In volume production each layer is processed in parallel up to this step. After via filling and conductor printing all layers will be collated with a special tool and will be fixed together to avoid misalignment. Collating and stacking can either be carried with a hand operated tool for standard precision or with an automatic stacking machine for high alignment accuracy. IMST's prototyping process allows three different LTCC coupon sizes (unfired): 3.5" x 3.5", 3" x 3" and 2" x 2". The following table gives an overview of the available coupons and its dimensions after firing for DuPont 951. Other X/Y-shrinkage factors are: DuPont 943 = 9.5%, Ferro A6S = 14.9%. The figures below give an impression of IMST's manual and automatic stacking process step.
| |
Coupon Size
(unfired) |
Usable Area
(unfired) |
Usable Area
(fired*) |
| |
| inch2 |
3.5 x 3.5 |
3 x 3 |
2.6 x 2.6 |
| mm2 |
88.9 x 88.9 |
76.1 x 76.1 |
66 x 66 |
| |
| inch2 |
3 x 3 |
2.5 x 2.5 |
2.2 x 2.2 |
| mm2 |
76.2 x 76.2 |
63.4 x 63.4 |
55 x 55 |
| |
| inch2 |
2 x 2 |
1.5 x 1.5 |
1.3 x 1.3 |
| mm2 |
50.8 x 50.8 |
38 x 38 |
33 x 33 |
Available coupon sizes for IMST's LTCC prototyping process
(* Shrinkage for DuPont 951 in unconstrained sintering: 13.1%)
Stacking tool: IS1-M from KEKO-Equipment
Unfired LTCC coupon on manual stacking tool (here: 3.5" x 3.5").
Geometric dimensions for unfired ceramic coupon with registration holes
(here: 3.5" x 3.5").
print view