JPH0316731A - Correcting method for warpage of printed circuit board - Google Patents

Abstract

PURPOSE:To effectively correct warpage of a printed circuit board by introducing the warped board into a holding jig formed by bending and warping a metal plate warped at the opposite side to the warpage of the board, heating it in this state by a heater, and then pressing it from the outside of the jig. CONSTITUTION:A printed circuit board A is so inserted into a holding jig F that the direction of the warpage of the board A is reverse to that of the warpage of the jig F, the jigs F in which the boards A are respectively inserted are supplied one by one on a conveyor 3 between guide bars 4a of a conveyor 10, and a plurality of the jigs F are set as one set. The jig F is fed into a dehumidifier E upon driving of the conveyor 3. When it is dehumidified, an opening/closing partition 2 is opened, and fed into a heater C to be heated. After heating, when the board A is fed to a press D side in a state that the board A is introduced into the jig F, the jig F is inserted between cooling plates 5. A cylinder 6 is operated, a rod 24 protrudes, and the board A is held therebetween under pressure while it remains held by the jig F. Thus, the warpage of the board can be effectively corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method for correcting warpage of a printed wiring board using a resin laminate as a substrate.

[Jumei no Fujutsu] Printed wiring boards undergo heating, humidification,
Due to the application of various external forces such as pressurization, warping occurs to a greater or lesser extent. Therefore, various methods of correcting the warpage of printed wiring boards are being investigated. The present applicant has already filed Japanese Patent Application No. 1983-251619 for a device for straightening printed wiring boards. The warp straightening device shown in Japanese Patent Application No. 63-251619 is a heating Ml! for straightening warp which heats a printed wiring board. ! And heat! ! The device is equipped with a press device that applies pressure to correct the warpage of a printed wiring board that has been heated in a heating device. This was then done by pressing the printed wiring board using a press machine to correct the warpage. Problem 1 to be Solved by the Invention However, in the above-mentioned conventional example, when heating with a heating device to correct the warpage and pressing while cooling with a press device, even if the warp is corrected by heating, The residual stress from the initial warping remains, and when it is cooled again during pressing, the printed wiring board made of epoxy laminate with a lath cloth base tends to return to its original warped state due to the residual stress, and even if pressed The problem was that residual stress from the initial warp still remained, making it impossible to correct the warp sufficiently. The present invention has been made in view of the above points, and provides a method for correcting warpage of a printed wiring board, which can reliably correct the warpage of the printed wiring board by eliminating the residual stress caused by the initial warpage. The purpose is to [Means for Solving the Problems J] A method for straightening warpage of a printed wiring board according to the present invention includes a heating device C for straightening warpage that heats a printed wiring board A;
When the warpage of the printed wiring board A is corrected using the warping correction device E, which is equipped with a press device D that presses the printed wiring board A heated by the heating device 1c to a state where the warpage is corrected, a warped printed wiring board is produced. Place A into a holding jig F made by folding back a metal plate that is warped to the opposite side of the warp of printed wiring board A, and place the warped printed wiring board A into this holding jig F. Heating with heating device C,
Thereafter, with the printed wiring board A placed in the clamp F, the press device D presses the printed wiring board A from the outside of the clamp F to correct the warpage of the printed wiring board A, and By adopting this structure, the above-mentioned object of the present invention has been achieved. [Operation] Then, the warped printed wiring board A is placed in a clamping jig F made by folding back the metal plate that is curved on the opposite side to the warping of the printed wiring board A, and inside this clamping jig F. By heating the warped printed wiring board A with the heating device C, the warped printed wiring board A can be heated with the heating device C.
is warped on the opposite side along the gripper F (that is, the printed wiring board A, which has been unwarped by heating, is forcibly warped on the opposite side from the original warp), and in this state The warpage is corrected by pressing and flattening with the press device D. [Example 1] The present invention will be described in detail below based on an example. An embodiment of the present invention is shown in FIGS. 1 to 4. In FIG. 1, E is the main body of the apparatus, which has a loading section 10 at the front, an unloading section l1 at the rear, and a loading section 1 between the loading section 10 and the unloading section 11.
Dehumidifying device B1 heating device MC, press device D in order from 01N
is arranged. Dehumidification! IliB is formed by a circulating warm air drying system in which a blower is driven by a motor, so that the printed wiring board A can be uniformly dehumidified. The heating device WC is also configured to uniformly heat the printed wiring board A by blowing hot air using a circulating dryer or the like whose blower is driven by a motor. In the drawings of FIGS. 1 and 2, the dehumidifying device B and the heating device C are continuous, and the dehumidifying device 11
An opening/closing partition 92 is provided between B and the heating device WIC.
Further, the entrance of the dehumidifying device B and the exit of the heating device C are provided with an entrance shutter 14 and an exit shutter 15, respectively, so that they can be opened and closed, respectively. Further, a conveyor 3, which is formed by a conveyor belt 7, is provided so as to extend from the carrying-in section 10 through the dehumidifying device B and the heating device LC to the carrying-out section 11. Along the upper side of this conveyor 3, as shown in FIG.
It is fixedly attached to something like 8. Each ID bar 4 has an input liff ID par 4m installed in the loading section 10, an ID par 4b installed in the dehumidifier fiB, and a heating! Ill! The inside of the heating device installed in C is Idpar 4.
c. The loading bar installed in the loading section 11 is 4d%:
It is divided. In addition, the carry-in guide par 4a, the guide par in the dehumidifying device 4b, and the guide par in the heating device 4c can also be formed as one continuous piece. In addition, the heating device internal guide par 4c and the unloading guide par 4d
A press device D is provided on the upper surface of the unloading section 11 between the two. The press device D is formed by several (for example, 11) cooling plates 5, such as aluminum plates or stainless steel plates, whose front and back surfaces are polished to 7-rat flat surfaces, and one end of each cooling plate 5 is Fixed cooling plate 5&,
The other part is a movable cooling plate 5b. Of these cooling plates 5, a fixed cooling plate 5a is fixed on the carrying-out part 11, and as shown in FIG. Each movable cooling plate 5b is slidably passed through and suspended, and a connection 14 such as a chain or wire is connected to each cooling plate 5.
g22 is stretched across the cooling plates 5 to restrict the width of the interval between each cooling plate 5. For example, each cooling plate 5 is formed to have a thickness of 20 mm, and the length of the connecting member 22 is set so that the distance between each cooling plate 5 is the maximum width. And a movable cooling plate 5b located at the opposite end of the fixed cooling plate 5a.
As shown in Figure 3, there is a cylinder 6 like an air cylinder.
The ends of the rods 24 are connected to each other, and by actuating the sill 6 and protruding the rods 24, each movable cooling plate 5a is pressed in turn, and conversely, by retracting the rod 24 into the sill 6, each movable cooling plate 5a is pressed down. Movable cooling plate 5
at! It is designed so that it can be separated in order by the action of one connected soldier 22. The holder [tAF is shaped like a metal plate made of steel, stainless steel, aluminum, etc., folded back, and the holder F is bent in the opposite direction to the warped printed wiring board A. be. In other words, if the printed wiring board A is curved so as to be convex in the A direction in Figure 5, as shown in the 5th UIU, then the printed wiring board A is curved so as to be convex in the B direction in Figure 5. It is. Here, the printed wiring board to be corrected in the present invention is a board made of a resin laminate. That is, a prepreg is made by impregnating a base material such as glass cloth or paper with a varnish of a thermosetting resin such as an epoxy resin or a 7-enol resin and drying it. After making a metal foil-clad laminate by stacking metal whistles and shaping them under heat and pressure, the metal foil of the metal whistle-clad laminate is further etched or perforated. A printed wiring board using a resin laminate as a substrate can be obtained. In order to dehumidify the warped printed wiring board A and to correct the warping, first,
Insert the warped printed wiring board A inside. In this case, the printed wiring board A is inserted into the gripper i4:F so that the direction of warpage of the printed wiring board A and the direction of the warp of the gripper F are opposite to each other. Then, the printed wiring board A placed in the clamping board F is carried in all the way.
IO is fed onto the conveyor 3 between each side of the id par 4&, and the clamps F containing each printed wiring board A are isolated and supported by the id pars 4a, so that they are placed vertically on the conveyor 3. Set multiple pcFs containing printed wiring board A into one set. Since the supporting jig F containing the printed wiring boards A is supported on the conveyor 3 in this upright state, a large number of boards (for example, one
0 sheets) can be set as one set, ensuring production efficiency, and even a small device can dehumidify a large number of printed wiring boards A at the same time and heat them to straighten them. Become,! The entire I-station can be made compact. Then, as the conveyor 3 is driven to move, the carrier F containing the printed wiring board A is sent into the dehumidifier 11B. Then, the printed wiring board A placed in the holding chamber F is dehumidified by heating it at 80° C. to 140° C. for 10 minutes to 15 minutes in this dehumidifier WIB. When the dehumidification is finished, the RR partition 2 is opened, the conveyor 3 is run, and the clamping Jihei F holding the printed wiring board A is heated to the heating device 1i! It is sent into C and the heating device r! I
Heat at 120°C to 170°C for 3 minutes in C. Furthermore, the conveyor 3 is operated intermittently at predetermined time intervals, and several sets of clampers F carrying the printed wiring boards A are introduced into the dehumidifying device B1 heating iuic in order to remove the printed wiring boards A. It is dehumidified and then heated to rewarp it, but when it is introduced into the heating device C from the dehumidifier IB, the first printed wiring board A that has already been introduced into the heating device C is The resin is heated to a temperature higher than the Huss transition point, and at this point, as the conveyor 3 is driven, the printed wiring board A is removed from the heating device raC.
is arranged so that it comes out at the unloading section 11. Here, when the resin constituting the resin laminate serving as the substrate of the printed wiring board A is, for example, epoxy resin, the 2-s transition point is 120 to 1
Since the temperature is 50°C, printed wiring board A is heated to a temperature higher than this temperature. As the printed wiring board A is heated in the heating device C to a temperature higher than the glass transition point, the warped printed wiring board A is straightened, and conversely, the printed wiring board A is heated in the holding jig F. At this point, it will warp in the opposite direction to the warp of the pincer F. The printed wiring board A, which has been heated in this way and has been warped on the opposite side from the original, is sent to the next press device Dll while still being placed in the holding jig F. In the press device D, a clamping guard F supporting the printed wiring board A in a state warped in the opposite direction is inserted between each cooling plate 5 disposed corresponding to the rear end of each idler 4c. Set.

Then, the cylinder 6 is actuated and the rod 24 protrudes, pressing the movable cooling plates 5a while sequentially moving them toward the fixed cooling plate 5b, and pressing the printed wiring board A while being supported by the clamps F between the cooling plates 5. Press and apply pressure with the 7-lat surface of the cooling plate 5 to correct the warpage of the printed wiring board A. By heating the printed wiring board A to a temperature above the glass transition point of the resin, cooling it and applying pressure, it is possible to correct the warpage while removing the residual stress of the printed wiring board. For example, the pressure is applied to a printed wiring board A of 30 cm×50 cm at a pressure of 5 to 100 k. It is sufficient to cross the line. Also, by bringing the cooling plate 5 into contact with the printed wiring board A in this way, the heat of the printed wiring board A is absorbed by the cooling plate 5 and radiated, and each printed wiring board A is heated to a temperature below the glass transition point. It is possible to cool the printed wiring board A to a temperature of 50 to 60°C at which it can be handled. After this, the cylinder 6 is operated again to draw the rod 24 into the cylinder 6, and each movable cooling plate 5b
are successively separated by the action of the connecting soldiers 22 and returned to their original state.
Then, with the operation of the conveyor 3, the printed wiring board A between the cooling plates 5 is moved to the darkness of the cooling plate 5 and carried out, and then the heating device C A set of clamps F containing the printed wiring board A coming out of is inserted into the cooling plate 5lwI and set.
Thereafter, in the same manner, the printed wiring boards A placed in the clamping unit F, which are sequentially carried into the carrying-in section 10, are dehumidified by the dehumidifier B''Ch, and then heated by the heating unit C, and the printed wiring boards A are placed in the clamping unit AF. After being warped in the opposite direction along the curves, the printed wiring boards A are cooled while being pressurized by the press device D, dehumidified, and the warpage is corrected.The printed wiring boards A can be sequentially carried out from the carrying-out section 11. Printed wiring board A
The printed wiring board A is warped and the handle F is warped on the opposite side.
The printed wiring board A is heated to a temperature above the glass transition point of the resin of the printed wiring board A to correct the warpage, and with the resin curved in the opposite direction, the printed wiring board A is cooled to a temperature below the glass transition point and pressed. Then, the printed wiring board A is pressed with the warp applied in the opposite direction, and the residual stress of the initial warp is canceled out by applying the warp in the opposite direction, and as a result, there is no residual stress of the warp. Therefore, the warp can be reliably corrected without causing the warp to return.

Next, another embodiment of the holder F will be described.

In this embodiment, the gripper F is shaped by a shape memory alloy, and before it is placed in the correction device E (that is, at room temperature), the gripper F becomes a flat surface as shown in FIG. 6(a). When heated in heating device C, the printed wiring board A is deformed to warp in the opposite direction to the warp of printed wiring board A, as shown in FIG. 6(b), and then when pressed in press device D, it is cooled. By doing so, the surface is set to be flat again as shown in Figure 6(c). By doing this, the straightening jig F will have a flat surface when inserting the printed wiring board A into the clamping tool F and when removing the printed wiring board A from the clamping tool F after straightening the warpage. It is easy to work with.

[Effects of the Invention] As described above, according to the present invention, a warped printed wiring board is placed in a shaped clamp by folding back the warped metal plate on the opposite side to the warping of the printed wiring board. The warped printed wiring board is placed in this holding jig and heated with a heating device, and then the printed wiring board is placed in the holding jig and pressed from the outside of the holding jig with a press device. Since the warpage of the printed wiring board is corrected, the residual stress of the original warpage that had occurred in the printed wiring board is canceled out and disappears by applying the warp in the opposite direction to the printed wiring board in the heated state, and this residual stress is eliminated. The warp can be corrected by pressing it in a state where the stress is canceled out and disappeared, and the warp can be corrected reliably. Fig. 1 is a perspective view of one embodiment of the present invention, Fig. 2 is a schematic front view of the same as above, and Fig. 1lS3 is the same as above! A partially exploded perspective view of Iffi, Figure 4 is the same as above! ! FIG. 5 is an exploded perspective view of the same printed wiring board and clamping jig before correction, and FIGS. FIG. 2 is an explanatory diagram showing a correction order using an example of

Claims (1)

[Claims] (1) A warpage straightening device that is equipped with a heating device for straightening printed wiring boards that heats the printed wiring board, and a press device that applies pressure to correct the warpage of the printed wiring board heated by the heating device. To correct the warpage, place the warped printed wiring board into a holding jig formed by folding back the warped metal plate on the opposite side of the printed wiring board, and place the warped printed wiring board inside the holding jig. The printed wiring board is heated in a heating device with the printed wiring board inserted, and then the printed wiring board is placed in the clamping jig and then transferred to the press machine and pressed from the outside of the clamping jig to correct the warpage of the printed wiring board. A distinctive method for straightening printed wiring boards.