JP2852456B2 - Solder reflow equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a solder reflow apparatus for heating a printed circuit board (hereinafter abbreviated as a board) or the like and soldering electronic components to the printed board.

(Prior Art) In recent years, various changes have occurred in solder reflow devices for circuit boards as electronic components have been mounted at higher density, mounted components have become larger, and boards have become thinner and larger. It has begun to appear.

FIGS. 5 and 6 show a conventional solder reflow apparatus.
This will be described with reference to the drawings. FIG. 5 is a side sectional view of a conventional solder reflow apparatus, and FIG. 6 is a perspective sectional view of a main part showing the transfer apparatus.

In FIG. 5, a conventional solder reflow apparatus is defined by a first preheating chamber 4, which is defined by partition walls extending from above and below and provided with panel heaters 1a and 1b, 2a and 2b, and 3a and 3b on its ceiling surface and bottom surface, respectively. A second preheating chamber 5 and a reflow heating chamber 6;
A cooling fan 7 disposed after the reflow heating chamber 6
And a pair of roller chains 11 that move from an inlet to an outlet along guide rails 9 provided on both sides as shown in FIG. It is composed of a chain conveyor 12 for use, a conveyor 13 for carrying out dropped substrates disposed below the chain conveyor 12, and an exhaust fan 14 installed at a part of the ceiling for exhausting the furnace atmosphere.

As shown in FIG. 5, the substrate 15 transported by the transport chain conveyor 12 is transported while being supported by pins 11a extending inside the roller chains 11 on both sides, as shown in FIG.

The operation of the solder reflow device configured as described above will be described.

First, the board 15 on which the electronic components are mounted enters the solder reflow device by the transport chain conveyor 12 from the entrance side, and the board 15 heated from above and below by the panel heaters 1a and 1b in the first preheating chamber 4 is 150 ° C to 160 ° C
Heat up to near. Next, the substrate transferred to the second preheating chamber 5
15 is kept at a constant temperature of 150 ° C. to 160 ° C. by the panel heaters 2a and 2b. Next, when the substrate 15 enters the reflow heating chamber 6, it is heated from above and below by the panel heaters 3a and 3b, and the temperature of the substrate 15 is 183 ° C., the melting point of the eutectic solder.
As a result, the temperature rises to about 230 ° C., which is lower than the heat resistant temperature of the component, and the cream solder dissolves. Subsequently, when cooled by the cooling fan 7 in the cooling chamber 8, the solder solidifies and adheres the components. During this time, the substrate 15 is conveyed with both ends held by the pins 11a of the roller chain 11 shown in FIG.

(Problems to be Solved by the Invention) However, in the above configuration, since the substrate 15 is supported only at both ends by the pins 11a of the roller chain 11, for example, the substrate 15 made of glass epoxy resin has a softening point. When the temperature rises to a certain temperature of about 170 ° C or higher, the board 15 warps, and the amount of warpage is increased when the board 15 is thin, has large dimensions, has a high mounting component density, or has a large IC package mounted. Are getting bigger and bigger. The substrate 15 warps,
When the flatness is deteriorated, there is a problem that a soldering defect such as floating of the soldered portion or displacement occurs. In addition, when the substrate 15 is cooled in such a state, the warpage is fixed, so that there is a problem in the next step, for example, that the substrate 15 is clogged during the transportation, that is, the height of the mounted components is different.

Further, there is a problem that the substrate 15 may fall off from the transfer chain conveyor 12 during transfer in the apparatus due to warpage.

The present invention is to solve the above-mentioned problem, and to provide a solder reflow apparatus in which the substrate 15 does not warp.

(Means for Solving the Problems) In order to solve the above problems, the present invention comprises a conveyor for transporting a substrate such as a printed circuit board on which electronic components are mounted by cream solder, and a heating chamber for heating the same. In the solder reflow device, a mechanism for intermittently operating the conveyor to temporarily stop the substrate in the heating chamber,
A backup pin provided in the heating chamber and a backup pin elevating mechanism for moving the backup pin so as to keep the substrate surface substantially flat while the conveyor is stopped and for supporting the lower surface of the substrate are provided.

Further, the present invention provides the backup pin elevating mechanism, comprising a mounting plate for mounting the backup pin, and an actuator for raising and lowering the mounting plate, further providing a plurality of mounting portions on the mounting plate, The number and mounting position of the backup pins can be arbitrarily set.

Further, in the present invention, a ceramic material having a low thermal conductivity is used for the backup pin.

Further, in the present invention, a temperature detection sensor is provided at the tip of the backup pin.

The present invention further includes a feedback control unit that optimally sets the heating source temperature based on the measured substrate temperature.

(Operation) With the above configuration, even if the substrate whose both ends are supported by the roller chain pins is softened by heating, the lower surface of the substrate is held at a fixed height by the backup pin.
No warping. In addition, since it is maintained at a constant height during cooling, it can be carried out to the next step while maintaining flatness. When the temperature detection sensor is attached to the tip of the backup pin, the temperature of the substrate being heated can be detected by the contact method. This can be fed back to the temperature setting of the panel heater to control the optimal heating state. .

(Embodiment) A second embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a side sectional view of a solder reflow apparatus showing a first embodiment of the present invention, and FIGS. 2 and 3 are perspective views of a pin mounting plate and a backup pin.

In FIG. 1, this embodiment differs from the conventional example shown in FIG. 5 in that the lengths of the first preheating chamber 4, the second preheating chamber 5, the reflow heating chamber 6 and the cooling chamber 8 are made equal, The operation of the chain conveyor 12 is intermittent, the board 15 is stopped at the center of each chamber, the dropped board unloading conveyor 13 is removed, and the actuator 16 is located immediately below the stop point.
This is the point that a pin mounting plate 18 on which a plurality of backup pins 17 which move up and down is mounted is provided. The other components are the same as those of the conventional example, and thus the same components are denoted by the same reference numerals and description thereof will be omitted.

In FIG. 2, about 10 mm
A large number of lattice-shaped pin holes 18a are provided at intervals, and a plurality of backup pins 17 are attached to these in accordance with the situation of the substrate 15. A ceramic coating is applied to the surface of the pin mounting plate 18 so that a far-infrared heating effect can be obtained.

In FIG. 3, the main body of the backup pin 17 is made of steel, and the head 17a at the tip is made of ceramic having low thermal conductivity. This prevents local temperature rise of the substrate 15 due to heat conduction from the backup pins 17.

The operation of the solder reflow device configured in this way
Since there is no difference from the conventional example except that the intermittent conveyance is performed and the backup pin 17 is supported during the stop, the description thereof is omitted, and only the effect of the warpage countermeasure will be described.

When the board 15 carried into the solder reflow device stops at the center of each chamber, the actuator 16 operates, and the backup pins 17 of the pin mounting plate 18 flatly support the board 15 that has been stopped from below, respectively. Substrate by heating
Even if 15 softens, no warping occurs. Note that the backup pin 17 may be made of ceramic.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a configuration diagram of a main part of the present embodiment.
The difference from the first embodiment shown in the figure is that the backup pin 17 is made of ceramic, and the temperature detection sensor 19
And a control unit 20 that sets the heating temperature of the panel heaters 1a and 1b, 2a and 2b or 3a and 3b to an optimum value based on the detection data of each room. As a result, a substrate 15 having stable soldering quality can be obtained.

(Effects of the Invention) As described above, according to the present invention, by moving the backup pin while the conveyor is stopped to support the lower surface of the board, the board is not warped and the soldering quality is stable. A highly reliable solder reflow device can be obtained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a solder reflow device showing a first embodiment of the present invention, FIGS. 2 and 3 are perspective views of a pin mounting plate and a backup pin, and FIG. 4 is a second embodiment. FIG. 5 is a side cross-sectional view of a conventional solder reflow device, and FIG. 6 is a perspective view of a main portion of a conveyer chain conveyor. 1a, 1b, 2a, 2b, 3a, 3b ... panel heater, 4 ... first preheating chamber, 5 ... second preheating chamber, 6 ... reflow heating chamber, 7 ...
Cooling fan, 8 Cooling chamber, 9 Guide rail, 10
Guide roller, 11 ... Roller chain, 11a ... Pin, 12
… Chain conveyor for transport, 13… Conveyor for unloading dropped boards, 14… Exhaust fan, 15 …… Printed circuit board (board), 16 …… Actuator, 17 …… Backup pin, 17a …… Head, 18 ... Pin mounting plate, 18a ... Pin hole, 19 ... Temperature detection sensor, 20 ... Control unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 62-109858 (JP, U) JP-A 59-158360 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 3/32-3/34

Claims (5)

(57) [Claims] In a solder reflow apparatus comprising a conveyor for transporting a substrate such as a printed circuit board on which electronic components are mounted by cream solder and a heating chamber for heating the substrate, the substrate is operated intermittently by operating the conveyor intermittently. A mechanism for temporarily stopping the heating chamber, a backup pin provided in the heating chamber, and a backup pin elevating mechanism for supporting the substrate lower surface by moving the backup pin so as to keep the substrate surface substantially flat while the conveyor is stopped. A solder reflow device comprising: 2. The backup pin raising / lowering mechanism comprises a mounting plate for mounting the backup pin, and an actuator for raising and lowering the mounting plate. Further, the mounting plate is provided with a plurality of mounting portions, 2. The solder reflow apparatus according to claim 1, wherein the number and the mounting position of the backup pins can be arbitrarily set. 3. The solder reflow apparatus according to claim 1, wherein a ceramic material having a low thermal conductivity is used for said backup pin. 4. The solder reflow apparatus according to claim 1, wherein a temperature detection sensor is provided at a tip portion of said backup pin. 5. The solder reflow apparatus according to claim 4, further comprising a feedback control unit for setting a heating source temperature optimally according to the measured substrate temperature.