April 2014 Archives

With some electronic component examples such as capacitors and LSI lead frames, the vital points of multiple pin simultaneous automated insertion will be explained.

(1) Examples of multiple pin simultaneous automated insertion

・For automated insertion of electronic components such as capacitors and LSIs, the components are fed from dedicated sticks (part holding carrier case with the parts inserted and aligned) or alignment trays.

・The pins of inserted components (LSI leads, etc.) are formed in dimensions within the specified tolerances for the holes where the pins are to be inserted. In case of LSI lead frames, the pins are formed to have 0°~10° angle spread in relation to the insertion holes.

・Before the insertion step, the pins are to be formed to match the hole locations in order not to cause deformations or vibrations to the PC boards.

・[Fig.1] is an example of forming multiple pins in specified dimensions for proper insertions with the automated insertion device gripper.

・After the insertion, some post insertion processes such as trimming and swaging (clinch processing) of the LSI leads may follow.

When designing the automation for insertion assembly schemes, the shapes of inserted components and insertion forces (part deformations due to insertion reaction forces) must be taken into consideration on the part holding mechanisms.

(1) Example of automated insertion of long shaft-like objects

・When inserting locating shafts and rotary shafts into circuit boards and plastic boards ([Fig.1]), adhesives are not used on the shafts, and elastic deformations of inserted holes are used to fix the shafts.

・In these cases, troublesome operation errors may be caused by difficult to repair PC board damages if the automated insertion errors occur.

・Elastic deformations of the PC boards at the time of insertion may cause unexpected complex reaction forces. Reaction forces and rotational twists. Part holding mechanisms ([Fig.3]) that reduce the effects of these variations are important.

Application examples regarding the vital points of automation designs for insertion assembly are explained.

(1) Vital points of automation designs for insertion assembly

1. Relationship between part chamfering dimensions and required positioning accuracy

Required positioning accuracy of the automation device in relation to the chamfers of the two parts to be insertion assembled can be derived from [Fig.1]. The relational equation shown is required for the low cost automation designs.

2. Overall positioning accuracy

・Please refer to the basics of positioning techniques explained over several volumes starting from the Technical tutorial Vol. 325.
・Overall accuracy of the positioning will be the accuracy of the total sum of various positioning accuracies.

・The overall accuracy of the multiple accuracies can be calculated as the square root of the sum of squares of each accuracy.