According to the Zhitong Finance APP, Qunzhi Consulting stated that due to the shortage of BT substrates, the capacity for BGA packaging remains tight, with delivery cycles extending to over 20 weeks. Meanwhile, the pressure on automakers to reduce costs has intensified, requiring that the cost of automotive camera modules decrease by more than 15% annually. In contrast, COB packaging does not require BT substrates, has stable raw material supply, and the packaging cost is approximately 15% lower than that of BGA, resulting in relatively ample production capacity and conditions for rapid expansion. Driven by multiple factors, some leading manufacturers of automotive camera sensors are increasingly inclined to promote the industry's adoption of COB packaging, and it is expected that the proportion of COB will continue to expand in the future, becoming a mainstream packaging solution alongside CSP, gradually replacing the higher-cost BGA packaging.
1. BT Substrate: The Core Carrier of BGA Packaging
BT resin (bismaleimide triazine) substrates serve as the core carrier for BGA packaging and hold an irreplaceable position in the high-end chip packaging field. Its unique low coefficient of thermal expansion (CTE) characteristics enable mechanical matching with silicon chips (CTE ≈ 4.2ppm/℃), ensuring solder joint reliability under extreme temperature cycling (-40~125℃). Unlike the thin film substrates used in CSP packaging, BGA packaging's BT substrates typically adopt a multilayer stacked structure (6-8 layers), forming a composite substrate by impregnating BT resin into glass fiber cloth, providing critical support for high-reliability chips.
2. Important Reasons for BT Substrate Shortage
According to research by Qunzhi Consulting (Sigmaintell), the shortage of BT substrates is a systemic crisis caused by multiple overlapping factors, with core contradictions including:
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The surge in demand for AI servers is squeezing BT material production capacity. TSMC's CoWoS advanced packaging capacity expansion (such as NVIDIA Blackwell GPU) has led to a skyrocketing demand for ABF substrates, which share some raw materials (such as low CTE glass fiber cloth and copper-clad laminates) with BT substrates, resulting in production capacity being prioritized for AI-related orders.
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Apple has requested its memory chip supplier (Western Digital) to adjust the packaging materials for the iPhone 17 series, using BT substrate packaging. The reason is that the low CTE characteristics of the glass fiber cloth in the raw materials can effectively suppress chip warping issues caused by temperature changes. It is predicted that future iPhone series memory chips will adopt this packaging solution, and demand will continue.
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From a supply perspective, a significant reason for the shortage of BT substrates is the tight supply of upstream raw materials. Key materials such as copper foil substrates (CCL), adhesive sheets (PPG), and high-grade glass fiber cloth have extended delivery times to 4-5 months, and Mitsubishi Gas Chemical (MGC) has notified customers of delivery delays.
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Geopolitical and tariff policy impacts. The uncertainty of U.S. tariff policies has prompted some manufacturers to stockpile in advance, amplifying short-term demand.
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The slow progress of domestic substitution. Domestic BT substrate manufacturers are still in a technological ramp-up phase, with insufficient high-end capacity and reliance on imported materials and equipment. As the core material of BT substrates, the supply pattern of low CTE glass fiber cloth (thermal expansion coefficient &lt; 3ppm) is highly concentrated:
<img src="https://imageproxy.pbkrs.com/http://img.zhitongcaijing.com/images/contentformat/c5da2b9f3d616377a9b54f4e3d3c3f07.jpg?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" alt="Image" original-src="https://imageproxy.pbkrs.com/http://img.zhitongcaijing.com/images/contentformat/c5da2b9f3d616377a9b54f4e3d3c3f07.jpg"/>
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Technological Gap: Japanese companies have improved the thermal stress dispersion capability by 300% through exclusive yarn arrangement technology at the same thickness. However, due to yarn density defects, domestic fiberglass cloth faces a significantly increased risk of delamination in the 150℃ aging test.
3. The Supply Turning Point for BT Substrates Will Arrive in 2026
The breakthrough path for the shortage of BT substrates has been clearly anchored in the second half of 2026, with the core driving force coming from the stepwise capacity ramp-up and the large-scale implementation of technological alternatives in East Asia. The first key milestone will arrive in Q4 2025: Mitsubishi Gas Chemical will start the certification process for Taiwanese fiberglass cloth suppliers, with an initial monthly capacity of about 50,000 square meters, which can alleviate 3%-5% of the supply gap, but is limited by the end-user acceptance of non-Japanese materials, mainly used for mid-range consumer electronics. Q3 2026 will be a concentrated effort period for Chinese manufacturers—Honghe Technology's Huangshi base will officially produce 50 million square meters in phase one, with Low CTE products accounting for over 40% (mainly 4-5 ppm), combined with TaiBo's 20 million square meters of capacity being released simultaneously, significantly increasing the supply ratio from mainland China. In Q4, Japanese manufacturers will complete the final puzzle: NITTOBO's Osaka factory will increase monthly supply to over 500,000 square meters (+18%) after expansion, while Mitsubishi will simultaneously introduce a new resin formula to reduce fiberglass cloth consumption by 20%.
This round of capacity peak is essentially a structural relief—according to Sigmaintell's research analysis, the total global supply of Low CTE fiberglass cloth is expected to reach 6.5 million square meters in 2026, a year-on-year increase of 26%, but Japan's leading &lt;3ppm advanced materials will still account for 78%. The supply chain tension is expected to substantially improve starting from Q2 2026, with the out-of-stock rate likely narrowing to 5%-7% by Q3. It is important to be cautious about the progress of automotive-grade certification (Honghe's product verification takes 16-22 months) and the non-linear growth of AI server demand, which may still lead to a sustained tight balance in high-end fields.
<img src="https://imageproxy.pbkrs.com/http://img.zhitongcaijing.com/images/contentformat/432ab5e82999a06f7aabb7753a9821d8.jpg?x-oss-process=image/auto-orient,1/interlace,1/resize,w_1440,h_1440/quality,q_95/format,jpg" alt="Image" original-src="https://imageproxy.pbkrs.com/http://img.zhitongcaijing.com/images/contentformat/432ab5e82999a06f7aabb7753a9821d8.jpg"/>

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Qunzhi Consulting pointed out that due to the shortage of BT substrates, the production capacity of BGA packaging is tight, and the delivery cycle has been extended to over 20 weeks. Automakers are facing cost reduction pressures, requiring the cost of automotive camera modules to decrease by more than 15% annually. In contrast, COB packaging does not require BT substrates, making its cost approximately 15% lower than that of BGA, with ample production capacity. It is expected that in the future, COB will parallel CSP to become a mainstream packaging solution, gradually replacing BGA packaging

- The shortage of BT substrates is causing ongoing capacity constraints in BGA packaging, extending delivery times to over 20 weeks.  
- In contrast, COB packaging, which does not require BT substrates, is experiencing stable raw material supply and lower costs, leading to a shift towards its adoption in the automotive camera module sector.  
- A significant increase in demand for BT substrates is driven by AI server needs, geopolitical factors, and slow domestic production progress, with a potential supply improvement expected by late 2026.

Qunzhi Consulting: BT substrate shortage leads to tight BGA packaging capacity, automotive CIS packaging solutions accelerate transformation