The top-two Taiwan-based IC backend services companies, Advanced Semiconductor Engineering (ASE) and Siliconware Precision Industries (SPIL), are expected to report mixed results for December due to different client bases, according to industry watchers.

ASE's December revenues, generating mainly from IC backend testing and packaging services and sales of packaging materials, are likely to reach NT$11.6-11.7 billion (US$399.1-402.6 million) compared to NT$11.83 billion posted in November, the sources estimated.

Orders from Qualcomm for 28nm telecommunications chips as well as continued orders from MediaTek contribute to steady revenues at ASE, said the sources.

Based on ASE's projected December revenues, ASE will also see its revenues grow 4% sequentially in the fourth quarter of 2012, meeting the company's guidance of a 3-5% growth, the sources added.

SPIL is likely to post revenues of NT$5.0-5.1 billion for December, lower than market expectations of NT$5.3 billion in light of decreasing demand from some clients, the sources pointed out.

Additionally, SPIL's fourth-quarter revenues will also slip 3% sequentially to NT$16.3-16.4 billion, meeting the company's low-end target of 0-3% negative growth, the sources forecast.