JPH07253450A - Method for testing electronic device attached to lead frame - Google Patents

Abstract

PURPOSE: To enhance the reliability by efficiently testing an electronic device fitted to a lead frame, and reducing the quantity of contaminant adhering to a testing fixture. CONSTITUTION: In a method for testing electronic devices 10, 12, 14 fitted to a lead frame 20, plural electronic devices 10, 12, 14 fitted to a common lead frame 20 are disposed under a testing fixture 50. The testing fixture 50 next comes into contact with the devices 10, 12, 14 to make an electric test. While being fitted to the common lead frame, plural devices are tested at one time, so that the efficiency of a test process is remarkably improved. Further, the devices 10, 12, 14 are disposed under the testing fixture 50, so that the quantity of contaminant staying on the testing fixture can be reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates generally to testing electronic devices, and more particularly to testing electronic devices mounted on leadframes.

[0002]

BACKGROUND OF THE INVENTION Part of standard manufacturing processes for electronic devices such as packaged semiconductor devices involves final electrical testing. In the past,
This final electrical test has been performed after the packaged electronic device has been separated from the leadframe connecting several devices during the process. Therefore, each device must be handled individually. Handling each device individually increases the complexity of the test operation, for example, it can be picked up individually and the test fixture (te
It must be aligned with the st fixture or test socket.

A technique that has been undertaken to provide a significant improvement over traditional testing is to test packaged electronic devices while they are still connected to a common leadframe. . Device (de
The handling of the vices) is greatly simplified, since some are connected together. As a result, only a single leadframe need be handled to test several devices. Moreover, electronic devices mounted on a common leadframe are essentially precisely aligned with respect to the leadframe in a particular direction. Thus, during testing, the devices mounted on the leadframe need not be individually aligned with the test fixture. Only the common leadframe needs to be aligned.

It is convenient to align the leadframes, because the leadframes have a certain track.
Because it can be transported and positioned along. Individually packaged devices are not as easily aligned as they must be moved by a pick-and-place or manual means. One such test-on-leadframe configuration disclosed in the past is Little Berry (Litt) on April 16, 1991.
U.S. Patent No. 5,008,
Seen at 615.

[0005]

However, one disadvantage of the system disclosed in the above-identified U.S. patents is that a test fixture that mates with a device mounted on a common leadframe lies beneath the leadframe. Is. This configuration allows contaminants such as dust and debris to deposit on the contacts where the leads of the electronic device make contact with the test fixture. The problem of the test fixture underlying the device under test is widespread over all prior art. Contaminants deposited on the electrical contacts of prior art test fixtures severely adversely affect testing and overall performance.

Another disadvantage of the prior art approaches is that device testing is often followed by trim and molding.
and-form) and the fact that it takes longer than the singulation step. Under these circumstances, the trim and molding equipment waits idle for the electrical test to complete. Such conditions result in inefficiencies in manufacturing and increased cycle times.

What is needed is a test structure for electronic devices that does not individually test each electronic device. Further, it would be desirable if the test structure did not cause trim and molding equipment idle conditions. Further, it would be extremely advantageous if the test facility could prevent contaminants from depositing on the electrical contacts of the test fixture.

[0008]

SUMMARY OF THE INVENTION Briefly, the present invention relates to a method for testing an electronic device mounted to a leadframe. Generally, the method includes providing a plurality of electronic devices mounted on a single lead frame. The electronic device has electrical contacts separated from each other. The leadframe is placed at a test site under a test fixture. The electrical contacts of the electronic device are placed in contact with the test fixture. The device is then electrically tested.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a significant improvement over prior art methods of testing electronic devices. The present invention tests the device while it is still attached to the common leadframe. As a result, each device does not have to be handled individually and can be easily aligned with the test fixture. Further, the preferred method of the present invention positions the test fixture over the device to be tested. As used herein and in the claims, the terms, above or above, over, below or below, and below.
h) relates to the direction of gravity. For example, if the test fixture is said to be above the device to be tested, this means that the test fixture is separate from the device to be tested in the opposite direction of gravity. Means This configuration is important because contaminants cannot settle on the electrical contacts of the test fixture when the test fixture is over the device to be tested. In the preferred arrangement, the test fixture is perpendicular to the direction of gravity.

Yet another method according to the present invention provides two or more separate test devices for testing two or more corresponding separate leadframes. After testing, the two or more leadframes are fed into a single trim and molding machine. as a result,
The potential for trim and molding equipment idle time is eliminated.

Turning now to the drawings, FIG. 1 is a top view of a plurality of electronic devices mounted on a single lead frame. Electronic devices 10, 12 and 14 are typical dual in-line packaged devices with a plastic (epoxy) encapsulant and extending leads represented by leads 16 and 18 of device 10. Each device has an encapsulant
on) integrated circuit or other similar solid state semiconductor device. The leads provide electrical contact to solid state devices within the package.

The devices 10, 12 and 14 are each mounted on a single lead frame 20. During the manufacturing process, the leads, eg 16 and 18, are initially connected to each other by the dambar portion of the leadframe. As shown in FIG. 1, the dambar has been removed to electrically isolate the individual leads for subsequent electrical testing of the device. However, each lead extends straight and is not yet trimmed and molded.

Although a 6-lead device is shown for simplicity and clarity, the preferred method of the present invention is a small outline integrated circuit (SOIC) 28-lead package or a quad-flat pack. Any type of electronic device can be tested, including those well known in the art, such as a package.

FIG. 2 is a simplified diagram of an apparatus that enables testing of electronic devices in accordance with the preferred method of the present invention. Storage area 30 represents an input storage area that can accommodate a leadframe magazine holding a plurality of leadframes, as is well understood in the art. Heater 32
Is preferably a hot air blower capable of heating the lead frame and the attached electronic device. The heater 32 is used when the device must be tested at elevated temperatures. When the heater 32 is used to heat the device, the storage area 30 is substantially enclosed and thermally insulated. Cable 34 represents a power cable that provides power to heater 32.

Walking beam 36
Represents a mechanism for transporting the leadframe and attached electronic devices through the apparatus. Numerous mechanisms can be used to move the leadframe 20 (FIG. 1) along the way. Often, leadframes are perforated at their edges.
d). In such cases, the leadframe can be moved by a properly positioned toothed sprocket. In the preferred method of the present invention, a pin (not shown) rises from underneath the burr 36 and moves laterally to slide the leadframe along. A resistive heater 38 is attached to the dynamic beam 36 to allow heat transfer between the resistive heater 38 and the dynamic beam 36.
Cable 37 represents a power cable that provides power to heater 38.

At the center of the moving beam 36, a test site (te
st site) 40 is arranged. The test site 40 is heated to the same temperature as the moving beam 30 by thermal conduction from the resistive heater 38 through the flash beam 36 and by a hot air blower 61 located between the test site 40 and the test fixture 50. It should be understood that
As a result, the electronic device attached to the lead frame can be heated via the heater 32, and its temperature passes through the beam and the heater 38 at the test site.
It can be maintained by the hot air blower 61.

The test site 40 is shown holding a lead frame similar to the lead frame shown in FIG. Electronic devices 42, 44 and 46 are devices to be mounted and tested on a single lead frame. The test site 40 can move up and down as indicated by arrow 48. In the preferred embodiment, the test site 40 lies just below the test fixture 50. Also, in the preferred embodiment, the test fixture 50 comprises subfixtures 52, 54 and 56. The sub-mounts each have electrical contacts (contacts 58) corresponding to leads extending from the underlying electronic device.
And 60).

In accordance with the preferred method of the present invention, the leadframe is dispensed from the storage area 30, transported along the moving beam 36 and placed at the test site 40. next,
The test site 40 is lifted straight up toward the test fixture 50 so that the leads of the electronic device contact the electrical contacts of the sub-mount. The electronic device is thus coupled to the fixture 50. The fixture 50 may be used for specific electronic devices that are being electrically tested.
It is coupled to traditional device test equipment that is typically software driven and capable of performing the appropriate electrical tests. It should also be understood that more than one electronic device can be tested at the same time. Preferably, all devices mounted on a single leadframe are tested simultaneously. Further alternatively, the test site 40 may be stationary and the test fixture may be pulled down to contact a device at the test site 40.

Before returning to FIG. 2 for the remainder of the test apparatus description, referring briefly to FIGS. 3 and 4, FIGS. 3 and 4 are enlarged views of test fixture 50. FIG. 3 is a side view of the sub-mount showing the pointed electrical contacts represented by contacts 58 and 60. Figure 4 shows the fixture 5
It is a bottom view of 0. FIG. 4 shows that the electrical contacts are arranged to correspond to the leads of an electronic device (shown in FIG. 1). It should be appreciated that the structure of the test fixture 50 will vary according to the structure of the electronic device to be tested. Test fixture 50
An important feature of is that the electrical contacts point straight down. This configuration provides a significant improvement over prior art test systems because it prevents contaminants from depositing on the electrical contacts.

In the prior art, the same test fixture was placed under or on the side of the device to be tested.
With such a configuration, long exposure to the test environment was essentially capable of collecting contaminants at the electrical contacts. Such contaminants cause serious penalties such as equipment failure and equipment downtime. The configuration according to the preferred method of the present invention significantly reduces contaminants that collect on the electrical contacts of the test fixture.

Returning to FIG. 2, the moving beam 36 is located at the test site 4
It extends beyond zero to the inker 62 and finally to the second storage site 64. After the electrical testing of a group of electronic devices attached to a particular leadframe is completed, the burr moves the leadframe to the printer 62. The printer 62 includes an ink brush 66.

It should be understood that the entire test apparatus is controlled by a computer (not shown) according to methods well known in the art. During testing of a group of devices, any defective device is identified by the computer. The computer commands the printer 62 to mark any defective devices, so that the defective devices can later be identified and separated from the good devices.

Finally, the leadframes are collected in a storage area, which preferably contains a leadframe magazine, which is removable and may be removed from other manufacturing equipment, namely trim and molding equipment. Can be moved to.

FIG. 5 is a block diagram showing a modification of the above-described method. The configuration shown in FIG. 5 is useful when the time required to electrically test the electronic device is longer than the time required to trim and mold the individual devices and to singulate the devices. is there. Boxes 72, 74 and 76 each represent a test rig system similar to that shown in FIG. Box 78 represents the trim, molding and singulation equipment that completes the molding of the leads of the electronic device and separates them from the connecting leadframe.

Traditionally, a single testing device has been used in combination with a single trim and molding device. However, in some cases electrical testing takes longer than trim and molding. If the predetermined time interval required for testing is longer than the predetermined time interval required for trim and molding, the trim and molding equipment will wait idle at some time during manufacturing. This situation results in increased cycle time and reduced efficiency. The solution is to provide multiple test devices, each testing multiple corresponding leadframes. After testing, all of those leadframes are fed into a single trim and molding machine 78, which allows the trim and molding machine 78 to be in continuous operation. It should be understood that an appropriate number of parallel test equipment can be selected depending on the length of time required for testing and the length of time required for trimming and molding.

[0026]

By now it should be appreciated that a method has been provided that allows multiple electronic devices to be tested at one time while the devices are still mounted on a common leadframe. This results in a substantial increase in efficiency. In addition, the method significantly limits the amount of contaminants that can attach to the test fixture. Additionally, a method of eliminating trim and molding equipment idle time has been provided.

[Brief description of drawings]

FIG. 1 is a top view of a plurality of electronic devices mounted on a single lead frame.

FIG. 2 is a simplified illustration of a test enabling device according to a preferred embodiment of the present invention.

3 is a side view of a test fixture included in the apparatus of FIG.

FIG. 4 is a bottom view of the test fixture of FIG.

FIG. 5 is a block diagram showing another method according to the present invention.

[Explanation of symbols]

 10, 12, 14 Electronic device 16, 18 Lead 20 Lead frame 30 Storage area 32, 38 Heater 34, 37 Cable 36 Moving beam 40 Test site 42, 44, 46 Electronic device 50 Test fixture 52, 54, 56 Sub Fixture 58,60 Contact point 61 Hot air blower 62 Printing machine 64 Second storage site 66 Ink brush 72,74,76 Test equipment system 78 Trim, molding and singulation equipment

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Simon H.S.S.C. Hong Kong, Kowloon, Twen One, Rear Block, 2 / F, Ho Pui Street 44 (72) Inventor Glenn Katie Cheung Hong Kong, Kowloon, Tsuan Wang, Luc Yun San Chuen, Brock Gee, 1808 (72) Inventor Park Soo Lee Hong Kong, Causeway Bay, Moreton Terras 11, Bayview Mansion, 9 / F, Blocksea, Flat 5 (72) Inventor Kwok Kheung Ho Hong, Kowloon, Canton Road Mon Koku 1042, 3 / F

Claims (3)

[Claims] 1. A method of testing an electronic device (10, 12, 14) mounted on a leadframe (20), comprising: a plurality of electronic devices (10, 12) mounted on a single leadframe (20). 12, 14) in which the electronic device comprises electrical contacts (1
6, 18) having the lead frame (20) for the test fixture (50)
The test fixture (50) at the test site (40) below the electrical contact (16, 1).
8) contacting with the electronic device (1
0, 12, 14) for electrically testing a method for testing an electronic device (10, 12, 14) mounted on a lead frame (20). 2. A method of testing an electronic device (10, 12, 14) mounted on a leadframe (20) comprising a plurality of integrated circuit packages (10) connected to a single leadframe (20). , 12, 14) in which the integrated circuit package (10, 12, 14) has extended leads (16, 18) separated from each other, the lead frame (20) being a first Transporting the leadframe (20) from the leadframe storage area (30) to the test site (40) along a moving beam, the test fixture (50) arranged in a direction perpendicular to the direction of gravity. Raising upward to engage with the test fixture, the test fixture having electrical contacts (58, 60), the extension lead (1)
6, 18) contacting the electrical contacts (58, 60) from below, electrically testing the integrated circuit packages (10, 12, 14), and moving the lead frame (20). Transporting from the test site to the second lead frame storage area (64) along (36), and singulating the integrated circuit package (10, 12, 14). A method of testing an electronic device (10, 12, 14) mounted on a featured lead frame (20). 3. A method of testing an electronic device (10, 12, 14) mounted on a lead frame (20), comprising a plurality of lead frames (10, 12, 14) mounted on an integrated circuit package (10, 12, 14). 20), providing a plurality of corresponding test devices (72, 74, 76), integrated circuit package (20) of each lead frame (20) in the corresponding test device (72, 74, 76). 1
0, 12, 14) for testing the lead frame (20) to the test fixture (5).
0) and moving the leadframe (20) upwards for coupling with the test fixture (50), and the plurality of leadframes (20) Trim the integrated circuit package (10, 12, 14) at a predetermined time interval of 1,
Single trim and molding device for shaping and singulation (7
8) A method for testing an electronic device (10, 12, 14) attached to a lead frame (20), which comprises: