所謂的 SAS 螺旋式上升模型 (Service After Sales，簡稱 SAS) 就是以售後服務為中心，努力增加利潤與擴大附加價值。企業透過積極收集關於顧客價值鏈的資訊，做為新附加價值服務的提案，並在下一次的循環中提供客戶，那是一種以售後服務為起點，不斷擴大與深化提案與所提供價值的螺旋式上升。然而實務上，我們發現部分企業與客戶維持的 SAS 螺旋循環關係，隨著時間逐漸演變最後幾近斷鏈。
本研究討論某晶圓代工廠(以下簡稱個案公司 A)失效分析部門與分別與其合作的兩家量測機台供應商(以下簡稱個案公司 B 和 C)之間的 SAS 螺旋循環關係。利用列舉機台供應商服務有關的18個重要項目進行標竿研究比較，並搭配 Mitchell (1997) 利害關係人鑑別理論，以及 Reinartz 和 Kumar (2002) 客戶關係群組分析，探討為何 Nanoprober 的供應商(個案公司 B)始終和個案公司 A 失效分析部門維持一個 SAS 螺旋循環的鏈結關係，而 C-AFM 的供應商(個案公司 C) 和個案公司 A 失效分析部門的SAS螺旋循環卻每下愈況，幾乎斷鏈，有關其SAS螺旋循環的斷鏈關鍵因素，值得加以探討。
個案分析結果顯示: C-AFM 的供應商 (個案公司 C ) SAS 螺旋循環的斷鏈關鍵因素主要來自本業所專注的領域與個案公司 A 不同。相較之下，專注在半導體領域的個案公司 B 較能與一樣專注在半導體領域的個案公司 A 建構一個較為穩固的 SAS 螺旋循環的鏈結。

SAS (Service After Sales) Helix Circulation, founded on service after sales, is widely used to gain more profits and raise added value. By means of gathering more useful information that helps know their clients’ value chain well, companies are more likely to be able to propose a higher value-added initiative and provide it to their clients afterwards in the next circulation. Based on service after sales, SAS Helix Circulation is capable of producing a higher value-added initiative with deep insight into it. In many practical affairs, however, it was observed that many companies failed to sustain successful SAS Helix Circulation with their clients.
This research studied the SAS (Service After Sales) Helix Circulation relationship of a foundry failure analysis department (case company A) with its two measurement system suppliers (case companies B and C). Using a benchmarking technique, the most important 18 service items provided by both companies B and C were listed and used to make a comparison in order to try to extract some key factors used to explain why a nanoprober supplier (case company B) can sustain SAS Helix Circulation relationship with the company A while a C-AFM supplier (case company C) cannot with an explanatory comment using both stakeholder identification theory (Mitchell, 1997) and customer relationship groups analysis (Reinartz and Kumar, 2002).
This case study reveals that the origin that causes an unsuccessful SAS Helix Circulation relationship between companies A and C mainly comes from the difference of the main fields that both companies A and C have long been focused on, respectively. Company B, which has been focused on the semiconductor field just like the company A can sustain a better SAS Helix Circulation relationship than the company C did with the company A.

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