JPH01197061A - Vapor phase soldering device - Google Patents

Abstract

PURPOSE:To restrain the descent of a saturated vapor phase level and to keep the ascent level of a vapor phase highly enough by providing a perforated plate on the upper face opening of a vapor recovery pocket. CONSTITUTION:The vapor and mist 144 overflowing vapor rise plates 41, 42 fall on perforated plates 54, 55 by its gravity and come into the inner part of pockets 51, 52 through a small hole 56. They are liquefied by getting into contact with the low temp. inert liquid fed from a cooling coil 53 or pipe lines 124, 127 inside the pockets 51, 52. The vapor and mist dropped into the pockets 51, 52 cannot be ascended again by the porous plates 54, 55. The vapor and mist which are made to leak out to the external part via a work carry-in port part 14 or carry-out port part 15 are condensed by cooling coils 16, 18 and the inert liquid liquefied falls into the pocket 51, 52 by descending the slope of the work carry-in and out port parts 14, 15. In that case, the re-ascent of the vapor and mist fed from the small hole 56 is prevented because the cooled inert liquid passes the small hole 56 of the porous plates 54, 55.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a vapor phase soldering device that performs reflow soldering using the latent heat of vaporization of a saturated vapor phase (hereinafter simply referred to as vapor). It is.

(Prior Art) As shown in Japanese Patent No. 1F11 1983-148083, a liquid tank is provided at the bottom of a steam tank, and a workpiece loading inlet and a workpiece unloading outlet are provided with this liquid tank in between. The inert liquid contained in the liquid tank is heated by a heater to form vapor inside the vapor tank, and the workpieces transported in this vapor are reflow soldered by the latent heat of vaporization of the vapor. Phase soldering devices are known.

Concave vapor recovery pockets are provided on the workpiece loading side and the workpiece loading side of the first part of the liquid, respectively. This steam recovery pocket collects the heavy vapor that attempts to leak out from the steam tank through the workpiece inlet or workpiece outlet, as well as relatively large mist floating around this vapor, and cools it inside the pocket. The inert liquid is liquefied and the inert liquid is returned to the liquid tank.

(Problems to be Solved by the Invention) This conventional steam recovery pocket has the following problems.

The cooling means in the vapor recovery pocket creates a significant thermal drop between the pocket and the area where the vapor is formed, causing the vapor and mist to flow into the vapor recovery pocket at a relatively high velocity. The vapor level used for reflow soldering in the tank tends to decrease, and the vapor level may not reach the workpiece transport level in some cases.

Furthermore, since the upper surface of the conventional steam recovery pocket is completely open, there is a risk that the vapor and mist that have fallen into the steam recovery pocket will rise again and move toward the outside.

The present invention provides a vapor phase soldering device that can prevent the vapor level in the steam tank from dropping by improving the vapor recovery pocket, and also prevent the vapor and mist collected in the vapor recovery pocket from rising again. The purpose is to provide.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a liquid tank section 12 at the lower part of a steam tank 11,
The inert liquid 13 contained in this liquid tank section 12 is heated to a heater 22.
is heated, and a saturated vapor phase 14 is formed inside the steam tank 11.
1, 142 are formed, and a workpiece W conveyed in this saturated vapor phase is reflow soldered by the latent heat of vaporization of the saturated vapor phase.
Concave steam recovery pockets 51, 52 are provided on the workpiece loading side and the workpiece loading side of 2, respectively, and a perforated plate 54 is provided at the upper surface opening of each steam recovery pocket 51, 52.
．． 55 is a vapor phase soldering device.

(Function) The present invention provides steam 4f! Saturated vapor phase 14 generated in 11
1, 142 flows down into the vapor recovery pocket 51.52 and its rate of liquefaction is slowed by the perforated plate 54.55.

This prevents the saturated vapor phase level from decreasing. At the same time, the vapor phase and mist that once fell into this vapor recovery pocket 51.52 through the holes of the perforated plate 54.55 are prevented from resurfacing by the perforated plate.

(Example) Hereinafter, the present invention will be described in detail with reference to actual flow examples shown in the drawings.

As shown in FIG. 1, an inner tank 12 as a liquid tank section is formed in the lower part of the steam tank 11, and an inert liquid 13 is stored inside this inner tank 12. This inert liquid 13 is a fluorinated inert solvent (trade name: Fluorinert) with a boiling point of 215°C. Further, the steam tank 11 is provided with a workpiece inlet 14 and a workpiece outlet 15 with the inner tank 12 in between. Inside the workpiece loading port 14, there is a cooling coil that condenses the saturated vapor phase (hereinafter simply referred to as vapor) evaporated from the inert liquid 13 and the mist floating around it to prevent it from leaking from the workpiece loading port. 16 are disposed above and below the workpiece transport conveyor 17 with Iυ in between, and a cooling coil 18 is installed inside the workpiece discharge port 15 to condense vapor and mist and prevent it from leaking from the workpiece discharge port. They are provided above and below the conveyor 17.

An outer tank 21 is disposed outside the inner tank 12, and a heater 22 is provided inside the outer tank 21, and is filled with at least a heat transfer medium 23 that becomes molten when heated by the heater 22. ing. This heat transfer medium 23 is for uniformly heating the inert liquid 13, and suitable materials include glycerin and solder.

Further, a vertical partition plate 31 is provided inside the inner tank 12 and is movable along a left-right movement guide means (not shown). A liquid passage gap 34 is provided between the secondary top portion 32 and the secondary sliding portion 33 on the workpiece delivery side. A female threaded member 35 is integrally attached to the vertical partition plate 31, and this female threaded member 35 is screwed onto a threaded rod 36.
6 is the motor 39 via the bevel gear 37 and rotation @38.
Rotated by Therefore, when the threaded rod 36 is rotated by this motor 39, the vertical partition plate 31 is moved to the workpiece loading side or the workpiece unloading side, and the above-mentioned secondary top part 32
The area ratio between the secondary sliding portion 33 and the secondary sliding portion 33 is variably adjusted.

In addition, steam rising plates 41 and 42 are provided at the upper part of the work loading side and the upper part of the workpiece unloading side of the inner tank 12, respectively, so as to be movable along vertical movement guide means (not shown).
Each of these steam rising plates 41 and 42 is connected to a motor 43, respectively.
, 44 (FIG. 2), the vertical movement is adjusted by a feed screw or a cam, etc. Then, the steam rising plate 41 on the workpiece loading side is adjusted to a relatively low level,
Further, the steam rising plate 42 on the workpiece unloading side is adjusted to a relatively high level.

Concave steam recovery pockets 51 and 52 are provided on the workpiece loading side and the workpiece unloading side of the inner portion 11i12. A cooling coil 53 is provided inside the steam recovery pocket 51 on the workpiece loading side, and a perforated plate 54 is provided in the upper opening. A perforated plate 55 is provided at the top opening of the steam recovery pocket 52 on the workpiece delivery side.

The perforated plates 54 and 55 are made of a stainless steel plate or the like with a large number of small holes 56, and are designed to control the speed at which the vapor formed in the steam tank 11 flows down into the steam recovery pockets 51 and 52 and is liquefied. The fluid resistance of the small holes 56 in the perforated plates 54 and 55 suppresses and slows down the flow. This prevents the saturated vapor phase level from decreasing.

At the same time, vapor and mist that have once fallen into the vapor recovery pockets 51.52 through the small holes 56 of the perforated plates 54, 55 are prevented from resurfacing by the perforated plates. In particular, the relatively low-temperature inert liquid condensed at the workpiece loading port 14 and the loading port 15 falls into the steam recovery pockets 51,52 through the small holes 56 of the perforated plate 54,55.
The small holes 56 of the perforated plates 54 and 55 are cooled, and the small holes 5
The re-upward limit of vapor and mist from 6 is effectively suppressed.

A liquid level detection device 61 is connected to the above-mentioned 4!12. In this liquid level detection device 61, a heat radiation header 63 made of a metal MIn body with a relatively large diameter is connected and communicated with the vibro 2 pulled out from the bottom of the inner tank 12.
Two transparent vibros 4 made of heat-resistant glass are vertically installed and communicated with each other. This liquid level detection device 61 functions as a communicating pipe with the inner tank 12, and the liquid level in the inner tank 12 appears as it is on the transparent vibro 4. This transparent vibro 4 includes a photosensor 65 for detecting the upper limit of the liquid level, a photosensor 66 for detecting the medium level of the liquid level, a photosensor 61 for detecting the lower limit of the liquid level, and a photosensor 61 for detecting the lower limit of the liquid level. A photosensor 68 is provided to detect the lowest limit. These seven sensors 65, 66, 67, and 68 each consist of a light emitter and a light receiver that face each other via the transparent vibro 4. This makes it possible to detect the presence or absence of inert liquid at each level, since the light emitted from the inert liquid may or may not be detected by the receiver.

Then, the heat dissipation header 63 causes the inside lll! 12
The high-temperature inert liquid inside is radiated to keep the temperature of the inert liquid entering the transparent vibro 4 low, and the photosensor provided on the side surface of the transparent vibro 4 is protected. When the upper limit sensor 65 detects the right side of the liquid, the pump (described later) for returning the inert liquid to the next tank section 32 is stopped, and when the lower limit sensor 67 detects that there is no liquid, the pump for returning the inert liquid to the next tank section 32 is stopped. 3. Start the pump to return inert liquid to 32. When the lowest limit sensor 68 detects the absence of liquid, the operation of the vapor phase soldering apparatus (work conveyor, heater, etc.) is stopped.

Next, the piping system diagram shown in FIG. 2 will be explained. The dotted line is a piping system related to mist collection, and the two lines are a piping system related to inert liquid circulation. ) are connected to the final return pipes 71, 72, 73, 74. Although the final return pipes 11°72, 73.74 are shown as being inserted from the upper part of the steam tank 11 in FIG. 2, they are actually inserted into the primary tank section 3 as shown in FIG.
Connected to the 2nd side.

The piping system related to mist collection indicated by the dotted line is provided with suction ports 81 at the upper and lower portions of the workpiece loading port 14 and the workpiece loading port 15, respectively, for sucking the mist to the outside. The conduit 82 is pulled out,
The pipe line 82 on the workpiece carry-in side is connected to the upper part of the tank 84 of the liquid recovery unit via a condensation pipe 83, and the pipe line 82 on the workpiece carry-out side is directly connected to the upper part of the tank 84. . Inside the tank 84 of the recovery unit, an air-cooled cooler 86 is provided inside the mist collision plate 85.
Air suction port 8 provided in the upper part between the mist collision plates 85
The suction side of a blower 89 is connected to 7 via a conduit 88.

The suction force of the blower 89 sucks the mist into the tank 84 from the suction port 81 of the steam tank 11, and the mist is liquefied by the cold W action of the mist collision plate 85 and the cooler 86. Exhaust by.

Cooling coils 16, 18, 53 in the steam tank 11 and cooling coils 93 in the condensing tank 83 are supplied with cold W water.

The inert liquid circulation piping system represented by the two-tree line is pocket 5.
The suction side of a circulation pump 104 is connected through a conduit 103 that communicates with both conduits 101 and 102 drawn out from 1.52, and the discharge side of this pump 104 is connected to the final return conduit 71. Similarly, pocket 51.5
The suction side of a circulation pump 106 is connected to the final return pipe 7 through a pipe 105 which is connected to both the pipes 101 and 102 drawn out from the pump 10G.
Connected to 2.

Further, a surge tank 114 is connected to a conduit 111 drawn out from the bottom of the inner tank 12 via an electric valve 113 in the conduit 112 . This surge tank 114 has 5 pockets.
The pipes 101 and 102 drawn out from the pipe 1.52 are also communicated via an electric valve 116 in the pipe 115. This surge tank 114 is connected to the electric valve 113 when filtering the activated liquid in the inner tank immediately after the device operation is stopped.
, 116 to cool the high-temperature inert liquid taken out from the inner tank 12, etc., to alleviate its thermal shock. The bottom of this surge tank 114 is connected to the electric valve 11.
7 is connected to a filtering tank 119 via a conduit 118 provided with a filter. A filter for removing flux and the like in the inert liquid is provided inside this tank 119, and the suction side of a liquid supply pump 122 is connected to a pipe line 121 drawn out from the bottom of this filtering tank 119. The discharge side of this pump 122 is the pipe line 12
3 to the final return pipe 73, and the pipe 1
24 to the pocket 52.

Similarly, the suction side of the liquid recovery pump 125 is connected to the lower part of the tank 84 of the recovery unit, and the discharge side thereof is connected to the pipe line 1.
It is connected to the final return line 73 via line 26, and to the pocket 52 via line 127.

An electric valve 13 is connected to the pipe line 111 drawn out from the bottom of the inner tank 12.
1 is connected to a pipe 132 for filtering during operation, and in this pipe 132 are provided a pre-stage filter 134 and a post-stage filter 135 used for removing pump 133° flux, etc., and this pipe 132 It is connected to the final return line 14.

An upper pre-heater 138 and a lower pre-heater 139 are provided at the work entry port of the steam tank 11 with a work transfer path in between, and the work is preheated by the pre-heaters 138 and 139.

Next, the movement of vapor and mist will be explained based on FIG. The inert liquid 1 is passed through the heat transfer medium 23 by the heater 22.
3 is heated, and a saturated vapor phase (hereinafter simply referred to as vapor) 1 is formed on the primary tank section 32 between the steam rising plate 41 and the vertical partition plate 31 at a level lower than the workpiece conveyance level.
41 is formed, and vapor 142 is formed on the secondary seed portion 33 between the steam rising plate 42 and the vertical partition plate 31 at a level higher than the workpiece conveyance level.

The reason why the vapor 141 on the primary tank section 32 does not rise sufficiently is that the pipes 71, 72, 73° 74
This is because the lower temperature inert liquid is returned. Secondary sliding part 3
Since the inert liquid preheated in the primary tank section 32 is gradually supplied to the tank 3 through the liquid passage gap 34, the vapor 142 on the secondary seed section 33 rises to a sufficiently high level. These vapors 141 and 142 are in a certain high temperature area (215°C)
However, in the upper temperature drop region 143 (around 200° C.), there is a mist whose particle size is larger than that of the vapor.

Therefore, the workpiece W is transported through the temperature drop area 143 on the secondary tank section 32, and is kept at a relatively low temperature (200°C).
The workpiece is preheated in the region 143, and then transported through the vapor 142 on the secondary seed section 33, where it is heated to this high temperature (21
The latent heat of vaporization of the vapor 142 (5° C.) melts the cream applied between the printed wiring board as a workpiece and the parts mounted on the board, and reflow soldering is performed.

Furthermore, the vapor and mist 144 that overflowed the steam riser plate 41.42 fall onto the perforated plate 54.55 due to its own weight, and enter the inside of the pocket 51.52 through the small hole 56. , contacts the low-temperature inert liquid supplied from the cooling coil 53 or the conduits 124 and 127 in the pocket, and liquefies it. The vapor and mist that have fallen into the pockets 51 and 52 are removed from the perforated plates 54 and 54.
55 makes it impossible to ascend again. In addition, the workpiece entrance section 1
4 or the vapor and mist that are about to leak to the outside through the workpiece loading/unloading port 15 are condensed by the cooling coil 16.18, and the inert liquid thus liquefied flows onto the inclined surface of the workpiece loading/unloading port 14, 15. It flows down into pockets 51 and 52. At this time, since the cooled inert liquid passes through the small holes 56 of the perforated plates 54 and 55, vapor and mist are effectively prevented from rising again from the small holes 56.

Further, since the pocket 52 exists, there is no fear that the low temperature inert liquid will directly flow into the secondary seed portion 33.

〔Effect of the invention〕

According to the present invention, since the perforated plate is provided at the upper opening of the vapor recovery pocket, the resistance of the perforated plate suppresses the flow rate of the vapor phase used for reflow soldering into the vapor recovery bow. The rise level of the vapor phase can be maintained at a sufficiently high level, and the perforated plate prevents the vapor phase and mist that have fallen into the vapor recovery pocket from rising again, thereby ensuring vapor recovery.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the vapor phase soldering apparatus of the present invention, and FIG. 2 is a piping system diagram thereof. W... Work, 11... Steam tank, 12... Inner tank as 1 part of liquid, 13... Inert liquid, 22... Heater, 51, 5
2...Steam recovery pocket, 54.55...Perforated plate, 14
1, 142...Saturated vapor phase.

Claims (1)

[Claims] (1) A liquid tank is provided at the bottom of the steam tank, and the inert liquid contained in this liquid tank is heated by a heater to form a saturated vapor phase inside the steam tank. In a vapor phase soldering apparatus in which workpieces being transported are reflow soldered using the latent heat of vaporization of a saturated vapor phase, concave steam recovery pockets are provided on the workpiece loading side and the workpiece loading side of the liquid tank, respectively, A vapor phase soldering device characterized in that a perforated plate is provided at the top opening of each vapor recovery pocket.