Multiline Newsline

Volume 1 Number 1 / Editor: Steve Scheinpflug / January/February 1997

Advantages of Plastic Riveting

Rivets for laminating six layer and above offer certain advantages to a multiplayer manufacture. Lower lamination plate costs, more flexible panel size options and now excellent registration is available using the new plastic riveting system by Multiline Technology. This new plastic riveting system has been developed in a joint effort with Cedal “Adara Presses” of Italy and Multiline Technology. Thes new plastic rivets, which

hold the multiplayer package in registration during lamination, allow for better accuracy than old conventional shoe machine brass

eyelets. Inner layers can be processed through a post etch punch that will punch four centerline slots and four round holes (other tooling patterns are also possible with the system). The inner layers are held in registration on a template via four centerline slotted tooling pins.

Plastic rivets are then placed in the four round holes. Upon completion of each board lay up, the operator places the template in the ultrasonic rivet machine. The machine is activated and the plastic rivets are ultrasonically formed. Registration is held by the four slots during the lay up and the rivet forming process during which ther is no side loading. Side loading of expanding eyelets is one of the major drawbacks of conventional brass eyeleting.

The plastic rivets are made of a thermoplastic and have a higher melt point than the prepreg being used. This insures that the registration is held while they are at the gel stage of the repreg during the lamination process.

Plastic rivets are sized to different lengths, this is dependent on the riveted package thicknesses. Sizing the rivet insures that there will be enough rivet material to hold the package together but not so much to cause damage to separator plates. This key step enables the production of thin boards, thus making it possible to easily perform sequential lamination processes such as buried and blind vias of PCMCIA cards.

To size the rivets this new tooling system utilizes a rivet trimmer which allows the customer to purchase only one length rivet. Plastic rivets are hopper fed to a trimming station which trims the rivets to the correct size required for the board being processed. This automated process results in the exact sizing of rivets for any thickness package and permits rivets to be used on thin multiplayer packages. Current brass eyelets cause problems in the manufacturing of eyeleted boards less than .040” thick.