Optimizing the cost of test for multi die systems in packaging (SIP) Presented at MEPTEC Omer Dossani, Sr. Director Test Technology and Marketing

Transcription

1 Optimizing the cost of test for multi die systems in packaging (SIP) Presented at MEPTEC Omer Dossani, Sr. Director Test Technology and Marketing

2 Introduction The cost of test is a vast field which starts at silicon design for test and package design for testability. Once the design phase is completed these parameters are essentially locked. The engineers that win the challenge to optimize test cost are the ones who can bring the cost down in a reasonable amount of time within the products life cycle. The role of engineering managers and management systems is even more critical to ensure that this cost optimization is done across a portfolio of products. In SIP modules the importance of starting with a cost effective known good die (KGD) is critical Complexities of multiple die require sound data tools to identify and fix problem areas and avail opportunities for cost reduction In a manufacturing environment cost has to be optimized across a larger time domain and a fleet of different ATEs 2

3 Evolution of ITMS Factory Infrastructure Customer Domain STATS ChipPAC Domain B to B Or Business Systems Capacity Planning WIP Planning Manual or Integrated Servers Secure FTP Site Web Portal LVM, HVM & Discovery Reports Secure Portal Server Yield Reports Remote Access WIP System Test Summary Data END OF PHASE 1 Test Hardware Test Offload Test Analysis Server & Applications Test Databases Manufacturing Control & Automation Tester Utilization Tracking Test Floor Auto Test Cell Controller Automatic test data pipeline GPIB 3

4 Evolution of ITMS Factory Infrastructure Customer Domain STATS ChipPAC Domain B to B Or Business Systems Capacity Planning WIP Planning Manual or Integrated Servers Secure FTP Site Web Portal LVM, HVM & Discovery Reports Test Analysis Server & Applications Secure Portal Server Yield Reports Test Databases Remote Access WIP System Test Summary Data Manufacturing Control & Automation ITMS Server Tester Utilization Tracking ITMS Dbase Test Offload Test Program Test Hardware Configuration Tester Licenses Test Floor Auto Test Cell Controller Auto Test Program Download Daily Auto Extraction of Tester Configuration and Tester Licenses Automatic test data pipeline GPIB 4

5 Increasing use of data driven decision making tools Fast parametric data collection and analysis Collecting parametric data so it doesn t slow down the ATE Use the data both real time and offline Applications Design Robustness Variance Analysis of parametric data and analog and Rf measurements Test Time Reduction Quick identification of parameters whose failure is tied to a parameter already being tested Quick identification of parameters which test good often enough that they can be sampled under the QA guidelines Identification of parameters susceptible to random outliers Not repeating the same tests at Sort and Final test 5

6 Increasing use of data driven decision making tools Applications Test Time Reduction (continued) Reducing test time in real time based on specific lot performance Effective automated reporting to ensure QA specifications are met Yield Learning Not just where yield is lost but how it is lost Software based control systems to prevent the loss real time Feedback to foundries Feedback to silicon designers Reduction of Retest and Retest time By implementing real time controls one increases the first pass yield Automatic re-plunge of failing units 6

7 Increasing use of data driven decision making tools Applications Reduction of Retest and Retest time (cont) Monitoring of quality of test hardware (probe cards, socket) Real time action based on these monitor Reduction of ATE equipment cost Though more a function of design for test the tools enable sufficient data confidence to ensure that things like reduced pin count testing, reduction of analog measurements etc can safely be implmented 7

8 Increasing use of data driven decision making tools What is required Investment in the right data collection tools for the scale of ones business Sufficient volumes to enable making these tools worthwhile Training of engineers in efficient usage of the tools A good internal sell through quality and design departments on validity of the tool Discipline in application of the tools Conclusion The best in class achieve significant yield improvement and TTR in a short time Test time reductions are done within weeks of production versus months High yields are gated only by design robustness (which itself can achieved faster) 8

9 Managing cost in 5+ year time frame and across a portfolio of silicon devices Loosely called test strategy Streamlining ATE configurations versus optimizing the cost of the ATE by device family Maintaining ATE consistency across Sort and Final Test or going with the lowest cost approach for each type Defining the lowest cost ATE. Is it the one the vendor can sell you at he lowest cost or is the one the supplier can provide at the lowest hourly rate What will be the cost of capacity expansions should products take off? What kind of flexibility can I have in my supply chain with the choice of ATE? 9

10 Managing cost (cont.) Streamlining ATE configurations versus optimizing the cost of the ATE by device family Corporate strategies span the range of optimizing configuration at the device level to across a wide range of products Within a ATE type one usually gets limited benefits by having more than 3 or four configurations A silicon manufacturer gets limited benefits beyond 3 ATE types For smaller companies this number can be 1 or 2 depending on their product portfolio Maintaining ATE consistency across Sort and Final Test or going with the lowest cost approach for each type Clearly the same ATE across sort and final test has benefits in test time reduction, development time reduction and higher utilization of equipment across sort and final test On the flip side the fact that Sort can tolerate a higher DPPM opens up opportunity for lower cost ATEs that are very tempting to leverage 10

11 Managing cost (cont.) Defining the lowest cost ATE In the OSAT world the tester at the lowest hourly rate is the lowest cost solution Too often ATE vendors will sell new instruments or new testers that are at a lower cost but this requires new investment and creates capacity bottlenecks Talk to both ATE suppliers and OSAT vendors or your operations managers Flexibility and speed of capacity expansion Some of the most successful companies choose widely available ATE as a SORT or even a final test solution because they can quickly add capacity in a crunch or bring up another supplier if required 11

12 Managing cost (cont.) Other Final Test Cost Considerations Does a second insertion make sense? How can sufficient sort testing lower the final test ATE cost and test time? Number of Suppliers Negotiating leverage with each supplier if one is a small customer to each of them or some of them What incentives do suppliers have to manage cost if they know you have 80% of your business with them 12