LED异常客诉8D报告

Section 1: Corrective Action Request

STATUS:

Interim Report

Failure Analysis Report # FA12P065 Customer Name Buckingham Industrial Corporation Bridgelux Sales

Contact Albert Ai

Customer Contact Name

Frank Yang

Date Initiated September 7, 2012 Customer Address No.89 Fengshou East Rd, Shipu, Qiandeng Town,

Kunshan City, Jiangsu, China Date Samples Received September 11, 2012 Customer Contact Phone #

86-512-57407561 Ext. 66521 Bridgelux Part Number BXRB-30E0360-A-03 BXRA-30E0360-A-03 Customer Contact Email Address frank@https://www.wendangku.net/doc/576487796.html, Part Description LS 1x4 Bridgelux Quality Contact Oscar Soriano Billy Florentino Lot Code/Date Code

Multiple

Defect Arrays Not Lit Bridgelux Customer Impacted

Buckingham Industrial Corporation Quantity

271 Arrays

Number Returns

1

Section 2: Bridgelux Response

D1: ESTABLISH TEAMS

Champion Team Leader

Jackie McNab Billy Florentino Members

Oscar Soriano, Phil Elizondo, Julius Joves

D2: PROBLEM DESCRIPTION

Failure Sample

Occurred: IQC

Process

Test

End User

Description:

Buckingham Lightings returned number of arrays with a complaint of

no lit at incoming test with DC source without soldering, total = 15 arrays no lit after soldering process, total = 216 arrays 1 or 3 LED chips no lit, total = 19 arrays

no lit after soldering process, total = 19 arrays Shine, drive at dc source, total = 1 array LM low, about 150LM, total = 1 array wrong part number, total = 24 arrays

The returned LED arrays were labeled into different group of tubes.

D3: CONTAINMENT ACTIONS

TBD

D4: ROOT CAUSE FAILURE ANALYSIS

Summary of the Analysis:

The customer complaint of no light up on returned arrays was confirmed during the in-house DIM test.

Returned arrays from incoming test and after soldering process yielded ~100% DIM failures. X-ray analysis found broken wires as a main cause of the failures. There are damages, cracks and scratches found on the LED lens that relates to the broken bond wires. This indicates a possibility of improper handling process from array assembly to customer luminaire assembly.

The customer complaints of some arrays are not fully functional and some dies do not light up during the test. Bridgelux found to have only 1 out of 19 returned arrays that exhibited a non-fully functional array during the in-house DIM test. Bridgelux datasheet requires minimum Vf of 11.3V. The setup made by the customer during the testing might have insufficient power supply to satisfy the LED requirement to power up and this yielded into partial light up of the dies.

Details of the Analysis:

The returned LED arrays were DIM tested to validate the failures. Table below showed the fallout rate of each group.

The DIM test confirmed customer complaint of no lit. Groups 1, 2, and 3 resulted to a very high DIM

failure rate.

Group 4 where customer complaint on some die having no lit during their testing with Vf of 9~12V, was found to have only 1 failure out of 19 arrays that exhibited a partial number of dies lighted and the rest of the 18 LED arrays found to be functionally good. Bridgelux datasheet requires minimum Vf of 11.3V.

Sample images of the DIM test results were attached below for reference.

The setup made by the customer during the testing might have insufficient voltage or current to satisfy the LED requirement to power up and this yielded into partial light up of the dies. There are LED chips that start to emit light at a different Vf values.

The settings made in BLX in-house DIM test were based on the datasheet minimum requirements and yielded 95% fully functional.

The unit (#30) that failed the DIM test found that the upper 2 dies do not light up at 10mA but fully

lighted at 100mA.

Further analysis through X-ray revealed a broken or fused wire on location 1x2. The wires appeared to be still in a very minimum contact which allows a flow of current for full light up. There was no visible

damage found on the lens or a stressed signature on the bond wires that might have caused the failure.

Bridgelux FA has not yet found the failure mechanism.Further investigation and failure simulations are being carried out and result of the analysis will be shared once findings and conclusion has finalized.

Group-1 where customer complaint of no lit during their incoming light up test, confirmed 100% DIM

failures. 5 arrays were taken into X-ray imaging and revealed the following.

The tables above showing broken bond wires were the major caused of the no lit failures. Visual

inspection on the LED array lens found damages and cracks directly on the area of the broken wires.

Images as shown below

The mode of failures discloses a relation to poor handling. The damages on the lens as seen on the images illustrate a scenario for having accidentally made a hard contact on the lens. The force applied on the lens induced the broken wires causing the prevention of current flow.

The backside of the array found to have prominent dark lines that appear to come from some sort of rail holder. The same signature observed from the earlier failures submitted for FA. Please refer to FA Report FA12P051.

Group 2 and 3, customer complaint of no lit after the soldering process. DIM test confirmed units are totally not functional. 15 arrays were taken into X-ray imaging and revealed the following.

X-ray resulted a 100% caused of no lit were broken wires. The majority of the locations of these broken wires were biased to the negative terminal side of the LED array.

There are visible lens damages on the area where the broken wires are located. Some of the damages cause slight peeling of the lens. The force applied on the lens resulted to a broken wire that causes a no light up.

These damages were all related to poor handling process. It is possible that these damages were induced accidentally during the soldering and/or during the luminaire assembly process.

D5: CORRECTIVE ACTIONS

1. All wrong part numbers to be coordinated by Field Sales for the RMA process.

2. Buckingham is advised to review possible issues of damaging the wire bonds of the LED array

during the IQA and assembly process.

3. Bridgelux Field Sales to discuss with the customer Bridgelux Application Note AN11 – “Handling and

Assembly of Bridgelux LED Arrays”

D6: IMPLEMENT CORRECTIVE ACTIONS

TBD

D7: PREVENT RECURRENCE

Bridgelux Field Sales to discuss with the customer Bridgelux Application Note AN11 – “Handling and Assembly of Bridgelux LED Arrays”.

Bridgelux quality to ensure a proper packaging process is observed at all CM sites.

D8: CONGRATULATE THE TEAM