ANOTHER BREAKTHROUGH IN TEST & BURN-IN SOCKET TECHNOLOGY
RELIABLE ULTRA FINE-PITCH 0.4mm BGA/CSP SOCKET IN COMPRESSION MOUNT TECHNOLOGY
The continuous miniaturization of mobile applications, and the resulting shrinking of chip sizes, requires ever smaller contact pitches. This miniaturization also presents a challenge to socket manufacturers, as not only the reliability, but also the processing capability of the contact systems for test & burn-in applications must be ensured. But YAMAICHI ELECTRONICS has shown how such obstacles can be overcome, on the way to a production-capable electromechanical ultra fine-pitch socket, thus once again demonstrating its technological leadership.
The challenges were, in particular, to ensure an electrically and mechanically reliable, high-quality precision contact system, considerations related to the requirements of the burn-in board and, finally, to achieve a sound cost-benefit ratio.
INTERFACE TO THE BURN-IN BOARD
Compression mount technology (CMT) was recognized as the best solution here, as it can be realized without any great effort in comparison to through hole (TH) or surface mount technology (SMT). The flexible buckling beam contacts are pressed onto the bond surfaces of the PCB, which is brought about by screwing the socket onto the PCB. YAMAICHI looks back on decades of experience with CMT in the test and burn-in sector. With a pitch of 0.4mm, however, there is so little space available that a "fan-out" using an auxiliary PCB (interposer) is normally necessary in order to ensure the routability of the burn-in boards. This, however, would have a negative effect on the electrical performance and the product costs.
YAMAICHI met this challenge by realizing the routing within the socket, thus achieving a PCB foot pattern of 0.4mm x 0.6mm. This not only ensures technological and cost-optimized producibility, but also trouble-free socket installation.
The 0.4mm pitch socket can therefore be used as a direct CMT socket. The contact is extremely reliable, as existing technologies have merely been refined and enhanced.
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What's more, the solution eliminates the need for the customarily required auxiliary PCB interposer, thereby saving costs.
CONTACTING THE BGA/CSP
ULTRA FINE-PITCH
The ball bonds of the IC are contacted by means of the so-called buckling beam, which is extremely space-saving due to it being vertically pressed on, and which also possesses excellent mechanical load qualities. Possible effects of the larger pin length on the electrical characteristics are negligible, as the semi-conductor devices to be contacted operate in the low current range and the burn-in is carried out at low frequency.
It would be pointless to list the advantages and disadvantages of all the other individual contacting systems at this point, whether tweezer style, spring probe or conducting polymers, etc. Suffice it to say, however, that these alternatives were collectively rejected, either on the basis of cost-inefficiency or from a mechanical point of view: e.g., high costs (pogo pin), overly large space requirement (tweezer style), general electromechanical weaknesses (for example, geometrical ball deformations, wear, coplanarity problems, soiling, adhesion, oxidation, etc).
With the 0.4 mm pitch BGA/CSP socket from the NP437 series, YAMAICHI impressively demonstrates that reliable, ultra fine-pitch applications are no longer a problem in test & burn-in technology. As such, the company has achieved an essential breakthrough, due to the already constantly growing demands of the market for increasingly miniaturized and multi-functional applications. YAMAICHI is the professional partner who continually demonstrates, as in the above case, that the most capable solutions can be found by adapting additional functionality to established socket architectures. Ultimately, this approach increases the yield and therefore also the customer's profitability and efficiency.
ABOUT YAMAICHI ELECTRONICS
YAMAICHI is a market leader for test & burn-in sockets, connectors and connection systems, the reliability and functional dependability of which are absolutely essential for the success of the overall project. YAMAICHI has very quickly established itself on the world market as a manufacturer of top-quality, reliable components for sophisticated applications in the fields of telecommunication infrastructure, industrial automation, mobile computer technology, mobile telephones, GPS systems, printers, digital cameras, camcorders and a multitude of other appliances for the retail trade, industry and electronics.
Has the above wet your appetite? Then don't hesitate to call:
Rene Haller, EXT 36
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