Effective Method for Wire Bonds Rework Using Conductive Epoxy
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The development of wire bonded chips requires us to go through multiple designs to achieve the best packaging performances. Nevertheless, some of the designs may not be tested due to defects preventing the wire bonds to be effectively completed. Unless an effective way to rework such failed assemblies is feasible, the invested resources in the design and manufacture are lost. The MiQro Innovation Collaborative Center, Bromont, QC, Canada, has developed a method to rework such assemblies. In this paper, we present a method where two silver-filled conductive epoxies are used to repair failed gold wire bonds. The mechanical adhesion and electrical properties of such rework assemblies were compared to reference gold wire bonds. The rework method consists of reattaching the sheared end of the wire to the landing pad on which a drop of conductive epoxy is deposited. Each group is at least composed of 40 samples for statistical analysis of the method reproducibility. Experiments were conducted on two identical test chips with gold pads on each substrate. A matrix of 1-mil-diameter gold wire bonds was realized. Then, on each substrate, the first group of wire bonds was used as a reference and the others were sheared at the stitch bond and reworked with two different silver-filled conductive epoxies. The pull tests revealed that all the wires (reference and reworked with epoxy 1 and 2) rupture at the neck of the first ball bond at a similar break load (~12 g). Visual inspection using the cross section of the reworked area showed no visual defect. We could also see that the deposited drop from epoxy 1 is much more likely to make a better electrical connection due to the presence of smaller silver flakes and a better capability to wet both the wire and the pad. The electrical resistance of reference and reworked wire bonds were measured on a two-probe station. On both samples, reworked wire bonds with epoxy 1 have similar resistance (94 mQ) than the reference (91 mQ) ones. The ones reworked with epoxy 2 have an electrical resistance (214 mQ) more than twice than the reference ones. Reliability testing showed increasing electrical resistance throughout 1000 deep thermal cycling cycles for epoxy 2, while epoxy 1 remained stable until 500 cycles. We demonstrated that failed wire bonds could be effectively reattached to the substrate using the appropriate conductive epoxy. This method enables us to reduce development costs by reworking failed considered assemblies to avoid the waste of resources and delays in the run to the market for the new product.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it