| US 7,482,180 B1 | ||
| Method for determining the impact of layer thicknesses on laminate warpage | ||
| Julien Sylvestre, Chambly (Canada); Jean Audet, Granby (Canada); Marco Gauvin, Granby (Canada); and Sylvain Pharand, St-Bruno (Canada) | ||
| Assigned to International Business Machines Corporation, Armonk, N.Y. (US) | ||
| Filed on Apr. 29, 2008, as Appl. No. 12/111,196. | ||
| Int. Cl. H01L 21/66 (2006.01) | ||
| U.S. Cl. 438—15 [438/125; 257/E21.525] | 1 Claim |

| 1. A method to analyze the warpage of organic laminates used in flip-chip packaging, the method comprising:
providing a plurality of organic laminates, each laminate comprising a plurality of layers;
collecting warpage data by measuring the warpage of each laminate;
gathering thickness data by measuring layer thicknesses of each laminate at several different points of each laminate;
performing a principal components analysis on the thickness data to calculate orthogonal basis vectors to re-express the thickness
data in a different basis;
projecting the thickness data for each laminate onto the orthogonal basis vectors;
forming a linear model expressing the warpage data for each laminate in terms of the projection of corresponding thickness
data onto the orthogonal basis vectors, each projection multiplied by a weight;
analyzing the weights to determine the contribution of each orthogonal basis vector to the variance of the warpage data; and
interpreting the contribution and structure of each orthogonal basis vector to estimate the importance of each layer or combination
of layers in contributing to the warpage of the laminates.
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