CN110954771A

CN110954771A - Aging method for COC (chip on chip) of optical module

Info

Publication number: CN110954771A
Application number: CN201911299721.6A
Authority: CN
Inventors: 唐永正; 李波; 王淑晖; 徐强; 潘双收
Original assignee: Wuhan Inphilight Technology Co Ltd
Current assignee: Wuhan Inphilight Technology Co Ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2020-04-03

Abstract

The invention relates to an aging method of an optical module COC, which comprises the steps of electrifying an optical module to enable the COC to emit light and actively couple a lens, and confirming that light passing through the lens is coupled into an optical fiber by monitoring the output optical power of the optical fiber; writing a preset test program in the optical module before aging, electrifying the optical module, and testing the performance parameters before aging by aligning a detector with a light outlet of the optical fiber; writing a preset aging program into the optical module, installing the optical module on an aging board, and putting the aging board into an aging environment; writing the aged optical module into a preset test program, and testing the aged COC performance parameters by aligning a detector with an optical fiber light outlet; and comparing the change of the related performance parameters before and after aging, and screening the early failure COC. The invention electrically connects the COC with the power supply optical module, and the aging COC is carried out by electrifying the two ends of the optical module and testing the related performance parameters of the optical module, and the aging is combined with the aging of the module, thereby saving the cost of a COC clamp, improving the testing efficiency and reducing the working hours.

Description

Aging method for COC (chip on chip) of optical module

Technical Field

The invention relates to the technical field of optical communication, in particular to an aging method of an optical module COC.

Background

With the rapid development of 5G communication and the increasing demand of data centers, the market demand for multiplexing optical modules of 100G, 400G and the like is increasing. Various electronic components (COCs) used by the optical module (Chip On Carrier, Chip On substrate or Chip On Chip) generally need to be aged to screen out early failure COCs, so that the long-term reliability of the COCs applied to the optical module is ensured. There are two common packaging forms of TOSAs (Transmitter Optical Subassembly): TO packages and BOX (housing) packages. The disadvantage of TO packages is that the rates that can be currently achieved are not high, so BOX packages still need TO be chosen for some high-rate devices. BOX packages, also called deep cavity packages, are superior TO packages in terms of transmission rate, heat dissipation, etc., but because mounting is completed in a housing with a small space, mounting difficulty and cost are much higher than those of TO packages. How to screen out the bad COC before packaging becomes a major problem to be solved by COC manufacturers. High-temperature power aging is a relatively multiple screening method adopted in the industry, and is characterized in that components are electrified to simulate the working conditions of the components in an actual circuit, and aging is carried out for several hours to dozens of hours at a high temperature of between 80 and 150 ℃ so as to accelerate the exposure of potential faults in the components, then electrical parameter measurement is carried out, and the components with failures or parameter changes are screened and removed, so that early failures are eliminated as far as possible.

However, the conventional aging process of a COC manufacturer generally ages a component on a COC aging test fixture, for example, the component is a laser, and a laser used by the optical module 6 generally needs to be aged to screen out an early-failure laser, so as to ensure long-term reliability of the laser applied to the optical module 6. As shown in fig. 1-2, a laser chip 3 is typically fabricated as a COC (chip on substrate) on a COC substrate 1 with a pre-deposited gold-tin solder 2, and the laser chip 3 and the COC substrate 1 are bonded together using a gold wire bonding process. The COC that has completed gold wire bonding is then loaded onto an aging jig 4 and energized using an energizing probe 5, and then the COC is put into an aging oven together with the aging jig 4 for aging. Before and after aging, relevant performance parameters of the laser chip 3, such as a series of parameters of Ith (threshold current), SMSR (edge-to-touch rejection ratio), wavelength, optical power and the like of the laser chip 3, need to be tested, and then the laser chip 3 which fails in an early stage is screened out by comparing the variation of the parameters before and after aging. The following problems exist in the existing aging method:

1. usually, in order to obtain good high-frequency performance, the size of the COC is designed to be very small, the requirement on the manufacturing accuracy of an aging fixture powered by the COC is very high, and thus the cost of the aging fixture of the COC is very high, so that the price of a good COC subjected to aging detection sold by a COC manufacturer to an optical module manufacturer containing components is 50% higher than that of a COC containing a defective product without aging detection, and the reject ratio of the common COC containing the defective product without aging detection is only 2% -5%;

2. in the traditional aging process, components (such as laser chips) are aged on a COC, the size of the COC is small, the heat productivity of the components is large, the COC is clamped on an aging clamp, and the good contact between the COC and the clamp is difficult to ensure, so that the actual temperature change of the COC is very large, and the test precision of the COC is influenced; the aging of components has very high temperature control requirements, and the temperature deviation is usually required to be not more than 5 ℃. In order to improve the heat dissipation of the COC, the manufacturing precision of a COC aging clamp needs to be improved, meanwhile, in order to ensure that the COC is well attached to the clamp, thick gold plating treatment needs to be carried out on the clamp, and the manufacturing cost of the clamp is further increased;

3. before the COC is aged, gold wire bonding needs to be carried out on the COC, and because the size of the COC is very small, the design precision requirement of a clamp for the COC gold wire bonding is very high, the manufacturing cost of the clamp is also very high; for example, if the aging is performed on the COC, expensive COC aging jigs need to be equipped; an aging fixture capable of holding 20 COCs usually needs 5000 yuan, calculated according to a module with 10k output per month, on average 2000 COCs need to be aged per day, about 100 aging fixtures are needed, the cost of the optical fixture needs 50 ten thousand yuan, and the maintenance cost of the fixture for one year needs at least 20 ten thousand yuan;

4. before gold wire bonding of the COC, the COC needs to be installed on a clamp which is already bonded by the gold wire, and after the gold wire bonding is finished, the COC needs to be detached from the clamp; similarly, before and after aging, the COC needs to be detached from and installed on an aging clamp; a large amount of manpower and material resources are consumed for COC clamping, and meanwhile, due to the fact that the size of the COC is very small, a laser is easily damaged in the clamping process, and extra material loss cost is brought; for example, in the conventional COC aging method, COC wire bonding and COC aging both require directly operating the COC with tweezers to perform loading and unloading, and the COC itself has a very small size, which usually results in yield loss of about 5%; the COC for 5% loss of operation, calculated as about 10k module of output, is 2500, calculated as 50 dollars per COC, the monthly loss is 12.5 ten thousand dollars;

5. the testing before and after the aging of the COC is to collect the light emitted by the laser by adopting a multimode optical fiber or an integrating sphere for testing, generally, the alignment operation between the laser and the optical fiber needs to be executed once when each COC is tested, the testing efficiency is relatively low, and the testing accuracy is difficult to guarantee.

Disclosure of Invention

The invention provides an aging method of an optical module COC, which solves the technical problems that the test cost of COC aging is high (an aging clamp), the test efficiency and precision are low, and the surface of an electronic component of an optical module is greatly damaged on the aging clamp in the test process in the prior art.

The scheme for solving the technical problems is as follows: an aging method for COC of an optical module comprises the following steps:

electrically connecting COC of a luminescent product to be aged with an optical module;

writing a first preset test program in the optical module before aging, enabling light passing through the lens to be coupled into the optical fiber by electrifying the optical module, COC (chip on chip) luminescence and coupling the lens, and confirming that the coupling of the lens meets the requirement by monitoring the optical power output by the optical fiber;

thirdly, testing relevant performance parameters before aging by using a detector to align a light outlet of the optical fiber;

writing a preset aging program into the optical module, then installing the optical module on an aging board, putting the optical module into an aging environment, and after the aging environment is stable, heating and electrifying the optical module for aging;

writing a second preset test program into the optical module after aging, then electrifying the optical module, and testing the related performance parameters of the COC before aging by aligning a light outlet of the optical fiber with a controller;

and sixthly, comparing the relevant performance parameters before and after aging, and screening out the COC with early failure according to a reasonable range of preset change by comparing the change values of the relevant performance parameters before and after aging.

Further, the optical fiber is an adapter.

Further, the detector is a photodetector.

Further, the reasonable range of the preset variation is 0-20%, and when the variation of the related performance parameters before and after the aging of the COC exceeds 20%, the COC can be judged to be early failure.

Further, the chip in the COC is a laser chip, and the related performance parameters include a threshold current, a side-to-die rejection ratio, a wavelength, and an optical power.

Furthermore, the number of the laser chips is multiple, and light emitted by the COCs is irradiated onto the lens through the multiplexer.

Further, the chip in the COC is a photodetector chip, and the related performance parameters include dark current and loudness.

Further, the first step further comprises the step of fixing the optical module, the COC and the lens on the metal shell, wherein the lens is fixed on the metal shell by firstly pasting with UV and then baking and drying.

Further, the COC of the to-be-aged luminous product is fixedly mounted on the metal shell in a glue and eutectic mode, and the electrical connection mode of the COC and the optical module adopts a gold wire bonding process.

Further, the method also comprises the following steps: repeating the third step to the sixth step on the optical module of the COC with the screened early failure to finish the aging test of other COCs; removing the COC with early failure and replacing the COC with a new COC; and continuously finishing the assembly and the test of other procedures on the aged good product.

The invention has the beneficial effects that: the invention provides an aging method of an optical module COC, which has the following advantages:

1. the optical module comprises a plurality of electronic components, each electronic component corresponds to one COC, the COC of a to-be-aged luminous product is electrically connected with the optical module, then the two ends of the optical module are directly electrified to age the COC and test related performance parameters of the optical module, and the aging of the optical module are combined, so that the COC aging process is omitted, the cost of a COC clamp is omitted, and the test efficiency and the test precision are greatly improved.

2. In a traditional COC aging mode, both COC routing and COC aging are to directly operate COC by using tweezers to carry out loading and unloading, the size of the COC is very small, and about 5% yield loss is caused by operation generally; according to the invention, the aging is carried out at the module end, the yield loss generated by the operation can be basically ignored, and the yield loss caused by the operation is completely avoided; the technical problem that the surface of an electronic component of the optical module is greatly damaged on an aging clamp in the testing process is solved.

3. The traditional aging method needs to wire COC and prepare a clamp for the wire COC. The COC is small in size and inconvenient to clamp. The COC routing is carried out after the COC is attached to the module by adopting the method of the invention, and is carried out together with routing of other components in the module. The method saves a process, simultaneously does not need a special COC routing clamp, and saves the cost.

4. The testing before and after the COC aging is carried out through the detector, the existing detection mode adopting a multimode optical fiber or an integrating sphere is replaced, and the testing efficiency and the testing accuracy are further improved.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings. The detailed description of the present invention is given in detail by the following examples and the accompanying drawings.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:

FIG. 1 is a schematic diagram of a COC structure in a light module in the prior art;

FIG. 2 is a schematic diagram of a prior art optical module with a COC mounted in a burn-in fixture;

fig. 3 is a schematic diagram of a structure to be tested in which an electronic component is mounted in an optical module according to an embodiment of the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

1. a COC substrate; 2. gold-tin solder; 3. a laser chip; 4. aging the clamp; 5. energizing the probe; 6. an optical module; 7. COC; 8. a metal housing; 9. a multiplexer; 10. a lens; 11. an adapter.

Detailed Description

The principles and features of the present invention are described below in conjunction with the accompanying fig. 1-3, which are provided by way of example only to illustrate the present invention and not to limit the scope of the present invention. The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in fig. 1 to 3, the present invention provides an aging method for COC of an optical module, which is characterized by comprising the following steps:

step one, electrically connecting COC7 of a luminescent product to be aged with an optical module 6;

writing a first preset test program in the optical module 6 before aging, enabling light passing through the lens 10 to be coupled into the optical fiber by electrifying the optical module 6, emitting light through the COC7 and coupling the lens 10, and confirming that the coupling of the lens 10 meets the requirement by monitoring the optical power output by the optical fiber;

writing a preset aging program into the optical module 6, then installing the optical module 6 on an aging board, putting the aging board into an aging environment, and after the aging environment is stable, heating and electrifying to age;

writing a second preset test program into the optical module 6 after aging, then electrifying the optical module 6, and testing the related performance parameters of the COC before aging by using the controller to align the light outlet of the optical fiber;

and sixthly, comparing the relevant performance parameters before and after aging, and screening out the COC7 with early failure according to a reasonable range of preset change by comparing the change values of the relevant performance parameters before and after aging.

It is understood that COC7 of the luminescent product to be aged may also be fixedly mounted to the lighting module 6 via the metal housing 8; the lens 10 can be fixed on the ground or on the metal shell 8; a plurality of electronic components are arranged on the optical module 6, and each electronic component corresponds to one COC 7; the first preset test program before aging, the preset aging program and the second preset test program after aging are all in the prior art and are easy to implement, so that the description is needless. The purpose of the pre-set burn-in procedure is to have each laser chip write the current required for burn-in through the optical module 6. The first and second preset test programs before and after aging may be the same or different according to the test requirements. The optical fiber may also be replaced with an adapter 11. The optical module 6 mainly functions as a power supply for the COC 7.

According to the background technology, high-temperature power aging is a relatively multiple screening method adopted in the industry, the high-temperature power aging is to electrify components, simulate the working conditions of the components in an actual circuit, age for several hours to dozens of hours at a high temperature of between +80 and +150 ℃ to accelerate the exposure of potential faults in the components, measure electrical parameters, screen and remove the components with failures or parameter changes, and eliminate early failures as far as possible.

The embodiment provides an aging method for an optical module COC, which has the following advantages:

1. the COC7 is electrically connected with the power supply optical module 6, then the aging COC7 is carried out by directly electrifying the two ends of the optical module 6, the relevant performance parameters are tested, and the aging is combined with the aging of the module, which is equivalent to the process of COC aging, the cost of a COC clamp is saved, and the testing efficiency and precision are greatly improved. If aging is performed at COC7, expensive COC aging fixtures need to be provided. An aging fixture capable of holding 20 COCs typically requires 5000 dollars, as calculated for a 10k module produced per month, on average 2000 COCs need to be aged a day, about 100 aging fixtures are required, the cost of the optical fixture is 50 ten thousand dollars, and the maintenance cost of the fixture is at least 20 ten thousand dollars a year. According to the invention, the COC7 is electrically connected with the power supply optical module 6, the aging COC7 is carried out by electrifying two ends of the optical module 6, the relevant performance parameters are tested, and the aging is combined with the aging of the module, so that the cost of a COC clamp is saved, the testing efficiency is improved, and the working hour is reduced.

2. In a traditional COC aging mode, both COC routing and COC aging are to directly operate COC by using tweezers to carry out loading and unloading, the size of the COC is very small, and about 5% yield loss is caused by operation generally; according to the invention, the aging is carried out at the module end, the yield loss generated by the operation can be basically ignored, and the yield loss caused by the operation is completely avoided; the technical problem that the surface of an electronic component of the optical module is greatly damaged on an aging clamp in the testing process is solved. The COC for 5% loss of operation, calculated as about 10k module of output, is 2500, calculated as 50 dollars per COC, and the monthly loss is 12.5 ten thousand dollars. According to the invention, the aging is carried out at the module end, the yield loss generated by the operation can be basically ignored, and the yield loss caused by the operation is completely avoided.

4. The testing before and after the aging of the COC7 is carried out by the detector, the existing detection mode adopting a multimode optical fiber or an integrating sphere is replaced, and the testing efficiency and the testing accuracy are further improved.

Preferably, the optical fiber is an adapter 11. Through being adapter 11 with optic fibre design, be convenient for more collect each way optic fibre, it is more convenient to use.

Preferably, the detector is a photodetector. The light detector can adopt a PD control mode, the PD detector is simple in design and low in cost, and the test function can be completed.

Preferably, the predetermined variation is within a reasonable range of 0-20%, and when the variation of the related performance parameter before and after the aging of COC7 exceeds 20%, the COC7 can be determined as early failure.

Preferably, the chip in COC7 is a laser chip, and the related performance parameters include threshold current, edge-to-die rejection ratio, wavelength, and optical power.

Preferably, the number of the laser chips 3 is plural, and light emitted from the plurality of COCs 7 is irradiated onto the lens through the multiplexer 9. The multiplexer 9 is adopted, so that the multiple data messages can share one channel. This sharing can be done well when the data streams on the multiplexed lines are continuous. It is obviously more economical to do this than to transmit one communication line per terminal.

Preferably, besides the laser, the chip in the COC7 may also be a light detector chip, and the related performance parameters include dark current and loudness; of course, the chip in COC7 may also be any other light emitting device.

Preferably, the COC7 of the to-be-aged light-emitting product is fixedly mounted on the optical module 6 by glue, and the electrical connection mode between the COC7 and the optical module 6 adopts a gold wire bonding process.

Traditional COC ageing mode, because COC's size is very little, and COC itself is the source of generating heat again, the ageing temperature of direct influence of COC and ageing anchor clamps contact, in case contact not good ageing actual temperature just can have very big deviation, this also can bring extra yield loss. According to the invention, a mode of directly aging the optical module 6 is adopted, and the COC7 is directly adhered to the metal shell 8 of the optical module 6 by glue, so that the contact between the COC7 and the metal shell 8 can be well ensured, the temperature control of the COC7 is well ensured, and the extra yield loss caused by poor contact is avoided.

Preferably, the first step further includes fixing the optical module 6, the COC7, and the lens 10 on the metal case 8, and the method for fixing the lens 10 on the metal case 8 includes firstly adhering the lens with UV, and then baking and drying the lens.

Preferably, the COC7 of the to-be-aged light-emitting product is fixedly mounted on the metal shell 8 in a glue and eutectic manner, and the electrical connection manner between the COC7 and the optical module 6 is a gold wire bonding process.

Preferably, the method further comprises the following steps: repeating the third step to the sixth step on the optical module 6 of the COC7 screened out of early failure to complete the aging test of other COCs 7; removing the early failed COC7 for replacement with a new COC 7; and continuously finishing the assembly and the test of other procedures on the aged good product.

In the embodiment shown in fig. 3, the above four aspects are mainly included: the optical engine that is aged at the optical module end needs to be equipped with the optical module 6, the laser chip 3, the multiplexer 9, the lens 10, and the adapter 11, and can be powered up normally. Before aging, the light emitted by the 4 laser chips 3 is coupled into the adapter 11 through the lens 10 shown in the figure in an active coupling mode, so that the optical power of each laser chip 3 coupled into the adapter 11 is at least-40 dBm when the optical module is powered on in aging.

The product shown in fig. 3 is mounted on an aging board, each laser chip 3 writes current required for aging through an optical module 6, then the optical module 6 is placed in an aging box, the temperature in the aging box is set to the temperature required for aging, and then the module is powered on for aging.

Aligning the large area PD detector to the light exit port of the adapter 11 (which may also be fiber) directly tests the Ith (threshold current) optical power of the laser. The test is performed once after aging before and after aging, and the laser chip 3 which is bad in the early stage is screened out by comparing Ith (threshold current) before and after aging and the variation of optical power.

The laser chips 3 screened out of early failure by aging adopt a method of re-aging after directly replacing COC of the corresponding channel.

The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner; the present invention may be readily implemented by those of ordinary skill in the art as illustrated in the accompanying drawings and described above; however, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the scope of the invention as defined by the appended claims; meanwhile, any changes, modifications, and evolutions of the equivalent changes of the above embodiments according to the actual techniques of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. An aging method for an optical module COC is characterized by comprising the following steps:

2. Method for aging of an optical module COC according to claim 1, characterized in that the optical fiber is an adapter.

3. Method for aging of a light module COC according to claim 1, characterized in that the detector is a light detector.

4. The method for aging the COC of the optical module as claimed in claim 1, wherein the reasonable range of the preset variation is 0-20%, and when the variation of the related performance parameters before and after the aging of the COC exceeds 20%, the COC can be determined as an early failure.

5. The method of claim 1, wherein the COC chips are laser chips, and the related performance parameters include threshold current, edge-to-die rejection ratio, wavelength, and optical power.

6. The method as claimed in claim 5, wherein the number of the laser chips is plural, and the light emitted from the plural COCs is irradiated onto the lens through the multiplexer.

7. The method of claim 1, wherein the chip in the COC is a photo-detector chip, and the related performance parameters include dark current and loudness.

8. The method for aging an optical module COC as claimed in claim 1, wherein the first step further comprises fixing the optical module, COC and lens on the metal shell by UV pasting and then baking and drying.

9. The method as claimed in claim 8, wherein the COC of the to-be-aged light-emitting product is fixedly mounted on the metal case by glue or eutectic method, and the COC and the optical module are electrically connected by gold wire bonding.

10. A method for aging an optical module COC according to claim 1, further comprising the steps of: repeating the third step to the sixth step on the optical module of the COC with the screened early failure to finish the aging test of other COCs; removing the COC with early failure and replacing the COC with a new COC; and continuously finishing the assembly and the test of other procedures on the aged good product.