JPS6221463A - Vapor phase type soldering equipment - Google Patents

Abstract

PURPOSE:To prevent a reduction of a moisture resistance, a heat breakdown, etc., caused by a heat stress of an IC package, by providing a solder tank on the inside of a vapor vessel, providing a pre-heater on the outside and the inside of an inlet side of the vapor vessel, respectively, and also providing a cooling fan on the outside of an outlet side of the vapor vessel. CONSTITUTION:Along a conveyor 51 for carrying in and carrying out an object 31 to be soldered, pre-heaters 61, 62 are provided on the outside and the inside of an inlet 41 side of a vapor vessel 12, respectively, and a cooling fan 81 is provided on the outside of an outlet 42 side of the vapor vessel 12. When a vapor phase 91 is formed in the vapor vessel 12 and the object 31 to be soldered is carried in, the object 31 to be soldered is heated quickly to a reflow temperature by a radiation heat of the pre-heaters 61, 62 and a latent heat of vaporization of the vapor phase 91. Also, the object 31 to be soldered which has been soldered in a solder tank 71 is cooled quickly by a cooling fan 81.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention utilizes the latent heat of vaporization released by the vapor phase formed by vaporizing a high-boiling liquid when it condenses on the surface of an object. The present invention relates to a vapor phase soldering device that performs reflow (melting) soldering.

[Conventional technology]

Conventionally, the vapor phase soldering apparatus shown in Japanese Patent Publication No. 57-39866, etc., has a vapor phase obtained by heating and evaporating a high-boiling liquid in a vapor chamber (referred to as a processing chamber in the above publication). supply, and carry the object to be soldered into the vapor phase,
Using the latent heat of vaporization of the vapor phase, reflow (paste solder) the solder (paste solder) that has been previously attached to the object to be soldered.
For example, a printed wiring board and electronic components mounted on this board are soldered together.

This vapor phase soldering device has the advantages of high heat transfer rate, can uniformly heat all parts on the board, and the maximum heating temperature never exceeds the boiling point of the liquid. Suitable for soldering surface mount boards.

[Problem that the invention seeks to solve]

This vapor phase soldering equipment has recently been attracting attention with the development of surface mount boards that solder small outline package ICs, quad flat package ICs, chip components, etc. on the surface of printed wiring boards in a high-density array. Became. Therefore, the history of this type of vapor phase soldering apparatus is new, and there are many points to be improved.

An object of the present invention is to improve the performance of a vapor phase soldering apparatus by adding various auxiliary devices to the apparatus.

[Means for solving problems]

In the present invention, a vapor phase 91 is formed inside the steam chamber 12, an object 31 to be soldered is carried into the vapor phase 91 from the inlet 41 of the vapor chamber 12, and the vapor phase 91 generates latent heat. Reflow soldering is performed using the steam chamber 12.
In the vapor phase soldering device, the soldering object 31 is carried out from the outlet 42 of the vapor-phase soldering device, and the soldering object 31 is carried into the steam chamber 12 through the inlet 41, and the soldering object 31 is carried from the steam chamber 12 to the outlet. 42 and then the soldering target (
) A conveyor 51 for carrying out the object 31 is provided, and along the conveyor 51, a first pre-heater 61 for preheating the object 31 to be soldered, etc. located outside the steam chamber 12, etc. A second pre-heater 62 located inside the chamber 12 and for preheating the object to be soldered 31
and an object 31 to be soldered inside the air chamber 12.
A soldering tank 71 in which soldering is performed and the steam chamber 1
2 and a cooling fan 81 for forcibly cooling the object 31 to be soldered are arranged in sequence.

[Effect]

In the present invention, first, the temperature of the solder-covered object 31 is slightly raised by the radiant heat of the first pre-heater 61, and then,
The radiant heat of the second pre-heater 62 and the latent heat of vaporization of the vapor phase 91 quickly raise the temperature of the soldering material 31, and then the temperature of the soldering material 31 increases rapidly due to the latent heat of vaporization of the vapor phase 91. 31 to the reflow temperature, and paste 1 to 1 of the surface mount board P as the object to be soldered.
Solder or the like is reflowed (melted), and the surface-mounted component W mounted on the board P is soldered to the top surface of the board P.

Before and after this vapor phase soldering, while preventing the oxidation of the molten solder in the solder tank 71 by the vapor phase 91, the molten solder in the solder tank 71 is mixedly mounted on the surface mounting board P. Solder the leads of the lead insertion type component to the bottom surface of the board P.

Further, at the stage of transporting the object 31 to be soldered to the outside from the steam chamber 12, the cooling fan 81 blows cold air onto the object 31 to be soldered (
= J The monster 31 is rapidly cooled, and this rapid cooling increases the toughness of the solder.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

11 is a steam tank, and a steam chamber 1 is provided inside this steam tank 11.
2 is provided, and a cooling coil 13 is further provided along the inner circumferential wall surface of the steam tank 11.

Further, a liquid tank 21 is provided at the bottom of the steam tank 11, and a liquid 22 that serves as a heat medium for vapor phase soldering is stored inside this liquid tank 21. For example, a fluorine-based inert organic solvent (trade name Fluorinert) is used.The boiling point of this liquid 22 is high, and the
It is ℃.

Inside the liquid tank 21, an iron plate 23 is provided as a conductor that is heated by electromagnetic induction.

Further, an electromagnetic induction generator 24 that generates electromagnetic induction in the iron plate 23 is disposed outside the liquid tank 21 on the lower side.

Further, an inlet 41 is provided on one side of the steam tank 11 for carrying in objects 31 to be soldered, and the steam tank 1
1 is provided with an outlet 42 for carrying out the soldering object 31. Then, hoods 43 and 44 are connected to the inlet 41 and the outlet 42, respectively,
Cooling coils 45.4 are attached to the outer peripheral surface of each hood 43.44.
6 are wrapped around each other. This cooling coil 45,46 and the cooling coil 13 of the steam chamber 12 are each supplied with cold water in a coiled tube.

Further, a part of a conveyor 51 for conveying the soldering object 31 is inserted from the inlet side hood 43 through the lower part of the steam chamber 12 to the outlet side hood 44 . This conveyor 51 is constructed by endlessly disposing a highly corrosion-resistant belt-shaped net (fluorocarbon resin coated glass fiber braided net, etc.), and by driving this net in rotation, the The object to be soldered 31 is transported.

The object to be soldered 31 is a mixed board, in which surface-mounted electronic components (such as surface-mounted ICs and chip components) W are surface-mounted on the surface of the printed wiring board P via paste solder, and leads are inserted. type electronic components (dual in-line package IC, etc.) L are mounted together.

Further, a pair of upper and lower first preheaters 61 are disposed outside the inlet 41 of the steam chamber 12 and inside the inlet-side hood 43 so as to face each other via the conveyor 51. In addition, the inlet 4 of the steam chamber 12
A pair of upper and lower second preheaters 62 are disposed on the inner side of the preheater 1 and are located opposite to each other with the conveyor 51 interposed therebetween. The first preheater 61 and the second preheater 62 are electric heaters, and heat the object to be soldered 31 from above and below inside and outside the entrance 41.

Further, in the center of the steam chamber 12 and below the conveyor 51, a solder WJ 71 for performing jet soldering on the object 31 to be soldered is disposed. This solder W
J71 is nozzle 7 for jetting molten solder to the upper part.
2, and a heater (not shown) is provided at the bottom for melting the solder in the solder girder and controlling the temperature to a predetermined temperature (250° C.).

Furthermore, a pair of upper and lower cooling fans 81 are disposed inside the hood 44 on the exit side and at the exit portion of the hood 44 so as to face each other via the conveyor 51. This cooling fan 81 is connected to the soldered object 31.
The soldering devices 31 are forcibly cooled, and each is driven to rotate by an external motor (not shown), and blows cold air onto the upper and lower surfaces of the object 31 to be soldered.

Next, to explain the operation of this embodiment, when the electromagnetic induction generator 24 is driven to change the magnetic flux acting on the conductor 23, an eddy current is induced in the conductor 23 due to electromagnetic induction. As a result, heat generation (Joule heat) occurs within the conductor 23 due to eddy current loss (induction heating is performed).

This heat heats, boils, and evaporates the liquid 22 in the liquid tank 21, forming an inert vapor phase 91 inside the vapor chamber 12.

Before the object to be soldered 31 is carried into the steam chamber 12, the humidity of the object to be soldered is slightly increased by the radiant heat from the first preheater 61. After the soldering object 31 is carried in, the radiant heat of the second preheater 62 and the vapor phase 91
The latent heat of vaporization is simultaneously applied to the soldering object 31,
The temperature of the object 31 to be soldered is rapidly increased.

Then, the object to be soldered 3 is placed inside the steam chamber 12.
1 is conveyed, the vapor phase 91 is condensed on the surface of the object to be soldered 31, and at the time of condensation, the vapor phase 91
The latent heat of vaporization is released to the soldering object 31, and the soldering object 31 is heated to the paste solder reflow temperature (215° C.) held by the latent heat. As a result, the paste solder applied in advance to the upper surface of the surface mount board P of the object to be soldered 31 is reflowed (melted), and the surface mount type electronic component (surface mount type electronic component) mounted on the board via this paste solder is (type IC, chip parts, etc.) W is soldered to the upper surface of the substrate P.

As mentioned above, the radiant heat from the first preheater 61,
When the radiant heat from the second preheater 62 and the latent heat of vaporization of the vapor phase 91 are sequentially applied to the object to be soldered 31, the time required for the glue to flow in the steam chamber 12 is 10
It can be shortened to less than seconds.

Since it takes about 20 seconds when using only the latent heat of vaporization (without a preheater), the reflow soldering time can be reduced to less than half.

In parallel with such vapor phase soldering, the vapor phase 9
1 prevents oxidation of the molten solder surface in the solder tank 71 and the molten solder jetted from the nozzle 72, while the jetted solder 73 protects the lead insertion type electronic component inserted into the printed wiring board P. Solder the leads to the bottom surface of the board P.

The object to be soldered 31 which has been subjected to vapor phase soldering and jet soldering in this way is placed in the steam chamber 1.
2, the pair of cooling fans 81 are removed from the hood 44 through the hood 44.
The object 31 to be soldered is rapidly cooled by blowing cold air thereon. This rapid cooling increases the toughness of the solder.

The vapor phase on the inner peripheral wall surface of the steam tank 11 condenses on the inner peripheral wall surface due to the cooling action of the cooling coil 13 and flows down into the liquid tank 21 . Further, the vapor phase that is about to flow out from the hoods 43 and 44 is removed from the cooling coil 4.
The hood 43.44 receives the cooling effect of 5.46.
It condenses on the inner wall of the liquid tank 2 from this hood 43,44.
1 will be collected.

In the embodiment described above, an induction heating method is employed as a means for heating the liquid 22 in the liquid tank 21, but this heating means may be performed by an electric heater inserted into the solder tank.

〔Effect of the invention〕

According to the present invention, in the vapor phase soldering apparatus, the first preheater is disposed outside the inlet side of the steam chamber, and the second preheater is disposed inside the steam chamber, and these preheaters Since the object to be soldered is preheated, the first and second preheaters are
By preheating in stages, it is possible to rapidly raise the temperature of the soldered object in a low temperature range in a short period of time.
After that, the time required for the temperature to rise to the reflow temperature due to the latent heat of vaporization of the vapor phase in the high temperature range can be significantly shortened. Therefore, it is possible to prevent a decrease in moisture resistance, thermal damage, etc. due to thermal stress of the TC package to be soldered, and it is possible to improve the reliability of the vapor phase soldering apparatus.

Further, since a soldering tank is disposed inside the steam chamber and the soldering object is soldered in the vapor phase, oxidation during soldering can be prevented by the vapor phase, and the object to be soldered can be soldered in the vapor phase. Even if the attachment is a mixed board that has surface mount type components and lead insertion type components mounted, it can be used, and the surface mount type components can be reflowed onto the board using the latent heat of the vapor phase. Not only can soldering be performed, but also the leads of the lead insertion type component can be soldered to the lower surface of the board using molten solder in the solder bath.

Furthermore, since a cooling fan is provided outside the outlet side of the steam chamber, and the cooling fan forcibly cools the objects to be soldered, the objects to be soldered are immediately cooled when they are carried out from the steam chamber. Since the solder is cooled in a short time by the cold air blown from the cooling fan, the toughness of the solder is increased and the soldering strength is improved.

[Brief explanation of drawings]

The figure is a sectional view showing an embodiment of the vapor phase soldering apparatus of the present invention. 12... Steam chamber, 31... Soldering object, 41... Inlet, 42... Outlet, 51... Conveyor, 61... First preheater, 62... Second preheater, 71... Solder bath , 81...Cooling fan, 91...Steam phase. -1/1. −

Claims (1)

[Claims] (1) A vapor phase is formed inside a steam chamber, an object to be soldered is carried into the vapor phase from the entrance of the vapor chamber, and reflow soldering is performed using the latent heat of the vapor phase; In a vapor phase soldering apparatus in which the object to be soldered is carried out from the outlet of a steam chamber, the object to be soldered is carried into the steam chamber through the inlet, and the object to be soldered is carried out from the steam chamber through the outlet. A first preheater is provided along the conveyor for carrying out the soldering object, and a first preheater is provided outside the steam chamber for preheating the object to be soldered, and a first preheater is provided inside the steam chamber for preheating the object to be soldered. a second preheater for preheating the object to be soldered; a soldering bath located inside the steam chamber for soldering the object to be soldered; and a soldering bath located outside the steam chamber for soldering the object to be soldered. A vapor phase soldering device characterized by sequentially disposing a cooling fan for forced cooling.