JP2674763B2 - Device for straightening printed wiring boards - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a device for correcting a warpage of a printed wiring board using a resin laminate as a substrate. [Background Art] In a processing step of a printed wiring board, various external influences such as heating, humidification, and pressurization are applied, so that a large or small warpage occurs. However, in the past, since the mounting on the printed wiring board was performed by the lead, the warpage of the printed wiring board was not a serious problem, but the warpage of the printed wiring board has become a big problem as the surface mounting increases. I have. For this purpose, various attempts have been made to correct the warpage of the printed wiring board. At present, however, the printed wiring board is re-warped by applying a force to bend the printed wiring board to the side opposite to the warpage. However, since this method is a manual operation, it requires a lot of manpower and has a problem of poor production efficiency.In addition, in order to correct the warpage without reverting, the printed wiring board is re-warped while being heated. Although it is necessary, since it is a manual operation, there is a limit to the temperature at which the printed wiring board is heated, and there has been a problem that it is not possible to reliably correct the warpage. [Object of the Invention] The present invention has been made in view of the above-mentioned points, and it is possible to correct the warp of a printed wiring board efficiently and reliably without the need for manual labor, and in addition, to heat the printed wiring board. An object of the present invention is to provide a warp correction device for a printed wiring board, which can be efficiently and uniformly performed. DISCLOSURE OF THE INVENTION A warp correction device for a printed wiring board according to the present invention, however, includes a heating furnace 2 provided at a substantially central portion of a device body 1.
Conveyor 3 for passing printed wiring board A to heating furnace 2
And a plurality of guide bars 4 arranged along the upper side of the conveyor 3 for holding the plurality of printed wiring boards A in an upright state on the conveyor 3, and at the exit of the heating furnace 2 in the middle of the guide bar 4. A cylinder 6 for sandwiching a plurality of printed wiring boards A, which are arranged and carried out from the heating furnace 2, between the plurality of cooling plates 5, and pressurizing the cylinder 6 so as to correct the warp. Yes, the printed wiring board A is sent to the heating furnace 2 by the conveyer 3 to heat the printed wiring board A, and the cylinder 6 works to pressurize the printed wiring board A between the cooling plates 5 so that the warp can be corrected without manpower. The printed wiring board A is sent to the heating furnace 2 in an upright state so that heat is well distributed to the entire printed wiring board A so that the printed wiring board A can be efficiently and uniformly heated. Explain in detail That. As shown in FIGS. 1 (a) and 1 (b), the apparatus main body 1 is provided with a loading section 10 at the front, a loading section 11 at the rear, and a heating section 12 at the center. And the heating part 12
Is provided with a heating furnace 2. The heating furnace 2 is formed by a circulating hot air dryer or the like in which a blower is driven by a motor 13 so that the printed wiring board A can be uniformly heated. An entrance and an exit are formed before and after the heating furnace 2, respectively.
14 and exit shutter 15 can be opened and closed respectively. Further, a conveyor 3 formed of a Birch conveyor is provided so as to pass from the loading section 10 to the unloading section 11 through the heating furnace 2. Several (for example, 11) guide bars 4 are provided along the upper side of the conveyor 3 as shown in FIG.
Is arranged in parallel with the conveyor 3 and is fixedly attached to the conveyor frame 18 or the like. Each guide bar 4 is a loading section
It is divided into a carry-in side guide bar 4a provided in 10, a heating furnace guide bar 4b provided in the heating furnace 2, and a carry-out side guide bar 4c provided in the carry-out section 11. The guide bar 4a on the loading side and the guide bar 4b in the heating furnace may be integrally formed and continuous. Further, a pressure device 19 is provided on the upper surface of the carry-out section 11 between the guide bar 4b in the heating furnace and the carry-out guide bar 4c. The pressurizing device 19 is formed by several cooling plates 5 (for example, 11 plates) such as an aluminum plate or a stainless plate whose both front and back surfaces are polished to flat planes. One is a fixed cooling plate 5a, and the other is a movable cooling plate 5b. Of the cooling plates 5, a fixed cooling plate 5a is fixed on the carry-out portion 11, and each of the cooling plates 5 is attached to a rod 21 which projects horizontally from the fixed cooling plate 5a in a direction perpendicular to the guide bar 4 as shown in FIG. A movable cooling plate 5b is slidably suspended and suspended, and a connecting member 22 such as a chain or a wire is stretched between the cooling plates 5 so as to restrict the spread of the space between the cooling plates 5. It is. For example, each cooling plate 5 is formed to have a thickness of 20 mm, and the length of the connector 22 is set so that the interval between the cooling plates 5 is 7 mm at the maximum. The tip of the rod 24 of the air cylinder 6 is connected to the movable cooling plate 5b located at the end opposite to the fixed cooling plate 5a, as shown in FIG. The movable cooling plates 5a are sequentially pressed by projecting the rods, and conversely, the rods 24 are retracted into the cylinder 6 so that the movable cooling plates 5a can be sequentially separated by the action of the connector 22. There is. still,
In FIG. 2, 25 is a lifting device formed by an air cylinder. Here, the printed wiring board to be corrected in the present invention is a board formed of a resin laminated board. In other words, a prepreg is created by impregnating a varnish of a thermosetting resin such as an epoxy resin or a phenol resin into a base material such as a glass cloth or paper and drying the prepreg, and the plurality of prepregs and a metal foil such as a copper foil are formed. After creating a metal foil-clad laminate by stacking and heating and pressing, the resin foil is laminated with a substrate by subjecting the metal foil of this metal-foil-clad laminate to etching or drilling. Printed wiring board can be obtained. In order to correct the warp of the printed wiring board, first, the printed wiring boards A are supplied one by one onto the conveyor 3 between the guide bars 4a of the carry-in section 10, and the printed wiring boards A are guided by the guide bars 4a. By separating and supporting them, a plurality of printed wiring boards A are set as one set on the conveyor 3 in a state of standing upright. Since the printed wiring board A is supported on the conveyor 3 in such an upright state, a large number (for example, 10) of printed wiring boards can be set as one set, and the production efficiency can be secured. Even a small heating furnace 2 can simultaneously heat a large number of printed wiring boards A, so that the entire apparatus can be made compact. The printed wiring board A is fed into the heating furnace 2 as the conveyor 3 is driven. In the heating furnace 2, each printed wiring board A is supported by the guide bar 4b and held in an upright state, which means that the printed wiring board A is heated in this state. The heat is applied to both the front and back sides, and it is possible to efficiently and uniformly heat the both sides. Moreover, each printed wiring board A
Since there is a guide bar 4b between them, there is a gap between each printed wiring board A, and heat is generated between each printed wiring board A.
It is possible to heat the printed wiring board A evenly over the entire surface of the printed wiring board A. As a result, the temperature difference between each part of the printed wiring board A is set within 5 ° C., and the temperature difference between the front and back of the printed wiring board A is set within 3 ° C. The conveyor 3 is operated intermittently at predetermined time intervals, and when several sets of the printed wiring boards A are sequentially introduced into the heating furnace 2, the first printed wiring board A becomes a resin glass of the board. The printed wiring board A is heated to a temperature higher than the transition point, and at this time, the printed wiring board A comes out of the heating furnace 2 to the unloading section 11 as the conveyor 3 is driven. Here, when the resin forming the resin laminated plate which is the substrate of the printed wiring board A is, for example, an epoxy resin, the glass transition point is 120 to 150.
Since the temperature is ° C, the printed wiring board A is heated so as to reach a temperature higher than this. The printed wiring boards A that have been heated in this way and then come out to the carry-out section 11 are inserted and set between the cooling plates 5 arranged corresponding to the rear ends of the guide bars 4b.
Then, the cylinder 6 is actuated, the rod 24 is projected, and the movable cooling plates 5a are sequentially slid and pressed toward the fixed cooling plate 5b side, and the printed wiring board A is pinched between the cooling plates 5 to cool the cooling plates 5a. Press the flat surface to fix the warp of the printed wiring board A. By heating the printed wiring board A to a temperature equal to or higher than the glass transition point of the resin and then applying pressure, the warpage can be corrected while the residual stress of the printed wiring board is removed. It is sufficient to apply 5 to 100 kg to the printed wiring board A having a size of 30 cm × 50 cm, for example. Further, by bringing the cooling board 5 into contact with the printed wiring board A in this manner, the heat of the printed wiring board A is absorbed by the cooling board 5 and radiated, and each printed wiring board A is moved below the glass transition point. It can be cooled down to a temperature of 50 to 60 ° C. at which the printed wiring board A can be further handled while being cooled to a temperature. After that, the cylinder 6 is operated again to move the rod 24 to the cylinder 6
The movable cooling plates 5b are sequentially pulled apart by the action of the connecting member 22 to return to the original state. Each of the printed wiring boards A between the cooling plates 5 with the operation of the conveyor 3
Is moved from between the cooling plates 5 to be carried out between the guide bars 4c, and at the same time, a set of printed wiring boards A coming out from the heating furnace 2 is inserted between the cooling plates 5 and set. In the same manner, the printed wiring boards A sequentially carried into the carry-in section 10 are heated in the heating furnace 2 and then cooled while being pressurized by the pressure device 19, and the printed wiring boards A whose warpage is corrected are sequentially carried out.
You can take it out from 11. As described above, when the printed wiring board A is cooled to a temperature below the glass transition point while heating the printed wiring board A to a temperature above the glass transition point of the resin to correct the warp, the printed wiring board warps. By fixing the warp, the warp can be surely corrected without the warp returning. For example, 250mm x 300
In a printed wiring board of mm size, warp of 1.0 mm is reduced to 0.1
mm or less. [Effects of the Invention] As described above, according to the present invention, the printed wiring board is sent to the heating furnace by the conveyor for heating and the printed wiring board is cooled while being pressed by the cooling plate by the function of the pressing mechanism. The state in which the printed wiring board is heated to a high temperature such as a temperature higher than the glass transition point of the resin so that the warp of the printed wiring board can be corrected without requiring human labor and the human labor is not required. The warp can be re-corrected and the warp can be surely corrected. In addition, the guide bar that holds the printed wiring board in an upright position on the conveyor and the printed wiring board that is placed in the guide bar at the exit of the heating furnace and carried out of the heating furnace are sandwiched between the cooling plates to correct the warp. Since it is equipped with a cylinder that pressurizes the printed wiring board, the printed wiring board can be sent to the heating furnace while being erected by the guide bar, and heat can be satisfactorily applied to both the front and back surfaces of the printed wiring board for efficient and uniform printed wiring. The board can be heated, and the printed wiring board coming out of the outlet of the heating furnace can be sandwiched between cooling plates in the middle of the guide bar while being held by the guide bar for pressurization and cooling. At the same time, the pressurized / cooled printed wiring board can be carried out while being held on the guide bar. In which it can be conveyed to the exit section. Furthermore, it is equipped with a plurality of guide bars so that a plurality of printed wiring boards can be held upright on the conveyor, and the plurality of printed wiring boards carried out from the heating furnace are sandwiched between the plurality of cooling plates. Since the warp is corrected with, it is possible to set a plurality of printed wiring boards as one set and perform the warping again, and it is possible to secure the production efficiency and simultaneously heat a large number of printed wiring boards. It is possible to pressurize and make the entire apparatus compact.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) and 1 (b) are perspective views seen from the front and rear of an embodiment of the device of the present invention, and FIG. 2 is a front view of the same device. , Fig. 3 is an exploded perspective view of a part of the above-mentioned device,
FIG. 4 is a perspective view of a part of the above apparatus. 1 is an apparatus main body, 2 is a heating furnace, 3 is a conveyor, 4 is a guide bar, 5 is a cooling plate, and 6 is a cylinder.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Masanori Arima               Matsushita, 1048 Kadoma, Kazuma, Osaka               Kou Co., Ltd.                (56) References JP-A-61-89694 (JP, A)

Claims (1)

(57) [Claims] A heating furnace provided in the substantially central part of the main body of the apparatus, a conveyor for passing the printed wiring board through the heating furnace, and a plurality of printed wiring boards which are arranged along the upper side of the conveyor and are held upright on the conveyor. A cylinder that presses a plurality of guide bars and a plurality of printed wiring boards that have been carried out of the heating furnace and that are placed in the middle of the guide bar at the exit of the heating furnace between the plurality of cooling plates to correct warpage A warp correction device for a printed wiring board, comprising: