The Novel Thin Flexible PCB Module for 3D Packages Bo Zhang Institute of Microelectronics Chinese Academy of Sciences, Beijing, China Email: zhangbo1@ime.ac.cn
Outlines Laboratory introduction Project presentations Applications Process Reliability test Partners
Bird's nest stadium The Institute of Microelectronics of Chinese Academy of Sciences PRC S PRC (P. R. China s package research center) 2km exterior IME
Technology Platform:Micro Assembly Test Line DEK printer Flip Chip Wire bonder Micro assembly area
Applications Project presentations 5 Ultramicro cardiac pacemaker Retinal repair Press rate and depth tester Limited space of medical device makes the packaging very challenging. In this project we through flexible substrate folding accomplish chips stacking, thereby, make the electronics become light, thin, short, small to be true.
6 As microelectronic technology continues to evolve, medical electronics will continue to be a fast-follower of consumer electronics product platforms for the foreseeable future. Each medical device is unique and may require application-specific packaging technologies. Medical devices need a maximum of miniaturization for highest functionality in smallest volumes. Limited space of medical device makes the packaging very challenging. To meet these challenging requirements, medical original equipment manufacturers (OEMs) have been forced to develop customized packaging and assembly solutions, which are high cost. Flexible printing circuit has showed excellent advantages of electronic equipment, such as flexional, folding, three-dimensional wiring, three dimensional, and played a more and more important role in reliable miniaturization interconnection. A folded and stacked package has many advantages including an extremely thin profile. However, an additional thorny question, the bonding pads of flexible circuit substrate could be probably polluted during the encapsulation processes, which would lead to the failure of the solder ball placement.
Process (1) Flip-chip Under fill (2) Folding and die attach (3) Encapsulation (4) Demould and ball placement Flow chart
3-D 封装, cont d 8 Encapsulation materials BGA ball Important bending zones Main processes: 2D package Die attach folding cured reflow Ball placement cured encapsulate reflow
9 Reliability test Acoustic microscopy (C-SAM) X-ray Multi-reflow (260 o C for 5 times) Auto-clave (RH 95%, 125 o C, 96 hours)
10 Underfill and encapsulate processes no voids be formed. To check voids, acoustic microscopy (C- SAM) was performed after underfilling process.
Process development-materials Before and after Multi reflow resistivity Before and after Auto clave resistivity After 260 multi reflow resistivity reduce After 125 95%RH auto clave resistivity didn t change
Electrical test Dc resistance test 设计与仿真模拟 A Test point on chip A C B Chip A Dc didn t change Chip B and Chip C Dc increse Bending to DC have influence
Microstrip line 设计与仿真模拟 BGA ball microstrip line <7GHz, didn t change <7GHz, weakening <3dB
Differential line 设计与仿真模拟 BGA ball side differential line <6GHz, didn t change >6GHz,after bending differential line reduce After bending,<14ghz, weakening <3dB
TDR 设计与仿真模拟 BGA ball TDR Bending didn t change
Samples Comparison diagram 2D folding 2D makeup Solid works model
Win-Win Cooperation
18