mixed, resulting in fine pitches and miniaturized lands. It is in a state.

Therefore, in order to cope with this, the solder bath has two jet ports instead of one, and surface-mounted electronic components b2 such as chip components can be reliably soldered with the first wave of molten solder C, and connectors and Insertable electronic components such as DIPs b
Various attempts have been made to have the first wave of molten solder C serve as a temporary attachment, and the second wave of molten solder C to perform the final attachment and finishing.

However, when it comes to insertion-type electronic components BL with a minute pitch such as 1.27 fins or surface-mounted electronic components B2 such as minute chip components of 3.2 x 1.6 m or less, conventional soldering techniques cannot In the part b1, defects such as the formation of a bridge e1 flag f, which causes a short circuit between the adjacent soldered parts d and d, and irradiation g occur.
Further, in the surface-mounted electronic component b2, defects such as excessive solder h1 icicles gl on the upper surface of the electrode, wrinkles (not shown), and uneven formation may occur.

The main cause of these defects is the solder breakage at the part where the second wave of molten solder C, which is the finishing wave, completes contact with the printed circuit board a, that is, the beading back point P.

The degree of solder breakage at the beading back point P is determined by the speed of the conveyor conveying the printed circuit board a, the active residual amount of flux applied to the printed circuit board a, the roughness of the surface of the molten solder C, and the oxide film. The presence or absence of soldering, the soldering temperature, the wave velocity of solder C, the magnitude of the surface tension of solder C, etc. are delicately intertwined, and when some of these factors become unbalanced, fluctuations occur and soldering defects occur. However, it has not been possible to prevent this variation and make the solder cutting condition of the solder back point P constant.

(Problems to be Solved by the Invention) As described above, in the conventional method, the degree of solder cutting at the beading back point P is not constant, and defects occur due to excess solder, which requires troublesome rework. This not only causes a decrease in yield, efficiency, and inspection efficiency, but also causes problems in that stable quality cannot be obtained and labor savings cannot be achieved.

The present invention has been made based on the above circumstances, and its purpose is to improve the solder cutting condition at the part where the contact between the molten solder and the printed circuit board is completed, while having a simple structure, and to improve the solder cutting quality at the part where the molten solder contacts the printed circuit board. , even when electronic components of the same size are mounted, it is possible to perform good soldering without defects, improving yield, efficiency, and inspection efficiency, as well as achieving stable quality and saving labor. The present invention aims to provide a soldering device that can also perform the following steps.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides, as a first means, a method in which a printed circuit board on which electronic components are mounted is exposed to molten solder flowing out from a jet port of a solder bath. be transported so that they are in contact with each other,
The soldering apparatus for soldering the electronic component and the printed circuit board is provided with an air blowing means for blowing air to a portion where the contact between the printed circuit board and the molten solder is completed to remove excess solder.

Further, as a second means, in the soldering apparatus for soldering the electronic component and the printed circuit board by transporting the printed circuit board on which the electronic component is mounted so as to contact the molten solder flowing out from the jet port of the solder bath, The printed circuit board has an air nozzle facing the part where the contact between the printed circuit board and the molten solder is completed, and an air blowing path that conducts air to the air nozzle and immerses the middle part in the molten solder in the solder bath. An air blowing means is provided for blowing hot air heated by the heat of the molten solder onto a portion where the contact with the molten solder is completed to remove excess solder.

(Function) In other words, in the present invention, since the air is blown toward the part where the contact between the printed circuit board and the molten solder is completed, the surface tension of the solder in this part is reduced and the solder cutting quality can be improved. , excess solder can be reliably removed. Even when electronic components with minute pitches and sizes are mounted, it is possible to prevent soldering defects such as the formation of bridges, flags, icicles, etc., and excessive solder on the top surface of chip component electrodes. It becomes possible.

Further, according to the second means, in addition to the effect of the first means, since the air blown toward the part where the contact between the printed circuit board and the molten solder is completed is heated hot air, the surplus Cooling of the solder is prevented and excess solder can be removed more smoothly. Furthermore, since the heat of the molten solder in the solder bath is used to heat the solder to a hot air state, a separate heating source is not required and the configuration can be simplified.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 is a side sectional view showing the configuration of the soldering apparatus of the present invention, and FIG. 3 is a plan view.

1 in the figure is a solder bath, and inside this solder bath 1 are sS
u 63% eutectic, melting temperature 183℃ solder at temperature 2
Molten solder 2 melted at around 50° C. is stored.

This solder bath 1 accommodates a first solder jet bath 3 that forms a first wave 2a of molten solder 2 and a second solder jet bath 4 that forms a second wave (finishing wave) 2a of molten solder 2. has been done.

In addition, the first solder jet tank 3 and the second solder jet #
Projections 3g and 4a are formed on one end side of a4,
Recesses 1a and 1 formed on one side of the solder bath 1
It is in a state that it is interposed within b. In addition, the bottom surfaces 3b and 4b of the first solder jet tank 3 and the second solder jet tank 4
There is a gap L'ffG between and the inner bottom surface 1c of the solder bath 1.
, G are formed, and the protrusions 3a, 4a
Molten solder suction ports 5 and 6 are formed on the bottom surface of the board. Further, a first pump 7 is located at a position corresponding to the molten solder suction port 5 at the inner bottom of the first solder jet tank 3.
In addition, a second pump 8 is disposed at a position corresponding to the molten solder suction port 6 at the inner bottom of the second solder jet tank 4, and each sucks the molten solder 2 from the bottom to supply the molten solder to the jet port. It is configured to eject from 9 and 10 along the shape of the wave former.

A turbulent flow forming member 11 consisting of a plurality of balls 11a... is provided at the jet port 9 of the first solder jet Jf3 that forms the first wave 2a. 2a is placed in a turbulent state to improve degassing of the flux.

Further, on the upper surface side of the solder bath 1, a first wave 2a of the molten solder 2 formed by the first solder jet tank 3 and a molten solder 2 formed by the second solder jet tank 4 are provided.
A conveyance path 16 is formed to convey the printed circuit board unit 15 so as to sequentially contact the second wave (finishing wave) 2a. This conveyance path 16 is constituted by a conveyor 17 that conveys the printed circuit board unit 15 by holding both ends thereof.

Furthermore, inside the solder bath 1, hot air H is directed toward the bee-back point P, which is the part where the contact between the printed circuit board unit 15 and the second wave 2b of the molten solder 2 is completed.
An air blowing means 18 is provided which sprays E in a knife shape to remove excess solder 2 near the soldered portion. The air blowing means 18 includes an air nozzle 19 facing the beering back point P, and an air nozzle 19 facing the beering back point P.
9 and a stainless steel duct 21 as a ventilation path for guiding air from a fan 20.

A plurality of air nozzles 19 are prepared that are suitable for a plurality of printed circuit boards 22 of different sizes, and they can be replaced according to the size of the printed circuit board 22, and the air nozzle 19 can be replaced to match the size of the printed circuit board 22, and to choose the width and thickness most suitable for blowing away excess solder. An air knife shape can be obtained.

The midway portion of the duct 21 has a flat and meandering shape and is immersed in the molten solder 2 of the solder bath 1 so that heat exchange with the molten solder 2 can be carried out well. The air is heated in this portion and can be discharged from the air nozzle 19 as hot air HE at a temperature of approximately 200°C to 220°C. In addition, the discharge pressure of hot air HE is 100AQ~80000A
Conditions of about Q are good, and preferably 100 for a normal printed circuit board 22 with a thickness of 1.6 mm.
About 00 Aq is good. Note that the printed circuit board 22 is
In addition to this plate thickness of 1.6 mm, there are thick plates of 2.3 l and thin plates of 0.6 to 0.8 mm.

FIG. 1 is an enlarged view of the peeling back point P part in FIG. 2, where 22 is a printed circuit board (CPC board), 23
23a is an insertion-type electronic component such as a DIP, and 23b is a surface-mounted die component such as a chip component.

Next, the operation of the soldering device configured as described above will be explained.

First, the printed circuit board unit 1 is formed by mounting the electronic components 23...' such as the insertion type electronic components 23a1 and the surface-mounted die part 23b to be soldered on the printed circuit board 22 in advance.
5 is conveyed by a conveyor 17 to a soldering device for a soldering process through a flux coating process and a preheating process (not shown).

The printed circuit board unit] 5 is conveyed by the conveyor 17, and the first wave 2a is ejected from the jet port 9 of the first jet tank 3 and the jet port 10 of the second jet tank 4. By sequentially contacting the second wave 2b, the electronic components 23... are soldered. In addition, by contacting with the first wave 2a, surface-mounted molded parts 23b such as chip parts are reliably soldered, and insertion-type electronic parts 23a such as connectors and DIPs are temporarily attached, and the next second wave 2a is soldered. The final attachment and finishing are performed by contact with 2b.

At this time, an insertion type electronic component 23a with a minute pitch such as 1.27 mm+ or 3.2X
If there is a surface-mounted die part 23b such as a minute chip part of 1.6 inches or less, whether the part extracted from the second wave 2b, that is, the peeling back point P, will cause a final solder defect. This is an important point. especially,
Among soldering defects, bridges, icicles, unevenness, wrinkles, etc. greatly affect the withdrawal speed, that is, the relative speed and withdrawal angle between the conveyor 17 and the flow of molten solder 2, and secondary to the effective components of the flux. The amount generated becomes larger as the pitch becomes narrower due to a complex interplay between the amount of dirt and the difference in the degree of surface contamination of the parts.

However, in the present invention, the active ingredient of the flux is
It is possible to reduce the surface tension of the molten solder 2 at the peeling back point P of the second wave 2b, which is stripped away by the first wave 2a and has almost no effect, to improve the cutting quality and prevent the soldering defects. That is, by spraying knife-shaped hot air HE toward the peeling back point P from the air nozzle 19, the surface tension of the solder 2 is lowered and excess solder is blown off.

Then, the bridge e1 flag f shown by the two-dot chain line in FIG.
, prevents defects such as icicles, and imposition die parts 23.
Excessive solder on the top surface of the electrode in b.

Defects such as icicles, wrinkles, and unevenness (not shown) can be prevented. Note that if the hot air HE discharge pressure is too strong, it may cause a pattern short.
The above-mentioned conditions of about 100 Aq to 60,000 Aq are good. .

In this way, by installing the air blowing means 18 that blows air at the part where the contact between the printed circuit board 22 and the molten solder 2 is completed, that is, the peeling back point P, 1) the fine pitch insertion type electronic component 23a; It is possible to prevent defects such as solder bridge e1 flag f and icicle g in ....

2) Surface support for chip parts etc. can prevent defects such as excessive solder on the upper surface of the electrodes in the molded element parts 23b, etc., as well as other defects such as icicles, wrinkles, and unevenness.

3) Good fillet shape can be formed.

Additionally, this eliminates the need for rework, resulting in significantly improved yields, improved inspection, stable quality, and labor savings.

Note that in the above embodiment, air nozzles 19 to 2
Although the configuration is such that hot air HE heated to 00° C. to 220° C. is blown, the temperature is not limited to this as long as the excess solder can be reliably blown off.

Although the configuration is such that air is continuously blown, for example, as shown by the dotted chain line in FIGS. 2 and 3, a flow path opening/closing means 25 such as an electromagnetic valve is installed at the base end of the duct 21. The printed circuit board 22 is provided with a second layer of molten solder 2.
The hot air HE may be sprayed only when facing the wave 2b. By doing this, the molten solder 2
Inadvertent cooling of the air can be prevented, and sufficiently heated hot air HE can always be blown onto the beer ring back point P.

In addition, it goes without saying that the present invention can be modified in various ways without departing from the gist.

C Effects of the Invention Since the present invention is configured as described above, it has the following effects.

The soldering device according to claim 1 is capable of improving the solder cutting condition to complete the contact between the printed circuit board and the molten solder, and is capable of mounting electronic components with minute pitches and sizes. Also, it is possible to perform good soldering without defects, improve yield, efficiency, and inspection efficiency, as well as obtain stable quality and save labor.

Further, in the soldering device according to claim 2,
In addition to the above effects, the air that is blown toward the area where the contact between the printed circuit board and the molten solder is completed is heated hot air, which prevents excess solder from cooling and allows for smoother removal of excess solder. be able to.

Further, since the heat of the molten solder in the solder bath is used to heat the solder to a hot air state, a separate heating source is not required, and the configuration can be simplified.

[Brief explanation of the drawing]

Figures 1 to 3 show one embodiment of the present invention.
2 is a schematic longitudinal sectional side view of the solder bath, FIG. 3 is a schematic plan view of the solder bath, and FIG. 4 is an enlarged view of the vicinity of the main portion of the conventional device. 1... Solder bath, 2... Molten solder, 9.10...
- Jet outlet, 18... Air blowing means, 22... Printed circuit board, 19... Air nozzle, 21... Ventilation path (duct)), 23... Electronic component, 23a... Insertion Shaped molded part, 23b...imposed molded part, HE・
...Hot air P...The part where the contact between the printed circuit board and the molten solder is completed (peeling back point)
. Figure 111 Applicant Representative Patent Attorney Takehiko Suzue

Claims (2)

[Claims] (1) In a soldering device that transports a printed circuit board on which electronic components are mounted so that it comes into contact with molten solder flowing out from a jet port of a solder bath, and solders the electronic component and the printed circuit board, the printed circuit board and the molten solder are soldered together. A soldering device characterized by being provided with an air blowing means for blowing air to a part where contact with the solder is completed to remove excess solder. (2) In a soldering device that solders the electronic component and printed circuit board by transporting the printed circuit board on which the electronic component is mounted so that it comes into contact with the molten solder flowing out from the jet port of the solder tank, the printed circuit board and the molten solder are soldered together. It has an air nozzle facing the part where the contact is completed, and a blowing path that conducts air to the air nozzle and immerses the middle part in the molten solder in the solder bath, and the contact between the printed circuit board and the molten solder is provided. 1. A soldering device comprising an air blowing means for blowing hot air heated by the heat of the molten solder onto a portion where contact is completed to remove excess solder.