JPH05315739A - Directed infrared reworking station - Google Patents

Abstract

PURPOSE: To provide a re-machining station, capable of directing a controlled heat quantity to a possibly limited region for replacing defective components of a circuit board, etc. CONSTITUTION: This re-machining station 1 comprises means 12, 13 for supporting a circuit board 2 and infrared radiation source 4, which has a linear infrared heater element conformed with the outline of a component. This element position is adjustable to be located immediately above and at the side of a connector leg of the component on the circuit board 2. The station 1 has a power control means 6 for controlling the power to be fed to the element, and the power is fed in one or more heating cycles of specified power and duration time.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a rework station using an infrared heat source.

[0002]

2. Description of the Prior Art Rework stations allow direct attachment and removal of separate electronic components to or from a support such as a printed circuit board. Typical applications for rework stations are circuit design and development or replacement of defective parts of prefabricated circuit boards.

A known reworking station using an infrared heat source is disclosed in British Patent No. 2194479, which is a reworking station comprising light sources for infrared and visible light. A rework station is described in which a lens arrangement and an aperture are placed between the and the article to be reworked to allow a spot of light of adjustable area to be focused on the part.

Other methods of heating components for rework include directing hot air at the circuit board or by directing the connector legs of the component to heated metal elements to conduct heat through the legs. , Melting the solder at the point where the legs are connected to the support.

[0005]

With the ever increasing number and miniaturization of circuit boards, a controlled amount of heat is possible to avoid unnecessary heating of components and other components or areas being reworked. It has become increasingly important to ensure that it is directed to as limited an area as possible.

It is an object of the present invention, when soldering or desoldering a component to a rework such as a circuit board, to direct a controlled amount of heat to the limited area possible. And to provide a rework station that avoids unnecessary heating to adjacent areas.

[0007]

SUMMARY OF THE INVENTION According to one aspect, the present invention resides in a rework station comprising a support means for supporting a circuit board to be reworked and an infrared radiation source. The external radiation source comprises a substantially linear infrared heating element shaped to follow a line around the perimeter of the part to approximately match the placement of connector legs on the perimeter of the part. The infrared radiation source is positionally adjustable with respect to the support means so that, in use, the element may be positioned immediately above or adjacent to the connector legs of the component to direct infrared radiation thereto. Providing a rework station.

The provision of a dedicated infrared radiation source in this way makes it possible to direct a controlled amount of infrared radiation in a very limited manner only in the region required, which is known in this respect. It is an improvement over the focused infrared radiation station. The term "substantially linear infrared heating element" in this context refers to curved and / or straight sections such that effective heating of the component legs occurs without undue heating of adjacent components. It is an elongated element having a narrow width.

Unlike the focusing device described above, the infrared radiation source of the present invention need not include visible light. In fact, invisible infrared light sources such as mid-infrared may be preferred for heating purposes. If the legs of the connector legs are facing away from the components, the element can be shaped to direct heat directly to these legs. Alternatively, the element instead
The radiation may be shaped to direct to the nip of the leg and conduction may cause heat to be transferred, for example, to the solder beneath the part's feet.

The legs of the component may be arranged only on a part of the outer circumference of the component. Under such circumstances, the heating element may be shaped to extend over a similar portion of the perimeter of the component. If necessary, provide an element with another shape,
You may make it match with the leg part of the other part of the outer periphery of the same component. Alternatively, it may instead be arranged in a closed graphic shape to match the placement of the connector legs on the entire perimeter of the component.

Preferably, the rework station comprises a plurality of replaceable heating elements having different shapes. By providing multiple elements of different shapes, a single rework station can process several different parts to be reworked. It should be noted that the alignment of the element with the particular component need not be precise, it is sufficient to be able to produce effective heating over a limited area that is determined by the placement of the legs of the component. .. Thus, providing a selected number of shaped elements is sufficient to handle a substantially greater number of shaped parts.

As an alternative to providing a plurality of replaceable elements, the rework station comprises a single infrared radiation source provided with a plurality of heating elements of different shaped sets. Good.

Preferably, the rework station may further comprise motor means for drivingly adjusting the distance between the element and the plane of the support means.

The rework station further comprises electronic positioning means adapted to control the motor means to adjust the vertical distance between the element and the plane of the support means. Advantageously, data concerning the height of the part is received so as to drive the motor means to automatically position the element directly above the part in use. The information may be typed in directly, for example by a PC terminal, or it may be received by manually positioning the element on the part and by sensing and storing this position.

For example, the components located somewhere in the plane of the circuit board carried by the support means may be aligned under the heating element during desoldering. Advantageously, the rework station further comprises alignment means for adjusting the position of said element relative to said support means in or parallel to the plane of said support means.

The rework station preferably comprises a magnifying device to assist in the alignment and / or vertical positioning of the heating element. This is a microscope or 1
It may take the form of the above video camera and associated display terminal. A preferred embodiment comprises a plurality of video cameras and a split screen display terminal for simultaneously displaying all the scenes shown by the video cameras.

In conventional rework stations, the intensity and duration of heating is manually adjusted. That is,
The operator determines the intensity of the heating and activates the heat source until observing that proper soldering or de-soldering is complete. British Patent No. 2194479 discloses a rework station having a continuous low heat mode and a high heat mode, which is provided with a timer for operating the high heat mode for a predetermined time. All of these devices lack accuracy in controlling the heating rate of the rework. That is, if the rework is heated too fast with too much heating power, the circuit board or component may be damaged due to the rapid rise in temperature of the circuit board. Similarly,
Heating power that is too weak may result in insufficient heating.

In a particularly preferred embodiment, there is further provided electronic control means operable to control the power supplied to the infrared heating element and to power said element during heating during one or more heating cycles. Each heating cycle consists of a plurality of levels of output, the power and duration of each level being predetermined and controllable by the electronic control means.

Further comprising electronic storage means for storing power and duration values for each level of the plurality of heating cycles, said control means communicating with said storage means and responsive to the heating cycle data provided therefrom. Preferably.

By using a predetermined staged heating cycle, the controlled stepwise heating of the rework with a smooth temperature rise allows efficient heating time while avoiding stress or impact on the rework. Is possible. The memory means is the type of circuit board to be reprocessed (including the size of the circuit board)
And / or allows selection from multiple automatic heating cycles that can be determined depending on the characteristics of the component.

The control means may further comprise the option of supplying heating power to the rework in accordance with the characteristics of one level of the heating cycle, eg the maximum power level. This may be desirable when the operator finds that the heating cycle does not correctly solder or desolder the joint during processing.

Alternatively or in addition to this feature,
The element may be operable at a plurality of different heating power levels for an operator controlled duration.

The rework station preferably also includes a background heater to raise the temperature of the larger area of the rework. The level and duration of the output level of the heater may be adjusted and stored by the control means and storage means of the preferred embodiment described above.

The rework station may include sensors to directly measure the temperature of the part being reworked to facilitate the selection of heating cycles and to provide the desired temperature / time characteristics during rework.

Advantageously, the rework station comprises pick-up means for automatically removing and placing components on the circuit board.

This may comprise a vacuum tube or the like. The pick-up means can be positioned vertically with respect to the support means and can be moved horizontally likewise the heating element described above. Also in the pickup means, new parts are automatically placed on the circuit board and soldered there, or old parts are detached (d).
esoldered), may be controllable by means of the control means of the particularly preferred embodiment so that it can be removed.

Viewed from another aspect, the present invention provides the power supplied to an infrared radiation source at a rework station comprising a support means for supporting an article to be reworked and the infrared radiation source. Further comprising electronic control means for controlling and operating to power said infrared radiation source during one or more heating cycles, each heating cycle comprising a plurality of levels of output, each heating cycle comprising: The power and duration of each level provides a rework station characterized in that it is predetermined and controllable by the electronic control means.

[0028] Further comprising electronic storage means for storing power and duration values for each level of the plurality of heating cycles, said control means communicating with said storage means and responsive to heating cycle data provided therefrom. Preferably.

The present invention is directed to a substantially linear infrared heating element that is shaped according to a line around the perimeter of the part to approximately match the placement of the connector legs on the perimeter of the part. A method of rework comprising providing a source of infrared radiation in the form of and positioning the element immediately above or next to a connector leg of the component on the rework and directing infrared radiation thereto. Reach

[0030]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, the rework station of the present invention comprises a main rework unit 1 to which is attached a circuit board 2 to be reworked, the unit 1 comprising a heater head. 3, an intermediate infrared radiation source, a vacuum tube 4 (arranged to extend through the heater head 3), and a pickup means in the form of a movable pickup plate 5.

Heater head 3 and pickup means 4
The operation of 5 and 5 is controlled by the central controller 6 together with the handheld control unit 7. Display terminal 11
The video cameras 9 and 10 for sending a signal to are movably mounted on the ring-shaped platen 8.

The heater head may also include a temperature sensor (not shown) to directly measure the temperature of the component during rework.

The unit 1 also comprises a fixed position background heater 19 located directly below the lower heater head 3 and vacuum tube 4 in the plane of the support means.

In use, the circuit board 2 is mounted between the clamps 12 and 13 movably mounted on the carriage 14. The carriage 14 can be mounted on the carriage 15 itself so as to be movable in the horizontal direction.
5 is now movable horizontally relative to the base 20 of the unit in a direction perpendicular to the base of the carriage 14.
Fine adjustment of the positions of the carriages 14 and 15 is performed by micrometers 17 and 18, respectively. Thus, the article to be reworked can be moved horizontally to align the part to be reworked directly under the heater head 3.

The video cameras 9 and 10 enlarge the area directly below the heater head of the reworked product, and the display terminal 11 displays the outputs of both cameras in a split screen mode. This helps in the alignment of the parts under the heater head 3. That is, when the component is soldered to the circuit board, it is useful for aligning the component suspended from the end of the vacuum tube 4 to a predetermined position on the circuit board.

The heater head 3 and the vacuum tube 4 are fixed in position in the horizontal direction with respect to the base 20 of the unit 1, but with respect to the plane of the base 20 (and hence the plane of the supporting means) and to each other. It can move vertically with respect to. The heater head 3 is connected via an arm 21 to a motor (not shown) in the housing of the unit 1 that controls the vertical movement of the heater head 3.

The vacuum tube 4 is further controlled by a motor in the housing of the unit 1. Similarly, the horizontal movement of the pickup plate is produced by another motor in the housing of the unit 1. The operation of these motors, the vertical movement of the heater head 3 and the vacuum tube 4, and the horizontal movement of the pickup plate are controlled by a central controller associated with the handheld unit 7.

FIGS. 2 and 3 show a typical rework component in the form of a chip 30 that includes a plurality of legs 31 disposed on the outer periphery, the legs 31 being the circuit board 2. It terminates in an outwardly extending foot 32 which is soldered to and allows the part to be grounded.

4 and 5 show heating element 3 shaped to match the placement of connector legs 31 on the outer periphery of chip 30.
The heater head 3 with 5 is shown in more detail. The rework station also comprises a plurality of other heater heads that can be replaced with the heater head 3, each with a different shaped heater head designed to match a particular part for rework. The head 3 also comprises a central aperture 36 through which the vacuum tube 4 extends in use.

When removing a component from the circuit board 2, the horizontal alignment of the circuit board 2 is adjusted by the micrometers 17 and 18 to position the selected component directly under the heater head 3. .. Vacuum tube 4
Penetrates through the center of the heater head 3, but its position may be used to help align the parts in place with the aid of the video cameras 9 and 10 and the display screen 11. Once in place, the heater head is lowered just above the component and infrared radiation is applied until the component is soldered off the circuit board. The parts may then be removed by the vacuum tube 4 and placed on the pickup plate 5. This operation will be described in more detail below.

When soldering a new component to the circuit board, the component is held at the tip of the vacuum tube 4 and the circuit board 2 is held.
Is horizontally below the chip using the video cameras 9, 10 and display 11 so that the feet of the chip are exactly aligned with the connector pads on the circuit board (ie, aligned; al).
igned). The heater head is then lowered and the heating cycle is activated to solder the parts in place. Heating element 3 shown in FIG.
5 is, for example, kanthal-nikrotha
l) It may consist of two coils made and combined of a suitable material, such as a wire, which gives a mid-infrared output by the application of electric power.

The controller 6 controls the vertical movement of the heater head 3 above the circuit board 2. Preferably, the controller 6 stores the height of the part to be reworked, for example by data from a PC, so that the heating element is as close as possible to the top of the leg of the part to be reworked,
It may be programmable so that the vertical position of the heater head 3 can be adjusted above the plane of the support means.

The central controller 6 is adapted to control the power to the heating element 5 at multiple levels of pre-programmed power and duration. In particular, the control device 6 provides three predetermined heating powers with powers P1, P2 and P3 (expressed in percentage of maximum power) and connection times T1, T2 and T3 (seconds). Its value is programmed into the controller by pushbuttons 40, 41 and 42. First, the button P1 of the button 40 is pushed down,
Power value (expressed as a percentage of total heating element output)
Is input by the push button 41. Next, the duration of this power is input by pressing the button T1 and inputting the time with the push button 41. The input power and duration values are displayed on the display 39. This is repeated for the values P2, T2 and P3, T3.

The controller includes a background heater 1
Buttons PB and TB for setting the output of 9 and the operating time are also included.

The complete operation of the controller in various modes will now be described with reference to the handheld controller shown in FIG.

When used in combination with the direction buttons 46, 47, 48 and 49, the push buttons 43, 44 and 45 allow the vertical movement of the heater head 3 and the vacuum tube 4 and the horizontal movement of the pickup plate 5, respectively. Control. For example, pressing buttons 43 and 46 simultaneously will raise the infrared heater head. The same applies to the other buttons. The heater head 3 and the vacuum tube 4 can be moved from their fully retracted home position to several positions below these home positions. Similarly, the pickup plate 50 can be moved from the home position (shown in FIG. 1) to a position directly below the heater head and vacuum tube.

Pushbuttons 50 and 51 activate predetermined heating and pickup cycles. Depressing pushbutton 50 lowers the heater head to its operating position, after which it follows a pre-programmed heating cycle defined by P1, T1, P2, T2, P3, T3 and PB, TB (see above). Heater head 3
Supply power to. Depressing the pick-up button 51 causes the vacuum tube to be lowered to an operating position above the component on the circuit board, activating the vacuum to pick up the component and then retracting the vacuum tube to a higher position. The vacuum button 52 controls activation and termination of the vacuum provided by the vacuum tube.

The solder release button 53 activates a predetermined desolder cycle. First, the infrared heater head is lowered just above the component and then a pre-programmed cycle is activated to release the component from the circuit board. After the end of this cycle, ie at the end of time T3, the operator is given the opportunity to check the solder release of the part to see if it is complete. The operator can restart the solder release cycle by depressing the solder release button 53 again, provided that the solder release work is successful. This causes the vacuum tube to be lowered above the component and the vacuum will begin to operate and the component will be picked up. The nozzle can then be retracted to a higher position where the part can be removed, for example by depressing the vacuum button 52 to deactivate the vacuum.

By pressing down the auto cycle button 55 in combination with the solder release button 53, the automatic solder release cycle operates. The operation of the automatic solder release cycle is to check whether the operator has completed the solder release of the joint. The operation is essentially the same as the operation of the solder release cycle described above, except that there is no suspension of the operation to perform.

By pressing down the soldering button 54,
The soldering cycle is activated. Under such circumstances, the parts to be soldered are placed on the pick-up plate 5. By pressing down the soldering button 54, the pickup plate 5 is moved horizontally,
The parts are placed under the vacuum tube 4 and the heater head 3 that have been drawn in. Next, the vacuum tube 4 slightly descends above the height of the component, the vacuum is switched on to pick up the component, the pickup plate 5 moves horizontally and recedes, then the tube descends and the component Position it just above the circuit board. The operator is then given the opportunity to align the leg of the component with the pad of the circuit board.
When ready, the soldering button 54 is depressed again to lower the heater head just above the part and begin the pre-programmed heating cycle. At the end of this cycle, the heater may be retracted and the vacuum button 52 switched off the vacuum. As a result, the vacuum tube 4 is retracted to its home position.

By pressing down the auto cycle button 56 in combination with the soldering button 54, the automatic soldering cycle is activated. This makes it possible, for example, for a preceding soldering operation involving the same component and circuit board, as the alignment of the component underneath the circuit board is already done. It is essentially the same as the soldering cycle outlined above, except that there is no suspension.

By pressing down the manual IR button 57, a manual heating operation can be performed. In the manual heating operation, the heater head 3 is lowered to a position immediately above the component, and then the heater is cycled in a predetermined cycle. Power P
2 for a time T2. This operation may be used when complete soldering or debonding of joints has not been completed. At the end of this time, the head retracts back to its home position.

By depressing the alignment button 58, the head of the vacuum tube 4 is lowered to a position slightly above the plane of the circuit board. The operator can then lower the tubes further by depressing buttons 44 and 48, for example until the tube 4 is just above the part to be de-soldered. Next, the horizontal alignment of the components under the tube and heater head can be performed. Depressing the alignment button 58 again retracts the pickup head to its home position.

By depressing the total change button 59, the vacuum nozzle 4 is retracted to its home position, and the heater head 3 is retracted to a position slightly below the heater head home position. With this arrangement, it is possible to replace the heater head 3 with another heater head while leaving the vacuum nozzle 4 away.

By pushing down the reset button 60, the vacuum nozzle and the heater head are retracted to their home positions, and the pickup plate 5 is moved to the home position.

By pushing down the stop button 61,
All movement is stopped at that point and the vacuum is switched off and the power to the heating element is switched off.

[0058]

Since the reworking station of the present invention has the above-mentioned structure, the controlled heat quantity is limited as much as possible when soldering or desoldering to a reworked article such as a circuit board. Unnecessary heating to the part and adjacent areas can be avoided towards the marked areas.

[Brief description of drawings]

FIG. 1 is a perspective view of a rework station of the present invention.

FIG. 2 is a plan view of a part to be reworked by the rework station of the present invention.

FIG. 3 is a side view of the component of FIG.

4 is a plan view of a heating element mounting head of the rework station of FIG. 1. FIG.

5 is a side view of the heating element mounting head of FIG. 4. FIG.

6 is a plan view of a heating element of the heater head of FIGS. 4 and 5. FIG.

7 shows a front panel of the control means of the rework station of FIG.

8 shows a handheld control unit of the rework station of FIG.

[Explanation of symbols]

 3 Heater Head 4 Vacuum Tube 5 Pickup Plate 6 Intermediate Control Device 7 Handheld Control Unit 35 Heating Element

Claims (19)

[Claims] 1. A rework station comprising a support means for supporting a circuit board to be reworked and an infrared radiation source, the infrared radiation source comprising: a connector leg on an outer periphery of a given part. A substantially linear infrared heating element shaped to follow a line around the perimeter of the component to approximately match the placement, the element being in use, immediately above the connector leg of the component. Alternatively, the rework station is characterized in that the infrared radiation source is adjustable in position relative to the support means so that it can be positioned next to it to apply infrared radiation thereto. 2. The rework station of claim 1, wherein the infrared radiation source is a mid-infrared light source. 3. A rework station according to claim 1 or claim 2, wherein the element is shaped to extend around a portion of the outer circumference of the part. 4. A rework station as claimed in claim 1 or claim 2, wherein the elements are arranged in a closed, graphic form to match the placement of connector legs on the entire perimeter of the component. 5. A rework station according to claim 1, comprising a plurality of transformable heating elements of different shapes. 6. A single infrared radiation source having a plurality of heating elements arranged in sets of different shapes.
The rework station according to any one of 4 to 4. 7. The rework station according to claim 1, further comprising motor means for drivingly adjusting a distance between the element and a plane of the supporting means. 8. An electronic positioning means is further provided for controlling said motor means to adjust a vertical distance between said element and the plane of said support means, said electronic positioning means comprising said motor positioning means. To drive the means to automatically position the element directly above the component in use,
8. A rework station according to claim 7, adapted to receive data regarding the height of the part. 9. Rework according to any one of the preceding claims, further comprising alignment means for adjusting the position of said element relative to said support means in or parallel to the plane of said support means. station. 10. The rework station according to claim 1, further comprising a magnifying device for assisting alignment and / or vertical positioning of the heating element. 11. An electronic control means is further provided for controlling the power supplied to the infrared heating element and operable to power said element during heating during one or more heating cycles, each comprising: A heating cycle comprising a plurality of levels of output, the power and duration of each level being predetermined and controllable by said electronic control means.
The reprocessing station according to any one of 0. 12. The heating cycle data further comprising electronic storage means for storing power and duration values for each level of the plurality of heating cycles, said control means communicating with said storage means and provided therefrom. Responding to
Rework station according to 1. 13. The control means is adapted to include the option of supplying heating power to the rework in accordance with the characteristics of one level of the heating cycle, eg the highest power level. Reprocessing station. 14. A sensor for direct measurement of the temperature of a part during rework to facilitate selection of a heating cycle and for providing a desired temperature / time profile during rework.
The reprocessing station according to any one of 13 above. 15. Pick-up means for automatically removing or placing a component on or from a circuit board so that a new component can be automatically placed on and soldered to the circuit board. Or picking up means that can be vertically positioned and horizontally controlled by said control means so that old parts can be automatically desoldered and removed. Item 15. The rework station according to any one of items 11 to 14. 16. The method according to claim 11, further comprising a background heater that raises the total ambient temperature, and the level and duration of the output level of the heater can be controlled by the control means and the storage means. The reprocessing station according to item 1. 17. In the form of a substantially linear infrared heating element shaped according to a line around the perimeter of the part to substantially match the placement of the connector legs on the perimeter of the part. A method of reworking comprising providing an infrared radiation source and locating the element immediately above or next to a connector leg of the component on the rework and directing infrared radiation thereto. 18. A rework station comprising a support means for supporting an article to be reworked and an infrared radiation source to control the power supplied to the infrared radiation source during one or more heating cycles. , Further comprising electronic control means operable to power the infrared radiation source, each heating cycle comprising a plurality of levels of output, the power and duration of each level of each heating cycle being: A rework station which is predetermined and controllable by the electronic control means. 19. The heating cycle data further comprising electronic storage means for storing power and duration values for each level of the plurality of heating cycles, said control means communicating with said storage means and provided therefrom. Responding to
Reprocessing station according to item 8.