Inspection system and method for leads of semiconductor devices

• US 5,956,134 A
• Filed: 04/28/1998
• Issued: 09/21/1999
• Est. Priority Date: 07/11/1997
• Status: Expired due to Term

• Current Assignee: ASTI Holdings Limited
• Original Assignee: Semiconductor Technologies & Instruments Incorporated
• Inventors: Epp, George Charles, Glucksman, Michael D., Harris, Charles Kenneth, Roy, Rajiv, Wahawisan, Weerakiat, Hasten, Paul Harris
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US09/069,056
• Time in Patent Office: 511 Days
• Field of Search: 356/237, 356/394, 356/398, 356/375, 356/376, 250/548, 250/560, 250/561, 348/87, 348/94, 348/125, 348/126, 382/154, 29/720, 29/740, 29/833, 29/846
• US Class Current: 356/237.5
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: H05K 13/0813 Controlling of single components prior to mounting, e.g. orientation, component geometry H05K13/0812 takes precedence

Abstract

A system for transporting and inspecting, seriatim, semiconductor devices with plural prong type or solder ball type leads includes a head for transporting the semiconductor devices from one support structure, such as a tray or tube, to a second support structure, such as a tray or tape, and wherein two dimensional and three dimensional measurements of the positional accuracy of the leads is carried out during the transport process. The inspection apparatus is interposed in the transport path and includes a first optical sensor such as a CCD camera oriented to capture a two dimensional image of the semiconductor device package and compare the image with a predetermined two dimensional image store in a central processing unit (CPU). A high intensity light source, such as a laser, generates a plane of light which is reflected off of the semiconductor device leads to a second optical sensor, also comprising a CCD camera, wherein a so-called three dimensional image is generated to be compared by the CPU with predetermined or calculated positional relationships of the leads to establish coplanarity of the lead tips, or lack thereof. The system includes a sensor located such that the semiconductor device is centered in a field of view of the cameras to capture the respective images. The transport head may be rotated to correct for improper positioning of the device prior to generation of the three dimensional image. The system may interchangeably inspect semiconductor device packages with prong leads extending from one or all sides of a rectangular substrate as well an array of solder ball leads supported on a substrate. A modified arrangement of the inspection system is adapted for inspecting multiple semiconductor devices with solder ball leads and supported on wafer type substrates.

Claims

1. A system for transporting semiconductor devices from one point to another, said semiconductor devices including a plurality of leads thereon, the existence of which and the positional accuracy of which is to be determined, said system including:

a transport apparatus including a frame;

a head operable to engage and support a semiconductor device and move said semiconductor device from one position to another with respect to said frame; and

a lead inspection apparatus mounted on said frame and interposed in a path of movement of said semiconductor device, relative to said lead inspection apparatus, said lead inspection apparatus being operable to inspect the existence of said leads on said semiconductor device, the positional accuracy of said leads in two dimensions with respect to a substrate of said semiconductor device and the positional accuracy of said leads with respect to a predetermined plane, while moving said semiconductor device from said one position to said another position, said inspection apparatus including;

a first optical sensor and a first light source for illuminating said semiconductor device to generate a two dimensional image by said first optical sensor;

a second light source and a second optical sensor disposed to generate a third dimensional image of said semiconductor device; and

a processing unit operably connected to said first and second optical sensors for comparing images generated thereby, respectively, with information stored in said processing unit for determining the existence of leads on said semiconductor device, the positional accuracy of said leads on said semiconductor device and the coplanarity of at least portions of said leads on said semiconductor device.

2. The invention set forth in claim 1 wherein:

said inspection apparatus is positioned between a first support structure for said semiconductor device and a second support structure for said semiconductor device and said system includes support means for said head for traversing said head between said first support structure and said second support structure.

3. The invention set forth set forth in claim 2 wherein:

said system includes motor means for moving said head along a substantially linear path between said first support structure and said second support structure and motor means operably connected to said head for orienting said semiconductor device supported by said head in a predetermined position upon generating said two dimensional image.

4. The invention set forth in claim 3 wherein:

said first optical sensor is operably connected to said processing unit for comparing said two dimensional image with a predetermined image of said semiconductor device to determine the existence of and the positional accuracy of said leads on said semiconductor device in two dimensions.

5. The invention set forth in claim 4 wherein:

said processing unit is operably connected to said head for causing said head to orient said semiconductor device in said predetermined position upon making said comparison of said two dimensional image with said predetermined image.

6. The invention set forth in claim 5 wherein:

said first optical sensor comprises a CCD camera.

7. The invention set forth in claim 6 including:

a sensor for energizing said first light source when said semiconductor device is moved to a predetermined position by said head with respect to said first optical sensor.

8. The invention set forth in claim 5 wherein:

said second light source is operable to generate a generally planar beam projected onto said semiconductor device and said second optical sensor is disposed in a position to receive and transmit an image generated by said second light source as a reflection from said semiconductor device for determining the positional accuracy of plural leads on said semiconductor device with respect to each other for determination of coplanarity of said leads.

9. The invention set forth in claim 8 wherein:

said processing unit includes information stored therein which is operable to enable said processing unit to compare the positions of respective ones of said leads as determined by said image generated by said second light source and said second optical sensor to determine said coplanarity.

10. The invention set forth in claim 9 wherein:

said second light source and said second optical sensor are disposed downstream of said first light source and said first optical sensor in relation to the direction of movement of said semiconductor device connected to said head as said head is transporting said device between said support structures.

11. The invention set forth in claim 9 wherein:

said second optical sensor is a CCD camera.

12. The invention set forth in claim 1 wherein:

said first optical sensor is disposed for receiving an image projected normal to a predetermined plane of said semiconductor device.

13. The invention set forth in claim 12 wherein:

said second light source is disposed for projecting a beam of light normal to said plane of said semiconductor device and said second optical sensor is disposed for receiving an image produced by light from said second light source reflected from said semiconductor device at an acute angle with respect to said plane and said semiconductor device.

14. An inspection apparatus for determining the existence of plural leads on a semiconductor device, the positional accuracy of said leads with respect to a predetermined position of said leads on said semiconductor device and the coplanarity of said plural leads, said apparatus comprising:

a first light source for illuminating said semiconductor device;

a first optical sensor for recording a two dimensional image of said semiconductor device when illuminated by said first light source, said first optical sensor being arranged for projection of said two dimensional image along an axis of said first optical sensor substantially normal to a plane of said semiconductor device;

a second light source operable to project a generally planar beam onto said semiconductor device, said planar beam being generally normal to said plane of said semiconductor device;

a second optical sensor arranged to receive an image of said leads of said semiconductor device generated by reflection of said second light source at an acute angle with respect to said plane of said semiconductor device for determining coplanarity of said leads;

a support for said semiconductor device arranged with respect to said first optical sensor and said second optical sensor for movement of said semiconductor device in a substantially linear path relative to said first optical sensor and said second optical sensor; and

control means for causing said first optical sensor and said second optical sensor to record said images while moving said semiconductor device along said path.

15. The apparatus set forth in claim 14 wherein:

said apparatus includes a position sensor operable to determine when said semiconductor device is in a field of view of said first optical sensor for energizing said first light source.

16. The apparatus set forth in claim 15 including:

a sensor operable to determine the position of said support for said semiconductor device and to cause said control means to energize said second light source at least once in response to predetermined relative movement between said semiconductor device, said first optical sensor and said second optical sensor.

17. The apparatus set forth in claim 14 wherein:

said first optical sensor comprises a CCD camera.

18. The apparatus set forth in claim 14 wherein:

said second optical sensor comprises a CCD camera.

19. The apparatus set forth in claim 14 wherein:

said second light source comprises a laser operable to project said planar beam onto said semiconductor device to illuminate plural rows of leads on said semiconductor device wherein said second optical sensor is operable to record images of each of said leads of said plural rows of leads to determine the coplanarity of said leads.

20. The apparatus set forth in claim 14 wherein:

said support for said semiconductor device is operable to change the orientation of said semiconductor device about an axis substantially normal to said plane of said semiconductor device in response to said first optical sensor recording an image of said semiconductor device.

21. The apparatus set forth in claim 14 wherein:

said support is operable to remove said semiconductor device from a first handling media and transport said semiconductor device to a second handling media after said images are recorded by said first optical sensor and said second optical sensor, respectively.

22. The apparatus set forth in claim 21 wherein:

said support for said semiconductor device is operable to transport said semiconductor device to a third handling media in response to comparison of said images recorded by said first optical sensor and said second optical sensor with corresponding predetermined images of said semiconductor device.

23. A system for handling semiconductor devices wherein each of said semiconductor devices includes a plurality of leads thereon, the existence of which and the positional accuracy of which is to be determined, said system including:

a frame including a support for one or more wafer-like substrates, each of said substrates including a plurality of semiconductor devices thereon, each of said semiconductor devices including a plurality of leads formed thereon;

a support member movable relative to said support for said substrates;

an inspection apparatus mounted on said support member for movement relative to said support for said substrates for inspecting the leads on each of said semiconductor devices, said inspection apparatus including a first optical sensor and a first light source for illuminating said semiconductor devices on said substrate to generate a two-dimensional image by said first optical sensor, a second optical sensor and a second light source disposed to project a generally planar beam on to the leads of each semiconductor device to generate a third dimensional image of said semiconductor device by said second optical sensor, said optical sensors and said light sources being spaced from each other to provide for recording a first image by said first optical sensor and a second image by said second optical sensor while moving said inspection apparatus relative to said one or more substrates, said first optical sensor being disposed to record an image projected from a predetermined plane of said semiconductor device and said second optical sensor being disposed to record an image projected at an acute angle with respect to said plane of said semiconductor device for determining the coplanarity of said leads; and

a processing unit operably connected to said first and second optical sensors for comparing images recorded thereby, respectively, with information stored in said processing unit for determining one of the existence of leads on said semiconductor device, the positional accuracy of said leads and the coplanarity of portions of said leads.

24. The system set forth in claim 23 wherein:

said apparatus is operable to move in at least two mutually perpendicular directions with respect to said substrate for recording images of each of plural ones of said semiconductor devices on said substrate.

25. A method for inspecting a plurality of leads on a semiconductor device to determine the existence of a predetermined number of said leads, the positional accuracy of said leads and the coplanarity of said leads, comprising the steps of:

providing an apparatus for transporting semiconductor devices, seriatim, from a first handling media to a second handling media for said semiconductor devices, said apparatus including a head for engaging and supporting a semiconductor device and for transporting said semiconductor device from said first handling media to said second handling media along a predetermined path;

providing an inspection apparatus including a first optical sensor for recording a two dimensional image of said semiconductor device and a second optical sensor for recording an image of a third dimension of said semiconductor device, said first optical sensor and said second optical sensor being spaced apart from each other on said inspection apparatus;

illuminating said semiconductor device with a first light source prior to recording said image with said first optical sensor;

illuminating said semiconductor device with a second light source comprising a generally planar beam prior to recording an image of said semiconductor device generated by said planar beam with said second optical sensor; and

causing said support for said semiconductor device to move said semiconductor device along said path and with respect to said inspection apparatus to a first position for recording an image by one of said optical sensors and then to a second position for recording an image by the other of said optical sensors.

26. The method set forth in claim 25 including the steps of:

comparing the position of said semiconductor device relative to said second light source with a predetermined image of said semiconductor device and illuminating said semiconductor device at predetermined intervals with said second light source as said semiconductor device passes a plane containing said beam generated by said second light source for recording images of successive rows of leads on said semiconductor device by said second optical sensor.

27. The method set forth in claim 26 including the step of:

comparing the images of said successive rows of leads of said semiconductor device recorded by said second optical sensor to determine if said leads are coplanar.

28. The method set forth in claim 25 including the step of:

rotating said head about an axis to orient said semiconductor device in a predetermined position in response to recording said two dimensional image by said first optical sensor and comparing said recorded image with a predetermined image of said semiconductor device.

29. The method set forth in claim 25 including the step of:

providing a sensor for sensing a position of said semiconductor device with respect to said first optical sensor for energizing said first light source to illuminate said semiconductor device when said semiconductor device is in a predetermined position relative to said first optical sensor.

30. The method set forth in claim 25 including the step of:

providing a sensor operable to determine the position of said semiconductor device relative to said second optical sensor and energizing said second light source at predetermined intervals in response to movement of said semiconductor device to plural predetermined positions of said semiconductor device relative to said second light source and said second optical sensor.