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Arco 2P T62M 32D (14 x 15 x 1.915 mm) Package

Technical Risk Assessment (TRA) Summary

Package Information

Item	Specification
Package Size	14 x 15 x 1.915 mm
Controller Die	3.4 x 4.3 x 0.10 mm
DRAM Die	6.8 x 10.9 x 0.045 mm
Die Attach Film	20 μm (Bottom 4 dies), 10 μm (Upper 28 dies)
Substrate Thickness	370 μm (100 μm Core + 20 μm Prepreg)
Mold Body Thickness	1151 μm
Chip-to-Mold Clearance	101 μm

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Key Technical Risks

1. Die Mark Exposure Risk

Risk Description

• Due to the relatively thick die stack and limited mold cap thickness, the top die surface may become exposed after molding.
• DRAM thickness variation may further reduce mold coverage margin.

Potential Impact

• Die mark exposure.
• Cosmetic defect and reliability concern.

Recommended Action

• Tighten incoming DRAM thickness tolerance control.
• Verify mold cap coverage through stack-up simulation and DOE evaluation.

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2. Underfill Dispensing Process Risk

Risk Description

• Available dispensing space between package edge and controller die edge is only 610 μm.
• Limited dispensing window may affect underfill flow and process stability.

Potential Impact

• Underfill voids.
• Incomplete filling.
• Yield loss.

Recommended Action

• Conduct underfill dispensing DOE.
• Optimize dispense pattern and process parameters.

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3. Strip Warpage Risk

Risk Description

• Thick substrate construction (370 μm) may generate substrate-side bending after underfill curing.
• Excessive strip warpage may affect die bond alignment accuracy.

Potential Impact

• CCD focusing difficulty.
• Die recognition failure.
• Die placement error and X-out.

Recommended Action

• Evaluate strip warpage after underfill curing.
• Perform assembly DOE to verify die bond process window.

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4. Substrate Material CTE Mismatch Risk

Risk Description

• High CTE substrate materials may increase thermal stress between substrate and silicon die.

Potential Impact

• Underfill non-wetting.
• Delamination.
• Reliability degradation.

Recommended Action

• Select low-CTE core and prepreg materials.
• Target substrate CTE as close as possible to silicon die CTE (3–5 ppm/°C).

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5. Wire Bond Clearance Risk

Risk Description

• Bond pad locations for Dies 2, 3, 6, 7, 31, and 32 are located too close to adjacent die edges.

Potential Impact

• Wire sweep.
• Wire-to-die interference.
• Bonding instability.

Recommended Action

• Recommend customer relocate bond pads further away from die edges.
• Verify wire loop profile through bonding simulation.

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6. Thin DRAM Cascade Bonding Risk

Risk Description

• Existing production experience is limited to 45 μm DRAM forward bonding with approximately 630 μm die overhang.
• No prior cascade bonding experience for 45 μm DRAM with 400 μm die overhang configuration.

Potential Impact

• Die crack.
• Die shift.
• Assembly yield risk.

Recommended Action

• Execute DOE evaluation to verify cascade bonding feasibility and process margin.

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7. Die Crack Risk Due to Limited Die Spacing

Risk Description

• Die-to-die spacing is limited, increasing mechanical stress during bonding.

Potential Impact

• Die edge crack.
• Silicon damage.

Recommended Action

• Implement cascade bumpless bonding for D3–D4.
• Reduce bonding tool impact frequency on lower dies.
• Verify die integrity through DOE validation.

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Overall Assessment

The package structure is technically feasible; however, the design presents elevated risks in the following areas:

1. Mold coverage margin.
2. Underfill processability.
3. Strip warpage after underfill curing.
4. Substrate CTE mismatch.
5. Wire bond clearance.
6. Thin die cascade bonding capability.
7. Die crack susceptibility due to limited die spacing.

Process DOE and material optimization are strongly recommended prior to production qualification.

Arco 2P T62M 32D 14x15x1.915mm package size TRA

 Arco 2P T62M 32D 14x15x1.915mm package size TRA summary request

Controller size: 3.4x4.3x0.1 mm

DRAM size: 6.8x10.9X0.045

Die attached film: 20um on 4 layers die & 10um on upper 28 dies

Substrate thickness: 370 um with 100um core & 20um Pregpreg

Mold body thickness: 1151um, chip to mold clearance :101um

Risk concern:

1. Die mark exposure if thicker die & thinner mold body, need special control DRAM thickness tolerance

2. Dispensing underfill space is limited, only remained 610um from package edge to controller edge, need special control

3. As the thicker substrate thickness, after underfill curing, the strip warpage may bend towards substrate side and caused die bond workability issue when the CCD cannot focus clearly on die and X-out

 4. need to select low CTE core & PP on substrate to close to die CTE(3~5ppm/oC) to avoid non-wetting risk 

5.The distance between higher die to bond point on substate are too close, especially die 2/3/6/7/31/32), suggest customer to place further away from die edge

6. As the DRAM 45um thickness only has forward bond experience on 630um overhang die, but we did not have cascase bond on 400um die , need DOE to confirm workability

7. As the distance between dies are too close, will try to use cascade bumpless bond on D3~D4 to reduce the hitting times on D3 to avoid die crack concern

How do i write this summary risk into report, or could you show the schematic for better understanding

Via last vs Via Middle

Common characteristic:
1.DRAM+interposer are already bonded (hybrid bond) before TSV
2.TSVs Cu embedded before incoming

Via last flow
i)BSG:BG-->Backside CVD-->PR litho
ii)TSV formation: TSV etch-->Linear deposition-->Etch-->TSV TiCu deposition
iii)RDL-->PI-->UBM-->C4 bump-->Dicing

1.TSV is etched after wafer thinning(435+12.5+50)
2. TSV depth is shorter(interposer 50um)

Via middle flow:
i)Early thinning & oxide: Wafer trim-->BG-->CVD oxide-->BG/Si CMP
ii)TSV reveal+TSV dielectric:TSV reveal etch-->TSV CVD-->Oxide CMP
iii) Bump : PVD TiCu-->PI PSV-->ECD Cu/SnAg-->reflow
iv)Final front side Grind-->Dicing

*TSV &bump is processed on thicker wafer (775+12.5+108um)

A Day of Fighting a Cold

 Over the past few days, I have not been feeling well. I developed a runny nose, my heart was beating faster than usual, and my body felt unusually warm at night while I was sleeping. These symptoms were also reflected in the data recorded by my Apple Watch, which made me even more concerned. I worried that my condition might worsen and turn into a cough in the coming days.

Because of this concern, I woke up earlier than usual today and went to the market to buy lemons and kumquats, hoping to strengthen my body with more vitamin C. After searching online, I learned that drinking coffee could cause dehydration, so I decided to give up my morning coffee and put it away in the refrigerator.

In the evening, after a meeting with my process team, I shared my condition with a colleague. He kindly gave me a packet of Japanese cold medicine to help relieve my symptoms. To my surprise, the medicine worked much faster and more effectively than the lemons and kumquats. Within thirty minutes of taking it, my runny nose completely stopped.

I felt deeply relieved and grateful. Thanks to my colleague’s kindness and the effectiveness of the medicine, my condition improved quickly. I thanked God for this small but meaningful recovery and hoped that my health would continue to improve in the coming days.

My Feelings About the Fall of President Maduro

When I heard the news about President Maduro being captured, my first reaction was a deep sense of relief. For many people, this may simply be another political headline, but for me, it is closely connected to the lives and suffering of my friends from Venezuela. Over the years, I have listened to their stories of economic collapse, fear, and hopelessness. Because of them, Venezuela is not just a country on the news—it is a place filled with real people I care about.

Under Maduro’s leadership, Venezuela’s economy deteriorated dramatically. Even well-educated professionals such as pharmacists and teachers struggled to survive. The value of the currency dropped so severely that ordinary citizens could no longer afford basic necessities. My friends told me about shortages, insecurity, and the constant stress of not knowing what tomorrow would bring. Hearing these experiences made me feel angry and helpless, as no government should allow its people to live in such conditions.

One of my close friends was a pharmacist in Venezuela, a profession that should have provided dignity and stability. However, she was forced to leave her country in order to have a chance at a normal life. Even though she now works in a position far below her qualifications, she lives with more safety and peace than she ever did back home. This reality deeply shaped my view of the Maduro government.

Because of this, I feel hopeful that Venezuela may finally have an opportunity for change. I sincerely wish that my friends who remain there can live safely, freely, and happily in the future. If international involvement—especially from the United States—can help restore stability, order, and economic recovery, then I hope it will lead Venezuela toward a better path. Above all, my wish is simple: that Venezuelan citizens can live without fear, with dignity, and with hope for tomorrow.

Bad habit and change

 A few years ago, I developed a bad habit without realizing it at first. I became somewhat addicted to alcohol. I used to tell myself that drinking was only for the weekend, a way to relax and help me fall asleep after a long week. At the beginning, it felt harmless and even comforting.

Over time, however, I noticed that I was depending on alcohol more than I should. Relaxation started to feel impossible without it. That was the moment I understood that this habit was no longer a choice—it was becoming a reliance.

I decided to make a change in a very simple but firm way. I stopped buying alcohol and made sure there was none in my refrigerator. By removing the temptation from my daily environment, I gave myself fewer chances to give in. At first, it was uncomfortable, and weekends felt strange without my usual routine. But gradually, my body and mind adapted.

Looking back, I am proud of this decision. Breaking a bad habit does not always require dramatic actions; sometimes it starts with a small, clear rule and self-discipline. This experience taught me that real relaxation comes from a healthy mind, not from escaping reality. It also reminded me that I am capable of changing when I truly decide to do so.

My precious baby Lingling

    I have a 13-year-old female Shiba Inu from Japan. She is old now, but she is still my precious baby. She has been spoiled her whole life, and I am happy to let her be. Every day, I carry her up and down the stairs just so she can go outside for a short walk. My arms or legs get tired, but my heart never complains.

    At mealtime, she eats with caution, constantly watching Amu, afraid he might steal her food. She eats quickly, nervously. And if the food is not enough, she barks at me again, trusting that I will understand her needs. She trusts me completely.

    Every night, after eating her dinner, she will bark at me again around midnight, asking for more food. Even when I pretend to be asleep, she knows. Her small barks are demanding, but they are also a reminder that she is still here, still hungry, still full of life.

    She needs a dog bed everywhere—one in the bedroom, one in the living room, and even one in my landlord’s room. Every place must have her own bed, as if she wants to leave her presence behind wherever she rests. When Amu, the Husky my landlord raises, takes her bed, she never blames him. Instead, she looks at me with angry eyes, as if saying, “Why didn’t you protect what belongs to me?” She is smart like that. She always knows who to blame.

    Last month, she became sick and was diagnosed with gastroenteritis after blood tests and an X-ray. The veterinarian told me she has many bone spurs around her spine. Hearing that broke my heart. Thankfully, I have been giving her Antinol regularly to ease her pain. The doctor praised me for taking good care of her and said that because of this, she can still walk properly. If she had not received this care, she might have become paralyzed suddenly.

I realized then how fragile her time is, and how precious every ordinary day has become. Carrying her, feeding her, listening to her bark—it is all love. As long as she needs me, I will be there.

Is it worth being married?

Today marks a new beginning, the first day of 2026. I find myself thinking seriously about marriage and whether raising a child is realistic in this generation, especially with my current income of about NTD 60,000 per month after tax.

When I look at my finances honestly, I know my resources are not abundant. Raising a child means endless expenses—food, childcare, school fees, and extra tutoring. Just imagining these costs already feels heavy. It’s hard to feel confident about the future when everything seems to require more money than I can comfortably afford.

I also think about marriage. If I were to marry, there seems to be an unspoken rule that the man should earn more than I do—maybe at least NTD 100,000 a month—to live a stable and comfortable life. But a higher income often comes with higher expectations. His family might expect regular visits during Lunar New Year and every major festival. There would be family gatherings, preparations, cooking, and gifts. If someone in his family became ill, I might be expected to take care of them, too. These responsibilities feel overwhelming when I imagine them becoming part of my everyday life.

Then there is the question that troubles me the most: the future. If I raise a child and they grow up, will they take care of me when I am old? In my mother’s generation, children naturally carried the responsibility of caring for their parents. But in this generation, shaped so strongly by the internet and individual freedom, nothing feels guaranteed anymore. People are no longer expected to sacrifice their lives for their parents, and I don’t know if it is fair—or realistic—to expect that kind of devotion.

Thinking about all of this, I feel that marriage and having children are no longer simple life milestones. They are complicated decisions filled with uncertainty, responsibility, and quiet fear. At the beginning of 2026, I don’t have clear answers—only questions that stay with me longer than I expected.

Reflow soldering process

 Solder paste is used to temporary attach to the anywhere to all the contact pads, after which the assembly is subjected to the controlled heat. Solder paste reflows in a molten state, creating permanent solder joints. Heating can be accomplished by passing the assembly, through a reflow oven.

Usually four stages: preheat,thermal soak, reflow, heating

Preheat zone: climb towards to a target soak, dwell temperature.

Why lead free?

1. Health care

2. Environment: To align with RoHS with the European Union

Tin frequently serves as a principle solder due to its low melting point and excellent wetting properties. Cu & Ag are sometimes added to enhance mechanical strength, and electrical properties of the solder. 

-->Lead based solder: Tin-60%, Pb-40%, melting point:188oC

 -->Lead free Solder: Sn-Ag-Cu, >95% Tin, melting point: 227oC, but less ductile than lead based solder, rendering it has susceptible to mechanical stress, tends to be oxidize more rapidly which can adversely affect its wetting properties and solder joint quality.

What is soldering

A process involves solder, to join together metal surfaces. The solder is heated until it melts and flows into the joint between the two surfaces. Upon cooling, it hardens and forms a reliable electrical and mechanical connection.

Before soldering, the surface of metal should be cleaned thoroughly to remove any oxidations or contaminations that could interfere the formation of a good solder joint.

Vaccum effectively reduce solder void in soldering process

Siemens-EDA Summary

A.Calibre 3D thermal

1.placement & stacking analysis

2.thermal verification :power map 

Simcenter Flotherm : golden tool for 3D thermal simulation & exporting 3D thermal results

Ease of use, designer friendly use, speed, high accuracy providing color maps in 1 day. From simplified power map to final design with detailed power & GDS inputs.

Accuracy: the worst-case difference between simulation and the measured data :3.75%

Customer experince: UMC, TSMC, Intel

B. 3Dblox

Unified format and standardized language

from introduce chiplet detail information, top down to confirm connectivity

C. DFT

scalable from 2D to 3D

die integration & dies at package level

test between dies after AP & diagnosis(in

Complaint with IEEE1149.1, IEEE1500, IEEE1838

Tessant: serial access port composed PTAP/STAP

die wrapper register (DWR) for dies isolation

HBM usually come with IEEE1500 interface, helps to validate the speed of SOC, HBM

bump map, probe map, spacing, die to die , bump analysis, repair method

D: Innovator XPD

macro complex data 

physical reuse- HBM net, auto-replacement, function: rotate, mirror,

original separately process, 500,000 pin can be processed in short time period

tuning in real time, 75% cycle time reduction

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信頼性を備えた小型　低背パックージとして、小型